AP Biology Flashcards: Complete 8-Unit Course Review
Review all 8 AP Biology units with original flashcards for concepts, pathways, experimental design, data interpretation, and FRQ reasoning.
Про цю колоду
AP Biology Flashcards: Complete 8-Unit Course Review
The current AP Biology framework covers eight units, from chemistry of life through ecology. This 540-card deck turns that full course into short, original retrieval prompts, with science-practice reasoning mixed into the biology instead of parked in a separate section.
What the cards practice
The cards connect terms to functions, structures to consequences, pathway steps to inputs, outputs, locations, and regulation, and evidence to biological claims. Separate prompts cover useful reverse mappings when they are real study tasks—for example, identifying a process from its location or choosing the inference supported by a result. Short original scenarios also practice describing patterns, explaining mechanisms, predicting changes, justifying claims, setting up calculations, and evaluating evidence.
The deck does not mechanically reverse every definition or pathway. It leaves out copied exam material, scoring language, official figures, exhaustive protocols, broad essay prompts, textbook-specific trivia, and advanced-college details outside the current course boundary.
Learning order
The sequence follows Units 1–8. Within each unit it moves from prerequisites to processes, applications, experiments, data, and FRQ-style reasoning, while spacing close variants apart. Long-term spacing and interleaving are left to the review scheduler.
What still needs practice
Flashcards are useful for recall and small reasoning moves, but they cannot replace laboratory work, graph construction, extended data analysis, or timed multiple-choice and free-response practice. Use the deck beside class labs and full original practice questions.
Scope and provenance
The course boundary was reviewed on September 1, 2026 against the College Board AP Biology course page, the Fall 2025 Course and Exam Description, its current clarifications and corrections, the 2026–27 course-change table, and the current exam page. The selection, prompts, answers, examples, sequence, metadata, and cover are independently created from common biological knowledge and source checks. No exam questions, scoring guidelines, CED text, answer keys, or official figures were copied or transformed.
The Common knowledge · CC0 1.0 label applies to the original wording, organization, metadata, and generated media to the extent applicable rights exist. It does not claim ownership of biological facts, AP or College Board names, or third-party source material.
This independent, unofficial study deck is not affiliated with, endorsed by, or sponsored by College Board. AP and College Board names identify the course and exam only. Official requirements: https://apcentral.collegeboard.org/courses/ap-biology
Картки в цій колоді
Картка 1
Питання
Why is a water molecule polar?
Відповідь
Oxygen pulls shared electrons more strongly than hydrogen, giving oxygen a partial negative charge and the hydrogens partial positive charges.
Картка 2
Питання
Which elements make up most biological molecules?
Відповідь
Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur—often shortened to CHNOPS.
Картка 3
Питання
What is the relationship between a monomer and a polymer?
Відповідь
Monomers are small building blocks; polymers are chains or networks made from repeated monomers.
Картка 4
Питання
What is a monosaccharide's main role in cells?
Відповідь
It can provide quick energy and serve as a building block for larger carbohydrates.
Картка 5
Питання
Why do lipids mix poorly with water?
Відповідь
Most of their bonds are nonpolar, so water cannot form favorable interactions with them.
Картка 6
Питання
What three parts make up a nucleotide?
Відповідь
A five-carbon sugar, a phosphate group, and a nitrogenous base.
Картка 7
Питання
What parts of an amino acid vary and stay constant?
Відповідь
The amino group, carboxyl group, hydrogen, and central carbon are shared; the side chain, or R group, varies.
Картка 8
Питання
What does pH measure?
Відповідь
The negative logarithm of hydrogen-ion concentration; lower pH means more hydrogen ions.
Картка 9
Питання
What is a hydrogen bond in liquid water?
Відповідь
A weak attraction between a partially positive hydrogen on one water molecule and a partially negative oxygen on another.
Картка 10
Питання
How does an unsaturated fatty acid differ from a saturated one?
Відповідь
An unsaturated fatty acid has at least one carbon–carbon double bond; a saturated fatty acid has none.
Картка 11
Питання
What bond links amino acids in a polypeptide?
Відповідь
A peptide bond.
Картка 12
Питання
What does dehydration synthesis do?
Відповідь
It joins subunits with a covalent bond while removing the elements of water.
Картка 13
Питання
How does cohesion help water move through a plant?
Відповідь
Hydrogen bonds keep water molecules linked, helping a continuous column rise through xylem.
Картка 14
Питання
How do plants and animals differ in short-term glucose storage?
Відповідь
Plants store glucose mainly as starch; animals store it mainly as glycogen.
Картка 15
Питання
What determines a protein's primary structure?
Відповідь
Its amino-acid sequence.
Картка 16
Питання
How does a cis double bond affect a fatty-acid tail?
Відповідь
It introduces a bend that prevents neighboring tails from packing tightly.
Картка 17
Питання
How does adhesion support water transport in narrow tubes?
Відповідь
Water sticks to polar surfaces, helping it resist gravity along cell walls.
Картка 18
Питання
Which base pairing distinguishes RNA from DNA?
Відповідь
RNA uses uracil, so adenine pairs with uracil instead of thymine.
Картка 19
Питання
What stabilizes common protein secondary structures?
Відповідь
Hydrogen bonds between atoms in the polypeptide backbone.
Картка 20
Питання
Why can carbon form so many biological structures?
Відповідь
It has four valence electrons and can form four stable covalent bonds, including chains, branches, and rings.
Картка 21
Питання
Why can some insects stand on water?
Відповідь
Cohesion among surface water molecules creates high surface tension.
Картка 22
Питання
What does hydrolysis do to a biological polymer?
Відповідь
It adds the elements of water to break a covalent bond between subunits.
Картка 23
Питання
What carbohydrate strengthens plant cell walls?
Відповідь
Cellulose.
Картка 24
Питання
Why are fats useful for long-term energy storage?
Відповідь
Their many C–H bonds store substantial chemical energy, and hydrophobic storage adds little water mass.
Картка 25
Питання
How does water buffer rapid temperature change?
Відповідь
Breaking and forming many hydrogen bonds absorbs or releases substantial heat, giving water a high specific heat.
Картка 26
Питання
What does antiparallel mean for a DNA double helix?
Відповідь
Its two strands run in opposite directions: one 5′→3′ and the other 3′→5′.
Картка 27
Питання
What mainly drives a protein's tertiary structure?
Відповідь
Interactions among side chains, including hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges.
Картка 28
Питання
What is a trace element?
Відповідь
An element an organism needs in very small amounts, such as iron in many electron-transfer proteins.
Картка 29
Питання
Why does sweating cool an organism?
Відповідь
The fastest water molecules escape as vapor, carrying heat away from the surface.
Картка 30
Питання
A cell builds a polysaccharide from sugars. Is water consumed or released?
Відповідь
Released. Forming each linkage by dehydration removes water.
Картка 31
Питання
Why can branching help a storage polysaccharide release glucose quickly?
Відповідь
More branch ends give enzymes more sites to work at once.
Картка 32
Питання
What makes a phospholipid amphipathic?
Відповідь
It has a polar, hydrophilic head and nonpolar, hydrophobic tails.
Картка 33
Питання
Where is biological information encoded in a nucleic acid?
Відповідь
In the linear sequence of nucleotide bases.
Картка 34
Питання
What is quaternary protein structure?
Відповідь
The arrangement of two or more polypeptide subunits into one functional protein.
Картка 35
Питання
Why does ice float on liquid water?
Відповідь
Stable hydrogen bonds hold ice molecules in an open lattice, making ice less dense than liquid water.
Картка 36
Питання
How does electronegativity affect a covalent bond?
Відповідь
A difference in attraction for electrons makes electron sharing unequal and can create a polar bond.
Картка 37
Питання
A digestive reaction adds water while splitting a macromolecule. What reaction is this?
Відповідь
Hydrolysis.
Картка 38
Питання
What links monosaccharides in a polysaccharide?
Відповідь
Glycosidic covalent bonds.
Картка 39
Питання
Why do phospholipids form bilayers in water?
Відповідь
Hydrophilic heads face water while hydrophobic tails cluster away from it.
Картка 40
Питання
To which end are nucleotides added during nucleic-acid synthesis?
Відповідь
The 3′ end of the growing strand.
Картка 41
Питання
Why can one amino-acid substitution change protein function?
Відповідь
It can alter side-chain interactions, folding, stability, or an active or binding site.
Картка 42
Питання
How does a buffer resist a pH change?
Відповідь
It can accept added hydrogen ions or donate them when hydrogen-ion concentration falls.
Картка 43
Питання
Why is water a useful solvent for cells?
Відповідь
Its partial charges surround ions and other polar molecules, separating and dispersing them.
Картка 44
Питання
Why do functional groups matter in organic molecules?
Відповідь
They give carbon skeletons predictable chemical properties, such as polarity, acidity, or reactivity.
Картка 45
Питання
Why can two polymers built from similar monomers have different functions?
Відповідь
Their monomer sequence, branching, length, and three-dimensional shape can differ.
Картка 46
Питання
A seedling consumes stored starch. What happens to the starch?
Відповідь
Hydrolysis breaks it into smaller sugars that can enter energy pathways.
Картка 47
Питання
What are two biological roles of steroids?
Відповідь
Some act as signaling molecules, and cholesterol helps stabilize animal cell membranes.
Картка 48
Питання
What bond forms the backbone of a nucleic-acid strand?
Відповідь
Covalent phosphodiester bonds link the sugar of one nucleotide to the phosphate of the next.
Картка 49
Питання
What does denaturation do to a protein?
Відповідь
It disrupts the protein's three-dimensional shape and often its function without usually breaking the primary peptide chain.
Картка 50
Питання
An enzyme works best near pH 7 but slows at pH 3. What is a likely explanation?
Відповідь
Extra hydrogen ions changed charges and interactions that maintain the enzyme's active shape.
Картка 51
Питання
What structure encloses every cell?
Відповідь
A plasma membrane.
Картка 52
Питання
What is the nucleus's main function?
Відповідь
It houses most eukaryotic DNA and is a major site of DNA replication and transcription.
Картка 53
Питання
Why does surface-area-to-volume ratio fall as a cell grows?
Відповідь
Volume increases with the cube of length, while surface area increases with the square.
