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 process of glycogen synthesis called?

  1. Glycogenesis

  2. Glycogenolysis

  3. Gluconeogenesis

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

Glycogenesis is the process by which glucose is converted into glycogen and stored in the liver and muscles.

Multiple choice

Which enzyme is responsible for the breakdown of glycogen into glucose?

  1. Glycogen phosphorylase

  2. Glycogen synthase

  3. Glucose-6-phosphatase

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

Glycogen phosphorylase catalyzes the breakdown of glycogen into glucose-1-phosphate.

Multiple choice

What is the process of glycogen mobilization called?

  1. Glycogenesis

  2. Glycogenolysis

  3. Gluconeogenesis

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

Glycogenolysis refers to the process of breaking down glycogen into glucose molecules for energy production.

Multiple choice

Which enzyme is responsible for the conversion of glucose-1-phosphate to glucose-6-phosphate?

  1. Glycogen phosphorylase

  2. Glycogen synthase

  3. Glucose-6-phosphatase

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

Phosphoglucomutase catalyzes the conversion of glucose-1-phosphate to glucose-6-phosphate, which can then enter glycolysis.

Multiple choice

What is the final product of glycolysis?

  1. Glucose-1-phosphate

  2. Glucose-6-phosphate

  3. Pyruvate

  4. Acetyl-CoA
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Glycolysis, the first stage of cellular respiration, converts glucose into pyruvate, generating energy in the form of ATP.

Multiple choice

What is the role of glucose-6-phosphatase in glycogen metabolism?

  1. Synthesis of glycogen

  2. Breakdown of glycogen

  3. Conversion of glucose-1-phosphate to glucose-6-phosphate

  4. Release of glucose from the liver
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Glucose-6-phosphatase catalyzes the removal of the phosphate group from glucose-6-phosphate, allowing glucose to be released from the liver into the bloodstream.

Multiple choice

Which enzyme is responsible for the synthesis of glycogen from glucose-1-phosphate?

  1. Glycogen phosphorylase

  2. Glycogen synthase

  3. Glucose-6-phosphatase

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

Glycogen synthase catalyzes the addition of glucose-1-phosphate to the growing glycogen chain during glycogen synthesis.

Multiple choice

What is the fate of pyruvate produced during glycolysis?

  1. Conversion to acetyl-CoA

  2. Conversion to glucose-1-phosphate

  3. Conversion to glucose-6-phosphate

  4. Conversion to fructose-1,6-bisphosphate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pyruvate, generated in glycolysis, is converted into acetyl-CoA, which enters the citric acid cycle for further energy production.

Multiple choice

Which enzyme catalyzes the first committed step in lipogenesis?

  1. Acetyl-CoA carboxylase

  2. Fatty acid synthase

  3. Glycerol-3-phosphate acyltransferase

  4. Malonyl-CoA decarboxylase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Acetyl-CoA carboxylase converts acetyl-CoA to malonyl-CoA, which is the first committed step in lipogenesis.

Multiple choice

What is the role of malonyl-CoA in lipogenesis?

  1. It is a substrate for fatty acid synthase

  2. It is a cofactor for acetyl-CoA carboxylase

  3. It is an inhibitor of fatty acid synthase

  4. It is a product of fatty acid synthase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Malonyl-CoA is a substrate for fatty acid synthase and is used to elongate the growing fatty acid chain.

Multiple choice

Which enzyme catalyzes the condensation of malonyl-CoA with acetyl-CoA?

  1. Acetyl-CoA carboxylase

  2. Fatty acid synthase

  3. Glycerol-3-phosphate acyltransferase

  4. Malonyl-CoA decarboxylase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Fatty acid synthase catalyzes the condensation of malonyl-CoA with acetyl-CoA to form a four-carbon intermediate.

Multiple choice

What is the role of NADPH in lipogenesis?

  1. It is a cofactor for acetyl-CoA carboxylase

  2. It is a cofactor for fatty acid synthase

  3. It is a cofactor for glycerol-3-phosphate acyltransferase

  4. It is a cofactor for malonyl-CoA decarboxylase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

NADPH is a cofactor for fatty acid synthase and is used to reduce the growing fatty acid chain.

Multiple choice

Which enzyme catalyzes the transfer of a fatty acid from acyl-CoA to glycerol-3-phosphate?

  1. Acetyl-CoA carboxylase

  2. Fatty acid synthase

  3. Glycerol-3-phosphate acyltransferase

  4. Malonyl-CoA decarboxylase
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Glycerol-3-phosphate acyltransferase catalyzes the transfer of a fatty acid from acyl-CoA to glycerol-3-phosphate, forming a phosphatidic acid.

Multiple choice

What is the role of glucagon in lipogenesis?

  1. It stimulates lipogenesis

  2. It inhibits lipogenesis

  3. It has no effect on lipogenesis

  4. It both stimulates and inhibits lipogenesis
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Glucagon inhibits lipogenesis by inactivating acetyl-CoA carboxylase and fatty acid synthase.

Multiple choice

What is the role of AMP-activated protein kinase (AMPK) in lipogenesis?

  1. It stimulates lipogenesis

  2. It inhibits lipogenesis

  3. It has no effect on lipogenesis

  4. It both stimulates and inhibits lipogenesis
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

AMPK inhibits lipogenesis by phosphorylating and inactivating acetyl-CoA carboxylase and fatty acid synthase.