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 complex is responsible for the majority of the reactions in the beta-oxidation pathway?

  1. Pyruvate dehydrogenase complex

  2. Citrate synthase

  3. Fatty acid synthase

  4. Electron transport chain
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Fatty acid synthase is the enzyme complex that catalyzes the majority of the reactions in the beta-oxidation pathway, including the dehydrogenation, hydration, and cleavage steps.

Multiple choice

What is the name of the enzyme that catalyzes the dehydrogenation step in the beta-oxidation pathway?

  1. Acyl-CoA dehydrogenase

  2. Enoyl-CoA hydratase

  3. 3-Hydroxyacyl-CoA dehydrogenase

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

Acyl-CoA dehydrogenase is the enzyme responsible for catalyzing the dehydrogenation step in the beta-oxidation pathway, converting acyl-CoA to enoyl-CoA.

Multiple choice

Which coenzyme is required for the dehydrogenation step in the beta-oxidation pathway?

  1. NADH

  2. FAD

  3. CoQ10

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

FAD (flavin adenine dinucleotide) is the coenzyme required for the dehydrogenation step in the beta-oxidation pathway, accepting electrons from acyl-CoA and transferring them to the electron transport chain.

Multiple choice

What is the name of the enzyme that catalyzes the hydration step in the beta-oxidation pathway?

  1. Enoyl-CoA hydratase

  2. 3-Hydroxyacyl-CoA dehydrogenase

  3. Thiolase

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

Enoyl-CoA hydratase is the enzyme responsible for catalyzing the hydration step in the beta-oxidation pathway, adding a water molecule to enoyl-CoA to form 3-hydroxyacyl-CoA.

Multiple choice

Which coenzyme is required for the hydration step in the beta-oxidation pathway?

  1. NADH

  2. FAD

  3. CoQ10

  4. H2O
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Water is the coenzyme required for the hydration step in the beta-oxidation pathway, adding a hydroxyl group to the double bond of enoyl-CoA.

Multiple choice

What is the name of the enzyme that catalyzes the cleavage step in the beta-oxidation pathway?

  1. Thiolase

  2. Acyl-CoA dehydrogenase

  3. Enoyl-CoA hydratase

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

Thiolase is the enzyme responsible for catalyzing the cleavage step in the beta-oxidation pathway, breaking down 3-hydroxyacyl-CoA into acetyl-CoA and a new acyl-CoA molecule.

Multiple choice

What is the name of the metabolic pathway that converts acetyl-CoA derived from fatty acid oxidation into glucose?

  1. Glycolysis

  2. Gluconeogenesis

  3. Glycogenesis

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

Gluconeogenesis is the metabolic pathway that converts acetyl-CoA derived from fatty acid oxidation into glucose, allowing the body to produce glucose from non-carbohydrate sources.

Multiple choice

Which enzyme catalyzes the rate-limiting step in de novo purine biosynthesis?

  1. Phosphoribosyl pyrophosphate amidotransferase (PPAT)

  2. Glutamine phosphoribosyl pyrophosphate amidotransferase (GPAT)

  3. Inosine monophosphate dehydrogenase (IMPDH)

  4. Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

PPAT catalyzes the first step in de novo purine biosynthesis, which is the conversion of phosphoribosyl pyrophosphate (PRPP) to 5-phosphoribosyl-1-amine (PRA).

Multiple choice

Which enzyme catalyzes the conversion of IMP to adenosine monophosphate (AMP) and guanosine monophosphate (GMP)?

  1. Adenylosuccinate synthetase

  2. Adenylosuccinate lyase

  3. Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)

  4. Inosine monophosphate dehydrogenase (IMPDH)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Adenylosuccinate synthetase catalyzes the conversion of IMP to adenylosuccinate, which is then converted to AMP by adenylosuccinate lyase.

Multiple choice

What is the final step in the de novo synthesis of purines?

  1. Conversion of IMP to AMP and GMP

  2. Conversion of PRA to GAR

  3. Conversion of SAICAR to AICAR

  4. Conversion of AICAR to IMP
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The final step in de novo purine synthesis is the conversion of IMP to AMP and GMP by adenylosuccinate synthetase and adenylosuccinate lyase.

Multiple choice

Which enzyme catalyzes the conversion of hypoxanthine to xanthine?

  1. Xanthine oxidase

  2. Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)

  3. Inosine monophosphate dehydrogenase (IMPDH)

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

Xanthine oxidase catalyzes the conversion of hypoxanthine to xanthine, which is then converted to uric acid by uricase.

Multiple choice

What is the final product of purine degradation?

  1. Hypoxanthine

  2. Xanthine

  3. Uric acid

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

Uric acid is the final product of purine degradation in humans and other primates.

Multiple choice

Which enzyme catalyzes the conversion of xanthine to uric acid?

  1. Xanthine oxidase

  2. Uricase

  3. Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)

  4. Inosine monophosphate dehydrogenase (IMPDH)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Uricase catalyzes the conversion of xanthine to uric acid.

Multiple choice

What is the name of the enzyme that catalyzes the hydrolysis of adenosine to adenine and ribose-1-phosphate?

  1. Adenosine deaminase

  2. Adenosine kinase

  3. Adenosine phosphorylase

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

Adenosine deaminase catalyzes the hydrolysis of adenosine to adenine and ribose-1-phosphate.

Multiple choice

Which enzyme catalyzes the conversion of guanine to xanthine?

  1. Guanine deaminase

  2. Guanine kinase

  3. Guanine phosphorylase

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

Guanine deaminase catalyzes the conversion of guanine to xanthine.