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 zoology respiratory system do plants breathe? plant respiration respiration-plants

Common phase between aerobic and anaerobic modes of respiration is

  1. Krebs cycle

  2. EMP/glycolysis

  3. Oxidative phosphorylation

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

Aerobic respiration is a type of respiration in which the breakdown of organic compounds takes place with the presence of oxygen and release a large amount of energy in the form of ATP.

In anaerobic respiration, the partial breakdown of organic compound takes place without using oxygen and release only a fraction of energy. The first breakdown of glucose takes place through glycolysis which is the common pathway between the aerobic and anaerobic respiration and it takes place in the cytoplasm.
So, the correct option is 'EMP/Glycolysis'

Multiple choice zoology respiratory system do plants breathe? plant respiration respiration-plants

End products of aerobic respiration are

  1. Sugar and oxygen

  2. Water and energy

  3. Carbon dioxide, water and energy

  4. Carbon dioxide and energy
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Aerobic respiration is the complete oxidation of sugars in presence of oxygen.

The carbohydrates are broken down into CO₂ and H₂O and this releases energy. This energy is stored in the form of ATP and later used in the body.
So, the correct option is 'Carbon dioxide, water, and energy'

Multiple choice zoology respiratory system do plants breathe? plant respiration respiration-plants

Products of anaerobic respiration are

  1. Ethyl alcohol and carbon monoxide

  2. Ethyl alcohol and lactic acid

  3. Lactic acid and glycogen

  4. Acetic acid and carbon dioxide
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Anaerobic respiration occurs in the absence of oxygen and is less efficient than aerobic respiration. Unlike aerobic respiration, the end products here are ethyl alcohol as in alcoholic fermentation and lactic acid as in animal cells. So the answer is 'Ethyl alcohol and lactic acid'.

Multiple choice zoology respiratory system do plants breathe? plant respiration respiration-plants

During aerobic respiration, acetyl CoA is synthesised in

  1. Cytosol.

  2. Mitochondrial matrix.

  3. Perichondrial space.

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

Acetyl CoA is synthesized during oxidative decarboxylation of pyruvic acid and the reaction takes place in the mitochondrial matrix in which two molecules of NADH are produced and it enters the citric acid cycle.

So the correct option is 'Mitochondrial matrix'.

Multiple choice zoology respiratory system do plants breathe? plant respiration respiration-plants

Pentose phosphate pathway, an alternative pathway of respiration was elucidated by

  1. Horecker

  2. Warburg and Dickens

  3. Blackman

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

The pentose phosphate pathway (PPP) or HMP shunt is a biochemical pathway parallel to glycolysis that generates NADPH (reduced energy) and pentoses. PPP was described by Warburg and Dickens. 

Multiple choice zoology respiratory system do plants breathe? plant respiration respiration-plants

In aerobic respiration, the ultimate or final electron acceptor is:

  1. Atomic oxygen

  2. Molecular oxygen
  3. Cytochrome $a _3$

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

In cellular respiration: NADH and FADH2 are converted to ATP through an electron transport chain with oxygen as the 'terminal electron acceptor'. Oxygen is the final electron acceptor. This is the only reason oxygen is required for living systems.

So, the correct option is 'Atomic oxygen'.

Multiple choice zoology respiratory system do plants breathe? plant respiration respiration-plants

Which of the following processes is not related to the pathway of respiration which occurs in both aerobic and anaerobic respiration?

  1. Dehydrogenation of triose phosphate

  2. Substrate level phosphorylation
  3. Reduction of coenzyme $NAD^+$

  4. Release of Carbon dioxide
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Substrate level phosphorylation provides quicker, less efficient, source of ATP, independent of external electron acceptors.This is only present in human erythrocytes which have no mitochondria and in oxygen depleted muscle. 

Multiple choice zoology respiratory system do plants breathe? plant respiration respiration-plants

Which one yields the maximum energy?

  1. Krebs cycle

  2. Anaerobic respiration

  3. Glycolysis

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

Maximum number of ATP is generated per glucose molecule oxidation by aerobic respiration.

Glycolysis gives 2 ATP by  substrate-level phosphorylation and 2 NADH yields 6 ATP (assuming 3 ATP per NADH) by oxidative phosphorylation, Transition Reaction gives 2 NADH yields 6 ATP (assuming 3 ATP per NADH) by oxidative phosphorylation, citric acid cycle gives 2 ATP from substrate-level phosphorylation, 6 NADH yields 18 ATP (assuming 3 ATP per NADH) by oxidative phosphorylation, 2 FADH$ _2$ yields 4 ATP (assuming 2 ATP per FADH$ _2$) by oxidative phosphorylation. So the total maximum yield of ATP generated from one glucose molecule is 38 ATP: 4 from substrate-level phosphorylation; 34 from oxidative phosphorylation.
So the correct option is 'Aerobic respiration'.

Multiple choice zoology respiratory system do plants breathe? plant respiration respiration-plants

Aerobic respiration occurs in 

  1. Mitochondria

  2. Peroxisomes

  3. Cytoplasm

  4. Cytoplasm and mitochondria
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Aerobic respiration occurs in the presence of oxygen. Glycolysis, Krebs' cycle and ETS are all stepwise processes of aerobic respiration. While glycolysis occurs in the cytoplasm, Krebs' cycle and ETS both take place in the mitochondria of the cell. 

So the answer is 'Cytoplasm and mitochondria'.

Multiple choice biology respiration in plants do plants breathe? plant respiration respiration-plants

The number of glucose molecules required to produce 38 ATP molecules under anaerobic condition by a yeast cells is

  1. 2

  2. 4

  3. 19

  4. 25

  5. 38
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In anaerobic respiration (fermentation) in yeast, 1 molecule of glucose yields 2 ATP molecules. To produce 38 ATP molecules, one needs 38 / 2 = 19 glucose molecules.

Multiple choice biology respiration in plants do plants breathe? plant respiration respiration-plants

Anaerobic respiration is also known as

  1. Intramolecular respiration.

  2. Intermolecular respiration.

  3. Extramolecular respiration.

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

Anaerobic respiration is a process of formation of energy in the absence of oxygen. Fermentation is a form of anaerobic respiration and called as intramolecular respiration. Intramolecular respiration is characteristic of certain tissues (the meristem, the fleshy parts of fruits, tubers). Chemically, the intramolecular respiration of green plants is closely related to alcoholic fermentation.