Картка 54
Питання
What does the fluid mosaic model describe?
Відповідь
A dynamic phospholipid bilayer containing mobile proteins, sterols, and carbohydrates.
Картка 55
Питання
What drives simple diffusion?
Відповідь
Random molecular motion produces net movement from higher to lower concentration.
Картка 56
Питання
How does active transport differ from facilitated diffusion?
Відповідь
Active transport moves a substance against its gradient using energy; facilitated diffusion moves it down a gradient.
Картка 57
Питання
Why does compartmentalization increase cellular efficiency?
Відповідь
It concentrates enzymes and substrates and maintains distinct conditions for different reactions.
Картка 58
Питання
When should a light microscope be preferred over an electron microscope?
Відповідь
When observing living cells or dynamic processes at lower resolution.
Картка 59
Питання
What does the nucleolus produce?
Відповідь
Ribosomal RNA and early ribosome subunits.
Картка 60
Питання
Does passive transport require direct cellular energy?
Відповідь
No. It moves substances down an electrochemical or concentration gradient.
Картка 61
Питання
What feature separates prokaryotic from eukaryotic cells?
Відповідь
Eukaryotic cells have a membrane-bound nucleus and other membrane-bound organelles; prokaryotic cells do not.
Картка 62
Питання
Which membrane region blocks most ions and polar molecules?
Відповідь
The hydrophobic interior formed by phospholipid tails.
Картка 63
Питання
What happens on rough endoplasmic reticulum?
Відповідь
Bound ribosomes make proteins for secretion, membranes, or the endomembrane system.
Картка 64
Питання
How does facilitated diffusion differ from simple diffusion?
Відповідь
It uses a channel or carrier protein but still moves a substance down its gradient.
Картка 65
Питання
Where is prokaryotic DNA usually located?
Відповідь
In a nucleoid region rather than inside a membrane-bound nucleus.
Картка 66
Питання
How does cholesterol affect an animal membrane?
Відповідь
It buffers fluidity, limiting excess movement when warm and preventing tight packing when cool.
Картка 67
Питання
What does smooth endoplasmic reticulum do?
Відповідь
It synthesizes lipids, detoxifies some compounds, and stores calcium in specialized cells.
Картка 68
Питання
What determines a channel protein's selectivity?
Відповідь
Its pore size, shape, charge, and gating behavior.
Картка 69
Питання
What does the sodium–potassium pump accomplish?
Відповідь
Using ATP, it exports three sodium ions and imports two potassium ions per cycle.
Картка 70
Питання
What do ribosomes do in both prokaryotic and eukaryotic cells?
Відповідь
They translate mRNA into polypeptides.
Картка 71
Питання
What is the Golgi apparatus's role?
Відповідь
It modifies, sorts, and packages proteins and lipids arriving from the endoplasmic reticulum.
Картка 72
Питання
What is osmosis?
Відповідь
Net movement of water across a selectively permeable membrane toward lower free-water concentration.
Картка 73
Питання
Why does a high surface-area-to-volume ratio help a cell?
Відповідь
It provides more membrane area per unit of cytoplasm for exchange with the environment.
Картка 74
Питання
How do unsaturated phospholipid tails affect membrane fluidity?
Відповідь
Their bends reduce tight packing, usually increasing fluidity.
Картка 75
Питання
Trace a secreted protein after translation begins.
Відповідь
Rough ER → transport vesicle → Golgi → secretory vesicle → plasma membrane.
Картка 76
Питання
What happens to an animal cell in a hypotonic solution?
Відповідь
Water enters; the cell swells and may lyse.
Картка 77
Питання
What is cotransport?
Відповідь
The downhill movement of one substance powers the uphill transport of another through the same protein.
Картка 78
Питання
What is the main role of a cell wall?
Відповідь
It provides structural support and helps prevent excessive expansion.
Картка 79
Питання
What do lysosomes do?
Відповідь
Their hydrolytic enzymes digest macromolecules and recycle damaged cell parts in an acidic compartment.
Картка 80
Питання
What happens to an animal cell in a hypertonic solution?
Відповідь
Water leaves; the cell shrinks.
Картка 81
Питання
How do intestinal microvilli improve absorption?
Відповідь
They increase membrane surface area without greatly increasing cell volume.
Картка 82
Питання
What can an integral membrane protein do?
Відповідь
It can transport substances, receive signals, catalyze reactions, or anchor cell structures.
Картка 83
Питання
What is a central vacuole's major role in a plant cell?
Відповідь
It stores solutes and water and helps maintain turgor pressure.
Картка 84
Питання
What happens to a plant cell in a hypotonic solution?
Відповідь
Water enters and turgor pressure rises; the cell wall helps prevent bursting.
Картка 85
Питання
How can a proton gradient power sucrose uptake in a plant cell?
Відповідь
Protons flow down their gradient through a symporter that carries sucrose uphill.
Картка 86
Питання
What evidence supports the endosymbiotic origin of mitochondria?
Відповідь
They have double membranes, circular DNA, bacterial-like ribosomes, and divide independently by a similar process.
Картка 87
Питання
Which overall energy-conversion pathway mainly occurs in mitochondria?
Відповідь
Most stages of aerobic cellular respiration and ATP production.
Картка 88
Питання
What happens to a plant cell in a hypertonic solution?
Відповідь
Water leaves, turgor falls, and the membrane may pull from the wall during plasmolysis.
Картка 89
Питання
Why can't a standard light microscope resolve a ribosome clearly?
Відповідь
A ribosome is smaller than the microscope's diffraction-limited resolution.
Картка 90
Питання
How do bacterial and plant cell walls differ?
Відповідь
Bacterial walls usually contain peptidoglycan; plant walls contain cellulose.
Картка 91
Питання
Which overall energy-conversion pathway occurs in chloroplasts?
Відповідь
Photosynthesis: converting light energy into chemical energy and fixing carbon.
Картка 92
Питання
A cubical cell doubles each side length. How do surface area and volume change?
Відповідь
Surface area increases 4-fold; volume increases 8-fold.
Картка 93
Питання
What is the role of membrane carbohydrates?
Відповідь
They help cells recognize and interact with one another.
Картка 94
Питання
What is water potential?
Відповідь
A measure predicting water movement; water moves from higher to lower water potential.
Картка 95
Питання
How do microtubules support a cell?
Відповідь
They resist compression, form tracks for motors, and build structures such as spindles, cilia, and flagella.
Картка 96
Питання
What is endocytosis?
Відповідь
The plasma membrane folds inward to bring material into the cell in a vesicle.
Картка 97
Питання
What evidence supports the endosymbiotic origin of chloroplasts?
Відповідь
They share bacterial-like DNA, ribosomes, division, and a double membrane consistent with engulfment.
Картка 98
Питання
In a membrane-permeability test, what is the independent variable?
Відповідь
The factor deliberately changed, such as temperature or solute identity.
Картка 99
Питання
How do microfilaments support cell movement?
Відповідь
Actin filaments interact with motor proteins to change cell shape, contract, and move materials.
Картка 100
Питання
What does the cytosol contain?
Відповідь
Water, ions, small molecules, and proteins where many metabolic reactions occur.
Картка 101
Питання
Why can diffusion limit cell size?
Відповідь
As dimensions grow, molecules must travel farther, while exchange area does not keep pace with metabolic volume.
Картка 102
Питання
What does selective permeability mean?
Відповідь
The membrane allows some substances to cross more readily than others.
Картка 103
Питання
What is an intermediate filament's general role?
Відповідь
It provides durable mechanical strength and helps anchor structures.
Картка 104
Питання
How does adding a nonpenetrating solute affect water potential?
Відповідь
It makes solute potential, and usually total water potential, more negative.
Картка 105
Питання
What is exocytosis?
Відповідь
A vesicle fuses with the plasma membrane and releases contents outside the cell.
Картка 106
Питання
Why can lysosomal enzymes digest safely inside a cell?
Відповідь
A membrane isolates the acidic enzymes from most cytosolic components.
Картка 107
Питання
Why include an untreated membrane sample in an experiment?
Відповідь
It provides a control baseline for judging the treatment's effect.
Картка 108
Питання
Why doesn't cell size alone identify whether a cell is prokaryotic?
Відповідь
Sizes overlap; the presence or absence of internal membrane-bound structures is stronger evidence.
Картка 109
Питання
Why are organelle interactions important?
Відповідь
Cell functions often require products to move through several specialized compartments rather than one organelle working alone.
Картка 110
Питання
What graph would show a size constraint clearly?
Відповідь
Plot cell size on the x-axis and surface-area-to-volume ratio on the y-axis; the ratio should decline as size rises.
Картка 111
Питання
Which molecules cross a phospholipid bilayer most easily without proteins?
Відповідь
Small nonpolar molecules, such as oxygen and carbon dioxide.
Картка 112
Питання
Two solutions have equal water potential. What is the net water movement?
Відповідь
None, although water molecules still move both ways.
Картка 113
Питання
Why is ATP loss likely to disrupt ion balance?
Відповідь
ATP-powered pumps stop maintaining gradients, so passive leaks move ions toward equilibrium.
Картка 114
Питання
How does folding an internal membrane help an organelle?
Відповідь
It increases surface area for membrane-bound reactions without a matching increase in volume.
Картка 115
Питання
A dye leaves heated cells faster than unheated cells. What conclusion is supported?
Відповідь
Heating increased membrane permeability under the tested conditions; the data alone do not identify the exact molecular damage.
Картка 116
Питання
What does an enzyme change in a reaction?
Відповідь
It lowers activation energy, increasing reaction rate without changing the reaction's overall free-energy change.
Картка 117
Питання
What makes a reaction exergonic?
Відповідь
It releases free energy and has a negative change in free energy under the stated conditions.
Картка 118
Питання
What are the overall inputs and outputs of photosynthesis?
Відповідь
Carbon dioxide and water use light energy to produce carbohydrate and oxygen.
Картка 119
Питання
What are the overall reactants and products of aerobic cellular respiration?
Відповідь
Organic fuel and oxygen are converted mainly to carbon dioxide, water, and ATP, with heat released.
Картка 120
Питання
How should reaction rate be calculated from product data?
