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 fate of pyruvate at the end of glycolysis?

  1. It is converted to acetyl-CoA and enters the citric acid cycle

  2. It is converted to lactate and excreted from the cell

  3. It is converted to ethanol and excreted from the cell

  4. It is converted to carbon dioxide and excreted from the cell
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Pyruvate is converted to acetyl-CoA by pyruvate dehydrogenase, which is the first step in the citric acid cycle.

Multiple choice

What is the role of NAD+ in glycolysis?

  1. It is a substrate for glycolysis

  2. It is a product of glycolysis

  3. It is a cofactor for glycolysis

  4. It is an inhibitor of glycolysis
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

NAD+ is a cofactor for glycolysis, and it is reduced to NADH during the oxidation of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate.

Multiple choice

What is the role of phosphoglycerate kinase in glycolysis?

  1. It catalyzes the phosphorylation of glucose

  2. It catalyzes the isomerization of glucose-6-phosphate to fructose-6-phosphate

  3. It catalyzes the cleavage of fructose-1,6-bisphosphate into two three-carbon molecules

  4. It catalyzes the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Phosphoglycerate kinase catalyzes the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate, which is a substrate-level phosphorylation reaction that produces ATP.

Multiple choice

What is the role of enolase in glycolysis?

  1. It catalyzes the phosphorylation of glucose

  2. It catalyzes the isomerization of glucose-6-phosphate to fructose-6-phosphate

  3. It catalyzes the cleavage of fructose-1,6-bisphosphate into two three-carbon molecules

  4. It catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enolase catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate, which is a substrate-level phosphorylation reaction that produces ATP.

Multiple choice

What is the role of pyruvate kinase in glycolysis?

  1. It catalyzes the phosphorylation of glucose

  2. It catalyzes the isomerization of glucose-6-phosphate to fructose-6-phosphate

  3. It catalyzes the cleavage of fructose-1,6-bisphosphate into two three-carbon molecules

  4. It catalyzes the conversion of phosphoenolpyruvate to pyruvate
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Pyruvate kinase catalyzes the conversion of phosphoenolpyruvate to pyruvate, which is a substrate-level phosphorylation reaction that produces ATP.

Multiple choice

What is the overall equation for glycolysis?

  1. Glucose + 2 NAD+ + 2 ADP + 2 Pi → 2 Pyruvate + 2 NADH + 2 ATP + 2 H2O

  2. Glucose + 2 NAD+ + 2 ADP + 2 Pi → 2 Pyruvate + 2 NADH + 4 ATP + 2 H2O

  3. Glucose + 2 NAD+ + 2 ADP + 2 Pi → 2 Pyruvate + 2 NADH + 6 ATP + 2 H2O

  4. Glucose + 2 NAD+ + 2 ADP + 2 Pi → 2 Pyruvate + 2 NADH + 8 ATP + 2 H2O
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The overall equation for glycolysis is Glucose + 2 NAD+ + 2 ADP + 2 Pi → 2 Pyruvate + 2 NADH + 2 ATP + 2 H2O.

Multiple choice

What is the role of glycolysis in cellular respiration?

  1. It is the first step in cellular respiration

  2. It is the only step in cellular respiration

  3. It is the final step in cellular respiration

  4. It is not a step in cellular respiration
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Glycolysis is the first step in cellular respiration, and it is responsible for the breakdown of glucose into two molecules of pyruvate.

Multiple choice

What is the role of glycolysis in the production of ATP?

  1. It is the only step in the production of ATP

  2. It is the first step in the production of ATP

  3. It is the final step in the production of ATP

  4. It is not a step in the production of ATP
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Glycolysis is the first step in the production of ATP, and it is responsible for the breakdown of glucose into two molecules of pyruvate, which are then used to produce ATP in the citric acid cycle and oxidative phosphorylation.

Multiple choice

What is the name of the process by which cells break down glucose to produce energy?

  1. Cellular respiration

  2. Photosynthesis

  3. Glycolysis

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

Cellular respiration is the process by which cells break down glucose to produce energy in the form of ATP.

Multiple choice

Which of the following is a common biocatalyst used in biochemical engineering?

  1. Enzymes

  2. Whole cells

  3. Immobilized cells

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enzymes, whole cells, and immobilized cells are all common biocatalysts used in biochemical engineering.

Multiple choice

What is the process by which microorganisms obtain energy from organic compounds?

  1. Photosynthesis

  2. Chemosynthesis

  3. Glycolysis

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

Respiration is the process by which microorganisms obtain energy from organic compounds by breaking them down in the presence of oxygen.

Multiple choice

What is the process by which microorganisms break down glucose into pyruvate?

  1. Photosynthesis

  2. Chemosynthesis

  3. Glycolysis

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

Glycolysis is the process by which microorganisms break down glucose into pyruvate.

Multiple choice

Which of the following is NOT a step in glycolysis?

  1. Phosphorylation of glucose

  2. Isomerization of glucose-6-phosphate to fructose-6-phosphate

  3. Phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate

  4. Cleavage of fructose-1,6-bisphosphate into two molecules of glyceraldehyde-3-phosphate
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cleavage of fructose-1,6-bisphosphate into two molecules of glyceraldehyde-3-phosphate is not a step in glycolysis, but rather a step in the citric acid cycle.

Multiple choice

What is the process by which microorganisms convert pyruvate into acetyl-CoA?

  1. Photosynthesis

  2. Chemosynthesis

  3. Glycolysis

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

The pyruvate dehydrogenase complex is the process by which microorganisms convert pyruvate into acetyl-CoA.

Multiple choice

Which of the following is NOT a step in the pyruvate dehydrogenase complex?

  1. Decarboxylation of pyruvate

  2. Oxidation of pyruvate to acetyl-CoA

  3. Reduction of NAD+ to NADH

  4. Generation of ATP
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Generation of ATP is not a step in the pyruvate dehydrogenase complex, but rather a step in the citric acid cycle.