IB Biology SL Flashcards: Complete Course Review
Review the current IB Biology Standard Level course with 960 independently written active-recall cards covering all 34 SL topics across molecules, cells, organisms, genetics, evolution, and ecology.
Apie šį rinkinį
Study the current IB Biology SL course with 960 independently written English flashcards. The deck covers all 34 Standard Level topics through four broad groups: molecules and cells; metabolism and genetics; organisms and systems; and evolution and ecology.
Cards move from essential terms and structures to functions, mechanisms, comparisons, predictions, and compact interpretation prompts. Useful two-way term cards are separated by at least three unrelated cards, while explanatory answers are kept in the direction that supports meaningful recall. Every card carries the root tag ib-bio-sl and exactly one broad group tag.
The order introduces prerequisite ideas before dependent ones and progresses from simpler recall to more demanding reasoning within each topic. The deck is designed for ongoing spaced review. It does not replace data-heavy practice papers, extended-response practice, laboratory work, or the scientific investigation.
Reviewed in 2026 against the current Biology Standard Level course, first assessed in 2025.
Independent, unofficial study aid based on common biological knowledge. Not affiliated with or endorsed by the International Baccalaureate Organization. No copied IB examination questions, mark schemes, or curriculum text are included.
Check the official IB Biology course page for authoritative requirements.
Šio rinkinio kortelės
1 kortelė
Klausimas
What is water polarity?
Atsakymas
The unequal sharing of electrons in a water molecule, giving oxygen a partial negative charge and the hydrogens partial positive charges.
2 kortelė
Klausimas
What is a hydrogen bond?
Atsakymas
A weak attraction between a partially positive hydrogen atom and a partially negative atom in another molecule.
3 kortelė
Klausimas
What is cohesion?
Atsakymas
Attraction between molecules of the same substance.
4 kortelė
Klausimas
What is adhesion?
Atsakymas
Attraction between molecules of different substances.
5 kortelė
Klausimas
Which term describes unequal charge distribution within a water molecule?
Atsakymas
water polarity
6 kortelė
Klausimas
Which term describes the intermolecular attraction that links neighboring water molecules?
Atsakymas
a hydrogen bond
7 kortelė
Klausimas
Which term describes attraction between molecules of the same substance?
Atsakymas
cohesion
8 kortelė
Klausimas
Which term describes attraction between water and a different material?
Atsakymas
adhesion
9 kortelė
Klausimas
What is a solvent?
Atsakymas
A liquid that dissolves solutes to form a solution.
10 kortelė
Klausimas
What is specific heat capacity?
Atsakymas
The energy required to raise the temperature of a unit mass of a substance by one degree.
11 kortelė
Klausimas
What is latent heat of vaporization?
Atsakymas
The energy required to vaporize a specified amount of liquid without changing its temperature.
12 kortelė
Klausimas
Why does ice float on liquid water?
Atsakymas
Hydrogen bonds hold water molecules in an open lattice in ice, making ice less dense than liquid water.
13 kortelė
Klausimas
Which term describes a liquid that dissolves solutes?
Atsakymas
a solvent
14 kortelė
Klausimas
Which term describes the energy needed to raise a unit mass by one degree?
Atsakymas
specific heat capacity
15 kortelė
Klausimas
Which term describes the energy needed to vaporize a liquid without a temperature change?
Atsakymas
latent heat of vaporization
16 kortelė
Klausimas
Which property of water makes sweating an effective cooling mechanism?
Atsakymas
Water absorbs substantial energy as it evaporates; the highest-energy molecules leave, carrying heat away from the skin.
17 kortelė
Klausimas
Why does water resist rapid temperature change?
Atsakymas
Many hydrogen bonds must absorb energy before molecular motion increases substantially, giving water a high specific heat capacity.
18 kortelė
Klausimas
How do cohesion and adhesion support water transport in narrow tubes?
Atsakymas
Cohesion keeps water molecules connected, while adhesion helps the water column cling to the tube wall.
19 kortelė
Klausimas
How does water participate differently in hydrolysis and condensation?
Atsakymas
Hydrolysis consumes water to split a bond; condensation forms a bond and releases water.
20 kortelė
Klausimas
How does floating ice protect aquatic life in winter?
Atsakymas
Surface ice insulates the liquid water below, slowing further heat loss and preventing the whole body of water from freezing rapidly.
21 kortelė
Klausimas
Why is water effective for transporting many biological solutes?
Atsakymas
Its polarity allows ions and other polar molecules to become surrounded and dispersed in solution.
22 kortelė
Klausimas
Why do nonpolar substances tend to cluster in water?
Atsakymas
Clustering reduces the nonpolar surface exposed to water, allowing more water molecules to maintain hydrogen-bond interactions.
23 kortelė
Klausimas
What is a nucleotide?
Atsakymas
A nucleic-acid monomer made of a pentose sugar, a phosphate group, and a nitrogenous base.
24 kortelė
Klausimas
What is a nucleoside?
Atsakymas
A nitrogenous base joined to a pentose sugar, without a phosphate group.
25 kortelė
Klausimas
What is a phosphodiester bond?
Atsakymas
A covalent bond linking the phosphate of one nucleotide to the sugar of the next nucleotide.
26 kortelė
Klausimas
What is DNA?
Atsakymas
A usually double-stranded nucleic acid that stores hereditary information in its base sequence.
27 kortelė
Klausimas
Which term describes a sugar-phosphate-base monomer?
Atsakymas
a nucleotide
28 kortelė
Klausimas
Which term describes a base joined to a sugar but no phosphate?
Atsakymas
a nucleoside
29 kortelė
Klausimas
Which term describes the covalent linkage in a nucleic-acid sugar-phosphate backbone?
Atsakymas
a phosphodiester bond
30 kortelė
Klausimas
Which term describes the nucleic acid that usually stores hereditary information?
Atsakymas
DNA
31 kortelė
Klausimas
What is RNA?
Atsakymas
A usually single-stranded nucleic acid involved in expressing and regulating genetic information.
32 kortelė
Klausimas
What are antiparallel DNA strands?
Atsakymas
Two DNA strands that run in opposite 5′ to 3′ directions.
33 kortelė
Klausimas
What is complementary base pairing?
Atsakymas
Specific pairing in which adenine pairs with thymine in DNA, or uracil in RNA, and cytosine pairs with guanine.
34 kortelė
Klausimas
What is a purine?
Atsakymas
A nitrogenous base with two fused rings; adenine and guanine are purines.
35 kortelė
Klausimas
Which term describes the usually single-stranded nucleic acid used in gene expression?
Atsakymas
RNA
36 kortelė
Klausimas
Which term describes DNA strands running in opposite directions?
Atsakymas
antiparallel DNA strands
37 kortelė
Klausimas
Which term describes specific A–T or A–U and C–G pairing?
Atsakymas
complementary base pairing
38 kortelė
Klausimas
Which term describes a two-ring nitrogenous base?
Atsakymas
a purine
39 kortelė
Klausimas
What is a pyrimidine?
Atsakymas
A nitrogenous base with one ring; cytosine, thymine, and uracil are pyrimidines.
40 kortelė
Klausimas
What is a genome?
Atsakymas
The complete genetic material of an organism or cell.
41 kortelė
Klausimas
What three structural features commonly distinguish RNA from DNA?
Atsakymas
RNA usually contains ribose, uses uracil instead of thymine, and is single-stranded rather than double-stranded.
42 kortelė
Klausimas
What determines the base sequence of the second DNA strand?
Atsakymas
Complementary base-pairing rules determine it: A pairs with T, and C pairs with G.
43 kortelė
Klausimas
Which term describes a one-ring nitrogenous base?
Atsakymas
a pyrimidine
44 kortelė
Klausimas
Which term describes the complete genetic material of an organism?
Atsakymas
a genome
45 kortelė
Klausimas
What do the 5′ and 3′ labels of a nucleic-acid strand refer to?
Atsakymas
They refer to numbered carbon atoms in the pentose sugar and define the strand's chemical direction.
46 kortelė
Klausimas
Where is genetic information encoded in DNA?
Atsakymas
In the order of nitrogenous bases along the DNA strand.
47 kortelė
Klausimas
Why is ATP classified as a nucleotide?
Atsakymas
It contains adenine, ribose, and phosphate groups, the three component types of a nucleotide.
48 kortelė
Klausimas
How do mRNA, tRNA, and rRNA contribute to protein synthesis?
Atsakymas
mRNA carries the coding sequence, tRNA delivers amino acids, and rRNA forms the catalytic and structural core of ribosomes.
49 kortelė
Klausimas
How are a gene and a chromosome related?
Atsakymas
A gene is a DNA sequence with a biological function; a chromosome is one long DNA molecule containing many genes and other sequences.
50 kortelė
Klausimas
What happens to double-stranded DNA when it is denatured by heat?
Atsakymas
Hydrogen bonds between complementary bases break and the two strands separate; the covalent backbones usually remain intact.
51 kortelė
Klausimas
Why can each DNA strand serve as a template during replication?
Atsakymas
Its base sequence determines a complementary sequence through specific base pairing.
52 kortelė
Klausimas
In which direction are new nucleic-acid strands synthesized?
Atsakymas
Nucleotides are added to the 3′ end, so synthesis proceeds 5′ to 3′.
53 kortelė
Klausimas
What is a monosaccharide?
Atsakymas
A single sugar unit that can serve as a carbohydrate monomer.
54 kortelė
Klausimas
What is a disaccharide?
Atsakymas
A carbohydrate formed from two monosaccharides joined by a glycosidic bond.
55 kortelė
Klausimas
What is a polysaccharide?
Atsakymas
A polymer made from many monosaccharide units.
56 kortelė
Klausimas
What is a glycosidic bond?
Atsakymas
A covalent bond joining monosaccharides in a carbohydrate.
57 kortelė
Klausimas
Which term describes a single sugar unit?
Atsakymas
a monosaccharide
58 kortelė
Klausimas
Which term describes two monosaccharides joined together?
Atsakymas
a disaccharide
59 kortelė
Klausimas
Which term describes a polymer of many sugar units?
Atsakymas
a polysaccharide
60 kortelė
Klausimas
Which term describes the covalent linkage between monosaccharides?
Atsakymas
a glycosidic bond
61 kortelė
Klausimas
What is a triglyceride?
Atsakymas
A lipid formed from glycerol joined to three fatty acids.
62 kortelė
Klausimas
What is a fatty acid?
Atsakymas
A hydrocarbon chain with a carboxyl group that can form part of many lipids.
63 kortelė
Klausimas
What is a saturated fatty acid?
Atsakymas
A fatty acid with no carbon-carbon double bonds in its hydrocarbon chain.
64 kortelė
Klausimas
What is a phospholipid?
Atsakymas
An amphipathic lipid with a phosphate-containing hydrophilic head and hydrophobic fatty-acid tails.
65 kortelė
Klausimas
Which term describes glycerol joined to three fatty acids?
Atsakymas
a triglyceride
66 kortelė
Klausimas
Which term describes a hydrocarbon chain ending in a carboxyl group?
Atsakymas
a fatty acid
67 kortelė
Klausimas
Which term describes a fatty acid without carbon-carbon double bonds?
Atsakymas
a saturated fatty acid
68 kortelė
Klausimas
Which term describes a lipid with a polar head and nonpolar tails?
Atsakymas
a phospholipid
69 kortelė
Klausimas
How is a glycosidic bond formed between two monosaccharides?
Atsakymas
A condensation reaction joins them and releases a molecule of water.
70 kortelė
Klausimas
How is a polysaccharide broken into smaller sugars?
Atsakymas
Hydrolysis adds water across glycosidic bonds, splitting the polymer.
71 kortelė
Klausimas
Which polysaccharides store glucose in plants and animals?
Atsakymas
Starch stores glucose in plants; glycogen stores glucose in animals and fungi.
72 kortelė
Klausimas
Why is cellulose suitable for plant cell walls?
Atsakymas
Its straight β-glucose chains hydrogen-bond into strong microfibrils that resist stretching.
73 kortelė
Klausimas
Why do lipids store more energy per gram than carbohydrates?
Atsakymas
Lipids contain more energy-rich carbon-hydrogen bonds and are more reduced.
74 kortelė
Klausimas
Why do phospholipids form bilayers in water?
Atsakymas
Hydrophilic heads interact with water while hydrophobic tails cluster away from water.
75 kortelė
Klausimas
Besides energy storage, what are three biological roles of lipids?
Atsakymas
They form membranes, provide thermal insulation and cushioning, and can act as signaling molecules.
76 kortelė
Klausimas
How do cis double bonds affect fatty-acid packing and melting point?
Atsakymas
They introduce bends that reduce close packing, usually lowering the melting point.
77 kortelė
Klausimas
What is an amino acid?
Atsakymas
A protein monomer with an amino group, a carboxyl group, a hydrogen, and a variable R group attached to a central carbon.
78 kortelė
Klausimas
What is a peptide bond?
Atsakymas
The covalent bond formed between the amino group of one amino acid and the carboxyl group of another.
79 kortelė
Klausimas
What is a polypeptide?
Atsakymas
A chain of amino acids joined by peptide bonds.
80 kortelė
Klausimas
What is protein primary structure?
Atsakymas
The amino-acid sequence of a polypeptide.
81 kortelė
Klausimas
Which term describes a protein monomer with amino, carboxyl, and variable R groups?
Atsakymas
an amino acid
82 kortelė
Klausimas
Which term describes the covalent linkage between amino acids?
Atsakymas
a peptide bond
83 kortelė
Klausimas
Which term describes a chain of peptide-linked amino acids?
Atsakymas
a polypeptide
84 kortelė
Klausimas
Which term describes a protein's amino-acid sequence?
Atsakymas
protein primary structure
85 kortelė
Klausimas
What is protein secondary structure?
Atsakymas
Local folding such as α-helices and β-sheets stabilized mainly by backbone hydrogen bonds.
86 kortelė
Klausimas
What is protein tertiary structure?
Atsakymas
The overall three-dimensional shape of one polypeptide produced by interactions among R groups and the backbone.
87 kortelė
Klausimas
What is protein quaternary structure?
Atsakymas
The arrangement of multiple polypeptide subunits in one functional protein.
88 kortelė
Klausimas
What is protein denaturation?
Atsakymas
Loss of a protein's normal three-dimensional shape and therefore usually its function.
89 kortelė
Klausimas
Which term describes local α-helix and β-sheet folding?
Atsakymas
protein secondary structure
90 kortelė
Klausimas
Which term describes the overall three-dimensional shape of one polypeptide?
Atsakymas
protein tertiary structure
91 kortelė
Klausimas
Which term describes the association of multiple polypeptide subunits?
Atsakymas
protein quaternary structure
92 kortelė
Klausimas
Which term describes loss of a protein's native shape?
Atsakymas
protein denaturation
93 kortelė
Klausimas
What mainly gives different amino acids their different chemical properties?
Atsakymas
Their variable R groups.
94 kortelė
Klausimas
What reaction forms a peptide bond?
Atsakymas
A condensation reaction releases water as the amino and carboxyl groups join.
95 kortelė
Klausimas
Why can high temperature denature a protein?
Atsakymas
Increased molecular motion disrupts weak interactions that maintain the protein's shape.
96 kortelė
Klausimas
Why can extreme pH denature a protein?
Atsakymas
It changes the charges of R groups and disrupts ionic and hydrogen-bond interactions.
97 kortelė
Klausimas
How do fibrous and globular proteins generally differ?
Atsakymas
Fibrous proteins are elongated and mainly structural; globular proteins are compact and often perform dynamic functions.
98 kortelė
Klausimas
Why is three-dimensional shape crucial to protein function?
Atsakymas
It creates specific binding, catalytic, structural, or interaction surfaces.
99 kortelė
Klausimas
Name four broad biological roles of proteins.
Atsakymas
Catalysis, transport, signaling, defense, movement, and structural support are major roles; any four are sufficient.
100 kortelė
Klausimas
How can changing one amino acid alter protein function?
Atsakymas
The substitution can change R-group interactions, folding, stability, or an active or binding site.
101 kortelė
Klausimas
What is cell theory?
Atsakymas
The principles that living organisms are made of cells, cells are the basic units of life, and cells arise from pre-existing cells.
102 kortelė
Klausimas
What is a prokaryotic cell?
Atsakymas
A cell without a nucleus or other membrane-bound organelles.
103 kortelė
Klausimas
What is a eukaryotic cell?
Atsakymas
A cell with DNA enclosed in a nucleus and with membrane-bound organelles.
104 kortelė
Klausimas
What is the nucleus?
Atsakymas
The double-membrane organelle that contains most of a eukaryotic cell's DNA.
105 kortelė
Klausimas
Which term describes the principles describing cells as life's basic units?
Atsakymas
cell theory
106 kortelė
Klausimas
Which term describes a cell lacking a nucleus and membrane-bound organelles?
Atsakymas
a prokaryotic cell
107 kortelė
Klausimas
Which term describes a cell with a nucleus and membrane-bound organelles?
Atsakymas
a eukaryotic cell
108 kortelė
Klausimas
Which term describes the organelle containing most eukaryotic DNA?
Atsakymas
the nucleus
109 kortelė
Klausimas
What is a ribosome?
Atsakymas
A molecular complex of rRNA and proteins that synthesizes polypeptides.
110 kortelė
Klausimas
What is the cytoplasm?
Atsakymas
The material inside the plasma membrane but outside the nucleus, including cytosol and organelles.
111 kortelė
Klausimas
What is the plasma membrane?
Atsakymas
The selectively permeable boundary separating a cell from its environment.
