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 parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

Energy releasing process in which substrate is oxidised without an external electron acceptor is

  1. Aerobic respiration.

  2. Fermentation.

  3. Photorespiration.

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

During glycolysis process the substrate pyruvic acid is formed from glucose is then oxidized into lactic acid in muscles by pyruvic acid, decarboxylase and alcohol dehydrogenase.

So the correct option is 'Glycolysis.'

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

Which of the following is incorrect for glycolysis?

  1. It produces ATP

  2. It uses ATP
  3. End products are CO$ _2$ and H$ _2$O

  4. None of the above.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During the process of glycolysis, ATP is utilized and produced but the carbon dioxide and water are not the end products.

So the correct option is 'End products are CO$ _2$ and H$ _2$O.'

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

NADH is produced in

  1. Photosystem II

  2. Photosystem I

  3. Glycolysis

  4. Both A and B
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

NADH is essentially produced only during the cellular respiration and it gets oxidised to release energy in the form of ATP. Glycolysis is a part of cellular respiration and leads to production of NADH. However, photosystem I and II produce NADPH rather than NADH as energy carriers. So the answer is 'Glycolysis'.

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

What occurs in glycolysis?

  1. Fixation.

  2. Reduction.

  3. Dehydrogenation.

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

Glycolysis takes place in the cytosol of cytoplasm without the involvement of oxygen. The by-product of glycolysis is pyruvate which entered into mitochondria and oxidized oxygen to carbon dioxide.

So the correct option is 'Oxidation.'

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

In glycolysis, enzyme enolase produces

  1. Phosphoglyceric acid

  2. Phosphoenol pyruvate

  3. Phosphoglyceraldehyde

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

In glycolysis, the respiratory substrate glucose is oxidised to pyruvic acid to release energy. The enzyme enolase converts phosphoglycerate to phosphoenol pyruvate with the release of H$ _2$O. So, the correct answer is 'Phosphoenol pyruvate'.

Multiple choice parts of respiration cellular respiration the respiratory system breathing for energy biology types of respiration

Glycolysis is part of

  1. Only anaerobic respiration

  2. Krebs cycle

  3. Only aerobic respiration

  4. Both aerobic and anaerobic respiration.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

There is no utilization oxygen is seen in the process of glycolysis which takes place in the cytoplasm and it is an anaerobic process. After finishing the glycolysis the cell needs to respirate through aerobic respiration in the presence of oxygen. Aerobic reactions occur in the mitochondria which require oxygen.

So the correct option is 'Both aerobic and anaerobic respiration'.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

How many ATP molecules will be produced when one molecule of 3-phosphosphoglyceric acid is completely oxidised : 

  1. 16

  2. 32

  3. 64

  4. 48
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

One molecule of 3-phosphoglyceric acid enters the glycolytic pathway after the initial steps. Its complete oxidation through glycolysis and the Krebs cycle yields 16 ATP molecules.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

How many ATP molecules are produced after complete oxidation of one molecule of fructose-1, 6-bis-phosphate ?

  1. 40

  2. 32

  3. 38

  4. 44
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Fructose-1,6-bisphosphate is already phosphorylated. It bypasses the initial investment phase of glycolysis, resulting in a net gain of 40 ATP molecules upon complete oxidation.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

ATP synthesis proposed by Peter Mitchell is 

  1. Phosphorylation

  2. Photophosphorylation

  3. Oxidative phosphorylation

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

Peter Mitchell proposed a theory to explain the production of ATP which is 'Mitchell's chemiosmotic coupling hypothesis'. According to this theory:

  1. Inner membrane of mitochondria acts as a transducer of energy and converts energy to chemical energy of ATP along the electrochemical gradient.
  2. Inner mitochondrial membrane is impermeable to NADH, ATP, H+, OH-.
  3. ATP synthesis and electron transport are coupled with proton gradient.
So the answer is 'Chemiosmotic synthesis'.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

ATP is injected in cyanide poisoning because it is

  1. Necessary for cellular functions
  2. Necessary for $Na^+$ - $K^+$ pump
  3. $Na^+$ - $K^+$ pump operates at the cell membranes

  4. ATP breaks down cyanide
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cyanide inhibits cytochrome c oxidase, blocking the electron transport chain and halting ATP production. Injecting ATP provides the necessary energy for vital cellular functions that would otherwise fail.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

Chemiosmotic hypothesis given by Peter Mitchell proposes the mechanism of

  1. Synthesis of ATP.
  2. Synthesis of FADH$ _2$.

  3. Synthesis of NADH.

  4. Synthesis of NADPH.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Peter Mitchell proposed a hypothesis known as the chemiosmotic hypothesis that an electrochemical concentration gradient of protons across a membrane could be utilized to make ATP. He linked this process to osmosis, the diffusion of water across a membrane, this is the reason it is called chemiosmosis.

So the correct option is 'Synthesis of ATP'.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

ATP does not provide phosphate in the reaction

  1. Glucose Glucose 6-P

  2. Fructose Fructose 6-P

  3. PGAL 1 : 3-diPGA

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

In the conversion of PGAL to 1,3-bisphosphoglycerate, the phosphate group is added via inorganic phosphate (Pi) and oxidation, not by transferring a phosphate from ATP.

Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

ATP formation in chloroplast and mitochondrion is explained by

  1. Cholodny-Went model

  2. Chemi-osmotic theory of Mitchell

  3. Munch's mass flow theory

  4. Relay pump theory of Godlewski
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A theory postulated by the biochemist Peter Mitchell in 1961 to describe ATP synthesis by way of a proton electrochemical coupling.
it is based on the proton gradient and transfer of an electron from the mitochondrial matrix in respiration or in the stroma with the photophosphorylation of photosystems forms ATP.
So the correct option is 'Chemi-osmotic theory of Mitchell'.
Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

When cell converts light energy into chemical energy, which of the following reaction would take place?

  1. ADP + iP = ATP

  2. ATP - iP = ADP

  3. AMP + iP = ADP

  4. GDP + iP = GTP
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cells convert light energy is converted into chemical energy. During this process, a phosphate is added to adenosine diphosphate molecule to cause the formation of ATP.

So the correct option is 'ADP + iP = ATP'.