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