Biology

Cellular Respiration and Enzymes

1,721 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 complex of the electron transport chain pumps protons across the inner mitochondrial membrane?

  1. Complex I (NADH dehydrogenase)

  2. Complex II (Succinate dehydrogenase)

  3. Complex III (Cytochrome c reductase)

  4. Complex IV (Cytochrome c oxidase)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Complex III, also known as cytochrome c reductase, pumps protons across the inner mitochondrial membrane, contributing to the proton gradient necessary for ATP synthesis.

Multiple choice

What is the final electron acceptor in the electron transport chain?

  1. NADH

  2. FADH2

  3. Oxygen

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

Oxygen is the final electron acceptor in the electron transport chain, receiving electrons from cytochrome c oxidase and combining with protons to form water.

Multiple choice

What is the process of ATP synthesis coupled to the electron transport chain called?

  1. Oxidative phosphorylation

  2. Glycolysis

  3. Krebs cycle

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

Oxidative phosphorylation is the process by which ATP is synthesized in the mitochondria using the energy released from the electron transport chain.

Multiple choice

What is the role of ATP synthase in oxidative phosphorylation?

  1. To generate a proton gradient

  2. To transfer electrons

  3. To synthesize ATP

  4. To produce NADH and FADH2
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

ATP synthase is an enzyme complex located in the inner mitochondrial membrane that uses the energy from the proton gradient to synthesize ATP from ADP and inorganic phosphate.

Multiple choice

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

  1. 2

  2. 10

  3. 32

  4. 38
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During oxidative phosphorylation, approximately 32 ATP molecules are produced per glucose molecule, representing the majority of ATP generated during cellular respiration.

Multiple choice

What is the significance of the electron transport chain in cellular respiration?

  1. It generates most of the ATP in the cell

  2. It produces NADH and FADH2

  3. It creates a proton gradient

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

The electron transport chain is crucial in cellular respiration as it generates most of the ATP, produces NADH and FADH2, and creates a proton gradient, which are all essential for energy production.

Multiple choice

Which complex of the electron transport chain contains iron-sulfur proteins?

  1. Complex I (NADH dehydrogenase)

  2. Complex II (Succinate dehydrogenase)

  3. Complex III (Cytochrome c reductase)

  4. Complex IV (Cytochrome c oxidase)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Complex I, also known as NADH dehydrogenase, contains iron-sulfur proteins that participate in the transfer of electrons from NADH to coenzyme Q.

Multiple choice

What is the role of cytochrome c oxidase in the electron transport chain?

  1. To transfer electrons from cytochrome c to oxygen

  2. To generate a proton gradient

  3. To synthesize ATP

  4. To produce NADH and FADH2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cytochrome c oxidase is the final enzyme complex in the electron transport chain that transfers electrons from cytochrome c to oxygen, the final electron acceptor.

Multiple choice

What is the overall efficiency of oxidative phosphorylation in converting glucose to ATP?

  1. 10%

  2. 20%

  3. 30%

  4. 40%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Oxidative phosphorylation is a highly efficient process, with an overall efficiency of approximately 40%, meaning that around 40% of the energy stored in glucose is converted into ATP.

Multiple choice

Which complex of the electron transport chain is also known as the rotenone-sensitive complex?

  1. Complex I (NADH dehydrogenase)

  2. Complex II (Succinate dehydrogenase)

  3. Complex III (Cytochrome c reductase)

  4. Complex IV (Cytochrome c oxidase)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Complex I, also known as NADH dehydrogenase, is also referred to as the rotenone-sensitive complex because it is inhibited by the chemical rotenone.

Multiple choice

What is the role of the proton gradient in oxidative phosphorylation?

  1. To generate ATP

  2. To transfer electrons

  3. To create a proton gradient

  4. To produce NADH and FADH2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The proton gradient across the inner mitochondrial membrane drives the synthesis of ATP by ATP synthase through a process called chemiosmosis.

Multiple choice

What is the first stage of cellular respiration?

  1. Glycolysis

  2. Krebs Cycle

  3. Electron Transport Chain

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

Glycolysis is the first stage of cellular respiration, where glucose is broken down into two molecules of pyruvate.

Multiple choice

What is the primary function of glycolysis?

  1. To produce ATP

  2. To produce NADH and FADH2

  3. To generate pyruvate

  4. To release carbon dioxide
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The primary function of glycolysis is to generate pyruvate, which is then used in the Krebs Cycle.

Multiple choice

How many molecules of ATP are produced during glycolysis?

  1. 2

  2. 4

  3. 6

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

During glycolysis, 2 molecules of ATP are produced.

Multiple choice

What is the second stage of cellular respiration?

  1. Glycolysis

  2. Krebs Cycle

  3. Electron Transport Chain

  4. Oxidative Phosphorylation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The Krebs Cycle, also known as the Citric Acid Cycle, is the second stage of cellular respiration.