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