112 kortelė
Klausimas
What is a cell wall?
Atsakymas
A rigid extracellular layer that supports and protects cells in plants, fungi, and most prokaryotes.
113 kortelė
Klausimas
Which term describes the complex that synthesizes polypeptides?
Atsakymas
a ribosome
114 kortelė
Klausimas
Which term describes cell contents inside the plasma membrane but outside the nucleus?
Atsakymas
the cytoplasm
115 kortelė
Klausimas
Which term describes the selectively permeable cell boundary?
Atsakymas
the plasma membrane
116 kortelė
Klausimas
Which term describes a rigid extracellular support layer?
Atsakymas
a cell wall
117 kortelė
Klausimas
What is the nucleoid?
Atsakymas
The non-membrane-bound region containing the main chromosome of a prokaryotic cell.
118 kortelė
Klausimas
What is the cytoskeleton?
Atsakymas
A dynamic network of protein filaments involved in cell shape, transport, division, and movement.
119 kortelė
Klausimas
What structures are shared by all cells?
Atsakymas
A plasma membrane, cytoplasm, genetic material, and ribosomes.
120 kortelė
Klausimas
Which structures distinguish a typical plant cell from a typical animal cell?
Atsakymas
A plant cell has a cellulose wall, chloroplasts in photosynthetic tissues, and a large central vacuole; an animal cell lacks these.
121 kortelė
Klausimas
Which term describes the prokaryotic chromosome-containing region?
Atsakymas
the nucleoid
122 kortelė
Klausimas
Which term describes the internal network of protein filaments?
Atsakymas
the cytoskeleton
123 kortelė
Klausimas
How is genetic material commonly organized in a prokaryotic cell?
Atsakymas
The main DNA is usually one circular chromosome in the nucleoid, often accompanied by smaller plasmids.
124 kortelė
Klausimas
How is microscope magnification calculated?
Atsakymas
Magnification = image size ÷ actual size, using the same units.
125 kortelė
Klausimas
What does microscope resolution describe?
Atsakymas
The ability to distinguish two close points as separate.
126 kortelė
Klausimas
Arrange these from smallest to largest: ribosome, bacterium, animal cell.
Atsakymas
Ribosome, bacterium, animal cell.
127 kortelė
Klausimas
How does the cytoskeleton support intracellular transport?
Atsakymas
Motor proteins move vesicles and other cargo along cytoskeletal filaments.
128 kortelė
Klausimas
Why does a small cell usually exchange materials more efficiently than a geometrically similar large cell?
Atsakymas
It has a larger surface-area-to-volume ratio, providing more exchange surface per unit of cell contents.
129 kortelė
Klausimas
Why is a cell more than a collection of isolated molecules?
Atsakymas
Organized interactions among components produce emergent functions such as metabolism, regulation, and reproduction.
130 kortelė
Klausimas
What major advantage do membrane-bound organelles give eukaryotic cells?
Atsakymas
They separate incompatible reactions and create specialized local conditions.
131 kortelė
Klausimas
What is a phospholipid bilayer?
Atsakymas
A double layer of phospholipids with hydrophilic heads facing water and hydrophobic tails facing inward.
132 kortelė
Klausimas
What is the fluid mosaic model?
Atsakymas
A model describing membranes as mobile phospholipids containing a changing mosaic of proteins and other components.
133 kortelė
Klausimas
What is an integral membrane protein?
Atsakymas
A protein embedded in the bilayer, often spanning it.
134 kortelė
Klausimas
What is a peripheral membrane protein?
Atsakymas
A protein attached to a membrane surface rather than embedded in the bilayer.
135 kortelė
Klausimas
Which term describes a double phospholipid layer with inward-facing tails?
Atsakymas
a phospholipid bilayer
136 kortelė
Klausimas
Which term describes the model of a mobile lipid layer containing varied proteins?
Atsakymas
the fluid mosaic model
137 kortelė
Klausimas
Which term describes a protein embedded within the lipid bilayer?
Atsakymas
an integral membrane protein
138 kortelė
Klausimas
Which term describes a protein attached to a membrane surface?
Atsakymas
a peripheral membrane protein
139 kortelė
Klausimas
What is membrane cholesterol?
Atsakymas
An amphipathic lipid that buffers membrane fluidity and reduces permeability in animal cells.
140 kortelė
Klausimas
What is a glycoprotein?
Atsakymas
A protein with an attached carbohydrate chain, often used in recognition, adhesion, or signaling.
141 kortelė
Klausimas
What is diffusion?
Atsakymas
Net movement of particles from a region of higher concentration to lower concentration due to random motion.
142 kortelė
Klausimas
What is osmosis?
Atsakymas
Net movement of water across a selectively permeable membrane from higher water potential to lower water potential.
143 kortelė
Klausimas
Which term describes the animal-membrane lipid that buffers fluidity?
Atsakymas
membrane cholesterol
144 kortelė
Klausimas
Which term describes a carbohydrate-bearing protein?
Atsakymas
a glycoprotein
145 kortelė
Klausimas
Which term describes net movement down a concentration gradient?
Atsakymas
diffusion
146 kortelė
Klausimas
Which term describes net water movement across a selectively permeable membrane?
Atsakymas
osmosis
147 kortelė
Klausimas
What is facilitated diffusion?
Atsakymas
Passive movement down a gradient through a membrane channel or carrier protein.
148 kortelė
Klausimas
What is active transport?
Atsakymas
Energy-requiring movement of a substance against its concentration or electrochemical gradient.
149 kortelė
Klausimas
Why is the phospholipid bilayer selectively permeable?
Atsakymas
Its hydrophobic interior allows small nonpolar molecules through more readily than ions and most large or polar molecules.
150 kortelė
Klausimas
How do simple diffusion and facilitated diffusion differ?
Atsakymas
Both are passive, but facilitated diffusion uses specific membrane proteins while simple diffusion passes through the bilayer.
151 kortelė
Klausimas
Which term describes passive transport through a channel or carrier?
Atsakymas
facilitated diffusion
152 kortelė
Klausimas
Which term describes energy-dependent transport against a gradient?
Atsakymas
active transport
153 kortelė
Klausimas
How do channel and carrier proteins differ?
Atsakymas
Channels provide hydrophilic pores; carriers bind solutes and change shape to move them.
154 kortelė
Klausimas
How can an ATP-driven pump maintain an ion gradient?
Atsakymas
It couples ATP hydrolysis to a conformational change that moves ions against their electrochemical gradient.
155 kortelė
Klausimas
How does endocytosis move material into a cell?
Atsakymas
The plasma membrane folds inward and pinches off a vesicle containing the material.
156 kortelė
Klausimas
How does exocytosis move material out of a cell?
Atsakymas
An intracellular vesicle fuses with the plasma membrane and releases its contents outside.
157 kortelė
Klausimas
What happens to an animal cell in a strongly hypotonic solution?
Atsakymas
Water enters by osmosis; without a cell wall, the cell may swell and lyse.
158 kortelė
Klausimas
Does molecular movement stop when diffusion reaches equilibrium?
Atsakymas
No. Molecules continue moving randomly, but there is no net movement between regions.
159 kortelė
Klausimas
How does decreasing temperature generally affect membrane fluidity?
Atsakymas
It reduces phospholipid movement and makes the membrane less fluid.
160 kortelė
Klausimas
Why do unsaturated fatty-acid tails increase membrane fluidity?
Atsakymas
Their cis double-bond bends prevent phospholipids from packing tightly.
161 kortelė
Klausimas
What changes increase the rate of simple diffusion across a membrane?
Atsakymas
A steeper gradient, larger surface area, higher temperature, shorter distance, and greater membrane permeability increase the rate.
162 kortelė
Klausimas
What is a mitochondrion?
Atsakymas
A double-membrane organelle where most aerobic ATP production occurs.
163 kortelė
Klausimas
What is a chloroplast?
Atsakymas
A double-membrane organelle where photosynthesis occurs in plants and algae.
164 kortelė
Klausimas
What is rough endoplasmic reticulum?
Atsakymas
A membrane network bearing ribosomes that synthesizes and begins processing many secreted and membrane proteins.
165 kortelė
Klausimas
What is smooth endoplasmic reticulum?
Atsakymas
A membrane network involved in lipid synthesis, detoxification, and calcium storage.
166 kortelė
Klausimas
Which term describes the main organelle of aerobic ATP production?
Atsakymas
a mitochondrion
167 kortelė
Klausimas
Which term describes the photosynthetic organelle of plants and algae?
Atsakymas
a chloroplast
168 kortelė
Klausimas
Which term describes the ribosome-studded membrane network?
Atsakymas
rough endoplasmic reticulum
169 kortelė
Klausimas
Which term describes the membrane network that lacks ribosomes and synthesizes lipids?
Atsakymas
smooth endoplasmic reticulum
170 kortelė
Klausimas
What is the Golgi apparatus?
Atsakymas
Stacked membranes that modify, sort, and package proteins and lipids into vesicles.
171 kortelė
Klausimas
What is a lysosome?
Atsakymas
An acidic enzyme-containing organelle that digests macromolecules and worn cellular components.
172 kortelė
Klausimas
What is a vesicle?
Atsakymas
A small membrane-bound compartment used for transport, storage, or chemical reactions.
173 kortelė
Klausimas
What is the central vacuole?
Atsakymas
A large plant-cell compartment that stores solutes and helps maintain turgor pressure.
174 kortelė
Klausimas
Which term describes the organelle that modifies and sorts cellular cargo?
Atsakymas
the Golgi apparatus
175 kortelė
Klausimas
Which term describes the acidic digestive organelle?
Atsakymas
a lysosome
176 kortelė
Klausimas
Which term describes a small membrane-bound transport compartment?
Atsakymas
a vesicle
177 kortelė
Klausimas
Which term describes the large plant compartment that supports turgor?
Atsakymas
the central vacuole
178 kortelė
Klausimas
Why can compartmentalization increase metabolic efficiency?
Atsakymas
It concentrates enzymes and substrates, maintains suitable local conditions, and separates incompatible reactions.
179 kortelė
Klausimas
How do mitochondrial cristae support ATP production?
Atsakymas
They increase inner-membrane area for electron transport chains and ATP synthase.
180 kortelė
Klausimas
Why are chloroplast thylakoids arranged as extensive membranes?
Atsakymas
They provide a large surface for light-absorbing complexes, electron transport chains, and ATP synthase.
181 kortelė
Klausimas
What is the main function of the nucleolus?
Atsakymas
It produces rRNA and assembles ribosomal subunits.
182 kortelė
Klausimas
Trace a secreted protein from synthesis to release.
Atsakymas
Ribosome on rough ER → ER lumen → transport vesicle → Golgi apparatus → secretory vesicle → plasma membrane → exocytosis.
183 kortelė
Klausimas
Why does a lysosome maintain an acidic interior?
Atsakymas
Its hydrolytic enzymes work best at low pH, and acidity helps confine their activity from the cytosol.
184 kortelė
Klausimas
How do the nucleus, ribosomes, ER, and Golgi cooperate in protein production?
Atsakymas
DNA instructions are transcribed in the nucleus; ribosomes translate them; ER folds or modifies many products; Golgi further modifies and sorts them.
185 kortelė
Klausimas
How are transport vesicles directed to the correct target membrane?
Atsakymas
Specific recognition proteins on vesicles and target membranes interact, allowing selective docking and fusion.
186 kortelė
Klausimas
What is cell differentiation?
Atsakymas
The process by which a cell develops specialized structure and function.
187 kortelė
Klausimas
What is a stem cell?
Atsakymas
An unspecialized cell able to self-renew and produce differentiated cells.
188 kortelė
Klausimas
What is gene expression?
Atsakymas
Use of genetic information to produce a functional RNA or protein product.
189 kortelė
Klausimas
What is a tissue?
Atsakymas
A coordinated group of similar or related cells performing a shared function.
190 kortelė
Klausimas
Which term describes development of specialized cell structure and function?
Atsakymas
cell differentiation
191 kortelė
Klausimas
Which term describes an unspecialized self-renewing cell?
Atsakymas
a stem cell
192 kortelė
Klausimas
Which term describes production of a functional product from genetic information?
Atsakymas
gene expression
193 kortelė
Klausimas
Which term describes a group of coordinated cells with a shared function?
Atsakymas
a tissue
194 kortelė
Klausimas
What is an organ?
Atsakymas
A structure made of multiple tissues working together for particular functions.
195 kortelė
Klausimas
What is the organ-system level of biological organization?
Atsakymas
A group of organs that coordinate to perform major functions for an organism.
196 kortelė
Klausimas
What is surface-area-to-volume ratio?
Atsakymas
The amount of surface area available relative to the volume it must serve.
197 kortelė
Klausimas
How can two specialized cells have the same genome but different structures?
Atsakymas
They express different sets and amounts of genes, producing different proteins and cellular features.
198 kortelė
Klausimas
Which term describes a structure composed of multiple tissue types?
Atsakymas
an organ
199 kortelė
Klausimas
Which term describes the level of biological organization formed by coordinated organs?
Atsakymas
an organ system
200 kortelė
Klausimas
Which term describes surface area available per unit volume?
Atsakymas
surface-area-to-volume ratio
201 kortelė
Klausimas
How is a mammalian red blood cell specialized for oxygen transport?
Atsakymas
Its biconcave shape increases exchange area, it is flexible, and loss of its nucleus leaves more space for hemoglobin.
202 kortelė
Klausimas
How is a sperm cell specialized for fertilization?
Atsakymas
It has a flagellum for movement, many mitochondria for ATP, a haploid nucleus, and an acrosome containing enzymes.
203 kortelė
Klausimas
How is a neuron specialized for rapid communication?
Atsakymas
Long processes carry signals over distance, branching dendrites receive inputs, and synaptic terminals transmit signals to other cells.
204 kortelė
Klausimas
How is a root hair cell specialized for mineral and water uptake?
Atsakymas
Its long projection increases surface area, its thin wall shortens the pathway, and membrane transport proteins take up ions.
205 kortelė
Klausimas
How is a palisade mesophyll cell specialized for photosynthesis?
Atsakymas
It contains many chloroplasts and is positioned near the upper leaf surface where light is strongest.
206 kortelė
Klausimas
How do ciliated epithelial cells help protect airways?
Atsakymas
Their cilia move mucus containing trapped particles and microbes toward the throat.
207 kortelė
Klausimas
Why can extreme specialization reduce a cell's independence?
Atsakymas
Resources and structures are committed to a narrow role, so the cell depends on other cells for functions it no longer performs well.
208 kortelė
Klausimas
What is water potential?
Atsakymas
The potential energy of water per unit volume relative to pure water, used to predict the direction of water movement.
209 kortelė
Klausimas
What is solute potential?
Atsakymas
The negative contribution of dissolved solutes to water potential.
210 kortelė
Klausimas
What is pressure potential?
Atsakymas
The contribution of physical pressure to water potential.
211 kortelė
Klausimas
What is turgor pressure?
Atsakymas
Outward pressure of a plant-cell interior against its cell wall after water uptake.
212 kortelė
Klausimas
Which term describes the tendency of water to move relative to pure water?
Atsakymas
water potential
213 kortelė
Klausimas
Which term describes the water-potential component lowered by dissolved solutes?
Atsakymas
solute potential
214 kortelė
Klausimas
Which term describes the water-potential component caused by physical pressure?
Atsakymas
pressure potential
215 kortelė
Klausimas
Which term describes pressure of plant-cell contents against the wall?
Atsakymas
turgor pressure
216 kortelė
Klausimas
What is plasmolysis?
Atsakymas
Separation of the plasma membrane from the cell wall after a plant cell loses water.
217 kortelė
Klausimas
What is a flaccid plant cell?
Atsakymas
A plant cell with insufficient turgor pressure to be firm.
218 kortelė
Klausimas
What is an isotonic condition?
Atsakymas
A condition in which two solutions have equal effective water potential and no net water movement occurs.
219 kortelė
Klausimas
In which direction does water move across a permeable membrane?
Atsakymas
From higher water potential to lower water potential.
220 kortelė
Klausimas
Which term describes membrane separation from the plant cell wall after water loss?
Atsakymas
plasmolysis
221 kortelė
Klausimas
Which term describes a plant cell lacking firm turgor?
Atsakymas
a flaccid plant cell
222 kortelė
Klausimas
Which term describes equal effective water potential across a membrane?
Atsakymas
an isotonic condition
223 kortelė
Klausimas
What is the water potential of pure water at standard pressure?
Atsakymas
Zero; adding solute makes water potential more negative.
224 kortelė
Klausimas
How are water potential, solute potential, and pressure potential related?
Atsakymas
Water potential equals solute potential plus pressure potential: Ψ = Ψs + Ψp.
225 kortelė
Klausimas
Why does a plant cell usually become turgid rather than burst in a hypotonic solution?
Atsakymas
Water entry raises pressure potential, while the rigid cell wall resists further expansion.
226 kortelė
Klausimas
What happens to a plant cell placed in a solution with much lower water potential?
Atsakymas
Water leaves the cell, turgor falls, and severe loss can cause plasmolysis.
227 kortelė
Klausimas
Can two solutions have different solute concentrations but equal water potential?
Atsakymas
Yes. A difference in pressure potential can offset a difference in solute potential.
228 kortelė
Klausimas
What is an enzyme?
Atsakymas
A biological catalyst that increases reaction rate without being consumed.
229 kortelė
Klausimas
What is an active site?
Atsakymas
The region of an enzyme where substrate binds and catalysis occurs.
230 kortelė
Klausimas
What is a substrate?
Atsakymas
A reactant molecule on which an enzyme acts.
