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

In which step is GTP produced in citric acid cycle?

  1. Convertion of alpha-keto glutarate to succinyl CoA

  2. Convertion of isocitrate to oxalosuccinate

  3. Conversion of succinyl CoA to succinate

  4. Conversion of succinate to fumarate

  5. Conversion of malate to oxaloacetate
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In this step, GTP is formed.

Multiple choice

The important enzyme involved in regulation of glycolysis is

  1. phosphoglucoisomerase

  2. enolase

  3. pyruvate kinase.

  4. phosphoglycerate kinase

  5. phosphofructose kinase
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This enzyme converts fructose 6-phosphate to fructose 1,6-bisphosphate. This is an important enzyme involved in regulation of glycolysis.

Multiple choice

An example of aldol condensation is

  1. convertion of phosphoglycerate to phosphoenolpyruvate

  2. convertion of phosphoenolpyruvate to pyruvate

  3. convertion of acetyl CoA to citrate

  4. convertion of isocitrate to alpha ketoglutarate

  5. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Condensation of acetyl CoA with oxaloacetate leads to the formation of citrate, which invoves the change in convertion of keto group of oxaloacetate to aldol form. This is known as aldol condensation.

Multiple choice

Priya was working in a laboratory and consumed cyanide. She was rushed to hospital where she was declared dead. Cyanide is a known inhibitor of Electron Transport chain (ETC). Which complex of ETC might have been inhibited?

  1. Complex I

  2. Complex II

  3. Complex III

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

In the above case the cyanide must have blocked complex IV. It  blocks complex IV by taking electrons from complex III in the electron transport chain in the mitochondira of cells, so not enough ATP is formed for the functions of the body. Thus the diaphragm becomes paralyzed and the person dies.

Multiple choice

While playing Mudit accidentally ingested a chemical and presented with high fever. The chemical is known to affect ATP formation in electron transport chain. Which of the following could cause similar manifestations?

  1. Rotenone

  2. 2,4-Dinitrophenol

  3. Antimycin A

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

It  is a chemical uncoupler of electron transport and oxidative phosphorylation. It permeabilizes the inner mitochondrial membrane to protons, killing the proton gradient . In this situation, electrons continue to pass through the electron transport system and reduce oxygen to water, but ATP is not synthesized in the process thus it produces similar manifestations as given in the above question.

Multiple choice

Which of the following enzymes catalyzes substrate level phosphorylation in Kreb's cycle?

  1. Malate dehydrogenase

  2. Phosphoenolpyruvate carboxykinase

  3. Succinate thiokinase

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

This enzyme catalyzes the reversible reaction of succinyl-CoA to succinate during TCA cycle. It aids in the the coupling of this reaction to the formation of a nucleoside triphosphate molecule (either GTP or ATP) from an inorganic phosphate molecule and a nucleoside diphosphate molecule (either GDP or ADP).