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 of the following matches of ‘reaction of the C3 carbon fixation: enzyme catalysing that step’ is not correct?

  1. Carboxylation of ribulose-1,5-bisphosphate : RuBisCO

  2. Gluconeogenesis : Phosphoglycerate kinase

  3. Spliting of fructose 1,6-bisphosphate : Aldolase

  4. Hexose monophosphate shunt : Ribose-5-phosphate isomerase

  5. Pentose phosphate pathway : Phosphoribulokinase
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In hexose monophosphate shunt, Xylulose 5-phosphate converts into ribulose 5-phosphate, is catalysed by ribulose-phosphate epimerase. Conversion of ribose 5-phosphate to Ribulose 5-phosphate is catalysed by ribose-5-phosphate.

Multiple choice

Which of the following statements are not true about C4 carbon fixation?

P. CO2 fixation occurs twice. Q. Phosphoenolpyruvate acts as CO2 acceptor in bundle sheath. R. Leaf anatomy is of Kranz type. S. Requires 18 ATP for synthesis of one molecule of glucose.

  1. 1 and 2

  2. 1 and 3

  3. 2 and 3

  4. 2 and 4

  5. 3 and 4
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Phosphoenolpyruvate  (PEP) in mesophyll cells and Ribulose-1,5-bisphosphate (RuBP) in bundle sheath functions as carbon dioxide acceptors. C4 plants require 30 ATP for synthesis of one molecule of glucose.

Multiple choice

The first product formed in Krebs cycle is

  1. acetyl CoA

  2. citric acid

  3. succinic acid

  4. iso-citrate

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The Krebs cycle begins with the condensation of acetyl-CoA with oxaloacetate to form citric acid.

Multiple choice

Assertion: The inhibition of glycolysis by oxygen is referred to as Pasteur effect. Reason: This is due to inhibition of the enzyme phosphohexokinase by ATP and 2-hydroxypropane-1,2,3-tricarboxylate (formed in the presence of oxygen).

Directions: In the following question there are two statements, Assertion (A) and Reason (R), consider both the statements independently and mark your answers as under:
1. A and R both are correct and R is correct explanation of A.
2. A and R both are correct and R is not correct explanation of A.
3. A is correct and R is incorrect.
4. A is incorrect and R is correct.
5. A and R both are incorrect.

  1. A and R both are correct and R is the correct explanation of A.

  2. A and R both are correct and R is not the correct explanation of A.

  3. A is correct and R is incorrect.

  4. A is incorrect and R is correct.

  5. A and R both are incorrect.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Both Assertion (A) and Reason (R) are correct and R is the correct explanation of A. The inhibition of glycolysis by oxygen is referred to as Pasteur effect. This is due to inhibition of the enzyme phosphohexokinase by ATP and 2-hydroxypropane-1,2,3-tricarboxylate (citrate) (formed in the presence of oxygen).