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 metabolic pathway that occurs in the mitochondria?

  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, takes place in the mitochondria and is a key step in cellular respiration.

Multiple choice

What is the role of NAD+ in metabolism?

  1. Electron carrier

  2. Energy storage molecule

  3. Coenzyme in redox reactions

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

NAD+ acts as a coenzyme in redox reactions, accepting electrons and protons to become NADH.

Multiple choice

What is the name of the process by which cells break down large molecules into smaller ones?

  1. Catabolism

  2. Anabolism

  3. Metabolism

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

Catabolism is the process by which cells break down complex molecules into simpler ones, releasing energy.

Multiple choice

What is the role of FADH2 in metabolism?

  1. Electron carrier

  2. Energy storage molecule

  3. Coenzyme in redox reactions

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

FADH2 acts as an electron carrier in the electron transport chain, transferring electrons to other molecules.

Multiple choice

How many rounds of beta-oxidation are required to completely oxidize a palmitic acid molecule?

  1. 7

  2. 8

  3. 9

  4. 10
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Palmitic acid is a 16-carbon fatty acid, and each round of beta-oxidation removes two carbons. Therefore, 7 rounds of beta-oxidation are required to completely oxidize a palmitic acid molecule.

Multiple choice

Which of the following 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 pyruvate.

Multiple choice

What is the net gain of ATP molecules 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 and 2 molecules of ATP are consumed, resulting in a net gain of 2 ATP molecules.

Multiple choice

Which of the following is a product of glycolysis?

  1. Pyruvate

  2. Acetyl CoA

  3. NADH

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

Pyruvate is one of the products of glycolysis, along with NADH and ATP.

Multiple choice

What is the role of pyruvate dehydrogenase in cellular respiration?

  1. Converts pyruvate to acetyl CoA

  2. Generates NADH and FADH2

  3. Produces ATP through oxidative phosphorylation

  4. Regulates the Krebs Cycle
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pyruvate dehydrogenase is an enzyme that converts pyruvate to acetyl CoA, which then enters the Krebs Cycle.

Multiple choice

How many molecules of ATP are produced during the Krebs Cycle?

  1. 2

  2. 4

  3. 6

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

During the Krebs Cycle, 2 molecules of ATP are produced per molecule of acetyl CoA.

Multiple choice

Which of the following is a product of the Krebs Cycle?

  1. Pyruvate

  2. Acetyl CoA

  3. NADH

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

NADH is one of the products of the Krebs Cycle, along with FADH2, ATP, and carbon dioxide.

Multiple choice

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

  1. Generates ATP through oxidative phosphorylation

  2. Produces NADH and FADH2

  3. Converts pyruvate to acetyl CoA

  4. Regulates the Krebs Cycle
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The electron transport chain is responsible for generating ATP through oxidative phosphorylation, using the energy released from the transfer of electrons.

Multiple choice

How many molecules of ATP are produced during oxidative phosphorylation?

  1. 2

  2. 4

  3. 6

  4. 32
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

During oxidative phosphorylation, approximately 32 molecules of ATP are produced per molecule of glucose.

Multiple choice

Which of the following is the final electron acceptor in the electron transport chain?

  1. Oxygen

  2. NADH

  3. FADH2

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

Oxygen is the final electron acceptor in the electron transport chain, and its reduction to water is coupled with the generation of ATP.

Multiple choice

What is the overall yield of ATP molecules from the complete oxidation of one molecule of glucose through cellular respiration?

  1. 2

  2. 38

  3. 32

  4. 68
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The complete oxidation of one molecule of glucose through cellular respiration yields approximately 38 molecules of ATP.