Відповідь
Divide the change in product amount by the elapsed time.
Картка 121
Питання
What makes an enzyme substrate-specific?
Відповідь
The active site's shape and chemical properties favor particular substrates.
Картка 122
Питання
Where do the light reactions occur?
Відповідь
In the thylakoid membranes of chloroplasts.
Картка 123
Питання
Where does glycolysis occur?
Відповідь
In the cytosol.
Картка 124
Питання
What makes a reaction endergonic?
Відповідь
It requires a net input of free energy and has a positive change in free energy.
Картка 125
Питання
What is induced fit?
Відповідь
Substrate binding shifts the enzyme's shape into a form that better supports catalysis.
Картка 126
Питання
Where does the Calvin cycle occur?
Відповідь
In the chloroplast stroma.
Картка 127
Питання
What does glycolysis produce per glucose?
Відповідь
Two pyruvate, a net two ATP, and two NADH.
Картка 128
Питання
How can cells drive an endergonic reaction?
Відповідь
They couple it to a sufficiently exergonic reaction so the combined free-energy change is negative.
Картка 129
Питання
Why isn't an enzyme consumed by the reaction it catalyzes?
Відповідь
It returns to a reusable form after products leave the active site.
Картка 130
Питання
What do photosynthetic pigments do?
Відповідь
They absorb particular wavelengths and transfer excitation energy into the light reactions.
Картка 131
Питання
Does glycolysis require oxygen directly?
Відповідь
No. It can run without oxygen if NAD⁺ is regenerated.
Картка 132
Питання
What does ATP hydrolysis commonly provide?
Відповідь
Usable free energy and a phosphate group that can change a molecule's reactivity or protein shape.
Картка 133
Питання
How does substrate concentration affect rate at low concentrations?
Відповідь
Rate usually rises because more substrate molecules collide with available active sites.
Картка 134
Питання
Why do chlorophyll-containing leaves reflect green light?
Відповідь
Chlorophyll absorbs green wavelengths less strongly than red and blue wavelengths.
Картка 135
Питання
Where does pyruvate oxidation occur in a eukaryotic cell?
Відповідь
In the mitochondrial matrix.
Картка 136
Питання
Why is ATP called an energy-coupling molecule?
Відповідь
Its hydrolysis links energy-releasing processes to cellular work.
Картка 137
Питання
Why does enzyme rate plateau at high substrate concentration?
Відповідь
Most active sites are occupied, so enzyme amount becomes limiting.
Картка 138
Питання
What is photolysis of water?
Відповідь
Light-driven splitting of water that supplies electrons and protons and releases oxygen.
Картка 139
Питання
What happens during pyruvate oxidation?
Відповідь
Each pyruvate becomes acetyl-CoA, releasing carbon dioxide and reducing NAD⁺ to NADH.
Картка 140
Питання
Why measure an initial enzyme rate?
Відповідь
Substrate depletion and product buildup have had less time to distort the rate.
Картка 141
Питання
How can high temperature reduce enzyme activity?
Відповідь
Heat can disrupt interactions that maintain the enzyme's functional shape.
Картка 142
Питання
What is photosystem II's key contribution?
Відповідь
It excites electrons and replaces them by oxidizing water.
Картка 143
Питання
Where does the citric acid cycle occur in eukaryotes?
Відповідь
In the mitochondrial matrix.
Картка 144
Питання
What is oxidation?
Відповідь
Loss of electrons, often accompanied by loss of hydrogen or gain of oxygen.
Картка 145
Питання
Why does each enzyme have an optimal pH range?
Відповідь
pH changes charges on amino-acid side chains and can alter binding or folding.
Картка 146
Питання
What does the photosynthetic electron transport chain build?
Відповідь
A proton gradient across the thylakoid membrane.
Картка 147
Питання
What is the citric acid cycle's main energy role?
Відповідь
It oxidizes acetyl groups and transfers electrons to NADH and FADH₂, making a small amount of ATP.
Картка 148
Питання
In a photosynthesis experiment, why keep leaf area constant?
Відповідь
Leaf area affects light capture and gas exchange, so changing it could confound the tested factor.
Картка 149
Питання
How does a competitive inhibitor reduce enzyme activity?
Відповідь
It competes with substrate for the active site.
Картка 150
Питання
How does chloroplast ATP synthase make ATP?
Відповідь
Protons flow from the thylakoid space to the stroma through ATP synthase, driving phosphorylation of ADP.
Картка 151
Питання
Where is the respiratory electron transport chain located in eukaryotes?
Відповідь
In the inner mitochondrial membrane.
Картка 152
Питання
What is reduction?
Відповідь
Gain of electrons, often accompanied by gain of hydrogen or loss of oxygen.
Картка 153
Питання
How can extra substrate weaken competitive inhibition?
Відповідь
More substrate increases the chance that substrate, rather than inhibitor, occupies the active site.
Картка 154
Питання
What is photosystem I's key contribution?
Відповідь
It re-energizes electrons used to reduce NADP⁺ to NADPH.
Картка 155
Питання
What is oxygen's role in aerobic respiration?
Відповідь
It is the final electron acceptor and combines with electrons and protons to form water.
Картка 156
Питання
A respiration graph gets steeper after temperature rises. What does the slope show?
Відповідь
A higher rate of the measured respiratory change, such as oxygen consumption per unit time.
Картка 157
Питання
How does a noncompetitive inhibitor act?
Відповідь
It binds away from the active site and changes enzyme activity, often by altering shape.
Картка 158
Питання
What products of the light reactions feed the Calvin cycle?
Відповідь
ATP and NADPH.
Картка 159
Питання
How does electron transport create a proton gradient?
Відповідь
Released electron energy pumps protons from the matrix to the intermembrane space.
Картка 160
Питання
What do NADH and FADH₂ carry?
Відповідь
High-energy electrons and associated hydrogen used in energy-transfer pathways.
Картка 161
Питання
What is allosteric regulation?
Відповідь
A regulator binds at one site and changes activity at another site on the protein.
Картка 162
Питання
What does carbon fixation accomplish?
Відповідь
It incorporates inorganic carbon dioxide into an organic molecule.
Картка 163
Питання
What is oxidative phosphorylation?
Відповідь
ATP production powered by electron transport and chemiosmosis.
Картка 164
Питання
Why use multiple biological replicates in a rate experiment?
Відповідь
They reveal natural variation and make the estimated treatment effect more reliable.
Картка 165
Питання
What is fermentation's central purpose?
Відповідь
It regenerates NAD⁺ so glycolysis can continue without an active electron transport chain.
Картка 166
Питання
How does feedback inhibition control a pathway?
Відповідь
A pathway's end product inhibits an earlier enzyme, reducing unnecessary production.
Картка 167
Питання
What enzyme fixes carbon in the Calvin cycle?
Відповідь
Rubisco.
Картка 168
Питання
How does mitochondrial ATP synthase make ATP?
Відповідь
Protons flow into the matrix through ATP synthase, driving ADP phosphorylation.
Картка 169
Питання
Why do cells use stepwise electron transfers?
Відповідь
They release energy in manageable increments that can be captured instead of lost mostly as heat.
Картка 170
Питання
What is a cofactor?
Відповідь
A nonprotein helper, often a metal ion or small organic coenzyme, required for some enzymes to function.
Картка 171
Питання
What are the three broad phases of the Calvin cycle?
Відповідь
Carbon fixation, reduction, and regeneration of the carbon-dioxide acceptor RuBP.
Картка 172
Питання
How does lactic-acid fermentation regenerate NAD⁺?
Відповідь
NADH reduces pyruvate to lactate, returning electrons to form NAD⁺.
Картка 173
Питання
What is substrate-level phosphorylation?
Відповідь
An enzyme transfers a phosphate directly from an intermediate to ADP.
Картка 174
Питання
Error bars overlap broadly between two treatments. What is a careful conclusion?
Відповідь
The graph alone does not show a clear difference; a suitable statistical analysis and design context are still needed.
Картка 175
Питання
Why run an enzyme assay without enzyme?
Відповідь
It measures the uncatalyzed background change and tests whether enzyme is required.
Картка 176
Питання
How does alcoholic fermentation regenerate NAD⁺?
Відповідь
Pyruvate loses carbon dioxide, and the remaining compound is reduced to ethanol as NADH becomes NAD⁺.
Картка 177
Питання
What is G3P's role in photosynthesis?
Відповідь
It is a three-carbon product that can leave the Calvin cycle and help build carbohydrates.
Картка 178
Питання
Why are mitochondrial cristae useful?
Відповідь
They increase inner-membrane area for electron transport chains and ATP synthase.
Картка 179
Питання
What does phosphorylation often do to a molecule?
Відповідь
It adds a phosphate group that can increase reactivity or alter a protein's shape and activity.
Картка 180
Питання
A mutation lowers an enzyme's maximum rate but not substrate binding. What is a plausible effect?
Відповідь
It may impair a catalytic step or reduce the number of functional enzyme molecules.
Картка 181
Питання
Why must the Calvin cycle regenerate RuBP?
Відповідь
RuBP is the carbon-dioxide acceptor needed for another turn of fixation.
Картка 182
Питання
A chemical lowers oxygen use but not glycolysis. Which stage is most directly implicated?
Відповідь
Aerobic electron transport or a process supplying it, because glycolysis itself does not consume oxygen.
Картка 183
Питання
How would closed stomata affect photosynthesis?
Відповідь
Carbon dioxide entry falls, which can limit carbon fixation even when light is available.
Картка 184
Питання
A plant receives green light only. Predict its photosynthetic rate.
Відповідь
It will usually be lower than under equally intense red or blue light because common chlorophylls absorb green poorly.
Картка 185
Питання
Why does fermentation yield less ATP per glucose than aerobic respiration?
Відповідь
It relies on glycolysis alone and leaves much of glucose's chemical energy in reduced end products.
Картка 186
Питання
How does low ATP affect respiration pathway activity?
Відповідь
It usually relieves inhibition of key enzymes, increasing fuel oxidation and ATP production.
Картка 187
Питання
How can oxygen production estimate photosynthetic rate?
Відповідь
Oxygen is a light-reaction product, so its production per unit time can serve as a rate proxy under controlled conditions.
