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 of the following is a key molecule in cellular respiration?

  1. Glucose

  2. ATP

  3. NADH

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

Glucose is the primary fuel molecule that undergoes cellular respiration to produce energy.

Multiple choice

What is the role of ATP in cellular metabolism?

  1. Energy currency of the cell

  2. Building block for DNA

  3. Carrier of genetic information

  4. Regulator of gene expression
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

ATP serves as the primary energy currency in cells, providing energy for various cellular processes.

Multiple choice

Which of the following is a metabolic pathway that occurs in the cytoplasm?

  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 that takes place in the cytoplasm, breaking down glucose into pyruvate.

Multiple choice

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

  1. Oxygen

  2. Carbon dioxide

  3. Water

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

Oxygen serves as the final electron acceptor in the electron transport chain, combining with electrons and protons to form water.

Multiple choice

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

  1. ATP

  2. NADH

  3. FADH2

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

The Krebs cycle produces NADH and FADH2, which are high-energy electron carriers that feed into the electron transport chain.

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

Which of the following is a metabolic pathway that occurs in the liver?

  1. Glycolysis

  2. Krebs cycle

  3. Gluconeogenesis

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

Gluconeogenesis is a metabolic pathway that occurs in the liver and kidneys, converting non-carbohydrate molecules into glucose.

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

Which of the following is a metabolic pathway that occurs in the endoplasmic reticulum?

  1. Glycolysis

  2. Krebs cycle

  3. Electron transport chain

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

Lipid synthesis occurs in the endoplasmic reticulum, where fatty acids and other lipids are produced.

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

Which enzyme initiates the process of fatty acid oxidation?

  1. Acetyl-CoA synthetase

  2. Carnitine palmitoyltransferase I (CPT I)

  3. 3-Hydroxyacyl-CoA dehydrogenase

  4. Enoyl-CoA hydratase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Carnitine palmitoyltransferase I (CPT I) is the enzyme that catalyzes the initial step of fatty acid oxidation, which is the transfer of long-chain fatty acids from the cytosol into the mitochondria.

Multiple choice

What is the role of carnitine in fatty acid oxidation?

  1. Transport of fatty acids across the mitochondrial membrane

  2. Activation of fatty acids for oxidation

  3. Generation of acetyl-CoA from fatty acids

  4. Regulation of fatty acid oxidation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Carnitine acts as a carrier molecule that transports long-chain fatty acids across the mitochondrial membrane, allowing them to enter the mitochondria for oxidation.

Multiple choice

Which of the following is a key intermediate in the beta-oxidation pathway?

  1. Acetyl-CoA

  2. Malonyl-CoA

  3. Citrate

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

Acetyl-CoA is a central intermediate in the beta-oxidation pathway, generated from the breakdown of fatty acids. It can then enter the citric acid cycle for further oxidation or be used in other metabolic processes.

Multiple choice

What is the final product of complete fatty acid oxidation?

  1. Glucose

  2. Acetyl-CoA

  3. Carbon dioxide

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

Complete oxidation of fatty acids results in the production of carbon dioxide as the final product, along with water and energy in the form of ATP.