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

Respiration is a process in which

  1. energy is stored in the form of ADP

  2. energy is used up

  3. energy is released in the form of ATP

  4. energy is not released at all
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During respiration, energy is released in the form of ATP along with carbon dioxide and water. So, option 3 is correct.

Multiple choice

During the course of metabolism, amino acids are converted to the following seven common metabolic intermediates:

  1. Pyruvate
  2. α-ketoglutarate
  3. Succinyl-CoA
  4. Fumarate
  5. Oxaloacetate
  6. Acetyl-CoA
  7. Acetoacetate

Which of the above metabolic intermediates are exclusively glucogenic?

  1. 1, 2, 3 and 4

  2. 1, 3, 5 and 7

  3. 2, 3, 4 and 5

  4. 3, 4, 5 and 6

  5. 4, 5, 6 and 7
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

α-ketoglutarate, Succinyl-CoA, Fumarate and Oxaloacetate: All are glucogenic intermediates (form glucose).

Multiple choice

Which of the following is an example of allosteric enzyme?

  1. Phosphofructokinase

  2. Glycogen synthase

  3. β-galactosidase

  4. Lactate dehydrogenase

  5. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Enzymes that are able to be regulated by binding specific ligands are defined as allosteric. Phosphofructokinase follows allosteric interaction regulation mechanism.

Multiple choice

Which of the following statements regarding TCA is incorrect?

  1. The major eventual substrate of the cycle is ADP.

  2. The regulation of TCA cycle is largely determined by product inhibition and substrate availability.

  3. For each acetyl group that enters the citric acid cycle, three molecules of NADH are produced.

  4. The citrate goes through a series of chemical transformations, losing two carboxyl groups as HCO3-.

  5. In TCA, citrate is used for feedback inhibition.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The citrate goes through a series of chemical transformations, losing two carboxyl groups as CO2. The carbons donated by acetyl-CoA become a part of the oxaloacetate carbon backbone after the first turn of the citric acid cycle.

Multiple choice

Which of the following statements regarding metabolites is INCORRECT?

  1. Alcohol is a primary metabolite.

  2. The metabolome forms a large network of metabolic reactions.

  3. The rate of degradation of a metabolite is an important determinant of the duration and intensity of its action.

  4. Some antibiotics use sceondary metabolites as precursors.

  5. A secondary metabolite has an important ecological function.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Some antibiotics use primary metabolites as precursors.

Multiple choice

Which of the following substances act as an inhibitor of the electron transport system between the flavoproteins and coenzyme Q?

  1. Antimycin A

  2. Amytal

  3. Atractyloside

  4. Azurin

  5. Bactoprenol
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Various inhibitors are used in the study of the electron transport system at various levels of electron carriers. Amytal (5-ethyl-5-isoamylbarbituric acid) is a barbiturate drug that inhibits the electron transport system between the flavoproteins and coenzyme Q.

Multiple choice

_________ is called reduced NADP.

  1. ATP

  2. ADP

  3. NATP

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

NADPH (Nicotinamide Adenine Dinucleotide Phosphate Hydrogen) is the reduced form of NADP. During photosynthesis, NADP+ accepts electrons (and H+) to become NADPH. ATP and ADP are energy currency molecules but are not related to NADP reduction. NATP is not a standard biological molecule.

Multiple choice

RuDP is

  1. Ribose di-phosphate

  2. Ribulose di-phospharous

  3. Ribose di-phosphorous

  4. Ribulose di-phosphate
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

RuDP (Ribulose diphosphate) is a 5-carbon sugar molecule that plays a crucial role in the Calvin cycle of photosynthesis, where it accepts carbon dioxide to begin carbon fixation.

Multiple choice

______ is called reduced NADP.

  1. ATP

  2. ADP

  3. NATP

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

NADPH is the reduced form of NADP (nicotinamide adenine dinucleotide phosphate). It serves as an electron carrier in photosynthesis, delivering energized electrons to the Calvin cycle for carbon fixation.

Multiple choice

ADP can be joined with a phosphate group by using energy to form ____.

  1. NADP

  2. ATP

  3. NADPH

  4. all the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

ADP (adenosine diphosphate) combines with a phosphate group using energy (typically from cellular respiration) to form ATP (adenosine triphosphate), the cell's primary energy currency. This reversible reaction stores and releases biochemical energy.

Multiple choice

ATP contains ______ phosphates in its molecule.

  1. 1

  2. 2

  3. 3

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

ATP (Adenosine Triphosphate) contains three phosphate groups in its molecular structure - hence the name 'Triphosphate'. These three phosphates are connected by high-energy bonds, with the third phosphate being the one most frequently transferred to release energy during cellular reactions.