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