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