Pre AP Biology -CELLS 7.2 Fermentation- MCQ Exam Style Questions -New Syllabus

Pre AP Biology -CELLS 7.2 Fermentation- MCQ Exam Style Questions – New Syllabus 2025-2026

Pre AP Biology -CELLS 7.2 Fermentation- MCQ Exam Style Questions – Pre AP Biology – per latest Pre AP Biology Syllabus.

Pre AP Biology – MCQ Exam Style Questions- All Topics

Question

You are growing a facultative anaerobic archaeon in culture under two conditions: one culture is in anaerobic conditions, and the other is in aerobic conditions. How would you expect the growth of the cells to compare between the two cultures?

a. Growth would be greater in the culture in aerobic conditions.

b. Growth would be greater in the culture in anaerobic conditions.

c. Growth would be great in both conditions.

d. Growth would be negligible in both conditions.

▶️ Answer/Explanation

Detailed solution

The correct option is a.
Facultative anaerobes can survive and grow in both the presence and absence of oxygen.
Under aerobic conditions, they perform aerobic respiration, which generates more ATP per glucose molecule.
This higher energy yield supports faster cell division and greater biomass accumulation.
In anaerobic conditions, they switch to less efficient processes like fermentation, yielding less ATP.
Thus, growth is typically slower and less abundant without oxygen.
Overall, the culture in aerobic conditions would exhibit greater growth compared to the anaerobic one.

Question

Oxidative phosphorylation is another name for the processes of the ETC and ATP synthase generating ATP. Which of the following correctly explains the meaning of oxidative phosphorylation in cellular respiration?

A. The ETC creates an $H^+$ gradient that requires oxygen gas, and ATP synthase phosphorylates ADP to make ATP.
B. The ETC splits water to make oxygen gas, and ATP synthase phosphorylates oxygen to make $CO_2$.
C. The ETC creates NADH requires oxygen gas, and ATP synthase phosphorylates oxygen to make $CO_2$.
D. The ETC splits water to make oxygen, electrons, and $H^+$, and ATP synthase phosphorylates ADP to make ATP.

▶️ Answer/Explanation

Detailed solution

The correct option is A.
In the Electron Transport Chain (ETC), electrons are passed along proteins to oxygen, the final electron acceptor.
This movement provides energy to pump $H^+$ ions across the membrane, creating an electrochemical gradient.
Oxygen gas ($O_2$) is essential here to accept electrons and form water ($H_2O$).
ATP synthase then uses the flow of $H^+$ ions back across the membrane to power the phosphorylation of ADP.
This process adds a phosphate group to $ADP$ to synthesize $ATP$.
Options B, C, and D are incorrect as they misidentify the substrates or the role of water and $CO_2$.

Question

The movement of which ion across the membrane from the intermembrane space to the matrix causes ATP synthase to spin and make ATP?

A. $\text{Na}^+$ ions
B. oxygen
C. $\text{H}^+$ ions
D. water

▶️ Answer/Explanation

Detailed solution

The correct answer is C. $\text{H}^+$ ions.
During cellular respiration, the electron transport chain pumps $\text{H}^+$ ions into the intermembrane space.
This creates a high electrochemical gradient (proton-motive force) relative to the mitochondrial matrix.
$\text{H}^+$ ions flow back into the matrix through the $\text{F}_0$ subunit of the ATP synthase enzyme.
This flow (chemiosmosis) triggers the rotation of the enzyme’s central shaft and the $\text{F}_1$ catalytic unit.
The mechanical energy from this “spinning” converts $\text{ADP} + \text{P}_i$ into $\text{ATP}$.
This entire process is fundamentally known as oxidative phosphorylation.

Pre AP Biology -CELLS 7.2 Fermentation- MCQ Exam Style Questions -New Syllabus