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AP Biology

AP Bio Unit 2.2-2.4 Quiz

Shared by ashtont · Oct 2, 2026 · 4 plays

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31 questions across 4 sections. After every answer you’ll see why each choice is right or wrong, not just the one you picked.

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Sample questions

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

A single 2 cm cube is cut into eight 1 cm cubes. Compared with the original, the total surface area and total volume are:
  1. A. Surface area doubles (24 to 48 cm^2); volume unchanged (8 cm^3) ✓
  2. B. Surface area x8; volume unchanged
  3. C. Surface area unchanged; volume halves
  4. D. Both unchanged, since it is the same amount of material

Correct answer: A. Each 1 cm cube has 6 cm^2, x8 = 48 cm^2, while total volume stays 8 cm^3, so SA:V rises from 3 to 6.

What makes the head of a phospholipid hydrophilic?
  1. A. Its C-H bonds share electrons equally
  2. B. It contains a C=C double bond that creates a kink
  3. C. Its phosphate group carries a negative charge and polar bonds that attract water molecules ✓
  4. D. It is attached to cholesterol

Correct answer: C. The charge and partial charges of the phosphate interact favorably with polar water.

'Because plant cells have cell walls, they cannot exchange materials through their plasma membranes.' Why is this statement false?
  1. A. Plant cells don't actually have plasma membranes; the wall does the exchanging
  2. B. Plant cells exchange materials only through plasmodesmata
  3. C. The cell wall is selectively permeable, so it handles exchange instead
  4. D. The wall is porous, so water and small solutes reach the plasma membrane, which still controls what enters ✓

Correct answer: D. The wall is a coarse outer layer; the membrane remains the selective barrier, and plasmodesmata connect neighboring cells.

Ammonia (NH3) is small, polar, and uncharged. How would it be expected to cross a cell membrane?
  1. A. It crosses freely and rapidly, like O2
  2. B. It passes through the bilayer in small amounts, like water ✓
  3. C. It can never cross without a pump
  4. D. It is blocked completely, like an ion

Correct answer: B. Small, polar, uncharged molecules cross the bilayer to a limited degree.

A student claims: 'Smaller molecules always cross the membrane more easily than larger ones.' Which observation best refutes this?
  1. A. Glucose requires a transport protein to enter cells
  2. B. O2 crosses faster than glucose
  3. C. K+ ions are smaller than glucose but still cannot cross the bilayer without a protein ✓
  4. D. Water crosses faster through aquaporins

Correct answer: C. Charge outweighs size; ions are blocked by the hydrophobic interior regardless of size.