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 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
A Correct answer
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

Calvin cycle has three stages.
$1$. Reduction during which carbohydrate is formed at the expense of photochemically made ATP and NaDPH.
$2$. Regeneration during which carbon dioxide acceptor $1, 5$-RuBP is formed.
$3$. Carboxylation during which $CO _2$ combines with $1, 5-$RuBP.
Identify the correct sequence.

  1. $3, 1, 2$
  2. $3, 2, 1$
  3. $1, 2, 3$
  4. $2, 1, 3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Calvin cycle consists of: 1. Carboxylation (CO2 + RuBP), 2. Reduction (using ATP/NADPH to form sugar), and 3. Regeneration (reforming RuBP). The sequence is 3, 1, 2.

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
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 $H _{2}O$ yields $686\ kcal$ and the useful chemical energy available in the high energy phosphate bond of one mole of ATP is $12\ kcal$?

  1. Two

  2. Thirty

  3. Fifty seven

  4. One
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 energy-carrying compound in the living cell is ATP.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

ATP captures chemical energy obtained from the breakdown of food molecules and its hydrolysis (ATP to ADP + Pi or ADP to AMP + Pi) releases energy that can be used to drive various energy-requiring processes in cells. So, the correct option is 'True'.

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

Choose the correct answers from the alternatives given .
Energy coupling of endergonic and exergonic reactions within cells

  1. Permits biological reactions to proceed at temperatures consistent with life

  2. Uses heat released by one reaction to fuel the other reaction

  3. Utilizes ATP to carry energy between the exergonic and endergonic reactions

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Energy coupling is the use of an exergonic process to carry out an endergonic process. The energy released in an exergonic process is used to develop an endergonic process. The ATP is responsible for mediating the energy coupling of cells, it is the energy currency. It is used to boost many cellular reactions that require energy. This also provides the energy required for reactions without too much increase in temperature. 
So, the correct option is 'All of the above'.