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