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

What is the primary function of oxidative phosphorylation in cellular respiration?

  1. Generation of ATP

  2. Breakdown of glucose

  3. Production of NADH and FADH2

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

Oxidative phosphorylation is the final stage of cellular respiration responsible for the majority of ATP production through the electron transport chain and chemiosmosis.

Multiple choice

Which enzyme complex initiates the electron transport chain?

  1. NADH dehydrogenase

  2. Succinate dehydrogenase

  3. Cytochrome oxidase

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

NADH dehydrogenase, also known as Complex I, is the first enzyme complex in the electron transport chain that accepts electrons from NADH and transfers them to ubiquinone.

Multiple choice

What is the role of ubiquinone in the electron transport chain?

  1. Electron carrier

  2. Proton carrier

  3. ATP synthase

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

Ubiquinone, also known as coenzyme Q, is a mobile electron carrier that transfers electrons between Complexes I and III in the electron transport chain.

Multiple choice

Which enzyme complex pumps protons across the inner mitochondrial membrane?

  1. NADH dehydrogenase

  2. Succinate dehydrogenase

  3. Cytochrome oxidase

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

Cytochrome oxidase, also known as Complex IV, is the final enzyme complex in the electron transport chain that transfers electrons to oxygen, creating a proton gradient across the inner mitochondrial membrane.

Multiple choice

What is the role of ATP synthase in oxidative phosphorylation?

  1. Electron transfer

  2. Proton pumping

  3. ATP synthesis

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

ATP synthase is an enzyme complex that utilizes the proton gradient generated by the electron transport chain to drive the synthesis of ATP from ADP and inorganic phosphate.

Multiple choice

Which molecule serves as the final electron acceptor in the electron transport chain?

  1. NADH

  2. FADH2

  3. Ubiquinone

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

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

Multiple choice

What is the term for the movement of protons across the inner mitochondrial membrane during oxidative phosphorylation?

  1. Electron transport

  2. Proton gradient

  3. Chemiosmosis

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

Chemiosmosis is the process by which protons move across the inner mitochondrial membrane, creating an electrochemical gradient that drives ATP synthesis.

Multiple choice

Which complex in the electron transport chain is responsible for the reduction of cytochrome c?

  1. NADH dehydrogenase

  2. Succinate dehydrogenase

  3. Cytochrome bc1 complex

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

The cytochrome bc1 complex, also known as Complex III, transfers electrons from ubiquinone to cytochrome c, contributing to the proton gradient across the inner mitochondrial membrane.

Multiple choice

What is the role of the FADH2-succinate reductase complex in oxidative phosphorylation?

  1. Electron transfer

  2. Proton pumping

  3. ATP synthesis

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

The FADH2-succinate reductase complex, also known as Complex II, transfers electrons from FADH2 and succinate to ubiquinone, contributing to the electron transport chain.

Multiple choice

Which component of the electron transport chain is responsible for the oxidation of NADH?

  1. NADH dehydrogenase

  2. Succinate dehydrogenase

  3. Cytochrome oxidase

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

NADH dehydrogenase, also known as Complex I, is responsible for the oxidation of NADH and the transfer of electrons to ubiquinone, initiating the electron transport chain.

Multiple choice

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

  1. Electron transfer

  2. Proton pumping

  3. ATP synthesis

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

The proton gradient across the inner mitochondrial membrane drives ATP synthesis through ATP synthase, utilizing the energy stored in the gradient to phosphorylate ADP.

Multiple choice

Which complex in the electron transport chain is responsible for the transfer of electrons from cytochrome c to oxygen?

  1. NADH dehydrogenase

  2. Succinate dehydrogenase

  3. Cytochrome oxidase

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

Cytochrome oxidase, also known as Complex IV, transfers electrons from cytochrome c to oxygen, reducing oxygen to water and completing the electron transport chain.

Multiple choice

What is the term for the process by which protons move down their concentration gradient through ATP synthase?

  1. Electron transport

  2. Proton gradient

  3. Chemiosmosis

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

Chemiosmosis is the process by which protons move down their concentration gradient through ATP synthase, driving the synthesis of ATP.

Multiple choice

Which enzyme complex in the electron transport chain is responsible for the oxidation of succinate?

  1. NADH dehydrogenase

  2. Succinate dehydrogenase

  3. Cytochrome oxidase

  4. ATP synthase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Succinate dehydrogenase, also known as Complex II, is responsible for the oxidation of succinate and the transfer of electrons to ubiquinone, contributing to the electron transport chain.

Multiple choice

What is the term for the overall process of oxidative phosphorylation, including both the electron transport chain and ATP synthesis?

  1. Cellular respiration

  2. Glycolysis

  3. Krebs cycle

  4. Oxidative phosphorylation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Oxidative phosphorylation is the term for the overall process that includes the electron transport chain and ATP synthesis, resulting in the generation of ATP from NADH and FADH2.