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 respiration in organisms glucose metabolism the need for energy in living organism respiratory function

When one molecule of sucrose is subjected to phosphorylation how many ATPs are consumed?

  1. 2

  2. 6

  3. 3

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

During the conversion of fructose-1,6-bis-phosphate to lactate, the pathway generates a total of four molecules of ATP, resulting in a net yield of two ATP per glucose consumed.

correct answer is A.

Multiple choice bio-chemistry respiration in organisms glucose metabolism the need for energy in living organism respiratory function

In pentose phosphate pathway, which of the following process is lacking?

  1. Kreb's cycle

  2. Glycolysis

  3. Oxidative phosphorylation

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The pentose phosphate pathway also called the hexose monophosphate shunt, is a shunt from glycolysis designed to produce either NADPH or ribose or both. There are two distinct phases in the pathway. The first is the oxidative phase, in which NADPH is generated, and the second is the non-oxidative synthesis of 5-carbon sugars. In the pentose phosphate pathway, glucose 6-phosphate is directly oxidized without entering glycolysis. Even Kreb's cycle and oxidative phosphorylation doesn't happen in pentose phosphate pathway.

So, the correct answer is 'All of the above'.


Multiple choice bio-chemistry respiration in organisms glucose metabolism the need for energy in living organism respiratory function

During the complete oxidation of one glucose, how many reduced coenzymes are produced due to following processes?
(A) Link reaction
(B) Glycolysis
(C) Krebs cycle
Choose the correct option from the following.

  1. $A = 1, B = 1, C = 4$
  2. $A = 2, B = 2, C = 4$
  3. $A = 2, B = 2, C = 3$
  4. $A = 2, B = 2, C = 8$
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

In the oxidation of one glucose molecule, during aerobic respiration, 2NADH2 in link reaction, 2NADH2 in glycolysis, 8NADH2 in Krebs cycle are formed.

So, the correct option is ‘A=1, B=1, C=4 or A=2, B=2, C=8’.

Multiple choice bio-chemistry respiration in organisms glucose metabolism the need for energy in living organism respiratory function

How many ${ CO } _{ 2 }$ molecules are produced from one pyruvate on complete oxidation :-

  1. 1

  2. 2

  3. 3

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

During the complete oxidation of pyruvate, two carbon atoms are lost in the form of CO2 - one during the conversion of isocitrate to alpha-ketoglutarate and the second during the conversion of alpha-ketoglutarate to succinyl CoA.
So, the correct answer is '2'.
Multiple choice bio-chemistry respiration in organisms glucose metabolism the need for energy in living organism respiratory function

Sequence of aerobic metabolic breakdown of glucose is

  1. Glycolysis-transition-citric acid cycle-electron transport system

  2. Transition-glycolysis-electron transport-citric acid cycle

  3. Electron transport system-citric acid cycle- transition-glycolysis

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

  • For the aerobic respiration the substrate glucose has  to undergo a following set of process 
  • First of which is glycolysis where the molecule of glucose is broken down to 2 molecules of pyruvate.
  • These pyruvate molecules are to be cconverted to Acetyl CoA so that it can enter the mitochondrial membrane and undergo kerb cycle.
  • After being converted to acetyl coA it takes part in kerb cycle where molecules of NADH, FADH and ATP are formed.
  • These NADH, FADH molecules are the electron acceptors which are used in ETS to transport electron and hydrogen ions through the complexs.
  • These electrons and hydrogen ions are used for the formation of ATP via ATP synthase.
  • Therefore the process for the aerobic breakdown of glucose is Glycolysis followed by transition of pyruvate then citric acid cycle which is followed by electron transport system.
  • Therefore the correct answer is 'Glycolysis-transition-citric acid cycle-electron transport system'








Multiple choice bio-chemistry respiration in organisms glucose metabolism the need for energy in living organism respiratory function

How many oxygen atoms are required for the complete oxidation of one molecule of pyruvate?

