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