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 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'.

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

Oxidative phosphorylation refers to

  1. Anaerobic production of ATP

  2. The citric acid cycle production of ATP

  3. Production of ATP by chemiosmosis

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

Oxidative phosphorylation is the process where ATP is formed as a result of the transfer of electrons from NADH or FADH2 to O2 by a series of electron carriers, coupled with chemiosmosis.

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

ATP synthesis in cell requires

  1. $H^+$ gradient across the membrane
  2. $K^+$ gradient across the membrane
  3. $PO^{3-} _4$ gradient across the membrane
  4. $Ca^{2+}$ gradient across the membrane
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
A) A ${ H }^{ + }$ gradient or proton pump is developed in the lumen of the thylakoid which helps in ATP synthesis.
B) ${ K }^{ + }$ does not play a role in ATP synthesis.
C) ${ PO } _{ 4 }^{ 3- }$ does not play a role in ATP synthesis.
D) ${ Ca }^{ 2+ }$ is involved in the photolysis of water.
So the correct answer is '${ H }^{ + }$ gradient across the membrane'.
Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

The chemiosmotic coupling hypothesis of oxidative phospohorylation proposes that adenosine triphosphate is formed because

  1. A Proton gradient forms across the inner membrane

  2. There is a change in the permeability of the inner mitochondria membrane toward adenosine diphosphate

  3. High energy bonds are formed in mitochondrial proteins

  4. ADP is pumped out of the matrix into the intermembrane space
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The chemiosmotic hypothesis states that the energy stored in a proton gradient across the inner mitochondrial membrane drives the synthesis of ATP by ATP synthase.

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

Chemiosmotic mechanism of ATP synthesis was proposed by 

  1. Warburg

  2. Dickens

  3. Krebs

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

Chemiosmosis is the movement of ions across a selectively permeable membrane, down their electrochemical gradient. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration or photosynthesis. Peter D. Mitchell proposed the chemisomotic hypothesis in 1961. The theory suggests essentially that most ATP synthesis in respiring cells  comes from the electrochemical gradient across the inner membranes of mitochondria by using the energy of $NADH _2$ and $FADH _2$ formed from the breaking down of energy-rich molecules such as glucose.

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

Chemiosmotic theory of ATP synthesis in the chloroplasts and mitochondria is based on

  1. Membrane potential

  2. Accumulation of K ions

  3. Proton gradient

  4. Accumulation of Na ions
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The chemiosmotic theory, proposed by Peter Mitchell, explains that ATP synthesis in both chloroplasts and mitochondria is driven by the electrochemical gradient of protons across the membrane.

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

ATP is known as energy currency of a cell. ATP is synthesized from ADP and Pi. The reaction is catalyzed by an enzyme called as ATP synthase. When the enzyme and substrate (ADP) are distant inside the cell, the reaction cannot take place spontaneously. Which of the following statements best explains the cause for the ATP synthase and ADP to interact?

  1. Electronegativity of ADP attracts ATP synthase

  2. ADP will be actively pumped to ATP synthase

  3. Random movements will bring ADP to ATP synthase

  4. ADP and ATP synthase always remain bound to oxysomes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Inside a living cell, molecules are in constant thermal motion, leading to random collisions. These random movements eventually bring the enzyme ATP synthase and its substrate ADP into contact so that catalysis can occur.

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

How many ATP molecules could maximally be generated from one molecule of glucose, if the complete oxidation of one mole of glucose to $CO _2$ and $H _2O$ yields $686$kcal and the useful chemical energy available in the high energy phosphate bond of one mole of ATP is $12$kcal?

  1. $1$
  2. $2$
  3. $30$
  4. $57.1$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice bio-chemistry biological oxidation chemiosmotic hypothesis living organisms and energy production mechanism of photosynthesis

The idea that pH gradients could provide energy for ATP formation in chloroplasts and mitochondria was first proposed by ____________.

  1. Bassham

  2. Hill

  3. Mitchell

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

Peter Mitchell proposed the chemiosmotic hypothesis, which states that proton gradients across thylakoid and inner mitochondrial membranes provide the driving force for ATP synthesis.

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

Direct gain of ATP from one mole of glucose during glycolysis or EMP pathaway ____________.

  1. 2 ATP

  2. 6 ATP

  3. 36 ATP

  4. 38 ATP
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Glycolysis (EMP pathway) produces a net gain of 2 ATP molecules per glucose molecule through substrate-level phosphorylation. While 4 ATP are grossly produced, 2 ATP are consumed in the energy investment phase, resulting in a net yield of 2 ATP.

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

How many ATP molecules could maximally be generated from on molecule of glucose, if the complete oxidation of one mole of glucose to $C{ O } _{ 2 }$ and $H _{ 2 }O$ yields 686 kcal and the useful chemical energy available in the high energy phosphate bond of one mole of ATP is 12 kcal ?

  1. $\displaystyle Two$
  2. $\displaystyle Thirty$
  3. $\displaystyle Fifty \ seven$
  4. $\displaystyle One$
Reveal answer Fill a bubble to check yourself
A Correct answer