Question 1

Which of the following correctly lists the four stages of aerobic cellular respiration in order, along with their specific locations in a eukaryotic cell?

Accepted Answer

1. Glycolysis (cytosol), 2. Pyruvate processing (mitochondrial matrix), 3. Citric acid cycle (mitochondrial matrix), 4. Electron transport chain & oxidative phosphorylation (inner mitochondrial membrane)

Question 2

During glycolysis, what is the primary reason the initial steps are referred to as the 'investment phase'?

Accepted Answer

ATP is consumed to phosphorylate glucose, making it more reactive for subsequent breakdown.

Question 3

Which of the following best describes the fate of carbon atoms from glucose during aerobic cellular respiration?

Accepted Answer

They are released as $$CO_2$$ during pyruvate processing and the citric acid cycle.

Question 4

What is the main function of the electron transport chain in the inner mitochondrial membrane?

Accepted Answer

To create a proton gradient by actively transporting $$H^+$$ ions into the intermembrane space using the energy from electron transfer.

Question 5

Which molecule acts as the final electron acceptor in the electron transport chain, and what is the resulting by-product?

Accepted Answer

Oxygen ($$O_2$$); water ($$H_2O)$$

Question 6

If a cell's inner mitochondrial membrane became permeable to protons ($$H^+$$), what would be the most likely consequence for ATP production?

Accepted Answer

ATP synthesis would decrease dramatically because the proton gradient would dissipate.

Question 7

During pyruvate processing, which of the following occurs per glucose molecule?

Accepted Answer

Two molecules of $$CO_2$$ are released and two molecules of acetyl-CoA are produced.

Question 8

Which of the following best explains why the citric acid cycle is considered the major oxidation stage of cellular respiration?

Accepted Answer

It produces the largest number of reduced electron carriers (NADH and FADH2) per glucose.

Question 9

Which of the following is TRUE regarding ATP production in the citric acid cycle per glucose molecule?

Accepted Answer

Two ATP (or GTP) molecules are produced per glucose.

Question 10

In the absence of oxygen, which process allows glycolysis to continue in animal muscle cells, and what is the main by-product?

Accepted Answer

Lactic acid fermentation; lactic acid

Question 11

Which stage of cellular respiration can occur in both the presence and absence of oxygen in yeast and animal muscle cells?

Accepted Answer

Glycolysis

Question 12

What is the net yield of ATP per glucose molecule during fermentation compared to aerobic respiration?

Accepted Answer

Fermentation yields 2 ATP per glucose, while aerobic respiration yields about 30-32 ATP per glucose.

Question 13

Which of the following best describes the flow of electrons during aerobic cellular respiration?

Accepted Answer

From glucose to NADH/FADH2 to the electron transport chain to oxygen

Question 14

What is the role of ATP synthase in oxidative phosphorylation?

Accepted Answer

It uses the energy from the proton gradient to synthesize ATP from ADP and inorganic phosphate.

Question 15

If oxygen were replaced by a less electronegative atom such as nitrogen at the end of the electron transport chain, what would be the most likely consequence?

Accepted Answer

The electron transport chain would be less efficient or stop, greatly reducing ATP production.

Question 16

Why can't protons ($$H^+) $$diffuse directly across the inner mitochondrial membrane?

Accepted Answer

The inner mitochondrial membrane is impermeable to charged ions like $$H^+$$ due to its hydrophobic core.

Question 17

During the electron transport chain, what is the immediate result of electrons moving down the chain?

Accepted Answer

Energy is released and used to pump protons ($$H^+) $$into the intermembrane space.

Question 18

Which molecule must be recycled for glycolysis to continue in both aerobic and anaerobic conditions?

Accepted Answer

NAD+

Question 19

In yeast cells under anaerobic conditions, what is the main by-product of fermentation, and at which step does fermentation diverge from aerobic respiration?

Accepted Answer

Ethanol; after glycolysis

Question 20

Which of the following best summarizes the energy transformations during aerobic cellular respiration?

Accepted Answer

Chemical energy in glucose is transferred to NADH/FADH2, then to a proton gradient, and finally to ATP.

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