Картка 188
Питання
What happens to electron transport if oxygen is removed?
Відповідь
The chain backs up because electrons lack a final acceptor; NADH accumulates and oxidative phosphorylation stops.
Картка 189
Питання
Why does a light-response curve eventually level off?
Відповідь
Another factor, such as carbon dioxide supply, temperature, or enzyme capacity, becomes limiting.
Картка 190
Питання
An uncoupler lets protons cross the inner mitochondrial membrane. What happens?
Відповідь
The gradient weakens, ATP production falls, and more energy is released as heat even if electron transport continues.
Картка 191
Питання
What is direct-contact signaling?
Відповідь
A membrane-bound molecule or cell junction communicates with an adjacent cell.
Картка 192
Питання
What are the three broad stages of cell signaling?
Відповідь
Reception, transduction, and response.
Картка 193
Питання
How can a receptor mutation block a response even when ligand is present?
Відповідь
The receptor may fail to bind ligand, change shape, or activate the first relay protein.
Картка 194
Питання
What is negative feedback?
Відповідь
A response reduces the original stimulus, helping stabilize a variable near a functional range.
Картка 195
Питання
What happens during G1 phase?
Відповідь
The cell grows, performs normal functions, and prepares for DNA replication.
Картка 196
Питання
Cells show response values of 2, 7, and 18 after rising ligand doses. Describe the trend.
Відповідь
The response increases with ligand dose across the tested range.
Картка 197
Питання
What happens during reception?
Відповідь
A ligand binds its receptor and changes the receptor's activity or shape.
Картка 198
Питання
What is paracrine signaling?
Відповідь
A cell releases a local regulator that acts on nearby target cells.
Картка 199
Питання
What happens during S phase?
Відповідь
DNA is replicated, producing sister chromatids for each chromosome.
Картка 200
Питання
A response occurs without ligand. What pathway defect is plausible?
Відповідь
A receptor or downstream relay protein may be constitutively active.
Картка 201
Питання
What happens during signal transduction?
Відповідь
Intracellular steps relay and often amplify information from the activated receptor.
Картка 202
Питання
What is synaptic signaling?
Відповідь
A neuron releases neurotransmitter across a short synaptic gap to a target cell.
Картка 203
Питання
What happens during G2 phase?
Відповідь
The cell grows, checks replicated DNA, and prepares the machinery for division.
Картка 204
Питання
Why compare receptor-positive and receptor-negative cells?
Відповідь
The comparison tests whether the receptor is necessary for the observed response.
Картка 205
Питання
What counts as a cellular response?
Відповідь
A change in gene expression, enzyme activity, ion flow, secretion, movement, division, or another cell behavior.
Картка 206
Питання
How does insulin participate in negative feedback?
Відповідь
High blood glucose promotes insulin release, which lowers blood glucose and reduces the original stimulus.
Картка 207
Питання
What happens during mitosis?
Відповідь
A eukaryotic nucleus separates duplicated chromosomes into two nuclei.
Картка 208
Питання
What is endocrine signaling?
Відповідь
Hormones travel through circulatory fluid to target cells that may be far away.
Картка 209
Питання
What does a protein kinase do?
Відповідь
It transfers a phosphate from ATP to a target protein.
Картка 210
Питання
A drug blocks a kinase, and the final response disappears. What is supported?
Відповідь
The kinase is required somewhere in that pathway under the tested conditions.
Картка 211
Питання
What happens during cytokinesis?
Відповідь
The cytoplasm divides to form separate daughter cells.
Картка 212
Питання
How does glucagon participate in glucose homeostasis?
Відповідь
Low blood glucose promotes glucagon release, which raises blood glucose toward the normal range.
Картка 213
Питання
What does a protein phosphatase do?
Відповідь
It removes a phosphate group from a target protein.
Картка 214
Питання
What is a ligand?
Відповідь
A signaling molecule that binds specifically to a receptor.
Картка 215
Питання
What is the G1 checkpoint's broad role?
Відповідь
It checks size, nutrients, growth signals, and DNA condition before replication.
Картка 216
Питання
Why can't one inhibitor experiment prove a protein's exact pathway position?
Відповідь
Off-target effects and indirect dependencies can produce the same outcome.
Картка 217
Питання
Why are phosphorylation cascades reversible?
Відповідь
Kinases add phosphates, while phosphatases remove them and reset pathway components.
Картка 218
Питання
What is positive feedback?
Відповідь
A response strengthens the initiating stimulus until a separate event stops the loop.
Картка 219
Питання
What is the G2 checkpoint's broad role?
Відповідь
It checks whether DNA replication is complete and damage is repaired before mitosis.
Картка 220
Питання
Why don't all cells respond to the same hormone?
Відповідь
Only cells with a compatible receptor and response machinery can respond.
Картка 221
Питання
What is a second messenger?
Відповідь
A small intracellular molecule or ion that relays a signal after receptor activation.
Картка 222
Питання
How can rescue with an active downstream protein map a pathway?
Відповідь
If the response returns despite an upstream block, the rescued protein likely acts downstream of that block.
Картка 223
Питання
What does the spindle checkpoint verify?
Відповідь
Every chromosome is correctly attached to spindle microtubules before sister chromatids separate.
Картка 224
Питання
Why is blood clotting a positive-feedback process?
Відповідь
Activated platelets recruit and activate more platelets until the break is sealed.
Картка 225
Питання
Name two common second messengers.
Відповідь
Cyclic AMP and calcium ions.
Картка 226
Питання
A mutant receptor binds ligand but never becomes phosphorylated. Predict downstream signaling.
Відповідь
It will likely fall or disappear if receptor phosphorylation is required to recruit relay proteins.
Картка 227
Питання
How do cyclins regulate the cell cycle?
Відповідь
Their concentrations rise and fall, activating cyclin-dependent kinases at specific stages.
Картка 228
Питання
Why must DNA replicate before mitosis?
Відповідь
Each daughter nucleus needs a complete copy of the genome.
Картка 229
Питання
Where do receptors for many peptide hormones sit?
Відповідь
In the plasma membrane, because these polar ligands do not readily cross the lipid bilayer.
Картка 230
Питання
How can a signaling pathway amplify a weak signal?
Відповідь
One activated component activates many downstream molecules at successive steps.
Картка 231
Питання
What is the dependent variable in a ligand-dose experiment?
Відповідь
The measured response, such as reporter activity, enzyme phosphorylation, or ion concentration.
Картка 232
Питання
What do cyclin-dependent kinases do?
Відповідь
When paired with cyclins, they phosphorylate targets that drive cell-cycle transitions.
Картка 233
Питання
Why doesn't positive feedback usually maintain homeostasis by itself?
Відповідь
It drives change away from the starting state and needs an external stop.
Картка 234
Питання
What is a G protein's signaling role?
Відповідь
It switches activity when bound to GTP and relays information from certain membrane receptors to effectors.
Картка 235
Питання
How would you test whether calcium is required for a response?
Відповідь
Block the calcium rise while keeping other conditions matched, then compare the response with a vehicle control.
Картка 236
Питання
What is apoptosis?
Відповідь
Programmed cell death that dismantles a cell in a controlled way.
Картка 237
Питання
Where are receptors for many steroid hormones?
Відповідь
Inside the cell, where lipid-soluble hormones can bind after crossing the membrane.
Картка 238
Питання
How can an ion-channel receptor create a rapid response?
Відповідь
Ligand binding opens or closes a pore, quickly changing ion movement and membrane conditions.
Картка 239
Питання
Why test several ligand concentrations?
Відповідь
A dose–response series can reveal sensitivity, saturation, and whether effects scale with ligand.
Картка 240
Питання
Why is apoptosis useful in multicellular organisms?
Відповідь
It removes damaged, infected, or unneeded cells with limited harm to neighbors.
Картка 241
Питання
A thermostat-like pathway overshoots repeatedly. What defect is plausible?
Відповідь
Delayed sensing or response can make negative feedback correct too late.
Картка 242
Питання
How can an intracellular receptor affect gene expression?
Відповідь
The ligand–receptor complex can act directly or indirectly as a transcription regulator.
Картка 243
Питання
Cells lacking protein X divide despite DNA damage. Justify a checkpoint claim.
Відповідь
Protein X likely supports a DNA-damage checkpoint because its absence links damage with continued division; rescue or pathway tests would strengthen the claim.
Картка 244
Питання
What aligns at the metaphase plate?
Відповідь
Duplicated chromosomes attached to spindle microtubules from opposite poles.
Картка 245
Питання
How can failed checkpoints contribute to cancer?
Відповідь
Cells with damage or abnormal signals can keep dividing instead of pausing or dying.
Картка 246
Питання
How can gap junctions support communication?
Відповідь
They connect neighboring animal-cell cytoplasms so small molecules and ions can pass directly.
Картка 247
Питання
Why can the same ligand trigger different responses in two cell types?
Відповідь
The cells can express different receptors, relay proteins, targets, or genes.
Картка 248
Питання
Two pathways share one relay protein. What can happen if that protein is blocked?
Відповідь
Both responses may weaken, showing pathway crosstalk or a shared component.
Картка 249
Питання
During which mitotic stage do sister chromatids separate?
Відповідь
Anaphase.
Картка 250
Питання
What defines a malignant tumor?
Відповідь
Its cells invade surrounding tissue and may spread to distant sites.
Картка 251
Питання
How would loss of a feedback inhibitor affect a biosynthetic pathway?
Відповідь
The pathway may stay active and overproduce its end product.
Картка 252
Питання
What ends a signaling response?
Відповідь
Ligand removal, receptor inactivation, GTP hydrolysis, messenger breakdown, or dephosphorylation can shut it down.
Картка 253
Питання
A pathway diagram shows A activates B, and B inhibits C. Predict C after A activation.
Відповідь
C activity should decrease, assuming the shown links are the relevant controlling interactions.
Картка 254
Питання
A phosphatase that normally turns off an activated relay protein is inhibited. Predict the effect on that pathway.
Відповідь
Phosphorylated targets may stay active longer, extending or strengthening the response.
Картка 255
Питання
A drug prevents spindle formation. Where should the cycle stop?
Відповідь
At the spindle checkpoint before anaphase, because chromosomes cannot attach correctly.
