Question 1

During cellular respiration, which molecule acts as the final electron acceptor in the electron transport chain, and what is the consequence if this molecule is unavailable?

Accepted Answer

O$$_2$$; electrons cannot be transferred, halting ATP production

Question 2

Which of the following processes occurs in the mitochondrial matrix?

Accepted Answer

Pyruvate oxidation

Question 3

If a cell cannot perform oxidative phosphorylation due to lack of oxygen, what alternative pathway does it use to regenerate NAD$$^+$$, and what is the main purpose of this pathway?

Accepted Answer

Lactic acid fermentation; to regenerate NAD$$^+$$ for glycolysis

Question 4

Which equation correctly represents the net reaction of glycolysis?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 2\ NAD^+ + 2\ ADP + 2\ P_i \rightarrow 2\ pyruvate + 2\ NADH + 2\ ATP + 2\ H_2O$$

Question 5

In photosynthesis, what is the primary function of the light harvesting complexes?

Accepted Answer

To absorb photons and transfer energy to the reaction center

Question 6

Which organelle compartment becomes acidified as a result of the electron transport chain in mitochondria?

Accepted Answer

Intermembrane space

Question 7

Why do chlorophyll molecules appear green to our eyes?

Accepted Answer

They absorb all colors except green, which is reflected

Question 8

Which of the following best describes the role of ATP synthase in chemiosmosis?

Accepted Answer

It allows protons to flow down their gradient, synthesizing ATP from ADP and $$P_i$$

Question 9

In the Calvin cycle, what is the function of the enzyme Rubisco?

Accepted Answer

It catalyzes the fixation of CO$$_2 to $$ribulose-1,5-bisphosphate

Question 10

Which of the following statements about C4 and CAM plants is correct?

Accepted Answer

C4 plants separate carbon fixation and the Calvin cycle in space; CAM plants separate them in time

Question 11

Which process in cellular respiration produces the most ATP per glucose molecule?

Accepted Answer

Electron transport chain and oxidative phosphorylation

Question 12

What is the main difference between the electron transport chains in mitochondria and chloroplasts?

Accepted Answer

Mitochondria use NADH as an electron donor, chloroplasts use water

Question 13

Which equation represents the overall reaction of photosynthesis?

Accepted Answer

$$6\ CO_2$ + 6\ H_2O \rightarrow C_6H_{12}O_6$ + 6\ O_2$

Question 14

Which molecule is the primary electron donor in the mitochondrial electron transport chain?

Accepted Answer

NADH

Question 15

What is the main purpose of fermentation in cells?

Accepted Answer

To regenerate NAD$$^+$$ for glycolysis

Question 16

Which of the following is a product of the citric acid cycle?

Accepted Answer

NADH

Question 17

In the light reactions of photosynthesis, what is the fate of the electrons released from water?

Accepted Answer

They are transferred to NADP$$^+ to $$form NADPH

Question 18

Which compartment of the chloroplast becomes acidified during the light reactions?

Accepted Answer

Thylakoid space (lumen)

Question 19

Which enzyme is responsible for the carboxylation step in the Calvin cycle?

Accepted Answer

Rubisco

Question 20

Which of the following best explains why photorespiration is considered a wasteful process in plants?

Accepted Answer

It consumes oxygen and releases CO$$_2$$ without producing ATP or sugar

Cellular Respiration and Photosynthesis: Key Concepts and Processes

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