Question 1

Which of the following best describes the main purpose of cellular respiration in eukaryotic cells?

Accepted Answer

To break down glucose and produce ATP for cellular work

Question 2

During glycolysis, what is the net gain of ATP and NADH molecules produced per molecule of glucose?

Accepted Answer

$$2$$ ATP and $$2$$ NADH

Question 3

Which enzyme is responsible for the phosphorylation of fructose-6-phosphate in glycolysis, and how is its activity regulated?

Accepted Answer

Phosphofructokinase; inhibited by high levels of ATP binding to a regulatory site

Question 4

In the absence of oxygen, which process allows glycolysis to continue by regenerating NAD$$^+$$?

Accepted Answer

Fermentation

Question 5

Which of the following statements about the electron transport chain (ETC) is correct?

Accepted Answer

The ETC pumps protons to create a gradient used by ATP synthase

Question 6

What is the final electron acceptor in aerobic cellular respiration, and what is produced as a result?

Accepted Answer

Oxygen; water

Question 7

Which of the following best explains why fats yield more ATP per gram than carbohydrates during cellular respiration?

Accepted Answer

Fats are broken down into acetyl CoA, which enters the citric acid cycle and produces more NADH and FADH$$_2$$

Question 8

A patient has a genetic defect that prevents the formation of functional ATP synthase. Which of the following would most likely occur?

Accepted Answer

A proton gradient would build up, but little ATP would be produced by oxidative phosphorylation

Question 9

Which of the following is a correct sequence of events for the complete oxidation of glucose in cellular respiration?

Accepted Answer

Glycolysis → Pyruvate processing → Citric acid cycle → Electron transport chain

Question 10

Which of the following best describes the role of feedback inhibition in cellular respiration?

Accepted Answer

It slows down metabolic pathways when end products like ATP or NADH are abundant

Question 11

If a cell is deprived of oxygen, which of the following will occur first?

Accepted Answer

The electron transport chain will stop, causing NADH to accumulate

Question 12

Which of the following is a product of lactic acid fermentation in human muscle cells?

Accepted Answer

Lactate

Question 13

How many turns of the citric acid cycle are required to fully oxidize one molecule of glucose?

Accepted Answer

$$2$$

Question 14

Which of the following statements about substrate-level phosphorylation is correct?

Accepted Answer

It directly transfers a phosphate group from a substrate to ADP to form ATP

Question 15

Which molecule is both a product of glycolysis and a substrate for pyruvate processing?

Accepted Answer

Pyruvate

Question 16

A mutation causes the enzyme malate dehydrogenase to be nonfunctional. Which process would be directly affected?

Accepted Answer

Citric acid cycle

Question 17

Which of the following best explains why oxygen is a highly efficient final electron acceptor in aerobic respiration?

Accepted Answer

Oxygen is highly electronegative, allowing a large release of energy when electrons are transferred to it

Question 18

Which of the following is a facultative anaerobe?

Accepted Answer

A cell that can switch between fermentation and aerobic respiration depending on oxygen availability

Question 19

Which of the following is NOT a direct product of the citric acid cycle?

Accepted Answer

Glucose

Question 20

Which of the following best describes the chemiosmosis hypothesis?

Accepted Answer

A proton gradient across a membrane drives ATP synthesis via ATP synthase

Cellular Respiration and Fermentation: Energy Production in Cells

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