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 bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

The function of ATP synthase enzyme is that

  1. It uses energy to move ions against their concentration gradient by removing a phosphate group from ATP.

  2. It uses the power of ions moving against their concentration gradient to add a phosphate group to ADP.

  3. It uses the power of ions moving down their concentration gradient to add a phosphate group to ADP.

  4. It uses the power of ions moving against their concentration gradient to remove a phosphate group from ATP.

  5. It uses the power of ions moving down their concentration gradient to remove a phosphate group from ATP.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Electron transport chain includes the downhill flow of electrons to final electron acceptor through a chain of membrane-bound carriers to facilitate the uphill transport of protons across a proton-impermeable membrane. It produces proton gradient that drives transport of protons (ions) down the concentration gradient through Fo particles of ATP synthase. The proton-motive force that drives movement of protons (ions) provides the energy for ADP phosphorylation. Thus, the correct answer is option C.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

NAD of Krebs cycle functions as

  1. Acceptor of hydrogen ion and electrons

  2. Oxygen acceptor

  3. Oxygen donor

  4. Donor of phosphate ions
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

NAD is a coenzyme which acts as an electron acceptor in Krebs cycle and acquires hydrogen ions to become NADH.

So the correct option is 'Acceptor of hydrogen ion and electrons'.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Oxidative phosphorylation occurs during 

  1. Transpiration

  2. Respiration

  3. Protein synthesis

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

Oxydative phosphorylation is the process of formation of ATP as a result of transfer of electrons from NADH or FADH$ _2$ to O$ _2$. This process which takes place in mitochondria and ATP is the major source of cellular respiration.

So, the correct option is 'Respiration'. 

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Enzymes of oxidative phosphorylation occur in

  1. Endoplasmic reticulum

  2. Chloroplasts

  3. Mitochondria

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

Enzymes that catalyze oxidative phosphorylation are present in the inner membrane which is much less permeable of mitochondria. Oxidative phosphorylation is the process of electrons are transferred from electron donors to electron acceptors 

So the correct option is 'Mitochondria'.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Which is end product of oxidative phosphorylation?

  1. ATP
  2. ATP + $H _2O$

  3. NADH

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

the process produces the 2 pyruvate molecule with 2 water molecule, 2 ATP, 2 NADH molecules, and 2 hydrogen ions. At the end of electron transport, oxygen is the final electron acceptor, and it combines also with hydrogen ions to form H2O. The end product of oxidative phosphorylation would be ATP molecules, which carry energy.

So the correct option is 'ATP + H$ _2$O'.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

FAD is electron acceptor during oxidation of 

  1. Ketoglutarate Succinyl CoA.

  2. Succinic acid Fumaric acid.

  3. Succinyl CoA Succinic acid.

  4. Fumaric acid Malic acid.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The hydrogen acceptor is FAD during the oxidation of Succinic acid Fumaric acid by succinate dehydrogenase.

So the correct option is 'Succinic acid Fumaric acid.'

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Differences between photophosphorylation (PP) and oxidative phosphorylation (OP) is 

  1. In PP, synthesis is of ATP while in OP it is of ADP.

  2. In PP, oxygen is evolved while in OP oxygen is taken up.

  3. Both cannot take place in light.

  4. PP can take place in green leaves while OP cannot occur in green leaves.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Both the oxidative phosphorylation and photophosphorylation are in which cells make energy in the form of ATP, oxidative phosphorylation occurs during cell respiration and photophosphorylation occurs during photosynthesis. Oxygen is released during photophosphorylation and oxygen is taken up.

So the correct option s 'In PP, oxygen is evolved while in OP oxygen is taken up'.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Mitochondrial electron transport chain is

  1. Cyclic phosphorylation.

  2. Oxidative phosphorylation.

  3. Noncyclic phosphorylation.

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

The electron is transferred from NADH to oxygen in mitochondria con­sists of four multi-protein complexes is coupled to the synthesis of ATP from ADP and inorganic phosphate (Pi) which is called as oxidative phosphorylation. 

So the correct option is 'Oxidative phosphorylation.'

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Coenzyme $NAD^+$ and FAD are connected with respiratory reactions as they

  1. Are involved in each step of ATP synthesis.

  2. Function in Krebs cycle and terminal oxidative phosphorylation.

  3. Act as hydrogen carrier.

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

NAD and FAD plays a major role in cellular respiration,  They carry the H+ and electrons to Electron Transport Chain to convert ADP + Pi ATP.

So the correct option is 'Act as a hydrogen carrier.'

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Glyceraldehyde phosphate is oxidised in glycolysis. The hydrogen atom and electron liberated cause

  1. Oxidation of NAD$^+$.
  2. Reduction of NAD$^+$.

  3. Change in oxaloacetic acid.

  4. Formation of methane.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Glyceraldehyde-3-phosphate is oxidized by the coenzyme nicotinamide adenine dinucleotide (NAD). NAD+ is an oxidizing agent - it accepts electrons from other molecules and becomes reduced.

So the correct option is 'Reduction of NAD+'.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Which of the following is a biological uncoupler of oxidative phosphorylation?

  1. Thermogenin.

  2. 2, 4-Dichlorophenoxyacetic acid.

  3. 2, 4-Dinitrophenol.

  4. Ethylene diaminotetra-acetic acid.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Brown adipose tissue is rich in mitochondria, containing an uncoupling protein (thermogenin) that uncouples oxidation and phosphorylation of adenosine diphosphate, reduces ATP production, and consequently enhances thermogenesis.

So the correct option is 'Thermogenin'.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

Identify the wrong statement.

  1. Proton motive force drives the uniport.
  2. Movement of NO$ _3$ ions in cotransport is against their own concentration gradient.

  3. Azides inhibit the process of respiration.

  4. ATPase serves as proton-translocating carrier protein.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Proton motive force drives ATP synthesis via ATP synthase, not uniport. The other statements describe known biological processes.

Multiple choice bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

In mechanism, photophosphorylation is very similar to

  1. substrate-level phosphorylation

  2. oxidative phosphorylation

  3. Calvin cycle

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

Oxidative phosphorylation is the process in which ATP is formed by the transfer of electrons from NADH or FADH 2 to O 2 by a series of electron carriers. The sunlight-driven production of ATP from ADP and inorganic phosphate is called photophosphorylation.

So, the correct option is, 'oxidative phosphorylation'.