231 kortelė
Klausimas
What is activation energy?
Atsakymas
The minimum energy input needed for a reaction to begin.
232 kortelė
Klausimas
Which term describes a biological catalyst?
Atsakymas
an enzyme
233 kortelė
Klausimas
Which term describes the substrate-binding catalytic region of an enzyme?
Atsakymas
an active site
234 kortelė
Klausimas
Which term describes a reactant bound and changed by an enzyme?
Atsakymas
a substrate
235 kortelė
Klausimas
Which term describes the energy barrier that must be overcome for a reaction?
Atsakymas
activation energy
236 kortelė
Klausimas
What is the induced-fit model?
Atsakymas
The model in which substrate binding changes active-site shape to improve catalytic interactions.
237 kortelė
Klausimas
What is enzyme denaturation?
Atsakymas
Loss of the active three-dimensional shape of an enzyme, usually causing loss of activity.
238 kortelė
Klausimas
What is competitive inhibition?
Atsakymas
Inhibition caused by a molecule competing with substrate for the active site.
239 kortelė
Klausimas
What is noncompetitive inhibition?
Atsakymas
Inhibition caused by binding away from the active site and reducing catalytic function.
240 kortelė
Klausimas
Which term describes the model where substrate binding reshapes the active site?
Atsakymas
the induced-fit model
241 kortelė
Klausimas
Which term describes loss of an enzyme's functional shape?
Atsakymas
enzyme denaturation
242 kortelė
Klausimas
Which term describes inhibition by active-site competition?
Atsakymas
competitive inhibition
243 kortelė
Klausimas
Which term describes inhibition by binding outside the active site?
Atsakymas
noncompetitive inhibition
244 kortelė
Klausimas
What is an enzyme optimum?
Atsakymas
The condition, such as temperature or pH, at which an enzyme's activity is highest.
245 kortelė
Klausimas
What is feedback inhibition?
Atsakymas
Control in which a pathway product inhibits an enzyme acting earlier in the pathway.
246 kortelė
Klausimas
How does an enzyme increase reaction rate?
Atsakymas
It stabilizes the transition state and provides a pathway with lower activation energy.
247 kortelė
Klausimas
Why does enzyme activity often rise and then fall as temperature increases?
Atsakymas
Molecular collisions initially increase, but excessive heat disrupts enzyme shape and denatures the active site.
248 kortelė
Klausimas
Which term describes the condition producing maximum enzyme activity?
Atsakymas
an enzyme optimum
249 kortelė
Klausimas
Which term describes pathway control by inhibition from an end product?
Atsakymas
feedback inhibition
250 kortelė
Klausimas
Why does each enzyme have a characteristic pH range?
Atsakymas
pH changes the ionization of amino-acid side chains, affecting active-site shape and chemical interactions.
251 kortelė
Klausimas
Why does increasing substrate concentration eventually stop increasing enzyme rate?
Atsakymas
At saturation, nearly all active sites are occupied and enzyme concentration limits the maximum rate.
252 kortelė
Klausimas
How does increasing enzyme concentration affect rate when substrate is abundant?
Atsakymas
More active sites are available, so the initial rate increases roughly in proportion to enzyme concentration.
253 kortelė
Klausimas
What gives an enzyme substrate specificity?
Atsakymas
The active site's shape, charge, polarity, and chemical groups complement particular substrates and transition states.
254 kortelė
Klausimas
What is one practical advantage of immobilizing an enzyme?
Atsakymas
The enzyme can be separated from products and reused while conditions around it are controlled.
255 kortelė
Klausimas
Does an enzyme change a reaction's equilibrium position?
Atsakymas
No. It speeds forward and reverse reactions but does not change the equilibrium constant or final equilibrium position.
256 kortelė
Klausimas
How can high substrate concentration reduce competitive inhibition?
Atsakymas
More substrate molecules increase the chance that substrate rather than inhibitor occupies the active site.
257 kortelė
Klausimas
Why are metabolic reactions commonly organized into pathways?
Atsakymas
A sequence of enzyme-controlled steps allows energy changes and intermediates to be controlled and coupled.
258 kortelė
Klausimas
What is ATP?
Atsakymas
A nucleotide that transfers usable energy through coupling of its hydrolysis to cellular processes.
259 kortelė
Klausimas
What is cellular respiration?
Atsakymas
Controlled release of energy from organic molecules to produce ATP.
260 kortelė
Klausimas
What is glycolysis?
Atsakymas
A cytosolic pathway that splits glucose into two pyruvate molecules and yields a small amount of ATP and reduced electron carriers.
261 kortelė
Klausimas
What is pyruvate?
Atsakymas
The three-carbon product of glycolysis that can enter aerobic or anaerobic pathways.
262 kortelė
Klausimas
Which term describes the cell's immediate phosphoryl-group energy carrier?
Atsakymas
ATP
263 kortelė
Klausimas
Which term describes controlled ATP-producing breakdown of organic molecules?
Atsakymas
cellular respiration
264 kortelė
Klausimas
Which term describes the cytosolic splitting of glucose into pyruvate?
Atsakymas
glycolysis
265 kortelė
Klausimas
Which term describes the three-carbon product of glycolysis?
Atsakymas
pyruvate
266 kortelė
Klausimas
What is aerobic respiration?
Atsakymas
Respiration that uses oxygen as the final electron acceptor and produces much more ATP than fermentation.
267 kortelė
Klausimas
What is anaerobic metabolism?
Atsakymas
ATP-producing metabolism that proceeds without oxygen.
268 kortelė
Klausimas
What is fermentation?
Atsakymas
An anaerobic pathway that regenerates oxidized electron carriers so glycolysis can continue.
269 kortelė
Klausimas
What is oxidation?
Atsakymas
Loss of electrons, often accompanied in biology by loss of hydrogen or gain of oxygen.
270 kortelė
Klausimas
Which term describes respiration using oxygen as final electron acceptor?
Atsakymas
aerobic respiration
271 kortelė
Klausimas
Which term describes ATP-producing metabolism without oxygen?
Atsakymas
anaerobic metabolism
272 kortelė
Klausimas
Which term describes anaerobic regeneration of electron carriers after glycolysis?
Atsakymas
fermentation
273 kortelė
Klausimas
Which term describes loss of electrons?
Atsakymas
oxidation
274 kortelė
Klausimas
What is reduction?
Atsakymas
Gain of electrons, often accompanied in biology by gain of hydrogen or loss of oxygen.
275 kortelė
Klausimas
What is a reduced electron carrier?
Atsakymas
A molecule such as NADH that carries high-energy electrons and hydrogen from one reaction to another.
276 kortelė
Klausimas
What is chemiosmosis?
Atsakymas
ATP production driven by ions moving down an electrochemical gradient through ATP synthase.
277 kortelė
Klausimas
What is the overall word equation for aerobic respiration of glucose?
Atsakymas
Glucose + oxygen → carbon dioxide + water + energy transferred to ATP and heat.
278 kortelė
Klausimas
Which term describes gain of electrons?
Atsakymas
reduction
279 kortelė
Klausimas
Which term describes a molecule carrying high-energy electrons between reactions?
Atsakymas
a reduced electron carrier
280 kortelė
Klausimas
Which term describes ATP production powered by an ion gradient?
Atsakymas
chemiosmosis
281 kortelė
Klausimas
Where does glycolysis occur?
Atsakymas
In the cytosol.
282 kortelė
Klausimas
What major stages of aerobic respiration occur in mitochondria?
Atsakymas
Pyruvate oxidation and the citric acid cycle occur in the matrix; electron transport and chemiosmosis occur at the inner membrane.
283 kortelė
Klausimas
What is oxygen's direct role in aerobic respiration?
Atsakymas
It accepts electrons and hydrogen ions at the end of the electron transport chain, forming water.
284 kortelė
Klausimas
Why does aerobic respiration yield much more ATP per glucose than fermentation?
Atsakymas
It transfers electrons through an electron transport chain and uses oxidative phosphorylation, extracting far more of glucose's energy.
285 kortelė
Klausimas
What is the purpose of lactate formation in oxygen-limited animal cells?
Atsakymas
It regenerates NAD⁺ so glycolysis can continue producing a small amount of ATP.
286 kortelė
Klausimas
What products are formed during alcoholic fermentation in yeast?
Atsakymas
Ethanol and carbon dioxide, while NAD⁺ is regenerated.
287 kortelė
Klausimas
Why is some energy released by respiration transferred as heat rather than captured in ATP?
Atsakymas
Energy conversions are not fully efficient, so part of the chemical energy becomes disordered molecular motion.
288 kortelė
Klausimas
What is substrate-level phosphorylation?
Atsakymas
Direct transfer of a phosphate group from a metabolic intermediate to ADP to form ATP.
289 kortelė
Klausimas
How does electron transport lead to ATP synthesis in mitochondria?
Atsakymas
Electron energy pumps protons across the inner membrane; proton flow back through ATP synthase drives ATP formation.
290 kortelė
Klausimas
Why can intense exercise increase lactate production?
Atsakymas
ATP demand can exceed oxygen delivery and aerobic capacity, so cells regenerate NAD⁺ through lactate formation to sustain glycolysis.
291 kortelė
Klausimas
What is photosynthesis?
Atsakymas
Conversion of light energy into chemical energy used to synthesize organic molecules from carbon dioxide.
292 kortelė
Klausimas
What is chlorophyll?
Atsakymas
A green pigment that absorbs light energy for photosynthesis.
293 kortelė
Klausimas
What is an absorption spectrum?
Atsakymas
A graph showing how strongly a pigment absorbs different wavelengths of light.
294 kortelė
Klausimas
What is an action spectrum?
Atsakymas
A graph showing the rate or effectiveness of photosynthesis at different wavelengths.
295 kortelė
Klausimas
Which term describes light-driven synthesis of organic molecules from carbon dioxide?
Atsakymas
photosynthesis
296 kortelė
Klausimas
Which term describes the principal green photosynthetic pigment?
Atsakymas
chlorophyll
297 kortelė
Klausimas
Which term describes a graph of pigment absorption versus wavelength?
Atsakymas
an absorption spectrum
298 kortelė
Klausimas
Which term describes a graph of photosynthetic effectiveness versus wavelength?
Atsakymas
an action spectrum
299 kortelė
Klausimas
What is photolysis of water?
Atsakymas
Light-driven splitting of water that supplies electrons and hydrogen ions and releases oxygen.
300 kortelė
Klausimas
What are light-dependent reactions?
Atsakymas
Photosynthetic reactions that use light to generate ATP and reduced electron carriers while releasing oxygen.
301 kortelė
Klausimas
What is the Calvin cycle?
Atsakymas
A set of chloroplast reactions that uses ATP and reduced electron carriers to convert carbon dioxide into carbohydrate precursors.
302 kortelė
Klausimas
What is carbon fixation?
Atsakymas
Incorporation of inorganic carbon dioxide into an organic molecule.
303 kortelė
Klausimas
Which term describes light-driven splitting of water?
Atsakymas
photolysis of water
304 kortelė
Klausimas
Which term describes photosynthetic reactions that directly capture light energy?
Atsakymas
light-dependent reactions
305 kortelė
Klausimas
Which term describes the carbon-reduction cycle of photosynthesis?
Atsakymas
the Calvin cycle
306 kortelė
Klausimas
Which term describes incorporation of carbon dioxide into organic matter?
Atsakymas
carbon fixation
307 kortelė
Klausimas
What is the role of a stoma in photosynthesis?
Atsakymas
A pore in the leaf epidermis that regulates carbon-dioxide entry as well as water loss.
308 kortelė
Klausimas
What is a limiting factor of photosynthesis?
Atsakymas
The environmental factor whose availability currently restricts the photosynthetic rate.
309 kortelė
Klausimas
What is the light compensation point?
Atsakymas
The light intensity at which photosynthetic carbon uptake equals respiratory carbon release.
310 kortelė
Klausimas
What is the overall word equation for oxygenic photosynthesis?
Atsakymas
Carbon dioxide + water → carbohydrate + oxygen, using light energy.
311 kortelė
Klausimas
Which term describes the regulated leaf pore controlling carbon-dioxide entry for photosynthesis?
Atsakymas
a stoma
312 kortelė
Klausimas
Which term describes the factor currently restricting photosynthetic rate?
Atsakymas
a limiting factor
313 kortelė
Klausimas
Which term describes the light level where photosynthesis and respiration balance?
Atsakymas
the light compensation point
314 kortelė
Klausimas
Where do the main stages of photosynthesis occur in a chloroplast?
Atsakymas
Light-dependent reactions occur in thylakoid membranes; carbon-fixation reactions occur in the stroma.
315 kortelė
Klausimas
What energy conversion occurs during photosynthesis?
Atsakymas
Light energy is converted into chemical energy stored first in ATP and reduced carriers and ultimately in organic molecules.
316 kortelė
Klausimas
From which reactant does the oxygen released by photosynthesis originate?
Atsakymas
Water.
317 kortelė
Klausimas
What role does RuBisCO play in photosynthesis?
Atsakymas
It catalyzes fixation of carbon dioxide by adding it to an organic acceptor molecule.
318 kortelė
Klausimas
What tradeoff is controlled when stomata open?
Atsakymas
Opening permits carbon dioxide entry but increases water loss by transpiration.
319 kortelė
Klausimas
Name three leaf features that support photosynthesis.
Atsakymas
A broad surface captures light, a thin structure shortens diffusion paths, and veins supply water and remove sugars; chloroplast-rich cells and stomata also help.
320 kortelė
Klausimas
What can a plant do with carbohydrate made by photosynthesis?
Atsakymas
Use it in respiration, convert it to storage or structural carbohydrates, or use its carbon to make lipids, amino acids, and other molecules.
321 kortelė
Klausimas
How are products of the light-dependent reactions used in carbon fixation?
Atsakymas
ATP supplies energy and NADPH supplies reducing power for conversion of fixed carbon into carbohydrate precursors.
322 kortelė
Klausimas
Why does increasing light intensity eventually stop increasing photosynthetic rate?
Atsakymas
Another factor, such as carbon dioxide supply, temperature, or biochemical capacity, becomes limiting.
323 kortelė
Klausimas
How can increasing carbon dioxide concentration affect photosynthetic rate?
Atsakymas
It can increase the rate until another factor becomes limiting.
324 kortelė
Klausimas
Why does photosynthetic rate usually have a temperature optimum?
Atsakymas
Enzyme-controlled reactions accelerate with temperature up to an optimum, then decline as enzymes and membranes lose effective function.
325 kortelė
Klausimas
Why does an action spectrum broadly resemble the combined absorption spectra of photosynthetic pigments?
Atsakymas
Wavelengths absorbed by the pigments supply more energy for photosynthesis than poorly absorbed wavelengths.
326 kortelė
Klausimas
What is semiconservative replication?
Atsakymas
DNA replication in which each daughter molecule contains one parental strand and one newly synthesized strand.
327 kortelė
Klausimas
What is DNA helicase?
Atsakymas
An enzyme that unwinds the double helix and separates the strands by disrupting base pairing.
328 kortelė
Klausimas
What is DNA polymerase?
Atsakymas
An enzyme that adds nucleotides to a growing DNA strand using a template.
329 kortelė
Klausimas
What is a primer?
Atsakymas
A short nucleic-acid segment providing a free 3′ end from which DNA polymerase can extend.
330 kortelė
Klausimas
Which term describes replication producing one old and one new strand per DNA molecule?
Atsakymas
semiconservative replication
331 kortelė
Klausimas
Which term describes the enzyme that separates DNA strands?
Atsakymas
DNA helicase
332 kortelė
Klausimas
Which term describes the enzyme that builds DNA from a template?
Atsakymas
DNA polymerase
333 kortelė
Klausimas
Which term describes the short segment providing a starting 3′ end?
Atsakymas
a primer
334 kortelė
Klausimas
What is the leading strand?
Atsakymas
The new DNA strand synthesized continuously toward the replication fork.
335 kortelė
Klausimas
What is the lagging strand?
Atsakymas
The new DNA strand synthesized discontinuously away from the replication fork.
336 kortelė
Klausimas
What is an Okazaki fragment?
Atsakymas
A short DNA segment synthesized on the lagging strand.
337 kortelė
Klausimas
What is DNA ligase?
Atsakymas
An enzyme that seals breaks in the sugar-phosphate backbone, joining DNA fragments.
338 kortelė
Klausimas
Which term describes the continuously synthesized daughter strand?
Atsakymas
the leading strand
339 kortelė
Klausimas
Which term describes the discontinuously synthesized daughter strand?
Atsakymas
the lagging strand
340 kortelė
Klausimas
Which term describes a short newly made segment of lagging-strand DNA?
Atsakymas
an Okazaki fragment
341 kortelė
Klausimas
Which term describes the enzyme that joins DNA fragments by sealing the backbone?
Atsakymas
DNA ligase
342 kortelė
Klausimas
How does complementary base pairing ensure accurate DNA copying?
Atsakymas
Each template base specifies the nucleotide added opposite it: A pairs with T, and C pairs with G.
343 kortelė
Klausimas
Why does DNA polymerase synthesize DNA only 5′ to 3′?
Atsakymas
It can add a nucleotide only to the free 3′ hydroxyl group of the growing strand.
344 kortelė
Klausimas
When in the cell cycle is nuclear DNA replicated?
Atsakymas
During S phase of interphase, before cell division.
345 kortelė
Klausimas
How can a replication error become a permanent mutation?
Atsakymas
If it escapes proofreading and repair, the altered sequence can be copied in later cell generations.
346 kortelė
Klausimas
Why are leading and lagging strands synthesized differently?
