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