Картка 256
Питання
What is the purpose of meiosis?
Відповідь
It produces haploid cells and reshuffles inherited alleles for sexual reproduction.
Картка 257
Питання
What is crossing over?
Відповідь
Exchange of corresponding DNA segments between nonsister chromatids of homologous chromosomes.
Картка 258
Питання
What does Mendel's law of segregation describe?
Відповідь
An individual's two alleles for a gene separate into different gametes.
Картка 259
Питання
Why do X-linked recessive traits often appear more frequently in XY individuals?
Відповідь
They have only one X chromosome, so one recessive allele on it can determine the phenotype.
Картка 260
Питання
What is incomplete dominance?
Відповідь
The heterozygote has a phenotype intermediate between the two homozygotes.
Картка 261
Питання
What does a chi-square goodness-of-fit test compare?
Відповідь
Observed category counts with counts expected under a stated model.
Картка 262
Питання
What is a homologous chromosome pair?
Відповідь
Two chromosomes carrying the same gene locations, one inherited from each parent, possibly with different alleles.
Картка 263
Питання
What does Mendel's law of independent assortment describe?
Відповідь
Alleles of genes on different chromosomes, or far apart on one chromosome, assort independently during gamete formation.
Картка 264
Питання
What is genetic linkage?
Відповідь
Genes close together on the same chromosome tend to be inherited together.
Картка 265
Питання
When does crossing over occur?
Відповідь
During prophase I after homologs pair.
Картка 266
Питання
How do sister chromatids differ from homologous chromosomes?
Відповідь
Sister chromatids are replicated copies of one chromosome; homologs are the maternal and paternal versions of the same chromosome type.
Картка 267
Питання
For Aa × Aa, what is the expected genotype ratio?
Відповідь
1 AA : 2 Aa : 1 aa.
Картка 268
Питання
How can linked genes produce recombinant offspring?
Відповідь
Crossing over can exchange DNA between the gene locations.
Картка 269
Питання
What is the usual null hypothesis for a Mendelian chi-square test?
Відповідь
Any difference between observed and expected counts is due to chance sampling under the proposed inheritance model.
Картка 270
Питання
What happens to homologous chromosomes in meiosis I?
Відповідь
They pair and then separate into different cells.
540 карток
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Картка 271
Питання
For Aa × Aa with complete dominance, what is the expected phenotype ratio?
Відповідь
3 dominant phenotype : 1 recessive phenotype.
Картка 272
Питання
How does crossing over increase variation?
Відповідь
It creates chromosomes with new combinations of parental alleles.
Картка 273
Питання
What does recombination frequency estimate?
Відповідь
Relative distance between linked genes; higher frequency generally means greater separation, up to the 50% limit.
Картка 274
Питання
What happens to sister chromatids in meiosis II?
Відповідь
Their centromeres separate, and the chromatids move into different cells.
Картка 275
Питання
What rule finds the probability of either of two mutually exclusive outcomes?
Відповідь
Add their individual probabilities.
Картка 276
Питання
What is codominance?
Відповідь
Both alleles contribute distinct, detectable products or traits in the heterozygote.
Картка 277
Питання
How is a chi-square contribution calculated for one category?
Відповідь
Subtract expected from observed, square the difference, and divide by expected.
Картка 278
Питання
When do homologous chromosomes pair as tetrads?
Відповідь
During prophase I.
Картка 279
Питання
What rule finds the probability that independent events both occur?
Відповідь
Multiply their individual probabilities.
Картка 280
Питання
What is independent assortment?
Відповідь
Each homologous pair orients independently at metaphase I, producing many maternal–paternal chromosome combinations.
Картка 281
Питання
Why can't recombination frequency exceed 50%?
Відповідь
At 50%, recombinant and parental combinations are equally common and the genes behave as if unlinked.
Картка 282
Питання
What aligns at the metaphase I plate?
Відповідь
Homologous pairs, with each homolog attached toward an opposite pole.
Картка 283
Питання
What is a test cross?
Відповідь
Crossing an individual with a dominant phenotype to a homozygous recessive individual to infer the unknown genotype.
Картка 284
Питання
How can one gene have multiple alleles?
Відповідь
More than two allele forms can exist in the population, although one diploid individual carries at most two.
Картка 285
Питання
How are total chi-square and category contributions related?
Відповідь
Total chi-square is the sum of all category contributions.
Картка 286
Питання
What separates during anaphase I?
Відповідь
Homologous chromosomes; sister chromatids remain joined.
Картка 287
Питання
How does random fertilization increase variation?
Відповідь
Any one genetically varied gamete from one parent can fuse with any compatible gamete from the other.
Картка 288
Питання
A test cross yields about half recessive offspring. What genotype is supported for the unknown parent?
Відповідь
Heterozygous.
Картка 289
Питання
What is nondisjunction?
Відповідь
Failure of homologous chromosomes or sister chromatids to separate normally.
Картка 290
Питання
What aligns during metaphase II?
Відповідь
Individual duplicated chromosomes in each haploid cell.
Картка 291
Питання
What is polygenic inheritance?
Відповідь
Multiple genes contribute to one trait, often producing continuous phenotypic variation.
Картка 292
Питання
For a simple goodness-of-fit test, how are degrees of freedom found?
Відповідь
Number of categories minus one.
Картка 293
Питання
Which meiotic events create variation before fertilization?
Відповідь
Crossing over and independent assortment.
Картка 294
Питання
How does ploidy change during meiosis?
Відповідь
Homolog separation reduces diploid cells to haploid cells; meiosis II separates chromatids without another ploidy reduction.
Картка 295
Питання
What pedigree pattern often suggests a recessive trait?
Відповідь
Unaffected parents can have an affected child, if both parents carry the allele.
Картка 296
Питання
How can meiotic nondisjunction affect gametes?
Відповідь
It can produce gametes with an extra or missing chromosome.
Картка 297
Питання
What is pleiotropy?
Відповідь
One gene influences multiple phenotypic traits.
Картка 298
Питання
Why is there no second DNA replication before meiosis II?
Відповідь
The goal is to separate existing sister chromatids, not duplicate the genome again.
Картка 299
Питання
What does a p-value below the chosen threshold support?
Відповідь
Rejecting the null model because the observed deviation would be unlikely if that model were correct.
Картка 300
Питання
Why are siblings genetically different even with the same parents?
Відповідь
They inherit different allele combinations through crossing over, independent assortment, and random fertilization.
Картка 301
Питання
Why do small families often deviate from expected Mendelian ratios?
Відповідь
Probability ratios describe long-run expectations; random sampling variation is large with few offspring.
Картка 302
Питання
A diploid cell has six chromosomes. How many chromosomes should each normal meiotic product have?
Відповідь
Three.
Картка 303
Питання
A trisomic zygote forms after fertilization. What meiotic error is a likely cause?
Відповідь
Nondisjunction produced a gamete carrying an extra copy of that chromosome.
Картка 304
Питання
Why can identical genotypes show different phenotypes?
Відповідь
Environmental conditions and developmental variation can alter gene expression or trait development.
Картка 305
Питання
What does failing to reject a genetic null hypothesis mean?
Відповідь
The data do not show a significant departure from the model; they do not prove the model true.
Картка 306
Питання
How do DNA and RNA sugars differ?
Відповідь
DNA contains deoxyribose; RNA contains ribose.
Картка 307
Питання
What does semiconservative DNA replication produce?
Відповідь
Each daughter DNA molecule contains one original strand and one newly synthesized strand.
Картка 308
Питання
What is transcription?
Відповідь
Synthesis of RNA using DNA as a template.
Картка 309
Питання
What is a point mutation?
Відповідь
A change affecting one nucleotide pair.
Картка 310
Питання
What is an operon?
Відповідь
A group of prokaryotic genes controlled together and transcribed from one promoter.
Картка 311
Питання
Why can muscle and nerve cells differ despite having the same genome?
Відповідь
They express different sets and amounts of genes.
Картка 312
Питання
What must a virus use from its host?
Відповідь
Host resources and at least some host-cell machinery to copy or express its genome and produce new particles.
Картка 313
Питання
What does PCR do?
Відповідь
It amplifies a chosen DNA region through repeated cycles of strand separation, primer binding, and extension.
Картка 314
Питання
What enzyme performs transcription?
Відповідь
RNA polymerase.
Картка 315
Питання
What does helicase do during replication?
Відповідь
It unwinds the double helix and separates the template strands.
Картка 316
Питання
How does a repressor reduce transcription?
Відповідь
It binds regulatory DNA and blocks or hinders transcription machinery.
Картка 317
Питання
What is a silent mutation?
Відповідь
A nucleotide change that does not change the encoded amino acid.
Картка 318
Питання
What does a promoter do?
Відповідь
It marks where transcription machinery assembles and helps set the transcription start and direction.
Картка 319
Питання
What does topoisomerase do ahead of a replication fork?
Відповідь
It relieves twisting strain caused by DNA unwinding.
Картка 320
Питання
How does an inducer affect an inducible operon?
Відповідь
It disables the repressor or otherwise turns transcription on when the pathway's substrate is present.
Картка 321
Питання
How do DNA and RNA bases differ?
Відповідь
DNA uses thymine, while RNA uses uracil; both also use adenine, cytosine, and guanine.
Картка 322
Питання
Which DNA strand does RNA polymerase read?
Відповідь
The template strand, read 3′→5′ while RNA is built 5′→3′.
Картка 323
Питання
Why is an RNA primer needed for DNA replication?
Відповідь
DNA polymerase can extend an existing 3′ end but cannot start a strand from nothing.
Картка 324
Питання
How does a corepressor affect a repressible operon?
Відповідь
It activates a repressor, turning off genes when the pathway's end product is abundant.
Картка 325
Питання
What is a missense mutation?
Відповідь
A nucleotide change that substitutes one amino acid for another.
Картка 326
Питання
How does an mRNA sequence relate to the coding DNA strand?
Відповідь
It matches the coding strand except RNA has uracil in place of thymine.
Картка 327
Питання
What does primase do?
Відповідь
It builds short RNA primers.
Картка 328
Питання
Why is the lac operon strongly expressed when lactose is present and glucose is scarce?
Відповідь
Lactose relieves repression, while low glucose supports positive activation of transcription.