Atsakymas
The templates are antiparallel while DNA polymerase works only 5′ to 3′, forcing one strand to be made discontinuously.
347 kortelė
Klausimas
How do proofreading and repair reduce replication errors?
Atsakymas
Incorrectly paired nucleotides are recognized, removed, and replaced before or after replication continues.
348 kortelė
Klausimas
What three repeating steps amplify DNA in PCR?
Atsakymas
Strand separation by heating, primer annealing during cooling, and DNA extension by a heat-stable polymerase.
349 kortelė
Klausimas
What determines which DNA region PCR amplifies?
Atsakymas
The sequences and positions of the two primers flanking the target region.
350 kortelė
Klausimas
What is transcription?
Atsakymas
Synthesis of RNA from a DNA template.
351 kortelė
Klausimas
What is RNA polymerase?
Atsakymas
The enzyme that synthesizes RNA complementary to a DNA template strand.
352 kortelė
Klausimas
What is messenger RNA?
Atsakymas
RNA carrying a coding sequence from DNA to ribosomes.
353 kortelė
Klausimas
What is a codon?
Atsakymas
A three-base sequence in mRNA that specifies an amino acid or a translation signal.
354 kortelė
Klausimas
Which term describes RNA synthesis from DNA?
Atsakymas
transcription
355 kortelė
Klausimas
Which term describes the enzyme that builds RNA from a DNA template?
Atsakymas
RNA polymerase
356 kortelė
Klausimas
Which term describes RNA that carries coding information to ribosomes?
Atsakymas
messenger RNA
357 kortelė
Klausimas
Which term describes a three-base mRNA unit?
Atsakymas
a codon
358 kortelė
Klausimas
What is translation?
Atsakymas
Synthesis of a polypeptide using the codon sequence of mRNA.
359 kortelė
Klausimas
What does a ribosome do during translation?
Atsakymas
It reads mRNA and catalyzes polypeptide synthesis using its rRNA-protein machinery.
360 kortelė
Klausimas
What is transfer RNA?
Atsakymas
RNA that carries a specific amino acid and pairs its anticodon with an mRNA codon.
361 kortelė
Klausimas
What is an anticodon?
Atsakymas
A three-base tRNA sequence complementary to an mRNA codon.
362 kortelė
Klausimas
Which term describes polypeptide synthesis from an mRNA sequence?
Atsakymas
translation
363 kortelė
Klausimas
Which term describes the translation complex that reads mRNA and builds a polypeptide?
Atsakymas
a ribosome
364 kortelė
Klausimas
Which term describes the adaptor RNA carrying an amino acid?
Atsakymas
transfer RNA
365 kortelė
Klausimas
Which term describes the tRNA triplet that pairs with a codon?
Atsakymas
an anticodon
366 kortelė
Klausimas
What is the genetic code?
Atsakymas
The set of rules relating mRNA codons to amino acids and translation signals.
367 kortelė
Klausimas
What are start and stop codons?
Atsakymas
mRNA signals that establish the reading frame or terminate translation.
368 kortelė
Klausimas
Where do transcription and translation occur in a eukaryotic cell?
Atsakymas
Transcription occurs in the nucleus; translation occurs on ribosomes in the cytoplasm or on rough ER.
369 kortelė
Klausimas
How is an mRNA sequence related to its DNA template strand?
Atsakymas
It is complementary and antiparallel, with uracil in RNA opposite adenine in DNA.
370 kortelė
Klausimas
Which term describes the codon-to-amino-acid rule set?
Atsakymas
the genetic code
371 kortelė
Klausimas
Which term describes codons that begin or end translation?
Atsakymas
start and stop codons
372 kortelė
Klausimas
What reaction does the ribosome catalyze as a polypeptide grows?
Atsakymas
Formation of peptide bonds between adjacent amino acids.
373 kortelė
Klausimas
What does it mean that the genetic code is degenerate?
Atsakymas
Most amino acids are specified by more than one codon.
374 kortelė
Klausimas
How can one mRNA produce many polypeptides quickly?
Atsakymas
Multiple ribosomes can translate the same mRNA simultaneously as a polyribosome.
375 kortelė
Klausimas
Why is translation not the final step in producing many functional proteins?
Atsakymas
The polypeptide must fold and may undergo cleavage, chemical modification, or assembly with other subunits.
376 kortelė
Klausimas
How does mRNA compare with the DNA coding strand?
Atsakymas
It has the same base sequence except that RNA contains uracil where DNA contains thymine.
377 kortelė
Klausimas
What happens during eukaryotic RNA splicing?
Atsakymas
Introns are removed and exons are joined to form mature mRNA.
378 kortelė
Klausimas
Why must codons be read in the correct reading frame?
Atsakymas
Changing the starting position changes every downstream triplet and therefore the amino-acid sequence.
379 kortelė
Klausimas
How is the correct amino acid matched to each mRNA codon?
Atsakymas
Each tRNA is charged with a particular amino acid, and its anticodon pairs with the complementary codon.
380 kortelė
Klausimas
How can a base substitution affect a protein?
Atsakymas
It may be silent, change one amino acid, create a stop codon, or sometimes alter RNA processing.
381 kortelė
Klausimas
What is a mutation?
Atsakymas
A change in a DNA sequence or chromosome structure that can be passed to daughter cells.
382 kortelė
Klausimas
What is a base substitution?
Atsakymas
Replacement of one nucleotide pair by another.
383 kortelė
Klausimas
What is an insertion mutation?
Atsakymas
Addition of one or more nucleotides to a DNA sequence.
384 kortelė
Klausimas
What is a deletion mutation?
Atsakymas
Loss of one or more nucleotides from a DNA sequence.
385 kortelė
Klausimas
Which term describes a lasting DNA-sequence or chromosome change?
Atsakymas
a mutation
386 kortelė
Klausimas
Which term describes replacement of one DNA base pair?
Atsakymas
a base substitution
387 kortelė
Klausimas
Which term describes addition of nucleotides to DNA?
Atsakymas
an insertion mutation
388 kortelė
Klausimas
Which term describes loss of nucleotides from DNA?
Atsakymas
a deletion mutation
389 kortelė
Klausimas
What is a frameshift mutation?
Atsakymas
A coding-sequence insertion or deletion not divisible by three that changes downstream codon grouping.
390 kortelė
Klausimas
What is a silent mutation?
Atsakymas
A sequence change that does not alter the encoded amino acid.
391 kortelė
Klausimas
What is a missense mutation?
Atsakymas
A mutation that changes a codon so a different amino acid is incorporated.
392 kortelė
Klausimas
What is a nonsense mutation?
Atsakymas
A mutation that changes an amino-acid codon into a stop codon.
393 kortelė
Klausimas
Which term describes a mutation that shifts downstream codon grouping?
Atsakymas
a frameshift mutation
394 kortelė
Klausimas
Which term describes a coding change that leaves the amino acid unchanged?
Atsakymas
a silent mutation
395 kortelė
Klausimas
Which term describes a mutation causing one amino-acid substitution?
Atsakymas
a missense mutation
396 kortelė
Klausimas
Which term describes a mutation creating a premature stop codon?
Atsakymas
a nonsense mutation
397 kortelė
Klausimas
How do germline and somatic mutations differ in inheritance?
Atsakymas
Germline mutations can enter gametes and be inherited; somatic mutations affect a cell lineage within the individual.
398 kortelė
Klausimas
What can cause mutations?
Atsakymas
Replication errors, spontaneous chemical changes, radiation, and mutagenic chemicals can alter DNA.
399 kortelė
Klausimas
How does DNA repair protect genome stability?
Atsakymas
Repair systems detect damaged or mismatched DNA and restore the correct structure or sequence when possible.
400 kortelė
Klausimas
Why are mutations essential to evolution despite often being neutral or harmful?
Atsakymas
They create new alleles, providing the heritable variation on which selection and drift act.
401 kortelė
Klausimas
What is the basic role of guide RNA in CRISPR gene editing?
Atsakymas
It directs a nuclease to a complementary DNA sequence.
402 kortelė
Klausimas
Why can the same type of DNA mutation have effects ranging from none to severe?
Atsakymas
Effects depend on location, genetic-code redundancy, protein role, cell type, and environmental context.
403 kortelė
Klausimas
How can accumulated mutations contribute to cancer?
Atsakymas
Mutations can activate growth-promoting genes or disable genes that restrain division, repair DNA, or trigger cell death.
404 kortelė
Klausimas
Why can repairing a CRISPR-induced DNA break produce different editing outcomes?
Atsakymas
Different cellular repair pathways may disrupt the target sequence or use a supplied template for a specific change.
405 kortelė
Klausimas
What is an off-target effect in gene editing?
Atsakymas
An unintended DNA change at a site sufficiently similar to the intended target.
406 kortelė
Klausimas
Why does heritable human genome editing raise additional ethical concerns?
Atsakymas
Changes could pass to future generations who cannot consent, with uncertain long-term biological and social effects.
407 kortelė
Klausimas
What is the cell cycle?
Atsakymas
The ordered sequence of cell growth, DNA replication, nuclear division, and cell division.
408 kortelė
Klausimas
What is interphase?
Atsakymas
The period of growth, normal activity, and DNA replication between nuclear divisions.
409 kortelė
Klausimas
What is mitosis?
Atsakymas
Nuclear division that usually produces genetically equivalent daughter nuclei.
410 kortelė
Klausimas
What is cytokinesis?
Atsakymas
Division of the cytoplasm to form separate daughter cells.
411 kortelė
Klausimas
Which term describes the ordered sequence from one cell division to the next?
Atsakymas
the cell cycle
412 kortelė
Klausimas
Which term describes the growth and DNA-replication period between divisions?
Atsakymas
interphase
413 kortelė
Klausimas
Which term describes division producing genetically equivalent nuclei?
Atsakymas
mitosis
414 kortelė
Klausimas
Which term describes physical division of the cytoplasm?
Atsakymas
cytokinesis
415 kortelė
Klausimas
What is a chromosome?
Atsakymas
One DNA molecule packaged with associated proteins.
416 kortelė
Klausimas
What are sister chromatids?
Atsakymas
The two replicated copies of a chromosome joined before separation.
417 kortelė
Klausimas
What is a centromere?
Atsakymas
The chromosome region that holds sister chromatids together and organizes kinetochore attachment.
418 kortelė
Klausimas
What is the mitotic spindle?
Atsakymas
A microtubule system that attaches to and separates chromosomes during cell division.
419 kortelė
Klausimas
Which term describes a protein-packaged DNA molecule?
Atsakymas
a chromosome
420 kortelė
Klausimas
Which term describes joined replicated copies of one chromosome?
Atsakymas
sister chromatids
421 kortelė
Klausimas
Which term describes the chromosome region joining sister chromatids?
Atsakymas
a centromere
422 kortelė
Klausimas
Which term describes the chromosome-separating microtubule system?
Atsakymas
the mitotic spindle
423 kortelė
Klausimas
What is the basic sequence of mitosis?
Atsakymas
Chromosomes condense, align at the cell equator, sister chromatids separate to opposite poles, and new nuclei form.
424 kortelė
Klausimas
Why must DNA replicate before mitosis?
Atsakymas
Each chromosome must have two copies so each daughter nucleus can receive a complete genome.
425 kortelė
Klausimas
Why are daughter cells from mitosis usually genetically similar?
Atsakymas
Replicated sister chromatids are separated so each daughter receives one copy of every chromosome.
426 kortelė
Klausimas
What are major roles of mitosis in multicellular organisms?
Atsakymas
Growth, tissue repair, cell replacement, and some forms of asexual reproduction.
427 kortelė
Klausimas
How do homologous chromosomes differ from sister chromatids?
Atsakymas
Homologs carry the same gene loci but may have different alleles; sister chromatids are replicated copies of one chromosome.
428 kortelė
Klausimas
What key outcome distinguishes mitosis from meiosis?
Atsakymas
Mitosis usually preserves chromosome number and similarity; meiosis halves chromosome number and generates genetically varied haploid cells.
429 kortelė
Klausimas
How does cytokinesis commonly occur in animal cells?
Atsakymas
A contractile ring tightens the plasma membrane into a cleavage furrow.
430 kortelė
Klausimas
How does cytokinesis commonly occur in plant cells?
Atsakymas
Vesicles fuse at the center to form a cell plate that develops into new membranes and a cell wall.
431 kortelė
Klausimas
What is the purpose of cell-cycle checkpoints?
Atsakymas
They delay progression when conditions are unsuitable or DNA and chromosome attachment are defective.
432 kortelė
Klausimas
How is loss of cell-cycle control related to cancer?
Atsakymas
Cells can divide despite damage or growth restraints, producing an expanding abnormal clone.
433 kortelė
Klausimas
What is a gene?
Atsakymas
A DNA sequence that contributes to a functional product and influences a characteristic or cellular process.
434 kortelė
Klausimas
What is an allele?
Atsakymas
One of the alternative DNA-sequence forms at a gene locus.
435 kortelė
Klausimas
What is a gene locus?
Atsakymas
The physical position of a gene on a chromosome.
436 kortelė
Klausimas
What is a genotype?
Atsakymas
The allele combination of an organism at one or more loci.
437 kortelė
Klausimas
Which term describes a functional DNA sequence?
Atsakymas
a gene
438 kortelė
Klausimas
Which term describes an alternative form of a gene?
Atsakymas
an allele
439 kortelė
Klausimas
Which term describes a gene's chromosome position?
Atsakymas
a gene locus
440 kortelė
Klausimas
Which term describes an organism's allele combination?
Atsakymas
a genotype
441 kortelė
Klausimas
What is a phenotype?
Atsakymas
An observable or measurable trait produced by genotype and environment.
442 kortelė
Klausimas
What is homozygous?
Atsakymas
Having two identical alleles at a diploid locus.
443 kortelė
Klausimas
What is heterozygous?
Atsakymas
Having two different alleles at a diploid locus.
444 kortelė
Klausimas
What is a dominant allele?
Atsakymas
An allele expressed in the phenotype of a heterozygote under a specified inheritance model.
445 kortelė
Klausimas
Which term describes an observable trait resulting from genes and environment?
Atsakymas
a phenotype
446 kortelė
Klausimas
Which term describes having two identical alleles at a locus?
Atsakymas
homozygous
447 kortelė
Klausimas
Which term describes having two different alleles at a locus?
Atsakymas
heterozygous
448 kortelė
Klausimas
Which term describes an allele expressed in a heterozygote?
Atsakymas
a dominant allele
449 kortelė
Klausimas
What is a recessive allele?
Atsakymas
An allele whose phenotype is masked by a dominant allele in a heterozygote.
450 kortelė
Klausimas
What is a genetic carrier?
Atsakymas
An unaffected heterozygote who can transmit a recessive disease allele.
451 kortelė
Klausimas
What is a test cross?
Atsakymas
A cross with a homozygous recessive individual used to infer an unknown dominant phenotype's genotype.
452 kortelė
Klausimas
What is a pedigree?
Atsakymas
A diagram showing biological relationships and occurrence of a trait across generations.
453 kortelė
Klausimas
Which term describes an allele masked in a heterozygote?
Atsakymas
a recessive allele
454 kortelė
Klausimas
Which term describes an unaffected heterozygote carrying a recessive disease allele?
Atsakymas
a genetic carrier
455 kortelė
Klausimas
Which term describes a cross used to reveal an unknown dominant genotype?
Atsakymas
a test cross
456 kortelė
Klausimas
Which term describes a family diagram tracking a trait across generations?
Atsakymas
a pedigree
457 kortelė
Klausimas
What does allele segregation mean during gamete formation?
Atsakymas
The two alleles at a diploid locus separate so each gamete receives one.
458 kortelė
Klausimas
What does a Punnett square predict?
Atsakymas
Expected genotype and phenotype probabilities from specified parental gametes, not guaranteed family outcomes.
459 kortelė
Klausimas
What phenotypic ratio is expected from Aa × Aa with complete dominance?
Atsakymas
Approximately 3 dominant phenotype : 1 recessive phenotype.
460 kortelė
Klausimas
What genotypic ratio is expected from Aa × Aa?
Atsakymas
1 AA : 2 Aa : 1 aa.
461 kortelė
Klausimas
What happens in codominance?
Atsakymas
Both alleles contribute distinctly to the heterozygous phenotype.
462 kortelė
Klausimas
What happens in incomplete dominance?
Atsakymas
The heterozygote has a phenotype intermediate between the two homozygotes.
463 kortelė
Klausimas
How can environment affect phenotype without changing genotype?
Atsakymas
Conditions alter development, physiology, or gene expression, changing the observed trait.
464 kortelė
Klausimas
What is the ultimate source of new alleles?
Atsakymas
Mutation.
465 kortelė
Klausimas
Why are X-linked recessive traits more common in XY individuals?
Atsakymas
They have only one X chromosome, so one recessive allele on it can determine the phenotype.
466 kortelė
Klausimas
When is the product rule used in genetic probability?
Atsakymas
For independent events that must both occur; multiply their probabilities.
467 kortelė
Klausimas
When is the sum rule used in genetic probability?
Atsakymas
For mutually exclusive alternative outcomes; add their probabilities.
468 kortelė
Klausimas
Why do polygenic traits often show continuous variation?
Atsakymas
Many loci contribute small effects, creating many possible genotypes and phenotypes, often further influenced by environment.
469 kortelė
Klausimas
What pedigree pattern can suggest an autosomal recessive trait?
Atsakymas
Unaffected parents can have affected children, and all sexes are affected at similar frequencies.
470 kortelė
Klausimas
What is a species?
