Gaokao Exam Gaokao Biology: Cell Biology and Metabolism 4 — Questions and Answers
Question 1: The net equation for glycolysis converting one glucose molecule is BEST represented as:
- C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 36 ATP
- C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
- C₆H₁₂O₆ → 2C₃H₄O₃ + 4H + 2 ATP (net) (Correct answer)
- C₆H₁₂O₆ + 6H₂O → 6CO₂ + 12H₂ + ATP
Correct answer: C₆H₁₂O₆ → 2C₃H₄O₃ + 4H + 2 ATP (net)
Glycolysis produces 2 pyruvate (C₃H₄O₃), 2 net ATP, 2 NADH, and 2 water molecules from one glucose in the cytoplasm without oxygen.
Question 2: Cholesterol molecules in the cell membrane serve to:
- Actively transport ions across the membrane
- Act as receptors for all hormones
- Regulate membrane fluidity at varying temperatures (Correct answer)
- Synthesize phospholipids for membrane repair
Correct answer: Regulate membrane fluidity at varying temperatures
Cholesterol intercalates between phospholipids; at high temperatures it restricts movement (decreasing fluidity), while at low temperatures it prevents packing (maintaining fluidity).
Question 3: In the electron transport chain, the final electron acceptor is:
- NAD⁺
- FAD
- Cytochrome c
- Molecular oxygen (O₂) (Correct answer)
Correct answer: Molecular oxygen (O₂)
Oxygen is the terminal electron acceptor in aerobic respiration; it accepts electrons and combines with H⁺ to form water at Complex IV.
Question 4: Which cell structure is responsible for modifying, sorting, and packaging proteins for secretion?
- Rough endoplasmic reticulum
- Golgi apparatus (Correct answer)
- Lysosome
- Peroxisome
Correct answer: Golgi apparatus
The Golgi apparatus receives proteins from the ER in vesicles, modifies them (e.g., glycosylation), sorts them, and packages them into secretory vesicles.
Question 5: When a plant cell is placed in a hypertonic solution, what occurs?
- The cell bursts due to excessive water intake
- The central vacuole expands and turgor pressure increases
- Plasmolysis occurs as water leaves the cell by osmosis (Correct answer)
- Cell wall dissolution causes cell death
Correct answer: Plasmolysis occurs as water leaves the cell by osmosis
In a hypertonic solution, water moves out of the cell by osmosis, causing the vacuole to shrink and the plasma membrane to pull away from the cell wall (plasmolysis).
Question 6: ATP synthase in the mitochondria produces ATP using energy derived from:
- Direct transfer of phosphate groups from NADH
- The proton gradient across the inner mitochondrial membrane (Correct answer)
- Substrate-level phosphorylation in the matrix
- Reduction of FAD to FADH₂
Correct answer: The proton gradient across the inner mitochondrial membrane
H⁺ ions flow down their electrochemical gradient through ATP synthase (Complex V) from the intermembrane space to the matrix, driving ATP synthesis via chemiosmosis.
Question 7: Which type of cell division produces four haploid daughter cells genetically different from the parent cell?
- Mitosis
- Binary fission
- Meiosis (Correct answer)
- Amitosis
Correct answer: Meiosis
Meiosis undergoes two rounds of division (meiosis I and II) after one round of DNA replication, producing four genetically unique haploid cells (gametes or spores).
Gaokao Exam Gaokao Biology: Cell Biology and Metabolism 4
The net equation for glycolysis converting one glucose molecule is BEST represented as: