Biology

Cellular Respiration and Enzymes

1,551 Questions

Explore key concepts of cellular respiration, including glycolysis, the Krebs cycle, and the electron transport chain. These questions also cover ATP production, anaerobic respiration, and essential metabolic pathways. This topic forms a core part of the biology syllabus for many competitive examinations.

Glycolysis and metabolic pathwaysKrebs cycle processesElectron transport chainATP production countAnaerobic respiration products

Cellular Respiration and Enzymes Questions

Multiple choice

Which of the following is a component of the electron transport chain?

  1. NADH dehydrogenase

  2. Cytochrome c

  3. ATP synthase

  4. FADH2 dehydrogenase
Reveal answer Fill a bubble to check yourself
Correct answer
Explanation

NADH dehydrogenase, cytochrome c, and FADH2 dehydrogenase are all components of the electron transport chain.

Multiple choice

What is the role of oxygen in oxidative phosphorylation?

  1. To accept electrons from the electron transport chain

  2. To generate a proton gradient across the mitochondrial membrane

  3. To synthesize ATP molecules

  4. To produce water as a byproduct
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Oxygen is the final electron acceptor in the electron transport chain, receiving electrons from cytochrome c oxidase.

Multiple choice

What is the name of the molecule that is reduced to form water in oxidative phosphorylation?

  1. NADH

  2. FADH2

  3. Oxygen

  4. Cytochrome c
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Oxygen is reduced to form water in oxidative phosphorylation.

Multiple choice

How many ATP molecules are produced per molecule of glucose during oxidative phosphorylation?

  1. 36

  2. 38

  3. 40

  4. 42
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Approximately 36 ATP molecules are produced per molecule of glucose during oxidative phosphorylation.

Multiple choice

Which of the following is an inhibitor of oxidative phosphorylation?

  1. Cyanide

  2. Carbon monoxide

  3. Oligomycin

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cyanide, carbon monoxide, and oligomycin are all inhibitors of oxidative phosphorylation.

Multiple choice

What is the significance of oxidative phosphorylation in cellular respiration?

  1. It is the final stage of cellular respiration

  2. It generates the majority of ATP molecules in cellular respiration

  3. It is the only stage of cellular respiration that produces ATP

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Oxidative phosphorylation is the final stage of cellular respiration, generates the majority of ATP molecules in cellular respiration, and is the only stage that produces ATP.

Multiple choice

What is the role of NADH and FADH2 in oxidative phosphorylation?

  1. To donate electrons to the electron transport chain

  2. To generate a proton gradient across the mitochondrial membrane

  3. To synthesize ATP molecules

  4. To produce water as a byproduct
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

NADH and FADH2 donate electrons to the electron transport chain, which is necessary for the generation of a proton gradient and the synthesis of ATP.

Multiple choice

What is the name of the enzyme that catalyzes the synthesis of ATP in oxidative phosphorylation?

  1. ATP synthase

  2. NADH dehydrogenase

  3. Cytochrome c oxidase

  4. FADH2 dehydrogenase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

ATP synthase is the enzyme that catalyzes the synthesis of ATP in oxidative phosphorylation.

Multiple choice

Which of the following is a product of oxidative phosphorylation?

  1. ATP

  2. NADH

  3. FADH2

  4. Water
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

ATP is the primary product of oxidative phosphorylation.

Multiple choice

What is the overall efficiency of oxidative phosphorylation in terms of ATP production?

  1. Approximately 30%

  2. Approximately 50%

  3. Approximately 70%

  4. Approximately 90%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The overall efficiency of oxidative phosphorylation in terms of ATP production is approximately 50%.

Multiple choice

Glycolysis is the first stage of cellular respiration in which glucose is broken down to produce energy. What is the net gain of ATP molecules during glycolysis?

  1. 2 ATP

  2. 4 ATP

  3. 6 ATP

  4. 8 ATP
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

During glycolysis, one molecule of glucose is broken down into two molecules of pyruvate, yielding a net gain of 2 ATP molecules.

Multiple choice

Which enzyme catalyzes the first step of glycolysis, where glucose is phosphorylated to form glucose-6-phosphate?

  1. Hexokinase

  2. Phosphofructokinase

  3. Glyceraldehyde-3-phosphate dehydrogenase

  4. Pyruvate kinase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Hexokinase is the enzyme responsible for the initial phosphorylation of glucose, converting it into glucose-6-phosphate.

Multiple choice

Which intermediate molecule in glycolysis is isomerized to form fructose-6-phosphate?

  1. Glucose-6-phosphate

  2. Glucose-1-phosphate

  3. Fructose-1,6-bisphosphate

  4. 3-Phosphoglycerate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Glucose-6-phosphate is isomerized to fructose-6-phosphate by the enzyme phosphoglucomutase.

Multiple choice

Which step in glycolysis involves the cleavage of fructose-1,6-bisphosphate into two molecules of glyceraldehyde-3-phosphate?

  1. Phosphorylation

  2. Isomerization

  3. Cleavage

  4. Oxidation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The cleavage of fructose-1,6-bisphosphate into two molecules of glyceraldehyde-3-phosphate is catalyzed by the enzyme aldolase.

Multiple choice

What is the role of glyceraldehyde-3-phosphate dehydrogenase in glycolysis?

  1. Oxidizes glyceraldehyde-3-phosphate to form 1,3-bisphosphoglycerate

  2. Converts glyceraldehyde-3-phosphate to dihydroxyacetone phosphate

  3. Phosphorylates glyceraldehyde-3-phosphate to form 1,3-bisphosphoglycerate

  4. Reduces glyceraldehyde-3-phosphate to form glycerol-3-phosphate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Glyceraldehyde-3-phosphate dehydrogenase catalyzes the oxidation of glyceraldehyde-3-phosphate to form 1,3-bisphosphoglycerate.