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

Which of the following statements about pentose phosphate pathway are correct?

a. It is an anabolic pathway. b. NADPH produced in this pathway is required for the prevention of the oxidative stress. c. The first step of PP pathway is a rate limiting step and is irreversible. d. Epimerase converts ketose ribulose-5-phosphate to aldose ribose-5-phosphate.

  1. All of the above

  2. Only a, b and c

  3. Only b, c and d

  4. Only a and b

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

This is the correct option. It is an anabolic pathway. NADPH produced in this pathway is required for the prevention of the oxidative stress. The first step of PP pathway is a rate limiting step and is irreversible.

Multiple choice

Which of the following enzymes is not involved in TCA?

  1. Citrate synthase

  2. Fumarase

  3. Malate dehydrogenase

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

Malate synthase is not involved in TCA cycle. It catalyses combination of glyoxylate with acetyl CoA to produce malate in glyoxylate pathway.

Multiple choice

Which of the following events occur in the oxidative phase of PP pathway?

a. Two molecules of NADP+ are reduced to NADPH. b. 6-phosphogluconolactonase catalyses dehydrogenation reaction. c. CO2 is generated in this phase. d. The rate-limiting reaction of pentose phosphate pathway is catalysed by glucose-6-phosphatase.

  1. All of the above

  2. Only a, b and c

  3. Only a, c and d

  4. Only b, c and d

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

This is the correct option. Two molecules of NADP+ are reduced to NADPH. CO2 is generated in this phase. The rate-limiting reaction of pentose phosphate pathway is catalysed by glucose-6-phosphatase.

Multiple choice

Which of the following is the significance of glyoxylate cycle in pathogenic fungi?

  1. It uses acetate as a carbon source.

  2. It increases affinity for the host.

  3. It synthesises chitin in the cell wall.

  4. It increases resistance to antifungals.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Glyoxylate cycle is a significant factor in the pathogenesis (increasing affinity for the host) of fungi. The levels of main glyoxylate enzyme greatly increase after getting in contact with a human host.

Multiple choice

Glucose-6-phosphate dehydrogenase (G6PDH) is the first enzyme that is required for initiation of pentose phosphate pathway. Which of the following is/are the effects of mutation in glucose-6-phosphate dehydrogenase (G6PDH)?

a. Liver problems in neonates b. Chronic granulomatous disease c. Resistance to malarial parasite d. Erythrocyte survival affected

  1. All of the above

  2. Only a, b and c

  3. Only b, c and d

  4. Only a, c and d
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Chronic granulomatous disease, resistance to malarial parasite and affect on erythrocyte survival are the effects that are caused due to mutations in G6PHD.

Multiple choice

Several drugs and toxins inhibit oxidative phosphorylation. Even if a single enzyme is inhibited, the whole process comes to a halt. One such inhibitor is oligomycin, which is used as an antibiotic. It blocks which of the following enzymes?

  1. ATP synthase

  2. Cytochrome c oxidase

  3. Succinate dehydrogenase (complex II)

  4. Cytochrome c reductase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Oligomycin inhibits ATP synthase by blocking the flow of protons through the Fo subunit of mitochondria.

Multiple choice

Phosphoenolpyruvate (PEP) is formed during glycolysis or gluconeogenesis metabolic pathway. It is used by bacteria for which of the following?

  1. Carbon fixation

  2. Chorismate synthesis

  3. Nitrogen fixation

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

PEP is used by bacteria for carbon fixation. Phosphoenolpyruvate carboxylase enzyme catalyses the addition of bicarbonate (HCO3−) to phosphoenolpyruvate (PEP) to form the four-carbon compound oxaloacetate and inorganic phosphate.

Multiple choice

_______ is the energy currency of a cell.

  1. Mitochondria

  2. ATP

  3. ADP

  4. DNA

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

ATP (Adenosine Triphosphate) is the primary energy carrier in all living organisms. It stores and releases energy for various cellular processes.

Multiple choice

TCA cycle is the oxidation of glucose. It takes place in the:

  1. nucleus

  2. plastids

  3. mitochondria

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

These are cylindrical or filamentous structures found in all aerobic eukaryotic cells except the mature and old mammalian RBCs. Each mitochondrion is a double membrane-bound structure enclosing a dense fluid called matrix. Mitochondria provide site for cellular respiration resulting in the formation of energy. Hence, they are termed as the power house or storage batteries or ATP mills. The respiratory pathways in the mitochondria (i.e. TCA cycle) provides substrates for the synthesis of important biomolecules such as chlorophyll, cytochromes and steroids.