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 regarding the TCA is incorrect?

  1. In TCA, citrate is used for feedback inhibition.

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

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

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

  5. The major eventual substrate of the cycle is ADP.
Reveal answer Fill a bubble to check yourself
B 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 part of the oxaloacetate carbon backbone after the first turn of the citric acid cycle.  

Multiple choice

Among the following steps, which one does not characterises glycolysis?

  1. For simple fermentations, the metabolism of one molecule of glucose to two molecules of pyruvate has a net yield of four molecules of ATP.

  2. Cells performing aerobic respiration synthesize much more ATP.

  3. The lower-energy production per glucose of anaerobic respiration relative to aerobic respiration results in greater flux.

  4. The second half of glycolysis is characterised by a net gain of the ATP and NADH.

  5. Hydrogen atom balance and charge balance are both maintained in the process of glycolysis.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For simple fermentations, the metabolism of one molecule of glucose to two molecules of pyruvate has a net yield of two molecules of ATP. Most cells will then carry out further reactions to 'repay' the used NAD+ and produce a final product of ethanol or lactic acid.

Multiple choice

Which of the following statements is/are false? a. Mitochondria provides energy for all the activities of the cell. b. Mitochondria uses glucose and hydrogen to produce energy. c. Compounds like water, carbohydrates, proteins, etc., are present in the protoplasm.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Statement 'b' is a false statement. Thus, it is the correct option. Mitochondria uses glucose and oxygen to produce energy.

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 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

ADP has ______ energy content.

  1. more

  2. less

  3. no

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

Adenosine diphosphate (ADP) has two phosphate groups, whereas adenosine triphosphate (ATP) has three. Consequently, ATP stores more energy, and ADP has less energy content compared to ATP. It functions as a lower-energy precursor that gets phosphorylated to become ATP.