Atsakymas
A group of organisms whose members can potentially interbreed and produce fertile offspring under natural conditions.
471 kortelė
Klausimas
What is binomial nomenclature?
Atsakymas
The two-part scientific naming system using a genus name followed by a specific epithet.
472 kortelė
Klausimas
What is taxonomy?
Atsakymas
The naming and classification of organisms.
473 kortelė
Klausimas
What is a biological domain?
Atsakymas
The broadest commonly used taxonomic rank, separating Bacteria, Archaea, and Eukarya.
474 kortelė
Klausimas
Which term describes a naturally interbreeding group producing fertile offspring?
Atsakymas
a species
475 kortelė
Klausimas
Which term describes the genus-plus-specific-epithet naming system?
Atsakymas
binomial nomenclature
476 kortelė
Klausimas
Which term describes the science of naming and classifying organisms?
Atsakymas
taxonomy
477 kortelė
Klausimas
Which term describes the broadest common taxonomic rank?
Atsakymas
a biological domain
478 kortelė
Klausimas
What is biodiversity?
Atsakymas
Variation of life at genetic, species, and ecosystem levels.
479 kortelė
Klausimas
What is an autotroph?
Atsakymas
An organism that makes organic compounds from inorganic carbon using light or chemical energy.
480 kortelė
Klausimas
What is a heterotroph?
Atsakymas
An organism that obtains organic carbon by consuming other organisms or their products.
960 kortelių
IB Biology SL Flashcards: Complete Course Review
Mokytis iš šio rinkinio nemokamaiAtsidarys Nibomo ir galėsite pradėti mokytis.
481 kortelė
Klausimas
What is a unicellular organism?
Atsakymas
An organism consisting of one cell that carries out all essential life functions.
482 kortelė
Klausimas
Which term describes variation of life across genes, species, and ecosystems?
Atsakymas
biodiversity
483 kortelė
Klausimas
Which term describes an organism that builds organic matter from inorganic carbon?
Atsakymas
an autotroph
484 kortelė
Klausimas
Which term describes an organism obtaining organic carbon from other organisms?
Atsakymas
a heterotroph
485 kortelė
Klausimas
Which term describes an organism made of one cell?
Atsakymas
a unicellular organism
486 kortelė
Klausimas
What is a multicellular organism?
Atsakymas
An organism composed of many cooperating cells, often with specialized cell types.
487 kortelė
Klausimas
What is a karyotype?
Atsakymas
An ordered display of chromosomes used to examine their number and large-scale structure.
488 kortelė
Klausimas
What broad feature distinguishes both Bacteria and Archaea from Eukarya?
Atsakymas
Their cells lack a nucleus and other membrane-bound organelles.
489 kortelė
Klausimas
What features characterize most plant cells?
Atsakymas
Cellulose walls, chloroplasts in photosynthetic tissues, and large vacuoles are typical features.
490 kortelė
Klausimas
Which term describes an organism made of many cooperating cells?
Atsakymas
a multicellular organism
491 kortelė
Klausimas
Which term describes an ordered display of an individual's chromosomes?
Atsakymas
a karyotype
492 kortelė
Klausimas
How do fungi obtain nutrients?
Atsakymas
They secrete digestive enzymes and absorb soluble products; their cells usually have chitin-containing walls.
493 kortelė
Klausimas
What distinguishes animal nutrition and cell structure?
Atsakymas
Animals ingest organic material, and their cells lack cell walls and chloroplasts.
494 kortelė
Klausimas
Why are scientific names useful across languages?
Atsakymas
A standardized name identifies the same organism internationally and reduces ambiguity from local common names.
495 kortelė
Klausimas
Why can genetic diversity improve a population's resilience?
Atsakymas
More heritable variation increases the chance that some individuals tolerate new diseases or environmental changes.
496 kortelė
Klausimas
What does ecosystem diversity measure?
Atsakymas
The variety of habitats, communities, and ecological processes within a region.
497 kortelė
Klausimas
Why are Archaea classified separately from Bacteria?
Atsakymas
They differ in genetic sequences, membrane chemistry, cell-wall composition, and aspects of molecular machinery.
498 kortelė
Klausimas
Why is the biological species concept difficult to apply to fossils or asexual organisms?
Atsakymas
Their ability to interbreed and produce fertile offspring cannot be tested in the usual way.
499 kortelė
Klausimas
Does a larger chromosome number necessarily mean a more complex organism?
Atsakymas
No. Chromosome number varies through fusion, fission, and duplication and does not directly measure biological complexity.
500 kortelė
Klausimas
Does genome size reliably predict organismal complexity?
Atsakymas
No. Large amounts of noncoding and repeated DNA make genome size a poor simple measure of complexity.
501 kortelė
Klausimas
What evidence can be combined when classifying organisms?
Atsakymas
Molecular sequences, cell structure, anatomy, development, physiology, and reproductive evidence can all contribute.
502 kortelė
Klausimas
What is gas exchange?
Atsakymas
Diffusion of respiratory gases between an organism and its environment or transport fluid.
503 kortelė
Klausimas
What is ventilation?
Atsakymas
Bulk movement of air or water over a gas-exchange surface.
504 kortelė
Klausimas
What is an alveolus?
Atsakymas
A microscopic air sac in the lung where gases diffuse between air and blood.
505 kortelė
Klausimas
What is pulmonary surfactant?
Atsakymas
A substance lining alveoli that lowers surface tension and reduces collapse.
506 kortelė
Klausimas
Which term describes diffusion of oxygen and carbon dioxide across a respiratory surface?
Atsakymas
gas exchange
507 kortelė
Klausimas
Which term describes bulk movement of respiratory medium over an exchange surface?
Atsakymas
ventilation
508 kortelė
Klausimas
Which term describes a microscopic lung air sac?
Atsakymas
an alveolus
509 kortelė
Klausimas
Which term describes the alveolar lining that lowers surface tension?
Atsakymas
pulmonary surfactant
510 kortelė
Klausimas
What is the diaphragm?
Atsakymas
A sheet of skeletal muscle whose contraction increases thoracic volume during inhalation.
511 kortelė
Klausimas
What is tidal volume?
Atsakymas
The volume of air moved in or out during a normal breath.
512 kortelė
Klausimas
What is a stoma?
Atsakymas
A regulated epidermal pore through which gases diffuse in leaves.
513 kortelė
Klausimas
What is countercurrent exchange?
Atsakymas
Exchange between fluids moving in opposite directions, maintaining a gradient along most of the surface.
514 kortelė
Klausimas
Which term describes the muscle sheet that expands the thorax during inhalation?
Atsakymas
the diaphragm
515 kortelė
Klausimas
Which term describes air volume moved in one normal breath?
Atsakymas
tidal volume
516 kortelė
Klausimas
Which term describes a regulated leaf gas-exchange pore?
Atsakymas
a stoma
517 kortelė
Klausimas
Which term describes opposite fluid flow that maintains an exchange gradient?
Atsakymas
countercurrent exchange
518 kortelė
Klausimas
What features make an efficient gas-exchange surface?
Atsakymas
Large area, short diffusion distance, permeability, and maintained concentration gradients.
519 kortelė
Klausimas
How is a steep oxygen gradient maintained across alveoli?
Atsakymas
Ventilation replenishes alveolar oxygen and blood flow removes absorbed oxygen.
520 kortelė
Klausimas
How does diaphragm contraction cause inhalation?
Atsakymas
Thoracic volume increases, lung pressure falls below atmospheric pressure, and air flows inward.
521 kortelė
Klausimas
What drives quiet exhalation?
Atsakymas
The diaphragm relaxes and elastic recoil reduces thoracic and lung volume, raising pressure and pushing air out.
522 kortelė
Klausimas
Why do ventilation rate and depth increase during exercise?
Atsakymas
They increase oxygen uptake and carbon dioxide removal to support higher cellular respiration.
523 kortelė
Klausimas
How does leaf structure shorten the pathway for carbon dioxide diffusion?
Atsakymas
Stomata open into air spaces, and mesophyll cells expose moist surfaces close to those spaces.
524 kortelė
Klausimas
Why does carbon dioxide diffuse from tissues into blood?
Atsakymas
Respiring cells produce carbon dioxide, making its partial pressure higher in tissues than in incoming blood.
525 kortelė
Klausimas
How does countercurrent flow improve oxygen uptake at fish gills?
Atsakymas
Blood continually meets water with a higher oxygen concentration, preserving diffusion along the lamella.
526 kortelė
Klausimas
Why does closing stomata reduce both water loss and photosynthesis?
Atsakymas
It limits water-vapor diffusion out but also restricts carbon dioxide diffusion into the leaf.
527 kortelė
Klausimas
What is a circulatory system?
Atsakymas
A transport system that moves a fluid carrying gases, nutrients, wastes, hormones, and heat through an organism.
528 kortelė
Klausimas
What is an artery?
Atsakymas
A blood vessel carrying blood away from the heart under relatively high pressure.
529 kortelė
Klausimas
What is a vein?
Atsakymas
A blood vessel carrying blood toward the heart, usually with low pressure and often valves.
530 kortelė
Klausimas
What is a capillary?
Atsakymas
A microscopic thin-walled vessel where substances exchange between blood and tissues.
531 kortelė
Klausimas
Which term describes an internal fluid-transport system?
Atsakymas
a circulatory system
532 kortelė
Klausimas
Which term describes a vessel carrying blood away from the heart?
Atsakymas
an artery
533 kortelė
Klausimas
Which term describes a vessel carrying blood toward the heart?
Atsakymas
a vein
534 kortelė
Klausimas
Which term describes a microscopic exchange blood vessel?
Atsakymas
a capillary
535 kortelė
Klausimas
What is the cardiac cycle?
Atsakymas
The repeating sequence of heart-chamber contraction and relaxation that pumps blood.
536 kortelė
Klausimas
What is hemoglobin?
Atsakymas
An iron-containing protein in red blood cells that binds oxygen reversibly.
537 kortelė
Klausimas
What is xylem?
Atsakymas
Plant vascular tissue that transports water and mineral ions and provides structural support.
538 kortelė
Klausimas
What is phloem?
Atsakymas
Plant vascular tissue that transports sucrose and other organic solutes between sources and sinks.
539 kortelė
Klausimas
Which term describes the repeating pumping sequence of the heart?
Atsakymas
the cardiac cycle
540 kortelė
Klausimas
Which term describes the oxygen-carrying protein of red blood cells?
Atsakymas
hemoglobin
541 kortelė
Klausimas
Which term describes plant tissue carrying water and minerals?
Atsakymas
xylem
542 kortelė
Klausimas
Which term describes plant tissue carrying organic solutes?
Atsakymas
phloem
543 kortelė
Klausimas
What is transpiration?
Atsakymas
Loss of water vapor from plant surfaces, mainly through stomata.
544 kortelė
Klausimas
What is phloem translocation?
Atsakymas
Movement of organic solutes through phloem from sources to sinks.
545 kortelė
Klausimas
How do a source and a sink differ in plant transport?
Atsakymas
A source releases assimilates to phloem; a sink removes them for use or storage.
546 kortelė
Klausimas
What makes human circulation a double circulation?
Atsakymas
Blood passes through the heart once in the pulmonary circuit and again in the systemic circuit during one complete journey.
547 kortelė
Klausimas
Which term describes water-vapor loss from plant surfaces?
Atsakymas
transpiration
548 kortelė
Klausimas
Which term describes movement of organic solutes through phloem?
Atsakymas
phloem translocation
549 kortelė
Klausimas
Which term describes the exporting and importing regions of phloem transport?
Atsakymas
source and sink
550 kortelė
Klausimas
How is an artery adapted to high pressure?
Atsakymas
It has thick elastic and muscular walls and a relatively narrow lumen.
551 kortelė
Klausimas
How is a vein adapted to return low-pressure blood?
Atsakymas
It has a wide lumen, thinner walls, and valves that reduce backflow.
552 kortelė
Klausimas
How does capillary structure support exchange?
Atsakymas
One-cell-thick walls give a short diffusion distance; extensive branching gives a large total area; narrow lumens slow flow and keep blood close to tissues.
553 kortelė
Klausimas
What determines whether a heart valve opens or closes?
Atsakymas
Pressure differences across the valve.
554 kortelė
Klausimas
Trace water from soil to the atmosphere through a plant.
Atsakymas
Soil → root hairs → root tissues → xylem → leaf mesophyll → leaf air spaces → stomata → atmosphere.
555 kortelė
Klausimas
Why may root cells use active transport to absorb mineral ions?
Atsakymas
Ion concentrations can be lower in soil than in root cells, so uptake must occur against a gradient.
556 kortelė
Klausimas
Why do large multicellular organisms need bulk transport systems?
Atsakymas
Their low surface-area-to-volume ratio and long diffusion distances make diffusion alone too slow for whole-body supply.
557 kortelė
Klausimas
Why does hemoglobin unload more oxygen in actively respiring tissues?
Atsakymas
Lower oxygen and often higher carbon dioxide and acidity reduce hemoglobin's oxygen affinity.
558 kortelė
Klausimas
How does transpiration pull water upward through xylem?
Atsakymas
Evaporation lowers leaf water potential and creates tension; cohesion transmits the pull through the continuous water column.
559 kortelė
Klausimas
How do wind and low humidity generally affect transpiration?
Atsakymas
Both maintain a steep water-vapor gradient outside the leaf, increasing transpiration if stomata remain open.
560 kortelė
Klausimas
What drives mass flow in phloem?
Atsakymas
Sugar loading draws in water and raises pressure at a source; unloading lowers pressure at a sink, producing bulk flow.
561 kortelė
Klausimas
Can the same plant organ be a source at one time and a sink at another?
Atsakymas
Yes. A storage organ may import sugars while filling and export them later during growth or germination.
562 kortelė
Klausimas
What is a neuron?
Atsakymas
An excitable cell specialized to receive, process, and transmit information.
563 kortelė
Klausimas
What is a sensory neuron?
Atsakymas
A neuron carrying information from a receptor toward the central nervous system.
564 kortelė
Klausimas
What is a motor neuron?
Atsakymas
A neuron carrying commands from the central nervous system to an effector.
565 kortelė
Klausimas
What is the resting potential?
Atsakymas
The voltage difference across an unstimulated neuron's membrane, with the inside negative relative to outside.
566 kortelė
Klausimas
Which term describes an excitable information-transmitting cell?
Atsakymas
a neuron
567 kortelė
Klausimas
Which term describes a neuron carrying receptor information to the CNS?
Atsakymas
a sensory neuron
568 kortelė
Klausimas
Which term describes a neuron carrying CNS commands to an effector?
Atsakymas
a motor neuron
569 kortelė
Klausimas
Which term describes the negative-inside voltage of an unstimulated neuron?
Atsakymas
the resting potential
570 kortelė
Klausimas
What is an action potential?
Atsakymas
A brief, self-propagating reversal and restoration of membrane potential along an excitable membrane.
571 kortelė
Klausimas
What is depolarization?
Atsakymas
A change that makes membrane potential less negative, and during an action potential often positive.
572 kortelė
Klausimas
What is repolarization?
Atsakymas
Return of membrane potential toward its resting negative value after depolarization.
573 kortelė
Klausimas
What is a synapse?
Atsakymas
A junction where one cell communicates with another cell.
574 kortelė
Klausimas
Which term describes a brief propagating change in neuron membrane voltage?
Atsakymas
an action potential
575 kortelė
Klausimas
Which term describes a membrane-voltage change toward a less negative value?
Atsakymas
depolarization
576 kortelė
Klausimas
Which term describes return toward resting membrane voltage?
Atsakymas
repolarization
577 kortelė
Klausimas
Which term describes a communication junction between cells?
Atsakymas
a synapse
578 kortelė
Klausimas
What is a neurotransmitter?
Atsakymas
A chemical released by a neuron that changes the activity of a target cell.
579 kortelė
Klausimas
What is the refractory period?
Atsakymas
A brief period after an action potential when another is impossible or requires a stronger stimulus.
580 kortelė
Klausimas
What is myelin?
Atsakymas
An insulating sheath around some axons that speeds impulse conduction.
581 kortelė
Klausimas
What happens when membrane depolarization reaches threshold?
Atsakymas
Voltage-gated channels trigger the self-amplifying events of an action potential.
582 kortelė
Klausimas
Which term describes a neuron-released signaling chemical?
Atsakymas
a neurotransmitter
583 kortelė
Klausimas
Which term describes the recovery interval after an action potential?
Atsakymas
the refractory period
584 kortelė
Klausimas
Which term describes the insulating axon sheath?
Atsakymas
myelin
585 kortelė
Klausimas
What does the all-or-none principle mean for an action potential?
Atsakymas
Once threshold is reached, the action potential has a characteristic size; stronger stimuli increase frequency, not its amplitude.
586 kortelė
Klausimas
How does myelin increase conduction speed?
Atsakymas
Depolarizing current travels rapidly beneath myelin and action potentials regenerate mainly at gaps in the sheath.
587 kortelė
Klausimas
What is the basic sequence at a chemical synapse?
Atsakymas
An impulse triggers neurotransmitter release; it diffuses across the cleft, binds receptors, and alters the postsynaptic cell.
588 kortelė
Klausimas
Why can a reflex response be rapid?
Atsakymas
A short neural pathway produces an automatic response without waiting for conscious processing.
589 kortelė
Klausimas
What is sensory transduction?
Atsakymas
Conversion of a physical or chemical stimulus into an electrical signal in a receptor cell.
590 kortelė
Klausimas
How does an action potential propagate along an axon?
Atsakymas
Local current depolarizes the next membrane region to threshold, opening voltage-gated channels there.
