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