Gaokao Exam Gaokao Biology: Cell Biology and Metabolism 2

Question 1

Which of the following best describes the function of the smooth endoplasmic reticulum (SER)?

Accepted Answer

Lipid synthesis and detoxification

Answer

The SER lacks ribosomes and is involved in lipid and steroid synthesis, detoxification of drugs, and calcium storage.

Question 2

During the Calvin cycle (light-independent reactions), CO₂ is first fixed to produce:

Accepted Answer

Two molecules of 3-phosphoglycerate (3-PGA)

Answer

RuBisCO catalyzes the carboxylation of RuBP with CO₂ to form an unstable 6-carbon compound that immediately splits into two molecules of 3-PGA.

Question 3

Which type of transport requires no energy input and moves substances from high to low concentration?

Accepted Answer

Facilitated diffusion

Answer

Facilitated diffusion uses protein channels or carriers to move substances down their concentration gradient without ATP expenditure.

Question 4

A competitive inhibitor of an enzyme reduces reaction rate by:

Accepted Answer

Occupying the active site and blocking substrate binding

Answer

Competitive inhibitors have a structure similar to the substrate and reversibly bind to the active site, competing directly with the substrate.

Question 5

Which stage of aerobic respiration yields the greatest number of ATP molecules?

Accepted Answer

Oxidative phosphorylation (electron transport chain)

Answer

Oxidative phosphorylation via the electron transport chain produces approximately 28–32 ATP per glucose, far exceeding the other stages.

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