Картка 329
Питання
Why are primers essential in PCR?
Відповідь
They define the target boundaries and provide 3′ ends for DNA polymerase.
Картка 330
Питання
What is the primary RNA transcript in a eukaryote?
Відповідь
The initial RNA copy before processing.
Картка 331
Питання
In which direction does DNA polymerase synthesize DNA?
Відповідь
5′→3′ by adding nucleotides to a 3′ end.
Картка 332
Питання
Why is the trp operon usually off when tryptophan is abundant?
Відповідь
Tryptophan acts as a corepressor, enabling repression of biosynthetic genes.
Картка 333
Питання
What holds complementary DNA bases together?
Відповідь
Hydrogen bonds: adenine pairs with thymine, and cytosine pairs with guanine.
Картка 334
Питання
What happens during RNA splicing?
Відповідь
Introns are removed and exons are joined.
Картка 335
Питання
Why is the leading strand synthesized continuously?
Відповідь
Its template orientation lets polymerase follow the replication fork while synthesizing 5′→3′.
Картка 336
Питання
How can histone acetylation affect transcription?
Відповідь
It often loosens chromatin and makes DNA more accessible to transcription machinery.
Картка 337
Питання
What is a nonsense mutation?
Відповідь
A nucleotide change that creates a premature stop codon.
Картка 338
Питання
What do the 5′ cap and poly-A tail help do?
Відповідь
They protect eukaryotic mRNA and support export and translation.
Картка 339
Питання
Why is the lagging strand synthesized in fragments?
Відповідь
Its template orientation forces repeated 5′→3′ synthesis away from the moving fork.
Картка 340
Питання
How can DNA methylation near a promoter affect transcription?
Відповідь
It often reduces transcription by limiting access or recruiting repressive proteins.
Картка 341
Питання
How does gel electrophoresis separate DNA fragments?
Відповідь
An electric field pulls negatively charged DNA through a matrix; smaller fragments usually travel farther.
Картка 342
Питання
How can alternative splicing increase protein diversity?
Відповідь
Different exon combinations from one transcript can produce different mRNAs and polypeptides.
Картка 343
Питання
What are Okazaki fragments?
Відповідь
Short DNA segments made on the lagging strand.
Картка 344
Питання
What does a transcription factor do?
Відповідь
It binds regulatory DNA and helps increase or decrease transcription of specific genes.
Картка 345
Питання
Why are DNA strands antiparallel?
Відповідь
Their sugar–phosphate backbones run in opposite 5′→3′ directions.
Картка 346
Питання
What is translation?
Відповідь
Ribosomes use an mRNA codon sequence to build a polypeptide.
Картка 347
Питання
What does DNA ligase do?
Відповідь
It seals breaks in the sugar–phosphate backbone, joining DNA fragments.
Картка 348
Питання
What is a frameshift mutation?
Відповідь
An insertion or deletion not in multiples of three that shifts downstream codon grouping.
Картка 349
Питання
How can an enhancer influence a distant promoter?
Відповідь
DNA looping brings enhancer-bound activators near the transcription machinery.
Картка 350
Питання
What does a codon specify?
Відповідь
An amino acid or a translation stop signal.
Картка 351
Питання
What do restriction enzymes do?
Відповідь
They cut DNA at particular recognition sequences.
Картка 352
Питання
What gives a nucleic-acid strand its 5′ and 3′ ends?
Відповідь
The chemical groups on the sugar: a 5′ phosphate end and a 3′ hydroxyl end.
Картка 353
Питання
How does proofreading improve replication accuracy?
Відповідь
DNA polymerases detect and replace many incorrectly paired nucleotides.
Картка 354
Питання
What does a tRNA anticodon do?
Відповідь
It base-pairs with an mRNA codon so the attached amino acid is placed correctly.
Картка 355
Питання
Why can a promoter mutation affect protein amount?
Відповідь
It can change transcription-factor or RNA-polymerase binding and alter transcription rate.
Картка 356
Питання
How can microRNA reduce gene expression?
Відповідь
It base-pairs with target mRNA and promotes degradation or blocks translation.
Картка 357
Питання
What maintains a differentiated cell's identity?
Відповідь
Stable regulatory networks and chromatin states keep characteristic genes active or silent.
Картка 358
Питання
What are the ribosome's broad roles?
Відповідь
It positions mRNA and tRNAs and catalyzes peptide-bond formation.
Картка 359
Питання
How can an RNA virus generate genetic variation quickly?
Відповідь
Many viral RNA polymerases lack strong proofreading, so replication introduces mutations frequently.
Картка 360
Питання
What can bacterial transformation demonstrate?
Відповідь
Cells can take up external DNA and express a selectable or observable trait.
Картка 361
Питання
Why is RNA usually more structurally varied than double-stranded DNA?
Відповідь
A single RNA strand can fold back on itself through internal base pairing.
Картка 362
Питання
What usually marks translation initiation?
Відповідь
A start codon positioned with an initiator tRNA and ribosomal subunits.
Картка 363
Питання
What problem do telomeres help solve?
Відповідь
They protect chromosome ends from losing essential genes during repeated linear-DNA replication.
Картка 364
Питання
Why can an intron splice-site mutation affect protein sequence?
Відповідь
Incorrect splicing can remove exon sequence or retain intron sequence in the mature mRNA.
Картка 365
Питання
How can protein degradation regulate a pathway quickly?
Відповідь
Destroying a key protein lowers its activity without waiting for transcription to change.
Картка 366
Питання
What happens at a stop codon?
Відповідь
A release factor ends translation and frees the polypeptide.
Картка 367
Питання
How can a signal change cell specialization?
Відповідь
It can activate transcription factors that launch a new gene-expression program.
Картка 368
Питання
What is a retrovirus's information flow?
Відповідь
Viral RNA is reverse-transcribed into DNA, which can integrate into the host genome.
Картка 369
Питання
What does DNA sequencing reveal directly?
Відповідь
The order of nucleotides in the analyzed DNA; biological effects require further interpretation.
Картка 370
Питання
Why is the genetic code called redundant?
Відповідь
More than one codon can specify the same amino acid.
Картка 371
Питання
Where does nucleotide sequence store information?
Відповідь
The order of bases encodes information that can be copied, transcribed, or translated.
Картка 372
Питання
Why is replication called bidirectional?
Відповідь
Two forks usually move away from each origin in opposite directions.
Картка 373
Питання
Why doesn't every DNA mutation change phenotype?
Відповідь
It may occur outside a functional sequence, be silent, have a mild effect, or be masked by another allele or environment.
Картка 374
Питання
How does a free ribosome's product usually differ from a rough-ER ribosome's product?
Відповідь
Free ribosomes often make cytosolic proteins; ER-bound ribosomes make many secreted, membrane, and endomembrane proteins.
Картка 375
Питання
Why can one signal coordinate many genes?
Відповідь
A shared transcription regulator or signaling pathway can control multiple target promoters.
Картка 376
Питання
Why does cell specialization depend on selective gene expression rather than gene loss?
Відповідь
Most specialized cells retain the genome but use only the genes needed for their role.
Картка 377
Питання
Why are viruses not described as independently living cells?
Відповідь
They lack cellular metabolism and cannot reproduce without a host cell.
Картка 378
Питання
A coding DNA triplet is 5′-ATG-3′. What is the matching mRNA codon?
Відповідь
5′-AUG-3′.
Картка 379
Питання
A PCR band is absent. Why isn't gene absence the only explanation?
Відповідь
Poor DNA quality, wrong primers, inhibitors, or failed reaction conditions can also prevent amplification.
Картка 380
Питання
Why can protein function require steps after translation?
Відповідь
The polypeptide may need folding, cleavage, chemical modification, or assembly with other subunits.
Картка 381
Питання
How do fossils support evolution?
Відповідь
They document organisms and transitions through time, including appearance, change, and extinction.
Картка 382
Питання
What conditions are required for natural selection?
Відповідь
Individuals vary, some variation is heritable, and variants differ in survival or reproductive success in that environment.
Картка 383
Питання
What is artificial selection?
Відповідь
Humans choose which organisms reproduce based on desired heritable traits.
Картка 384
Питання
What does an allele frequency measure?
Відповідь
The fraction of all copies of a gene in a population represented by one allele.
Картка 385
Питання
What does a node on a phylogenetic tree represent?
Відповідь
A common ancestor where descendant lineages diverge.
Картка 386
Питання
What is biological speciation?
Відповідь
Evolution of reproductive isolation between populations, producing independently evolving lineages.
Картка 387
Питання
What is extinction?
Відповідь
Permanent loss of a species when no living members remain.
Картка 388
Питання
A pesticide-treated population becomes mostly resistant. What evidence distinguishes selection from acclimation?
Відповідь
Resistance should be heritable and increase across generations through differential reproduction, not just appear temporarily in exposed individuals.
Картка 389
Питання
What changes during evolution by natural selection?
Відповідь
Allele frequencies in a population across generations.
Картка 390
Питання
For two alleles under Hardy–Weinberg notation, what does p + q equal?
Відповідь
1.
Картка 391
Питання
What is a clade?
Відповідь
An ancestor and all of its descendants.
Картка 392
Питання
What does homologous anatomy suggest?
Відповідь
Similar underlying structures with different functions can indicate inheritance from a common ancestor.
Картка 393
Питання
Do individual organisms evolve by natural selection?
Відповідь
No. Individuals are selected; populations evolve as inherited variants change in frequency.
Картка 394
Питання
Under Hardy–Weinberg equilibrium, what does p² represent?
Відповідь
Expected frequency of one homozygous genotype.
Картка 395
Питання
What is a shared derived character?
Відповідь
A trait that evolved in a common ancestor and helps identify one of its descendant clades.
Картка 396
Питання
What is mutation's evolutionary role?
Відповідь
It creates new alleles, the ultimate source of new genetic variation.
Картка 397
Питання
What is biological fitness?
Відповідь
Relative contribution of viable, reproducing offspring to the next generation in a particular environment.
Картка 398
Питання
Under Hardy–Weinberg equilibrium, what does 2pq represent?
Відповідь
Expected frequency of heterozygotes.
Картка 399
Питання
Which two tips on a tree are most closely related?