591 kortelė
Klausimas
Why does an action potential normally travel in one direction along an axon?
Atsakymas
The membrane just behind it is refractory and cannot immediately fire again.
592 kortelė
Klausimas
How is neurotransmitter action ended?
Atsakymas
The transmitter is removed by enzymatic breakdown, reuptake, or diffusion away.
593 kortelė
Klausimas
What is sensory adaptation?
Atsakymas
Reduced receptor or neural response during a constant, unchanging stimulus.
594 kortelė
Klausimas
How can a drug alter synaptic transmission?
Atsakymas
It may mimic or block a transmitter, change its release, or change its removal from the synaptic cleft.
595 kortelė
Klausimas
What is an organ system?
Atsakymas
A group of organs coordinating to perform major functions for an organism.
596 kortelė
Klausimas
What is a hormone?
Atsakymas
A signaling molecule released into transport fluid and acting on target cells with suitable receptors.
597 kortelė
Klausimas
What is an endocrine gland?
Atsakymas
A gland that secretes hormones into extracellular fluid and blood rather than through a duct.
598 kortelė
Klausimas
What is a hormone target cell?
Atsakymas
A cell able to respond because it has the appropriate receptor.
599 kortelė
Klausimas
Which term describes a coordinated group of organs?
Atsakymas
an organ system
600 kortelė
Klausimas
Which term describes a long-distance chemical messenger carried in body fluid?
Atsakymas
a hormone
601 kortelė
Klausimas
Which term describes a ductless hormone-secreting gland?
Atsakymas
an endocrine gland
602 kortelė
Klausimas
Which term describes a cell with a receptor for a particular hormone?
Atsakymas
a hormone target cell
603 kortelė
Klausimas
What is digestion?
Atsakymas
Mechanical and chemical breakdown of food into molecules small enough to absorb.
604 kortelė
Klausimas
What is absorption?
Atsakymas
Movement of digested nutrients across an exchange surface into blood or lymph.
605 kortelė
Klausimas
What is peristalsis?
Atsakymas
Coordinated waves of smooth-muscle contraction that move material through the digestive tract.
606 kortelė
Klausimas
What is an intestinal villus?
Atsakymas
A finger-like projection increasing the absorptive surface of the small intestine.
607 kortelė
Klausimas
Which term describes breakdown of food into absorbable molecules?
Atsakymas
digestion
608 kortelė
Klausimas
Which term describes movement of digested nutrients into transport fluids?
Atsakymas
absorption
609 kortelė
Klausimas
Which term describes wave-like gut contractions moving contents?
Atsakymas
peristalsis
610 kortelė
Klausimas
Which term describes a finger-like intestinal absorption projection?
Atsakymas
an intestinal villus
611 kortelė
Klausimas
What is excretion?
Atsakymas
Removal of metabolic waste products from the body.
612 kortelė
Klausimas
What is a nephron?
Atsakymas
The microscopic functional unit of the kidney that filters blood and modifies filtrate into urine.
613 kortelė
Klausimas
What is ultrafiltration?
Atsakymas
Pressure-driven filtration of small molecules from blood into a kidney capsule while cells and most proteins remain in blood.
614 kortelė
Klausimas
What is selective reabsorption?
Atsakymas
Recovery of useful substances and regulated amounts of water and ions from kidney filtrate into blood.
615 kortelė
Klausimas
Which term describes removal of metabolic wastes?
Atsakymas
excretion
616 kortelė
Klausimas
Which term describes the kidney's microscopic functional unit?
Atsakymas
a nephron
617 kortelė
Klausimas
Which term describes pressure filtration at the start of a nephron?
Atsakymas
ultrafiltration
618 kortelė
Klausimas
Which term describes return of useful substances from kidney filtrate to blood?
Atsakymas
selective reabsorption
619 kortelė
Klausimas
What is skeletal muscle?
Atsakymas
Striated voluntary muscle attached to the skeleton and used for movement and posture.
620 kortelė
Klausimas
What is an antagonistic muscle pair?
Atsakymas
Two muscles producing opposite movements at a joint because muscles pull but do not push.
621 kortelė
Klausimas
How do nervous and endocrine signaling generally differ?
Atsakymas
Neural signals are rapid and targeted; hormonal signals are usually slower, longer-lasting, and distributed through body fluids.
622 kortelė
Klausimas
Why does a circulating hormone affect only some cells?
Atsakymas
Only target cells express receptors that recognize the hormone and activate a response.
623 kortelė
Klausimas
Which term describes voluntary striated muscle that moves the skeleton?
Atsakymas
skeletal muscle
624 kortelė
Klausimas
Which term describes two muscles producing opposite joint movements?
Atsakymas
an antagonistic muscle pair
625 kortelė
Klausimas
What is the final absorbable product of most dietary carbohydrate digestion?
Atsakymas
Monosaccharides, especially glucose.
626 kortelė
Klausimas
What are the main absorbable products of protein digestion?
Atsakymas
Amino acids and small peptides that are completed to amino acids during absorption.
627 kortelė
Klausimas
How is the small intestine adapted for absorption?
Atsakymas
Folds, villi, and microvilli increase area; a thin epithelium, rich blood supply, and lymph vessels support transport.
628 kortelė
Klausimas
Name three integrative roles of the liver.
Atsakymas
It processes absorbed nutrients, regulates blood chemistry, detoxifies substances, produces bile, and converts ammonia to urea; any three are sufficient.
629 kortelė
Klausimas
Why are blood cells and most plasma proteins absent from normal kidney filtrate?
Atsakymas
They are too large to cross the filtration barrier.
630 kortelė
Klausimas
How do muscles move a bone at a joint?
Atsakymas
Contraction shortens the muscle, pulling through a tendon on the bone.
631 kortelė
Klausimas
Why are antagonistic muscles needed at many joints?
Atsakymas
A muscle can pull in one direction but cannot push itself back, so an opposing muscle produces the reverse movement.
632 kortelė
Klausimas
Why must organ systems be integrated rather than acting independently?
Atsakymas
Each system depends on materials, signals, waste removal, and stable conditions supplied by other systems.
633 kortelė
Klausimas
Why do many absorbed lipids enter lymph before blood?
Atsakymas
Intestinal cells package them into lipoprotein particles too large to enter ordinary blood capillaries directly.
634 kortelė
Klausimas
Why is glucose normally absent from final urine?
Atsakymas
Filtered glucose is selectively reabsorbed into blood when transporter capacity is not exceeded.
635 kortelė
Klausimas
How do respiratory, circulatory, and muscular systems cooperate during exercise?
Atsakymas
Ventilation supplies oxygen, circulation transports gases and fuels, and muscles use ATP while returning carbon dioxide, heat, and metabolites.
636 kortelė
Klausimas
How do liver, circulation, and kidneys cooperate in nitrogen-waste removal?
Atsakymas
The liver converts toxic ammonia to urea, blood carries urea, and kidneys filter and excrete it.
637 kortelė
Klausimas
What is a pathogen?
Atsakymas
A biological agent capable of causing disease.
638 kortelė
Klausimas
What is an antigen?
Atsakymas
A molecule recognized specifically by an antibody or lymphocyte receptor.
639 kortelė
Klausimas
What is innate immunity?
Atsakymas
Rapid, nonspecific defense mechanisms present without prior exposure.
640 kortelė
Klausimas
What is adaptive immunity?
Atsakymas
Specific defense that develops through lymphocyte activation and can form memory.
641 kortelė
Klausimas
Which term describes a disease-causing biological agent?
Atsakymas
a pathogen
642 kortelė
Klausimas
Which term describes a molecule specifically recognized by adaptive immune receptors?
Atsakymas
an antigen
643 kortelė
Klausimas
Which term describes rapid nonspecific immune defense?
Atsakymas
innate immunity
644 kortelė
Klausimas
Which term describes specific immune defense capable of memory?
Atsakymas
adaptive immunity
645 kortelė
Klausimas
What is a phagocyte?
Atsakymas
A cell that engulfs and digests microbes, particles, or damaged cells.
646 kortelė
Klausimas
What is a lymphocyte?
Atsakymas
An adaptive immune cell with receptors specific to particular antigens.
647 kortelė
Klausimas
What is an antibody?
Atsakymas
A secreted immunoglobulin that binds a specific antigen.
648 kortelė
Klausimas
What is a B lymphocyte?
Atsakymas
A lymphocyte that can differentiate into antibody-secreting plasma cells and memory cells.
649 kortelė
Klausimas
Which term describes an engulfing immune cell?
Atsakymas
a phagocyte
650 kortelė
Klausimas
Which term describes an antigen-specific adaptive immune cell?
Atsakymas
a lymphocyte
651 kortelė
Klausimas
Which term describes a secreted antigen-binding immunoglobulin?
Atsakymas
an antibody
652 kortelė
Klausimas
Which term describes the lymphocyte lineage that produces antibody-secreting cells?
Atsakymas
a B lymphocyte
653 kortelė
Klausimas
What is a helper T cell?
Atsakymas
A lymphocyte that coordinates immune responses through contact signals and cytokines.
654 kortelė
Klausimas
What is an immune memory cell?
Atsakymas
A long-lived lymphocyte that responds rapidly after re-exposure to its antigen.
655 kortelė
Klausimas
What is vaccination?
Atsakymas
Deliberate exposure to a safe form or component of an antigen to generate protective immune memory.
656 kortelė
Klausimas
What is an antibiotic?
Atsakymas
A substance that kills bacteria or inhibits their growth at clinically useful doses.
657 kortelė
Klausimas
Which term describes the T cell that coordinates other immune cells?
Atsakymas
a helper T cell
658 kortelė
Klausimas
Which term describes a long-lived lymphocyte enabling faster re-exposure response?
Atsakymas
an immune memory cell
659 kortelė
Klausimas
Which term describes safe antigen exposure used to create immune memory?
Atsakymas
vaccination
660 kortelė
Klausimas
Which term describes a drug acting against bacteria?
Atsakymas
an antibiotic
661 kortelė
Klausimas
What are examples of first-line defenses against pathogens?
Atsakymas
Intact skin, mucus, cilia, antimicrobial secretions, stomach acidity, and competing microbiota.
662 kortelė
Klausimas
How does inflammation help defend damaged tissue?
Atsakymas
It increases local blood flow and vessel permeability and recruits immune cells and defensive molecules.
663 kortelė
Klausimas
What happens during phagocytosis?
Atsakymas
A cell surrounds a particle in a vesicle, then fuses it with digestive compartments to destroy or process it.
664 kortelė
Klausimas
How can antibodies help eliminate a pathogen?
Atsakymas
They can neutralize targets, block attachment, clump particles, and mark them for phagocytosis or complement attack.
665 kortelė
Klausimas
Why can a vaccine generate protection without causing the full disease?
Atsakymas
It presents antigen in a weakened, inactivated, partial, or encoded form that stimulates immunity with much lower risk.
666 kortelė
Klausimas
Why do antibiotics not treat viral infections?
Atsakymas
Viruses lack the bacterial structures and independent metabolic processes targeted by antibiotics.
667 kortelė
Klausimas
What determines the antigen specificity of a lymphocyte?
Atsakymas
The molecular shape and chemistry of its unique surface receptor.
668 kortelė
Klausimas
What is clonal selection?
Atsakymas
An antigen activates lymphocytes with matching receptors, causing them to proliferate and differentiate.
669 kortelė
Klausimas
Why is a secondary adaptive immune response usually faster and stronger?
Atsakymas
Memory cells are more numerous and activate rapidly, producing effective cells and antibodies sooner.
670 kortelė
Klausimas
How can high vaccination coverage protect some unvaccinated people?
Atsakymas
Reduced transmission makes encounters with infectious individuals less likely, though protection is incomplete and pathogen-dependent.
671 kortelė
Klausimas
How does antibiotic use select for resistant bacteria?
Atsakymas
Susceptible bacteria are removed while resistant variants survive and reproduce, increasing resistance-allele frequency.
672 kortelė
Klausimas
Why can unnecessary or incomplete antibiotic exposure promote resistance?
Atsakymas
It creates selection favoring resistant cells while potentially leaving surviving bacteria to multiply and spread.
673 kortelė
Klausimas
What is an allergy?
Atsakymas
An immune response to a normally harmless antigen that causes tissue symptoms or damage.
674 kortelė
Klausimas
What is asexual reproduction?
Atsakymas
Production of offspring from one parent without fusion of gametes.
675 kortelė
Klausimas
What is sexual reproduction?
Atsakymas
Production of offspring involving fusion of haploid gametes.
676 kortelė
Klausimas
What is a gamete?
Atsakymas
A haploid reproductive cell able to fuse with another gamete.
677 kortelė
Klausimas
What is fertilization?
Atsakymas
Fusion of gamete nuclei to form a diploid zygote.
678 kortelė
Klausimas
Which term describes reproduction without gamete fusion?
Atsakymas
asexual reproduction
679 kortelė
Klausimas
Which term describes reproduction involving gamete fusion?
Atsakymas
sexual reproduction
680 kortelė
Klausimas
Which term describes a haploid reproductive cell?
Atsakymas
a gamete
681 kortelė
Klausimas
Which term describes fusion of gamete nuclei?
Atsakymas
fertilization
682 kortelė
Klausimas
What is a zygote?
Atsakymas
The diploid cell formed by fertilization.
683 kortelė
Klausimas
What is meiosis?
Atsakymas
Cell division that halves chromosome number and usually produces genetically varied haploid cells.
684 kortelė
Klausimas
What is ovulation?
Atsakymas
Release of a secondary oocyte from an ovary.
685 kortelė
Klausimas
What is implantation?
Atsakymas
Attachment and embedding of an early embryo in the uterine lining.
686 kortelė
Klausimas
Which term describes the first diploid cell after fertilization?
Atsakymas
a zygote
687 kortelė
Klausimas
Which term describes division producing varied haploid cells?
Atsakymas
meiosis
688 kortelė
Klausimas
Which term describes release of an oocyte from an ovary?
Atsakymas
ovulation
689 kortelė
Klausimas
Which term describes embedding of an early embryo in the uterine lining?
Atsakymas
implantation
690 kortelė
Klausimas
What is the placenta?
Atsakymas
A temporary organ that exchanges materials between maternal and fetal blood supplies without normally mixing them directly.
691 kortelė
Klausimas
What is pollination?
Atsakymas
Transfer of pollen from an anther to a receptive stigma.
692 kortelė
Klausimas
Why does sexual reproduction usually produce more genetic variation than asexual reproduction?
Atsakymas
Meiosis reshuffles alleles and random fertilization combines genomes from two gametes.
693 kortelė
Klausimas
Why must gametes be haploid?
Atsakymas
Fusion of two haploid gametes restores the diploid chromosome number instead of doubling it each generation.
694 kortelė
Klausimas
Which term describes the maternal-fetal exchange organ?
Atsakymas
the placenta
695 kortelė
Klausimas
Which term describes transfer of pollen to a stigma?
Atsakymas
pollination
696 kortelė
Klausimas
What are major roles of FSH in the ovarian cycle?
Atsakymas
It stimulates follicle development and supports estrogen secretion.
697 kortelė
Klausimas
What is a major role of the mid-cycle LH surge?
Atsakymas
It triggers ovulation and formation of the corpus luteum.
698 kortelė
Klausimas
How does estrogen contribute to the uterine cycle?
Atsakymas
It promotes repair and thickening of the uterine lining after menstruation.
699 kortelė
Klausimas
How does progesterone contribute to the uterine cycle?
Atsakymas
It maintains a thick, secretory uterine lining after ovulation.
700 kortelė
Klausimas
Where does human fertilization usually occur?
Atsakymas
In an oviduct, before the early embryo reaches the uterus.
701 kortelė
Klausimas
What happens after compatible pollen reaches a flower's stigma?
Atsakymas
A pollen tube grows toward an ovule and delivers male nuclei for fertilization.
702 kortelė
Klausimas
Why does menstruation usually begin if pregnancy does not occur?
Atsakymas
The corpus luteum degenerates, progesterone and estrogen fall, and the uterine lining is no longer maintained.
703 kortelė
Klausimas
What substances commonly cross the placenta between mother and fetus?
Atsakymas
Oxygen and nutrients move toward the fetus; carbon dioxide and nitrogenous wastes move toward the mother.
704 kortelė
Klausimas
How can contraception prevent pregnancy in different ways?
Atsakymas
Methods can inhibit ovulation, block sperm from reaching an egg, prevent fertilization, or permanently interrupt the reproductive ducts.
705 kortelė
Klausimas
What is homeostasis?
Atsakymas
Maintenance of internal conditions within ranges compatible with normal function despite change.
706 kortelė
Klausimas
What is negative feedback?
Atsakymas
Control in which a deviation triggers responses that oppose the original change.
707 kortelė
Klausimas
What is a set point?
Atsakymas
The target value or range around which a regulated variable is maintained.
708 kortelė
Klausimas
What is a homeostatic receptor?
Atsakymas
A sensor that detects a change in a regulated variable.
709 kortelė
Klausimas
Which term describes maintenance of a stable functional internal environment?
Atsakymas
homeostasis
710 kortelė
Klausimas
Which term describes feedback that counteracts a deviation?
Atsakymas
negative feedback
711 kortelė
Klausimas
Which term describes the target around which a variable is regulated?
Atsakymas
a set point
712 kortelė
Klausimas
Which term describes the sensor in a feedback system?
Atsakymas
a homeostatic receptor
713 kortelė
Klausimas
What is a control center?
Atsakymas
The component that compares information with a target and coordinates a response.
714 kortelė
Klausimas
What is an effector?
