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 zoology respiration in organisms active transport and passive transport types of plant transport atp

Common immediate source of energy in cellular activity or energy currency of the cell is

  1. DNA

  2. ATP

  3. RNA

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

The common immediate source of energy in cellular activity is ATP molecule. It is also called as energy currency of the cell. ATP molecules are formed as a result of phosphorylation. It is used in various cellular processes for providing energy.

Multiple choice

What is the primary molecule responsible for energy transfer and metabolism in cells?

  1. Glucose

  2. ATP

  3. NADH

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

ATP (adenosine triphosphate) is the primary energy currency of cells. It acts as a short-term energy storage molecule, providing energy for various cellular processes.

Multiple choice

Which process in cells is responsible for the breakdown of glucose to produce energy?

  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, releasing energy in the form of ATP and NADH.

Multiple choice

What is the role of the Krebs Cycle in cellular respiration?

  1. Glucose Breakdown

  2. Electron Transport

  3. ATP Production

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

The Krebs Cycle, also known as the Citric Acid Cycle, is a series of chemical reactions that further oxidize pyruvate, derived from glycolysis, to produce NADH, FADH2, and ATP.

Multiple choice

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

  1. Oxygen

  2. Carbon Dioxide

  3. Glucose

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

Oxygen is the final electron acceptor in the electron transport chain. It combines with electrons and protons to form water, releasing energy in the form of ATP.

Multiple choice

Which process is responsible for the breakdown of fats to produce energy?

  1. Glycolysis

  2. Krebs Cycle

  3. Beta-Oxidation

  4. Electron Transport Chain
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Beta-oxidation is the process by which fatty acids are broken down into acetyl-CoA molecules, which can then enter the Krebs Cycle for further energy production.

Multiple choice

What is the role of coenzymes in cellular respiration and photosynthesis?

  1. Electron Carriers

  2. Energy Storage

  3. Substrate Binding

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

Coenzymes, such as NADH and FADH2, act as electron carriers in cellular respiration and photosynthesis, transferring electrons between different molecules and facilitating energy transfer.

Multiple choice

Which process generates the majority of ATP in cellular respiration?

  1. Glycolysis

  2. Krebs Cycle

  3. Electron Transport Chain

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

Oxidative phosphorylation, which occurs in the electron transport chain, generates the majority of ATP in cellular respiration through the process of chemiosmosis.

Multiple choice

What is the primary role of ATP synthase in cellular respiration?

  1. Glucose Breakdown

  2. Electron Transport

  3. ATP Production

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

ATP synthase is an enzyme complex located in the mitochondrial inner membrane. It utilizes the proton gradient generated by the electron transport chain to produce ATP from ADP and inorganic phosphate.

Multiple choice

What is the primary role of the Krebs Cycle in cellular metabolism?

  1. Generation of ATP

  2. Synthesis of amino acids

  3. Production of NADH and FADH2

  4. Breakdown of glucose
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Krebs Cycle, also known as the Citric Acid Cycle, is primarily responsible for generating NADH and FADH2, which are high-energy electron carriers used in the electron transport chain for ATP production.

Multiple choice

How many stages make up the Krebs Cycle?

  1. 6

  2. 8

  3. 10

  4. 12
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The Krebs Cycle consists of eight distinct stages, each involving specific enzymatic reactions that transform various intermediates.

Multiple choice

Which molecule serves as the initial substrate for the Krebs Cycle?

  1. Acetyl CoA

  2. Glucose

  3. Pyruvate

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

Acetyl CoA is the starting molecule for the Krebs Cycle, derived from the breakdown of carbohydrates, fats, and proteins during cellular respiration.

Multiple choice

What is the final product of the Krebs Cycle?

  1. Oxaloacetate

  2. Malate

  3. Fumarate

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

The Krebs Cycle completes a full cycle when oxaloacetate, the final product, is regenerated, ready to accept another acetyl CoA molecule and initiate the cycle again.

Multiple choice

Which enzyme catalyzes the conversion of citrate to isocitrate in the Krebs Cycle?

  1. Aconitase

  2. Isocitrate dehydrogenase

  3. α-Ketoglutarate dehydrogenase

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

Aconitase is the enzyme responsible for the isomerization of citrate to isocitrate, a crucial step in the Krebs Cycle.

Multiple choice

What is the name of the enzyme complex that catalyzes the oxidative decarboxylation of α-ketoglutarate to succinyl CoA?

  1. Pyruvate dehydrogenase complex

  2. α-Ketoglutarate dehydrogenase complex

  3. Succinate dehydrogenase complex

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

The α-Ketoglutarate dehydrogenase complex is the enzyme responsible for the conversion of α-ketoglutarate to succinyl CoA, releasing carbon dioxide as a byproduct.