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AP Biology

AP Bio Unit 3 MCQ Set C Mock Progress Check

Shared by Ashton · Nov 12, 2026 · 0 plays

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19 questions across 5 sections. After every answer you’ll see why each choice is right or wrong, not just the one you picked.

Round length
Sections (none selected means all)

Sample questions

Open a question to see the answer choices and the correct answer.

Which value is the activation energy of the enzyme-catalyzed reaction?
  1. A. 60 kJ/mol
  2. B. 30 kJ/mol ✓
  3. C. 15 kJ/mol
  4. D. 45 kJ/mol

Correct answer: B. The catalyzed curve is the lower one (Curve 2). Eₐ = peak − reactants = 50 − 20 = 30 kJ/mol.

A mutation changes one amino acid far from an enzyme's active site, and the enzyme's activity drops sharply. What is the most likely explanation?
  1. A. The change alters folding, which changes the active site's shape ✓
  2. B. Amino acids far from the active site are the ones that bind substrate
  3. C. The mutant enzyme is now consumed in each reaction it catalyzes
  4. D. The mutation raises the reaction's ΔG so it can no longer happen

Correct answer: A. Structure determines function. A distant change can alter the tertiary structure (3.2.A.1).

Enzymes from bacteria that live in 80 °C hot springs still work at that temperature. Compared with human enzymes, these enzymes most likely have
  1. A. a higher activation energy, so heat is needed to start them
  2. B. more interactions holding their folded shape ✓
  3. C. no hydrogen bonds, so there is nothing for heat to break
  4. D. active sites that no longer depend on the enzyme's shape

Correct answer: B. Extra stabilizing interactions resist the heat that breaks H-bonds and causes denaturation.

Enzyme and substrate are mixed in a test tube. The rate slows over 30 minutes, though the enzyme is still fully active when tested afterward. The best explanation is that
  1. A. the enzyme is slowly denatured by the reaction it catalyzes
  2. B. the temperature of the tube rises above the enzyme's optimum
  3. C. substrate is being used up and product is building up ✓
  4. D. the enzyme is consumed and must be replaced by the cell

Correct answer: C. Relative concentrations of substrate and product set how efficiently the reaction proceeds (3.2.B.1).

If the cell constantly pumps D out so that D never builds up, what is the most likely result?
  1. A. Enzyme 3 stops working because it has no product left
  2. B. Enzyme 1 is inhibited more strongly and A builds up
  3. C. Substance A is converted straight into D, skipping B and C
  4. D. Enzyme 1 stays active and B, C and D keep being made ✓

Correct answer: D. Without D to inhibit enzyme 1 allosterically, feedback inhibition is lost and the pathway keeps running.