Atsakymas
A muscle, gland, or other component that carries out a control response.
715 kortelė
Klausimas
What is thermoregulation?
Atsakymas
Control of body temperature within a functional range.
716 kortelė
Klausimas
What is vasodilation?
Atsakymas
Widening of blood vessels, often increasing blood flow near the skin.
717 kortelė
Klausimas
Which term describes the feedback component that evaluates input and directs a response?
Atsakymas
a control center
718 kortelė
Klausimas
Which term describes the component that executes a physiological response?
Atsakymas
an effector
719 kortelė
Klausimas
Which term describes physiological regulation of body temperature?
Atsakymas
thermoregulation
720 kortelė
Klausimas
Which term describes widening of blood vessels?
Atsakymas
vasodilation
721 kortelė
Klausimas
What is vasoconstriction?
Atsakymas
Narrowing of blood vessels, often reducing blood flow near the skin.
722 kortelė
Klausimas
What is insulin?
Atsakymas
A pancreatic hormone that lowers elevated blood glucose by promoting uptake and storage.
723 kortelė
Klausimas
What is glucagon?
Atsakymas
A pancreatic hormone that raises low blood glucose by promoting release of stored fuel.
724 kortelė
Klausimas
What are the main components of a homeostatic feedback loop?
Atsakymas
A regulated variable, receptor, control center, effectors, and responses that alter the variable.
725 kortelė
Klausimas
Which term describes narrowing of blood vessels?
Atsakymas
vasoconstriction
726 kortelė
Klausimas
Which term describes the pancreatic hormone that lowers blood glucose?
Atsakymas
insulin
727 kortelė
Klausimas
Which term describes the pancreatic hormone that raises blood glucose?
Atsakymas
glucagon
728 kortelė
Klausimas
What happens when blood glucose rises after a meal?
Atsakymas
Insulin secretion increases, promoting glucose uptake and storage so blood glucose falls toward its normal range.
729 kortelė
Klausimas
What happens when blood glucose falls during fasting?
Atsakymas
Glucagon secretion increases, promoting glycogen breakdown and glucose release by the liver.
730 kortelė
Klausimas
How does sweating cool the body?
Atsakymas
Evaporation of water from skin transfers heat to the environment.
731 kortelė
Klausimas
How does skin vasodilation increase heat loss?
Atsakymas
It brings more warm blood near the surface, increasing transfer of heat to the environment.
732 kortelė
Klausimas
How does shivering warm the body?
Atsakymas
Rapid involuntary muscle contractions increase respiration and heat production.
733 kortelė
Klausimas
Does homeostasis keep internal conditions perfectly constant?
Atsakymas
No. Variables fluctuate within controlled ranges around target values.
734 kortelė
Klausimas
How does ADH help conserve water?
Atsakymas
It increases water permeability in kidney collecting ducts, so more water is reabsorbed and urine becomes more concentrated.
735 kortelė
Klausimas
How should ADH secretion change during dehydration?
Atsakymas
It should increase, promoting greater water reabsorption by the kidneys.
736 kortelė
Klausimas
How does positive feedback differ from negative feedback?
Atsakymas
Positive feedback amplifies a change until an endpoint; negative feedback opposes a change and stabilizes a variable.
737 kortelė
Klausimas
Why can diabetes mellitus cause persistently high blood glucose?
Atsakymas
Insulin production may be insufficient or target cells may respond poorly to insulin.
738 kortelė
Klausimas
What is biological evolution?
Atsakymas
Change in heritable characteristics or allele frequencies of a population across generations.
739 kortelė
Klausimas
What is allele frequency?
Atsakymas
The proportion of gene copies in a population represented by a particular allele.
740 kortelė
Klausimas
What is microevolution?
Atsakymas
Evolutionary change in allele frequencies within populations over relatively short timescales.
741 kortelė
Klausimas
What is speciation?
Atsakymas
Evolutionary formation of new species.
742 kortelė
Klausimas
Which term describes change in a population's heritable composition across generations?
Atsakymas
biological evolution
743 kortelė
Klausimas
Which term describes the proportion of a population's gene copies that are one allele?
Atsakymas
allele frequency
744 kortelė
Klausimas
Which term describes short-timescale allele-frequency change within populations?
Atsakymas
microevolution
745 kortelė
Klausimas
Which term describes formation of new species?
Atsakymas
speciation
746 kortelė
Klausimas
What is reproductive isolation?
Atsakymas
Barriers that prevent or greatly reduce gene flow between populations.
747 kortelė
Klausimas
What is allopatric speciation?
Atsakymas
Speciation after populations become geographically separated and diverge.
748 kortelė
Klausimas
What is sympatric speciation?
Atsakymas
Speciation without geographic separation, through reproductive isolation within the same area.
749 kortelė
Klausimas
What are homologous structures?
Atsakymas
Structures similar because they were inherited from a common ancestor, even if their functions differ.
750 kortelė
Klausimas
Which term describes barriers reducing gene flow between populations?
Atsakymas
reproductive isolation
751 kortelė
Klausimas
Which term describes speciation following geographic separation?
Atsakymas
allopatric speciation
752 kortelė
Klausimas
Which term describes speciation within the same geographic area?
Atsakymas
sympatric speciation
753 kortelė
Klausimas
Which term describes structures similar through common ancestry?
Atsakymas
homologous structures
754 kortelė
Klausimas
What are analogous structures?
Atsakymas
Structures with similar functions that evolved independently rather than from the same ancestral structure.
755 kortelė
Klausimas
What is a common ancestor?
Atsakymas
An ancestral population from which two or more descendant lineages evolved.
756 kortelė
Klausimas
How does the fossil record provide evidence for evolution?
Atsakymas
It documents organisms from different times, including appearance, change, persistence, and extinction of lineages.
757 kortelė
Klausimas
How do DNA and protein sequences provide evidence of common ancestry?
Atsakymas
Shared sequences are inherited; greater similarity generally indicates more recent common ancestry.
758 kortelė
Klausimas
Which term describes functionally similar structures of independent evolutionary origin?
Atsakymas
analogous structures
759 kortelė
Klausimas
Which term describes an ancestral population shared by descendant lineages?
Atsakymas
a common ancestor
760 kortelė
Klausimas
What is the evolutionary significance of extinction?
Atsakymas
It permanently ends a lineage and can alter ecological opportunities and the future diversification of survivors.
761 kortelė
Klausimas
Do individual organisms evolve during their lifetimes?
Atsakymas
No. Individuals develop and acclimate; evolution is heritable change in populations across generations.
762 kortelė
Klausimas
Why is evolution represented as a branching tree rather than a ladder?
Atsakymas
Lineages split from common ancestors; living species are not arranged as stages toward a single goal.
763 kortelė
Klausimas
How can island species support evolutionary explanations?
Atsakymas
Their similarities to nearby mainland ancestors and unique local adaptations fit divergence after colonization and isolation.
764 kortelė
Klausimas
How can geographic isolation lead to reproductive isolation?
Atsakymas
Separated populations accumulate different mutations and experience different selection and drift until interbreeding is reduced.
765 kortelė
Klausimas
Why can continuing gene flow slow speciation?
Atsakymas
Movement of alleles between populations counteracts genetic divergence.
766 kortelė
Klausimas
Why can unrelated species evolve similar traits?
Atsakymas
Similar environmental challenges can favor similar functional solutions through convergent evolution.
767 kortelė
Klausimas
Which parts of evolution are random and which are nonrandom?
Atsakymas
Mutation and many sampling effects are random with respect to need; natural selection nonrandomly favors variants that reproduce better in a given environment.
768 kortelė
Klausimas
What is conservation biology?
Atsakymas
The science and practice of protecting biodiversity, ecological processes, and evolutionary potential.
769 kortelė
Klausimas
What is habitat fragmentation?
Atsakymas
Division of continuous habitat into smaller, isolated patches.
770 kortelė
Klausimas
What is an endangered species?
Atsakymas
A species facing a high risk of extinction in the wild.
771 kortelė
Klausimas
What is in situ conservation?
Atsakymas
Protection of species in their natural habitats and ecological communities.
772 kortelė
Klausimas
Which term describes the protection of biodiversity and ecological processes?
Atsakymas
conservation biology
773 kortelė
Klausimas
Which term describes division of habitat into isolated patches?
Atsakymas
habitat fragmentation
774 kortelė
Klausimas
Which term describes a species at high risk of extinction?
Atsakymas
an endangered species
775 kortelė
Klausimas
Which term describes conservation within natural habitat?
Atsakymas
in situ conservation
776 kortelė
Klausimas
What is ex situ conservation?
Atsakymas
Protection of organisms or genetic material outside the natural habitat.
777 kortelė
Klausimas
What is a population bottleneck?
Atsakymas
A sharp population reduction that can remove genetic variation by chance.
778 kortelė
Klausimas
What is a wildlife corridor?
Atsakymas
Habitat connecting isolated patches to permit movement and gene flow.
779 kortelė
Klausimas
What major human-driven processes threaten biodiversity?
Atsakymas
Habitat loss, overexploitation, invasive species, pollution, and climate change.
780 kortelė
Klausimas
Which term describes conservation outside natural habitat?
Atsakymas
ex situ conservation
781 kortelė
Klausimas
Which term describes a severe population reduction that loses genetic diversity?
Atsakymas
a population bottleneck
782 kortelė
Klausimas
Which term describes habitat linking isolated populations?
Atsakymas
a wildlife corridor
783 kortelė
Klausimas
What makes a protected area more effective than a boundary alone?
Atsakymas
Adequate size, representative habitat, enforcement, connectivity, local support, and management of external threats.
784 kortelė
Klausimas
Why is long-term population monitoring important in conservation?
Atsakymas
It reveals trends, tests whether management works, and provides early warning of decline.
785 kortelė
Klausimas
How can ecosystem services support the case for conservation?
Atsakymas
Healthy ecosystems provide benefits such as pollination, water purification, carbon storage, soil formation, and cultural value.
786 kortelė
Klausimas
Why are very small populations especially vulnerable to extinction?
Atsakymas
Chance events, inbreeding, low genetic diversity, and difficulty finding mates can reinforce decline.
787 kortelė
Klausimas
What are benefits and limits of captive-breeding programs?
Atsakymas
They can prevent immediate extinction and manage breeding, but may lose diversity, alter behavior, and fail without safe habitat for release.
788 kortelė
Klausimas
Why can controlling an invasive species aid conservation?
Atsakymas
It can reduce predation, competition, disease, or habitat alteration affecting native species.
789 kortelė
Klausimas
Why must conservation priorities consider more than species count?
Atsakymas
Endemism, evolutionary distinctness, ecological roles, threat severity, feasibility, and human needs also matter.
790 kortelė
Klausimas
What is an adaptation?
Atsakymas
A heritable characteristic that increases reproductive success in a particular environment.
791 kortelė
Klausimas
What is acclimation?
Atsakymas
A reversible physiological or behavioral adjustment by an individual to environmental change.
792 kortelė
Klausimas
What is a structural adaptation?
Atsakymas
An inherited anatomical feature that improves performance in an environment.
793 kortelė
Klausimas
What is a physiological adaptation?
Atsakymas
An inherited functional or biochemical feature that improves performance in an environment.
794 kortelė
Klausimas
Which term describes a heritable trait improving reproductive success in context?
Atsakymas
an adaptation
795 kortelė
Klausimas
Which term describes an individual's reversible adjustment to environmental change?
Atsakymas
acclimation
796 kortelė
Klausimas
Which term describes an adaptive anatomical feature?
Atsakymas
a structural adaptation
797 kortelė
Klausimas
Which term describes an adaptive functional or biochemical feature?
Atsakymas
a physiological adaptation
798 kortelė
Klausimas
What is a behavioral adaptation?
Atsakymas
An inherited behavior pattern that improves survival or reproduction.
799 kortelė
Klausimas
What is an environmental tolerance range?
Atsakymas
The range of an abiotic condition within which an organism can survive and reproduce.
800 kortelė
Klausimas
What is evolutionary fitness?
Atsakymas
Relative contribution of an individual or genotype to future generations.
801 kortelė
Klausimas
How can a thick cuticle and reduced leaves help a desert plant?
Atsakymas
The cuticle lowers surface permeability, while smaller leaves reduce the area from which water can evaporate.
802 kortelė
Klausimas
Which term describes an adaptive behavior pattern?
Atsakymas
a behavioral adaptation
803 kortelė
Klausimas
Which term describes the survivable range of an abiotic condition?
Atsakymas
an environmental tolerance range
804 kortelė
Klausimas
Which term describes relative reproductive contribution to future generations?
Atsakymas
evolutionary fitness
805 kortelė
Klausimas
How can a streamlined body adapt an aquatic animal to movement?
Atsakymas
It reduces drag, lowering the energy needed to move through water.
806 kortelė
Klausimas
Does an organism develop an adaptation because it needs one?
Atsakymas
No. Heritable variants arise without regard to need, and selection changes their frequencies across generations.
807 kortelė
Klausimas
Why may organisms from different thermal environments have enzymes with different temperature optima?
Atsakymas
Selection favors protein structures that balance flexibility and stability under local temperatures.
808 kortelė
Klausimas
Why is an adaptation rarely beneficial in every environment?
Atsakymas
Traits carry costs and their advantage depends on local resources, competitors, predators, and physical conditions.
809 kortelė
Klausimas
How does phenotypic plasticity differ from genetic adaptation?
Atsakymas
Plasticity lets one genotype produce different phenotypes; adaptation is a heritable population trait shaped across generations.
810 kortelė
Klausimas
What is local adaptation?
Atsakymas
A population has higher fitness in its home environment than foreign populations because selection favored local traits.
811 kortelė
Klausimas
What is an ecological niche?
Atsakymas
The set of environmental conditions, resources, interactions, and functional roles associated with a species.
812 kortelė
Klausimas
What is a habitat?
Atsakymas
The physical place or environment where an organism lives.
813 kortelė
Klausimas
What is a fundamental niche?
Atsakymas
The full range of conditions and resources a species could use without limiting biotic interactions.
814 kortelė
Klausimas
What is a realized niche?
Atsakymas
The conditions and resources a species actually uses after competition and other interactions.
815 kortelė
Klausimas
Which term describes a species' environmental requirements and ecological role?
Atsakymas
an ecological niche
816 kortelė
Klausimas
Which term describes the place where an organism lives?
Atsakymas
a habitat
817 kortelė
Klausimas
Which term describes the potential niche without limiting biotic interactions?
Atsakymas
a fundamental niche
818 kortelė
Klausimas
Which term describes the niche actually occupied in nature?
Atsakymas
a realized niche
819 kortelė
Klausimas
What is competition?
Atsakymas
An interaction in which organisms reduce one another's access to a limited resource.
820 kortelė
Klausimas
What is mutualism?
Atsakymas
An interaction in which both participating species benefit.
821 kortelė
Klausimas
What is predation?
Atsakymas
An interaction in which one organism kills and consumes another.
822 kortelė
Klausimas
How does a habitat differ from a niche?
Atsakymas
A habitat is where an organism lives; a niche includes how it uses conditions and resources and interacts there.
823 kortelė
Klausimas
Which term describes an interaction over a limited resource that harms both competitors?
Atsakymas
competition
824 kortelė
Klausimas
Which term describes an interspecific interaction benefiting both partners?
Atsakymas
mutualism
825 kortelė
Klausimas
Which term describes an interaction where one organism kills and eats another?
Atsakymas
predation
826 kortelė
Klausimas
What kinds of factors define a niche?
Atsakymas
Abiotic factors such as temperature and moisture, plus biotic factors such as food, competitors, predators, and partners.
827 kortelė
Klausimas
What does competitive exclusion predict?
Atsakymas
Species with effectively identical niches cannot coexist indefinitely under stable conditions; one is excluded or niches diverge.
828 kortelė
Klausimas
How can resource partitioning reduce competition?
Atsakymas
Species use different resources, places, or times, reducing niche overlap.
829 kortelė
Klausimas
What is a keystone species?
Atsakymas
A species whose effect on community structure is disproportionately large relative to its abundance.
830 kortelė
Klausimas
Why can an introduced species expand rapidly in a new community?
Atsakymas
It may encounter abundant resources, suitable climate, and fewer predators, pathogens, or competitors.
831 kortelė
Klausimas
Can an organism alter the niche conditions of other species?
Atsakymas
Yes. Ecosystem engineers modify habitat structure or resource availability, changing opportunities for other organisms.
832 kortelė
Klausimas
What is a population?
Atsakymas
Individuals of the same species living in the same area at the same time.
833 kortelė
Klausimas
What is an ecological community?
Atsakymas
Populations of different species living and interacting in an area.
834 kortelė
Klausimas
What is an ecosystem?
Atsakymas
A community together with its physical environment and their interactions.
835 kortelė
Klausimas
What is carrying capacity?
Atsakymas
The population size an environment can sustain over time under given conditions.
836 kortelė
Klausimas
Which term describes same-species individuals sharing an area and time?
Atsakymas
a population
837 kortelė
Klausimas
Which term describes interacting populations of different species?
Atsakymas
an ecological community
838 kortelė
Klausimas
Which term describes a community plus its abiotic environment?
Atsakymas
an ecosystem
839 kortelė
Klausimas
Which term describes the long-term supportable population size?
Atsakymas
carrying capacity
840 kortelė
Klausimas
What is population density?
Atsakymas
The number of individuals per unit area or volume.
841 kortelė
Klausimas
What is a limiting factor?
Atsakymas
A resource or condition that restricts population growth or distribution.
842 kortelė
Klausimas
What is a density-dependent factor?