Відповідь
Those sharing the most recent common ancestor, regardless of how close their names appear on the page.
Картка 400
Питання
What is a vestigial structure?
Відповідь
A reduced feature inherited from ancestors that has lost much or all of its earlier function.
Картка 401
Питання
What is an adaptation?
Відповідь
A heritable trait that became common because it improved fitness in past environments.
Картка 402
Питання
Under Hardy–Weinberg equilibrium, what does q² represent?
Відповідь
Expected frequency of the other homozygous genotype.
Картка 403
Питання
How does recombination affect evolution?
Відповідь
It reshuffles existing alleles into new combinations but does not itself create new alleles.
Картка 404
Питання
Does rotating branches around a node change relationships?
Відповідь
No. The branching pattern stays the same.
Картка 405
Питання
Why isn't an adaptation always beneficial in every setting?
Відповідь
Fitness effects depend on the environment and can involve tradeoffs.
Картка 406
Питання
What are the Hardy–Weinberg assumptions?
Відповідь
A very large population, random mating, no mutation, no migration, and no natural selection at the locus.
Картка 407
Питання
How can embryological similarities support common ancestry?
Відповідь
Shared developmental patterns can reflect inherited developmental genes and pathways.
Картка 408
Питання
What is gene flow?
Відповідь
Movement of alleles between populations through migration and reproduction.
Картка 409
Питання
Does natural selection create needed mutations?
Відповідь
No. Mutations arise without regard to need; selection changes the frequencies of their inherited effects.
Картка 410
Питання
Why is Hardy–Weinberg equilibrium useful?
Відповідь
It provides a null model for detecting or reasoning about evolutionary change.
Картка 411
Питання
Does left-to-right tip order show evolutionary progress?
Відповідь
No. Tip order is a drawing choice, not a ranking from primitive to advanced.
Картка 412
Питання
What is allopatric speciation?
Відповідь
Geographic separation reduces gene flow, allowing populations to diverge.
Картка 413
Питання
What is directional selection?
Відповідь
Selection favors one end of a phenotypic range, shifting the population mean.
Картка 414
Питання
If q² = 0.09, what is q?
Відповідь
0.30.
Картка 415
Питання
Why is DNA sequence similarity evidence for relatedness?
Відповідь
Related lineages inherit sequences from common ancestors, with differences accumulating over time.
Картка 416
Питання
How does gene flow often affect differences between populations?
Відповідь
It tends to make allele frequencies more similar.
Картка 417
Питання
What is stabilizing selection?
Відповідь
Selection favors intermediate phenotypes and removes extremes.
Картка 418
Питання
If q = 0.30, what is p?
Відповідь
0.70.
Картка 419
Питання
What can branch length mean?
Відповідь
Only what the figure defines—sometimes time or amount of change, and sometimes nothing quantitative.
Картка 420
Питання
What is sympatric speciation?
Відповідь
Reproductive isolation evolves without geographic separation, for example through polyploidy or strong niche and mating differences.
Картка 421
Питання
What is disruptive selection?
Відповідь
Selection favors both extremes over intermediate phenotypes.
Картка 422
Питання
If p = 0.70 and q = 0.30, what is 2pq?
Відповідь
0.42.
Картка 423
Питання
Why include an untreated population in a selection experiment?
Відповідь
It shows how allele or trait frequencies change without the selective treatment.
Картка 424
Питання
Why is the nearly universal genetic code evidence of common ancestry?
Відповідь
A deeply conserved information system is most simply explained by inheritance from early shared ancestors.
Картка 425
Питання
What is balancing selection?
Відповідь
Natural selection that maintains two or more alleles in a population, such as through heterozygote advantage or selection that varies across environments.
Картка 426
Питання
What is genetic drift?
Відповідь
Random change in allele frequencies caused by chance sampling across generations.
Картка 427
Питання
If 16% of a Hardy–Weinberg population shows a recessive phenotype, what is q?
Відповідь
0.40, because q is the square root of 0.16.
Картка 428
Питання
Why use an outgroup in tree analysis?
Відповідь
It helps infer which character states are ancestral versus derived in the focal group.
Картка 429
Питання
What is a prezygotic barrier?
Відповідь
A barrier that prevents mating or fertilization.
Картка 430
Питання
Allele A rises from 0.20 to 0.45. Describe the evolutionary result.
Відповідь
The population evolved at that locus because allele frequency changed.
Картка 431
Питання
How does biogeography support evolution?
Відповідь
Species distributions often match isolation history, dispersal, and descent from nearby ancestors.
Картка 432
Питання
What is sexual selection?
Відповідь
Differences in mating success drive changes in traits that affect mate attraction or competition.
Картка 433
Питання
When is genetic drift strongest?
Відповідь
In small populations.
Картка 434
Питання
Why can a rare recessive allele persist?
Відповідь
Selection cannot remove copies hidden in heterozygotes as efficiently as copies expressed in homozygotes.
Картка 435
Питання
How can molecular data revise a phylogenetic tree?
Відповідь
Sequence comparisons can reveal relationships not obvious from morphology or distinguish convergence from homology.
Картка 436
Питання
What is a postzygotic barrier?
Відповідь
A barrier that reduces hybrid survival, fertility, or later-generation success after fertilization.
Картка 437
Питання
How can rapid environmental change increase extinction risk?
Відповідь
Populations may lack enough suitable variation or time to adapt or move.
Картка 438
Питання
A small island population loses alleles after a storm. Which mechanism is most direct?
Відповідь
Genetic drift through a bottleneck.
Картка 439
Питання
What is convergent evolution?
Відповідь
Unrelated lineages independently evolve similar traits under similar selective pressures.
Картка 440
Питання
Why can antibiotic resistance spread rapidly?
Відповідь
Treatment strongly favors resistant variants already present or newly introduced, which leave more descendants.
Картка 441
Питання
What is a bottleneck effect?
Відповідь
A sharp population reduction leaves a random, often less diverse sample of the original gene pool.
Картка 442
Питання
How do genotype counts yield allele frequency?
Відповідь
Count two copies from each homozygote and one from each heterozygote, then divide by twice the number of diploid individuals.
Картка 443
Питання
What is maximum parsimony in tree building?
Відповідь
Preferring the tree that requires the fewest evolutionary changes under the model.
Картка 444
Питання
How can different breeding times isolate populations?
Відповідь
Temporal isolation prevents individuals from mating even when they share a location.
Картка 445
Питання
Why can mass extinctions reshape evolution?
Відповідь
They remove many lineages and open ecological opportunities for survivors.
Картка 446
Питання
Two similar traits evolved on distant tree branches. What explanation should be evaluated?
Відповідь
Convergent evolution under similar selection, alongside the possibility of an incorrect tree or unrecognized homology.
Картка 447
Питання
Why are analogous structures weak evidence of close ancestry?
Відповідь
Their similar function may have evolved independently rather than from the same ancestral structure.
Картка 448
Питання
Why doesn't natural selection produce perfection?
Відповідь
It works with existing variation under tradeoffs, historical constraints, chance, and changing environments.
Картка 449
Питання
What is a founder effect?
Відповідь
A new population starts from a small, nonrepresentative sample of a source population.
Картка 450
Питання
Observed genotypes differ from Hardy–Weinberg expectations. What is supported?
Відповідь
At least one model assumption may not hold, or sampling error may matter; the deviation alone does not identify the cause.
Картка 451
Питання
Why is a phylogenetic tree a hypothesis?
Відповідь
It is an evidence-based reconstruction that can change when new data or methods appear.
Картка 452
Питання
How can behavioral differences cause isolation?
Відповідь
Different courtship signals reduce mating between populations.
Картка 453
Питання
What evidence can test origin-of-life hypotheses?
Відповідь
Chemistry experiments, geological records, molecular comparisons, and plausible self-replicating or membrane-forming systems.
Картка 454
Питання
How should fitness be compared in an experiment?
Відповідь
Measure relative reproductive contribution, such as viable offspring, under the same environmental conditions.
Картка 455
Питання
What does the fossil record not provide?
Відповідь
A complete sample of every organism or every transitional population.
Картка 456
Питання
How can a neutral trait change in frequency?
Відповідь
Genetic drift can shift it by chance, especially in small populations.
Картка 457
Питання
How can drift reduce adaptive potential?
Відповідь
It can remove alleles and lower genetic diversity needed under future environmental change.
Картка 458
Питання
Why does a large population support Hardy–Weinberg stability?
Відповідь
Chance sampling has less effect on allele frequencies, reducing drift.
Картка 459
Питання
If A and B share a more recent node with each other than either shares with C, what does that mean?
Відповідь
A and B are sister taxa and share a more recent common ancestor with each other than with C.
Картка 460
Питання
What is adaptive radiation?
Відповідь
Rapid diversification of one ancestral lineage into species using different ecological roles.
Картка 461
Питання
What can experiments producing organic molecules from simple chemicals show?
Відповідь
That some building blocks can form under modeled conditions; they do not recreate or prove the exact origin of life.
Картка 462
Питання
A correlation links beak size with survival. Why isn't causation settled?
Відповідь
Other traits or habitats may covary with beak size; controlled or multivariable evidence is needed.
Картка 463
Питання
Why does agreement among fossils, anatomy, and molecules strengthen an evolutionary claim?
Відповідь
Independent evidence types pointing to the same history make alternative explanations less plausible.
Картка 464
Питання
A drought favors deeper beaks. What must be measured to show selection?
Відповідь
Heritable beak variation and differences in survival or reproduction linked to beak depth.
Картка 465
Питання
Why can artificial selection produce unintended traits?
Відповідь
Selected genes may be linked to other alleles, and inbreeding can expose harmful recessive alleles.
Картка 466
Питання
What data are needed to test Hardy–Weinberg genotype expectations?
Відповідь
Population genotype counts or reliable genotype frequencies for the locus.
Картка 467
Питання
Why doesn't one living species count as the ancestor of another on a typical tree?
Відповідь
Living tips represent lineages that have both evolved since their shared ancestral lineage.
Картка 468
Питання
Why can reduced gene flow accelerate divergence?
Відповідь
Populations retain separate mutations, drift independently, and respond to different selective pressures.
Картка 469
Питання
Why are ribozymes relevant to early-life hypotheses?