  1. 2

  2. 5

  3. 4

  4. 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Under Anaerobic conditions, Pyruvic Acid enters in matrix of mitochondrion and undergoes oxidative decarboxylation to form 2 carbon energy rich compound called Acetyl Co A.

This process utilizes 2 oxygen atoms. Incomplete oxidation of Pyruvate leads to the formation of lactic acid in muscles and formation of ethyl alcohol in yeast as a process of fermentation.

So, the correct answer is '2'

Multiple choice bio-chemistry respiration in organisms glucose metabolism the need for energy in living organism respiratory function

How many molecules of NADH are produced when four molecules of phosphoglyceraldehde are converted into four molecules of pyruvate?

  1. $2$
  2. $6$
  3. $8$
  4. $4$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Glycolysis is a series of reactions that extract energy from glucose by splitting it into two three-carbon molecules called pyruvates. Glycolysis takes place in the cytosol of a cell, and it can be broken down into two main phases: the energy-requiring phase and  the energy-releasing phase. Each three-carbon sugar is converted into another three-carbon molecule, pyruvate, through a series of reactions. In these reactions, ATP molecules and one NADH molecule are made. Because this phase takes place twice, once for each of the two three-carbon sugars, it makes four ATP and two NADH overall.

So the correct option is '2'.

Multiple choice bio-chemistry respiration in organisms glucose metabolism the need for energy in living organism respiratory function

Substrate -level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?

  1. $0\%$
  2. $2\%$
  3. $10\%$
  4. $100\%$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Substrate-level phosphorylation is the direct transfer of phosphate group to ADP to form ATP. It accounts of 100% of the ATP formed by the reactions of glycolysis. The first substrate-level phosphorylation occurs when 1, 3 - diphosphoglyceraldehyde is converted to 1, 3 - diphosphoglyceric acid and 2 NADH$ _2$ are formed, that is 6 ATP are formed. The 1, 3-diphosphoglyceric acid is then dephosphorylated to 3 phosphoglyceric acid producing 2 ATP via substrate-level phosphorylation. The second substrate-level phosphorylation occurs when phosphoenolpyruvic acid is converted to pyruvic acid producing 2 ATP molecules.

Thus, the correct answer is option D. 

Multiple choice bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

Which among the following is the anabolic process?

  1. Glucose converts to lactic acid.

  2. Acetic acid is converted to cholesterol

  3. Glucose converted to pyruvic acid

  4. Glycogen converted to glucose
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Anabolic process involves the synthesis of complex molecules from simple molecules. Cholesterol is a large and complicated molecule. The starting point of cholesterol synthesis is acetic acid.
So, the correct option is 'Acetic acid is converted to cholesterol'
Multiple choice bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

Heterotrophs can metabolize lipids by a process called ___________ into monomers of _____________ and fatty acids.

  1. Hydrolysis; Glycerol

  2. Dehydration synthesis; Glycerol

  3. Hydrolysis; Glycolipids

  4. Dehydration synthesis; Glycolipids
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Heterotrophs can metabolize lipids by a process of hydrolysis, where water molecule is added to break down a chemical compound (lipids). 

Lipids on hydrolysis yield fatty acids and glycerol
So, the correct answer is 'Hydrolysis; Glycerol'

Multiple choice evs food components energy from different food components nutritional requirements of the body need for nutrients simple test for nutrients test for nutrients

Sugars are not as good as fats as a source of energy for cellular respiration, because sugars.

  1. Produce toxic amino groups when broken down

  2. Contain more hydrogen

  3. Usually bypass glycolysis and the Krebs cycle

  4. Contain fewer hydrogen atoms and electrons
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sugars, when broken down, produces toxic amino groups. During Cellular Respiration, sugar is broken down to CO$ _2$and H$ _2$O, and in the process, ATP is made that can then be used for cellular work. Carbohydrates, fats, and proteins can all be used as fuels in cellular respiration, but glucose is most. In glycolysis, the 6-carbon sugar, glucose, is broken down into two molecules.

So the correct answer is 'Produce toxic amino groups when broken down'.