Atsakymas
A factor whose effect strengthens as population density increases.
843 kortelė
Klausimas
What is a density-independent factor?
Atsakymas
A factor whose effect is not primarily determined by population density.
844 kortelė
Klausimas
Which term describes individuals per unit area or volume?
Atsakymas
population density
845 kortelė
Klausimas
Which term describes a resource or condition restricting a population?
Atsakymas
a limiting factor
846 kortelė
Klausimas
Which term describes a factor with stronger effects at higher density?
Atsakymas
a density-dependent factor
847 kortelė
Klausimas
Which term describes a factor acting largely regardless of population density?
Atsakymas
a density-independent factor
848 kortelė
Klausimas
What is exponential population growth?
Atsakymas
Growth at a constant per-capita rate, producing a J-shaped curve under ideal conditions.
849 kortelė
Klausimas
What is logistic population growth?
Atsakymas
Growth that slows as population size approaches carrying capacity, producing an S-shaped model.
850 kortelė
Klausimas
What four processes directly change population size?
Atsakymas
Births and immigration increase it; deaths and emigration decrease it.
851 kortelė
Klausimas
Under what conditions can exponential growth occur temporarily?
Atsakymas
Resources are abundant and limiting effects such as competition, disease, and predation are weak.
852 kortelė
Klausimas
Which term describes J-shaped growth at constant per-capita rate?
Atsakymas
exponential population growth
853 kortelė
Klausimas
Which term describes S-shaped growth that slows near carrying capacity?
Atsakymas
logistic population growth
854 kortelė
Klausimas
Why is infectious disease often density dependent?
Atsakymas
Close or frequent contact at high density increases transmission opportunities.
855 kortelė
Klausimas
Give an example of a density-independent population factor.
Atsakymas
A severe storm, wildfire, drought, or freeze can affect populations regardless of their initial density.
856 kortelė
Klausimas
When is quadrat sampling useful?
Atsakymas
For estimating abundance or frequency of sessile or slow-moving organisms in defined areas.
857 kortelė
Klausimas
What can a transect reveal?
Atsakymas
How species occurrence or abundance changes along an environmental gradient.
858 kortelė
Klausimas
What can happen when a population overshoots carrying capacity?
Atsakymas
Resource depletion may raise mortality or lower reproduction, causing decline or oscillation.
859 kortelė
Klausimas
What is the basic mark–recapture estimate of population size?
Atsakymas
First sample marked × second sample total ÷ marked individuals recaptured.
860 kortelė
Klausimas
What assumptions improve a mark–recapture estimate?
Atsakymas
Marks persist and do not affect survival, marked individuals mix, capture probability is similar, and the population is effectively closed.
861 kortelė
Klausimas
Why does a correlation between two population variables not prove causation?
Atsakymas
A third factor, reverse influence, chance, or biased sampling could produce the association.
862 kortelė
Klausimas
What is a trophic level?
Atsakymas
A feeding position in a food chain or web.
863 kortelė
Klausimas
What is a producer?
Atsakymas
An autotroph that converts inorganic carbon into organic matter.
864 kortelė
Klausimas
What is a consumer?
Atsakymas
An organism obtaining energy and matter by eating other organisms or organic material.
865 kortelė
Klausimas
What is a decomposer?
Atsakymas
An organism that externally digests dead material and wastes and absorbs the products.
866 kortelė
Klausimas
Which term describes a feeding position in an ecosystem?
Atsakymas
a trophic level
867 kortelė
Klausimas
Which term describes an autotroph forming organic matter?
Atsakymas
a producer
868 kortelė
Klausimas
Which term describes an organism feeding on other organic matter?
Atsakymas
a consumer
869 kortelė
Klausimas
Which term describes an organism digesting dead organic matter externally?
Atsakymas
a decomposer
870 kortelė
Klausimas
What is a food chain?
Atsakymas
A linear representation of feeding and energy-transfer relationships.
871 kortelė
Klausimas
What is a food web?
Atsakymas
A network of interconnected feeding relationships in a community.
872 kortelė
Klausimas
What is gross primary productivity?
Atsakymas
The total rate at which producers capture energy into organic matter.
873 kortelė
Klausimas
What is net primary productivity?
Atsakymas
Producer energy stored as new biomass after subtracting producer respiration from gross primary productivity.
874 kortelė
Klausimas
Which term describes a linear feeding sequence?
Atsakymas
a food chain
875 kortelė
Klausimas
Which term describes a network of connected food chains?
Atsakymas
a food web
876 kortelė
Klausimas
Which term describes the total producer energy-capture rate?
Atsakymas
gross primary productivity
877 kortelė
Klausimas
Which term describes producer biomass gain after respiration?
Atsakymas
net primary productivity
878 kortelė
Klausimas
What is ecological productivity?
Atsakymas
The rate of biomass or energy production per unit area or volume.
879 kortelė
Klausimas
What is a biogeochemical cycle?
Atsakymas
Movement of an element or compound through organisms and the physical environment.
880 kortelė
Klausimas
Why is less energy available at each higher trophic level?
Atsakymas
Not all biomass is eaten or digested, and organisms use energy in respiration, movement, maintenance, and heat loss.
881 kortelė
Klausimas
Why does energy flow rather than cycle through an ecosystem?
Atsakymas
Energy enters mainly as light and ultimately disperses as heat, which ecosystems cannot fully recycle.
882 kortelė
Klausimas
Which term describes the rate of biomass or energy production?
Atsakymas
ecological productivity
883 kortelė
Klausimas
Which term describes cycling of matter through living and nonliving reservoirs?
Atsakymas
a biogeochemical cycle
884 kortelė
Klausimas
Why can matter cycle through an ecosystem?
Atsakymas
Atoms are conserved and repeatedly transferred among organisms, detritus, soil, water, and atmosphere.
885 kortelė
Klausimas
Why is a pyramid of energy always upright?
Atsakymas
Usable energy decreases between trophic levels because every transfer includes losses.
886 kortelė
Klausimas
How are gross and net primary productivity related?
Atsakymas
NPP = GPP − producer respiration.
887 kortelė
Klausimas
How do decomposers support nutrient cycling?
Atsakymas
They break down dead material and wastes, releasing inorganic nutrients for reuse.
888 kortelė
Klausimas
What processes move carbon rapidly between organisms and the atmosphere?
Atsakymas
Photosynthesis removes carbon dioxide; respiration, decomposition, and combustion release it.
889 kortelė
Klausimas
Why is nitrogen fixation important?
Atsakymas
It converts atmospheric nitrogen gas into forms that can enter biological nitrogen metabolism.
890 kortelė
Klausimas
How can excess nitrogen or phosphorus cause eutrophication?
Atsakymas
Nutrient enrichment drives algal growth; decomposition of the biomass consumes oxygen and can create hypoxic water.
891 kortelė
Klausimas
Why can a persistent pollutant reach higher concentrations at higher trophic levels?
Atsakymas
Predators consume contaminant stored in many prey, and the substance is not readily broken down or excreted.
892 kortelė
Klausimas
How is trophic-transfer efficiency calculated?
Atsakymas
Energy or biomass gained by the higher trophic level ÷ energy or biomass available at the lower level × 100%.
893 kortelė
Klausimas
What is phenotypic variation?
Atsakymas
Differences in observable traits among individuals of a population.
894 kortelė
Klausimas
What is heritable variation?
Atsakymas
Trait differences that can be transmitted genetically to offspring.
895 kortelė
Klausimas
What is a selection pressure?
Atsakymas
An environmental factor causing differences in survival or reproduction among phenotypes.
896 kortelė
Klausimas
What is relative fitness?
Atsakymas
An individual's reproductive success compared with others in the population.
897 kortelė
Klausimas
Which term describes observable differences among individuals?
Atsakymas
phenotypic variation
898 kortelė
Klausimas
Which term describes genetically transmissible trait differences?
Atsakymas
heritable variation
899 kortelė
Klausimas
Which term describes an environmental factor producing differential reproductive success?
Atsakymas
a selection pressure
900 kortelė
Klausimas
Which term describes reproductive success relative to other individuals?
Atsakymas
relative fitness
901 kortelė
Klausimas
What is directional selection?
Atsakymas
Selection favoring one extreme phenotype and shifting a population's trait distribution.
902 kortelė
Klausimas
What is stabilizing selection?
Atsakymas
Selection favoring intermediate phenotypes and acting against extremes.
903 kortelė
Klausimas
What is disruptive selection?
Atsakymas
Selection favoring both extreme phenotypes over intermediates.
904 kortelė
Klausimas
What is sexual selection?
Atsakymas
Selection arising from differences in mating success.
905 kortelė
Klausimas
Which term describes selection shifting a trait toward one extreme?
Atsakymas
directional selection
906 kortelė
Klausimas
Which term describes selection favoring intermediate phenotypes?
Atsakymas
stabilizing selection
907 kortelė
Klausimas
Which term describes selection favoring both trait extremes?
Atsakymas
disruptive selection
908 kortelė
Klausimas
Which term describes selection caused by unequal mating success?
Atsakymas
sexual selection
909 kortelė
Klausimas
What conditions are required for natural selection?
Atsakymas
Individuals vary, some variation is heritable, more offspring are produced than can reproduce, and variants differ in reproductive success.
910 kortelė
Klausimas
How does natural selection produce antibiotic-resistant bacterial populations?
Atsakymas
Existing resistant variants survive treatment and reproduce more than susceptible bacteria.
911 kortelė
Klausimas
Does an antibiotic cause bacteria to mutate specifically toward resistance?
Atsakymas
No. Resistance variants arise without regard to need; treatment selects among them.
912 kortelė
Klausimas
Can an individual become genetically adapted through natural selection?
Atsakymas
No. Selection acts on individuals, but adaptation is a population change across generations.
913 kortelė
Klausimas
How does artificial selection differ from natural selection?
Atsakymas
Humans choose breeding traits in artificial selection; environmental conditions determine differential reproduction in natural selection.
914 kortelė
Klausimas
How does natural selection change a population?
Atsakymas
Individuals with advantageous heritable variants leave more offspring, increasing those alleles over generations.
915 kortelė
Klausimas
Why is fitness environment-dependent?
Atsakymas
A trait that improves reproduction in one environment may be neutral or costly in another.
916 kortelė
Klausimas
How does genetic drift differ from natural selection?
Atsakymas
Drift changes allele frequencies by chance sampling; selection changes them through consistent fitness differences.
917 kortelė
Klausimas
What is ecosystem stability?
Atsakymas
The capacity of an ecosystem to maintain or recover its structure and functions despite disturbance.
918 kortelė
Klausimas
What is an ecological tipping point?
Atsakymas
A threshold beyond which feedbacks can drive a large and difficult-to-reverse ecosystem shift.
919 kortelė
Klausimas
What is a mesocosm?
Atsakymas
A controlled, simplified ecosystem used to investigate ecological processes under more realistic conditions than a small laboratory vessel.
920 kortelė
Klausimas
What is a sustainable yield?
Atsakymas
A harvest rate that can continue without causing long-term resource decline under prevailing conditions.
921 kortelė
Klausimas
Which term describes the capacity of an ecosystem to persist or recover after disturbance?
Atsakymas
ecosystem stability
922 kortelė
Klausimas
Which term describes a threshold triggering a major hard-to-reverse ecosystem shift?
Atsakymas
an ecological tipping point
923 kortelė
Klausimas
Which term describes a controlled model ecosystem used for experiments?
Atsakymas
a mesocosm
924 kortelė
Klausimas
Which term describes a harvest rate that avoids long-term depletion?
Atsakymas
a sustainable yield
925 kortelė
Klausimas
What is eutrophication?
Atsakymas
Nutrient enrichment of water that stimulates excess primary production and can lead to oxygen depletion.
926 kortelė
Klausimas
What is biomagnification?
Atsakymas
Increase in concentration of a persistent pollutant at successively higher trophic levels.
927 kortelė
Klausimas
What is rewilding?
Atsakymas
Ecosystem restoration that rebuilds natural processes, species interactions, and self-sustaining ecological function.
928 kortelė
Klausimas
What features can make an ecosystem more stable?
Atsakymas
Diverse functional roles, connected habitats, intact food webs, nutrient cycling, and balancing feedbacks can help the system resist or recover from disturbance.
929 kortelė
Klausimas
Which term describes nutrient enrichment that can deplete oxygen in water?
Atsakymas
eutrophication
930 kortelė
Klausimas
Which term describes increasing pollutant concentration up a food chain?
Atsakymas
biomagnification
931 kortelė
Klausimas
Which term describes restoration focused on natural processes and self-sustaining ecosystems?
Atsakymas
rewilding
932 kortelė
Klausimas
How could extensive Amazon deforestation push the ecosystem toward a tipping point?
Atsakymas
Loss of trees can reduce rainfall recycling and increase heat and fire, which cause further forest loss and may shift large areas toward a drier state.
933 kortelė
Klausimas
What are a benefit and a limitation of using a mesocosm?
Atsakymas
It allows controlled experiments with interacting organisms, but its simplified scale cannot reproduce every process or long-term influence in a natural ecosystem.
934 kortelė
Klausimas
Why should a fishery harvest below an uncertain maximum sustainable yield?
Atsakymas
Population estimates and recruitment vary, so a safety margin reduces the chance that error or a poor breeding year drives long-term decline.
935 kortelė
Klausimas
How can intensive agriculture reduce ecosystem stability?
Atsakymas
Habitat loss, low crop diversity, soil degradation, heavy water use, pesticides, and nutrient runoff can weaken food webs and ecosystem processes.
936 kortelė
Klausimas
Why can microplastic pollution harm aquatic ecosystems?
Atsakymas
Small persistent particles can be ingested, carry additives or other pollutants, damage feeding and tissues, and move through food webs.
937 kortelė
Klausimas
How can rewilding improve ecosystem stability?
Atsakymas
Restoring native species, habitat connections, and natural disturbance or grazing processes can rebuild feedbacks and allow the ecosystem to maintain itself with less intervention.
938 kortelė
Klausimas
What is the greenhouse effect?
Atsakymas
Warming caused when atmospheric gases absorb and re-emit outgoing infrared radiation.
939 kortelė
Klausimas
What is a greenhouse gas?
Atsakymas
An atmospheric gas that absorbs infrared radiation at wavelengths emitted by Earth.
940 kortelė
Klausimas
What is carbon dioxide (CO₂)?
Atsakymas
A long-lived greenhouse gas increased mainly by fossil-fuel combustion, cement production, and land-use change.
941 kortelė
Klausimas
What is methane (CH₄)?
Atsakymas
A potent greenhouse gas emitted by sources including fossil-fuel systems, livestock, rice cultivation, wetlands, and waste.
942 kortelė
Klausimas
Which term describes warming from absorption and re-emission of infrared radiation?
Atsakymas
the greenhouse effect
943 kortelė
Klausimas
Which term describes an atmospheric infrared-absorbing gas?
Atsakymas
a greenhouse gas
944 kortelė
Klausimas
Which term describes the long-lived greenhouse gas strongly increased by fossil fuels?
Atsakymas
carbon dioxide (CO₂)
945 kortelė
Klausimas
Which term describes the potent short-lived greenhouse gas from biological and fossil sources?
Atsakymas
methane (CH₄)
946 kortelė
Klausimas
What is albedo?
Atsakymas
The fraction of incoming radiation reflected by a surface.
947 kortelė
Klausimas
What is a carbon sink?
Atsakymas
A reservoir that absorbs more carbon than it releases over a specified period.
948 kortelė
Klausimas
What is ocean acidification?
Atsakymas
Decline in seawater pH caused mainly by absorption of human-emitted carbon dioxide.
949 kortelė
Klausimas
What is climate change?
Atsakymas
A persistent change in the statistical patterns of climate over decades or longer.
950 kortelė
Klausimas
Which term describes surface reflectivity?
Atsakymas
albedo
951 kortelė
Klausimas
Which term describes a reservoir with net carbon uptake?
Atsakymas
a carbon sink
952 kortelė
Klausimas
Which term describes seawater pH decline from absorbed carbon dioxide?
Atsakymas
ocean acidification
953 kortelė
Klausimas
Which term describes long-term change in climate patterns?
Atsakymas
climate change
954 kortelė
Klausimas
What is the enhanced greenhouse effect?
Atsakymas
Additional warming caused by human-driven increases in greenhouse-gas concentrations.
955 kortelė
Klausimas
How do climate mitigation and climate adaptation differ?
Atsakymas
Mitigation limits the magnitude of climate change; adaptation reduces harm from changes that occur.
956 kortelė
Klausimas
How does increasing greenhouse-gas concentration alter Earth's energy balance?
Atsakymas
Less outgoing infrared energy initially escapes to space, so the climate warms until energy balance is restored at a higher temperature.
957 kortelė
Klausimas
How can melting ice amplify warming?
Atsakymas
Less bright ice lowers albedo, so darker land or water absorbs more solar energy and causes further warming.
958 kortelė
Klausimas
How can climate change alter species distributions?
Atsakymas
Temperature, rainfall, seasons, sea level, and interactions shift, moving or shrinking areas with suitable conditions.
959 kortelė
Klausimas
Why can ocean acidification harm calcifying organisms?
Atsakymas
Carbonate chemistry changes, reducing availability of carbonate ions used to build calcium-carbonate structures.
960 kortelė
Klausimas
How can ecosystem protection contribute to climate mitigation?
Atsakymas
Protecting forests, wetlands, soils, and coastal habitats can avoid emissions and maintain or increase carbon storage.
960 kortelių
IB Biology SL Flashcards: Complete Course Review
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