Відповідь
RNA can both store information and catalyze reactions, offering a possible bridge before modern DNA–protein systems.
Картка 470
Питання
What makes an evolutionary argument strong?
Відповідь
A clear claim, relevant population-level evidence, and reasoning that connects inheritance and differential reproduction to the observed change.
Картка 471
Питання
How can a directional response help an organism?
Відповідь
Moving toward resources or away from hazards can improve survival and reproduction.
Картка 472
Питання
What is a trophic level?
Відповідь
A feeding position in the flow of energy through an ecosystem.
Картка 473
Питання
What processes move carbon into and out of biological molecules?
Відповідь
Photosynthesis fixes carbon; respiration, decomposition, and combustion release carbon dioxide.
Картка 474
Питання
What does exponential population growth assume?
Відповідь
Resources are effectively unlimited and the per-capita growth rate stays constant.
Картка 475
Питання
What is a density-dependent limiting factor?
Відповідь
Its effect strengthens as population density rises, such as competition, disease, or predation.
Картка 476
Питання
What is a keystone species?
Відповідь
A species whose ecological effect is disproportionately large relative to its abundance.
Картка 477
Питання
What are three levels of biodiversity?
Відповідь
Genetic diversity, species diversity, and ecosystem diversity.
Картка 478
Питання
What is the independent variable in a fertilizer–algae experiment?
Відповідь
The fertilizer amount or nutrient concentration deliberately changed.
Картка 479
Питання
What shape represents exponential growth over time?
Відповідь
A J-shaped curve.
Картка 480
Питання
What do primary producers do?
Відповідь
They capture external energy and build organic molecules from inorganic carbon.
Картка 481
Питання
What is a density-independent limiting factor?
Відповідь
Its effect is not primarily set by population density, such as a severe freeze or wildfire.
Картка 482
Питання
Why is nitrogen fixation necessary?
Відповідь
Most organisms cannot use atmospheric nitrogen gas directly, so it must be converted to biologically available compounds.
Картка 483
Питання
What does logistic growth add to the exponential model?
Відповідь
Growth slows as population size approaches carrying capacity.
Картка 484
Питання
What is gross primary productivity?
Відповідь
The total rate at which producers capture energy in organic matter.
Картка 485
Питання
What is competition?
Відповідь
An interaction in which organisms using the same limited resource reduce one another's access or fitness.
Картка 486
Питання
What is ecological succession?
Відповідь
Change in community composition after new habitat forms or a disturbance alters an existing community.
Картка 487
Питання
What shape represents ideal logistic growth?
Відповідь
An S-shaped curve.
Картка 488
Питання
What is net primary productivity?
Відповідь
Gross primary productivity minus producers' respiratory energy use.
Картка 489
Питання
Why does genetic diversity matter for conservation?
Відповідь
It increases the range of inherited responses available under disease or environmental change.
Картка 490
Питання
What organisms perform much biological nitrogen fixation?
Відповідь
Certain prokaryotes, including free-living and symbiotic bacteria.
Картка 491
Питання
What is carrying capacity?
Відповідь
The population size an environment can sustain over time under current conditions.
Картка 492
Питання
Why is net primary productivity important to consumers?
Відповідь
It is the producer biomass and energy available for growth and the next trophic levels.
Картка 493
Питання
What is competitive exclusion?
Відповідь
Species with identical limiting-resource niches cannot coexist indefinitely under stable conditions.
Картка 494
Питання
How do primary and secondary succession differ?
Відповідь
Primary succession begins without developed soil; secondary succession begins where soil remains.
Картка 495
Питання
Why can carrying capacity change?
Відповідь
Resources, habitat, climate, competitors, disease, and disturbance can change.
Картка 496
Питання
Why does available energy decline up a food chain?
Відповідь
Organisms use much energy for metabolism and lose it as heat and waste rather than storing it as biomass.
Картка 497
Питання
What is an ecosystem service?
Відповідь
A benefit people receive from ecosystems, such as pollination, water purification, soil formation, or climate regulation.
Картка 498
Питання
What does nitrification do?
Відповідь
Microbes oxidize ammonium to nitrite and then nitrate.
Картка 499
Питання
What does per-capita growth rate measure?
Відповідь
Population change per individual per unit time.
Картка 500
Питання
What is ecological efficiency?
Відповідь
The percentage of energy or production transferred from one trophic level to the next.
Картка 501
Питання
What is resource partitioning?
Відповідь
Competing species use different resources, places, or times, reducing direct overlap.
Картка 502
Питання
What is resilience in an ecosystem?
Відповідь
The ability to recover structure or function after disturbance.
Картка 503
Питання
How is population growth estimated from births, deaths, immigration, and emigration?
Відповідь
Births + immigration − deaths − emigration.
Картка 504
Питання
If producers store 10,000 kJ and primary consumers receive 10%, how much do they receive?
Відповідь
1,000 kJ.
Картка 505
Питання
How does habitat fragmentation affect populations?
Відповідь
It shrinks and isolates habitat, reducing movement and gene flow while increasing edge effects.
Картка 506
Питання
Why sample several sites within each habitat?
Відповідь
Replication captures spatial variation and reduces the chance that one unusual site drives the result.
Картка 507
Питання
A population grows from 200 to 230 in one year. What is its percent growth?
Відповідь
15%, because the increase of 30 divided by 200 is 0.15.
Картка 508
Питання
What is a circadian rhythm?
Відповідь
An internal roughly 24-hour cycle that environmental cues can reset.
Картка 509
Питання
Why are food webs more realistic than simple food chains?
Відповідь
Most species eat or are eaten by multiple species, creating connected pathways.
Картка 510
Питання
What does denitrification do?
Відповідь
Microbes convert nitrate to nitrogen gases, returning nitrogen to the atmosphere.
Картка 511
Питання
What characterizes an r-selected life-history strategy?
Відповідь
Many offspring, early reproduction, and relatively low investment per offspring in variable environments.
Картка 512
Питання
What is mutualism?
Відповідь
An interaction that benefits both species.
Картка 513
Питання
What is resistance in an ecosystem?
Відповідь
The ability to remain relatively unchanged during disturbance.
Картка 514
Питання
How can climate change shift species ranges?
Відповідь
Organisms track suitable temperature, moisture, seasons, or interacting species when movement is possible.
Картка 515
Питання
What characterizes a K-selected life-history strategy?
Відповідь
Fewer offspring, later reproduction, and higher investment per offspring near carrying capacity.
Картка 516
Питання
A population curve levels near 800. What does the model suggest?
Відповідь
About 800 is the carrying capacity under those measured conditions, not a permanent universal value.
Картка 517
Питання
How can seasonal cues affect reproduction?
Відповідь
Changes such as day length can trigger hormonal and behavioral shifts timed to favorable conditions.
Картка 518
Питання
What role do decomposers play?
Відповідь
They break down dead material and waste, returning nutrients to forms other organisms can use.
Картка 519
Питання
Why can phosphorus limit ecosystems?
Відповідь
It is essential but often released slowly from rocks and lacks a large atmospheric gas phase.
Картка 520
Питання
What does a Type I survivorship curve show?
Відповідь
High survival through early and middle life, followed by a steep decline at older ages.
Картка 521
Питання
What is commensalism?
Відповідь
One species benefits while the other has no clear benefit or harm.
Картка 522
Питання
Why can diversity improve ecosystem stability?
Відповідь
Multiple species or response types can keep functions going when one component declines.
Картка 523
Питання
Why can overharvesting destabilize a population?
Відповідь
Removal faster than replacement lowers abundance and can alter age structure or genetic diversity.
Картка 524
Питання
Predator and prey peaks alternate over time. What can the graph establish?
Відповідь
Their abundances covary with a lag; the graph alone cannot prove the predator caused every prey change.
Картка 525
Питання
What is acclimation?
Відповідь
A reversible phenotypic adjustment by an individual to an environmental change.
Картка 526
Питання
Does energy cycle through an ecosystem?
Відповідь
No. Energy flows through and is ultimately dissipated as heat; matter cycles.
Картка 527
Питання
How does the water cycle connect ecosystems?
Відповідь
Evaporation, transpiration, condensation, precipitation, runoff, and infiltration move water and dissolved materials.
Картка 528
Питання
What does a Type II survivorship curve show?
Відповідь
A roughly constant mortality risk across ages.
Картка 529
Питання
What is parasitism?
Відповідь
A parasite benefits while reducing its host's fitness.
Картка 530
Питання
What is an invasive species?
Відповідь
A nonnative species that spreads and causes ecological, economic, or human-health harm.
Картка 531
Питання
How can a wildlife corridor help fragmented populations?
Відповідь
It supports movement, recolonization, and gene flow between habitat patches.
Картка 532
Питання
How should biodiversity be compared when sample effort differs?
Відповідь
Standardize sampling effort or use a method that accounts for unequal effort before comparing.
Картка 533
Питання
How does acclimation differ from adaptation?
Відповідь
Acclimation occurs within an individual; adaptation is an inherited population change across generations.
Картка 534
Питання
How can removal of a top predator affect lower trophic levels?
Відповідь
It can trigger a trophic cascade by changing prey abundance and the organisms prey consume.
Картка 535
Питання
Why can extra fertilizer cause low oxygen in water?
Відповідь
Nutrient enrichment drives algal growth; decomposition then consumes dissolved oxygen.
Картка 536
Питання
What does a Type III survivorship curve show?
Відповідь
High early mortality with much better survival among those reaching later stages.
Картка 537
Питання
How can predation maintain diversity?
Відповідь
A predator can prevent one strong competitor from dominating the community.
Картка 538
Питання
How can disturbance increase or decrease diversity?
Відповідь
Its effect depends on frequency and intensity; it may create habitat variety or eliminate sensitive species.
Картка 539
Питання
Why protect multiple habitats rather than one small reserve?
Відповідь
Different habitats, disturbances, and climate trajectories preserve more species and ecological options.
Картка 540
Питання
A restoration site gains species but not nutrient cycling. How should success be evaluated?
Відповідь
Use both composition and ecosystem-function measures; one metric alone gives an incomplete result.
540 карток
AP Biology Flashcards: Complete 8-Unit Course Review
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