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 enzyme catalyzes the phosphorylation of 1,3-bisphosphoglycerate to 3-phosphoglycerate?

  1. phosphoglycerate kinase

  2. glyceraldehyde-3-phosphate dehydrogenase

  3. triose phosphate isomerase

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

Phosphoglycerate kinase catalyzes the phosphorylation of 1,3-bisphosphoglycerate to 3-phosphoglycerate.

Multiple choice

What is the role of phosphoglycerate mutase in glycogenesis?

  1. converts 3-phosphoglycerate to 2-phosphoglycerate

  2. converts 2-phosphoglycerate to 3-phosphoglycerate

  3. converts phosphoenolpyruvate to pyruvate

  4. converts pyruvate to phosphoenolpyruvate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Phosphoglycerate mutase catalyzes the conversion of 3-phosphoglycerate to 2-phosphoglycerate.

Multiple choice

Which enzyme catalyzes the dehydration of 2-phosphoglycerate to phosphoenolpyruvate?

  1. enolase

  2. phosphoglycerate kinase

  3. phosphoglycerate mutase

  4. glyceraldehyde-3-phosphate dehydrogenase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Enolase catalyzes the dehydration of 2-phosphoglycerate to phosphoenolpyruvate.

Multiple choice

What is the role of pyruvate kinase in glycogenesis?

  1. converts phosphoenolpyruvate to pyruvate

  2. converts pyruvate to phosphoenolpyruvate

  3. converts glucose-6-phosphate to fructose-6-phosphate

  4. converts fructose-1,6-bisphosphate to dihydroxyacetone phosphate and glyceraldehyde-3-phosphate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pyruvate kinase catalyzes the conversion of phosphoenolpyruvate to pyruvate.

Multiple choice

Which enzyme catalyzes the transfer of the glycosyl unit from UDP-glucose to glycogen?

  1. glycogen synthase

  2. glycogen phosphorylase

  3. glycogen branching enzyme

  4. glycogen debranching enzyme
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Glycogen synthase catalyzes the transfer of the glycosyl unit from UDP-glucose to glycogen.

Multiple choice

What is the role of glycogen branching enzyme in glycogenesis?

  1. creates branch points in the glycogen molecule

  2. removes branch points from the glycogen molecule

  3. transfers the glycosyl unit from UDP-glucose to glycogen

  4. converts glucose-6-phosphate to fructose-6-phosphate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Glycogen branching enzyme creates branch points in the glycogen molecule.

Multiple choice

Which enzyme catalyzes the removal of branch points from the glycogen molecule?

  1. glycogen debranching enzyme

  2. glycogen branching enzyme

  3. glycogen synthase

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

Glycogen debranching enzyme catalyzes the removal of branch points from the glycogen molecule.

Multiple choice

What is the role of glycogen phosphorylase in glycogenesis?

  1. catalyzes the breakdown of glycogen to glucose-1-phosphate

  2. catalyzes the synthesis of glycogen from glucose-1-phosphate

  3. creates branch points in the glycogen molecule

  4. removes branch points from the glycogen molecule
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

Multiple choice

What is the process by which carbohydrates are broken down into glucose?

  1. Glycolysis

  2. Gluconeogenesis

  3. Glycogenolysis

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

Glycolysis is the process by which carbohydrates are broken down into glucose.

Multiple choice

What is the process by which carbohydrates are converted into fats?

  1. Glycolysis

  2. Gluconeogenesis

  3. Glycogenolysis

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

Lipogenesis is the process by which carbohydrates are converted into fats.

Multiple choice

What are the main precursors for gluconeogenesis?

  1. Lactate

  2. Glycerol

  3. Alanine

  4. Glutamine

  5. All of the above
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The main precursors for gluconeogenesis are lactate, glycerol, alanine, and glutamine, which are derived from the breakdown of proteins, fats, and lactate.

Multiple choice

What is the first step in gluconeogenesis?

  1. Conversion of pyruvate to oxaloacetate

  2. Conversion of oxaloacetate to phosphoenolpyruvate

  3. Conversion of phosphoenolpyruvate to fructose-1,6-bisphosphate

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

The first step in gluconeogenesis is the conversion of pyruvate to oxaloacetate, which is catalyzed by the enzyme pyruvate carboxylase.

Multiple choice

What is the final step in gluconeogenesis?

  1. Conversion of pyruvate to oxaloacetate

  2. Conversion of oxaloacetate to phosphoenolpyruvate

  3. Conversion of phosphoenolpyruvate to fructose-1,6-bisphosphate

  4. Conversion of fructose-1,6-bisphosphate to glucose-6-phosphate
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The final step in gluconeogenesis is the conversion of fructose-1,6-bisphosphate to glucose-6-phosphate, which is catalyzed by the enzyme glucose-6-phosphatase.

Multiple choice

What is the net energy yield of gluconeogenesis?

  1. 6 ATP

  2. 8 ATP

  3. 10 ATP

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

The net energy yield of gluconeogenesis is 6 ATP molecules per molecule of glucose produced.

Multiple choice

What is the physiological significance of gluconeogenesis?

  1. To maintain blood glucose levels during fasting or starvation

  2. To provide energy for muscle contraction

  3. To synthesize glycogen for storage

  4. To produce glucose for the brain

  5. All of the above
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Gluconeogenesis has several physiological significances, including maintaining blood glucose levels during fasting or starvation, providing energy for muscle contraction, synthesizing glycogen for storage, and producing glucose for the brain.