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