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

Anaerobic respiration takes place in

  1. Ribosome

  2. Nucleus

  3. Vacuole

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

Anaerobic respiration takes place in the the cytoplasm of the cell, at a distance from mitochondria. After the glycolysis, pyruvate is further oxidised anaerobically producing energy which is much less than that produced aerobically.

So the answer is 'Cytoplasm'.

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

Aerobic respiration occurs in

  1. Thylakoid.

  2. Golgi body.

  3. Grana.

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

Glycolysis takes place in the anaerobic condition in the cytosol of cytoplasm in all cells, Krebs cycle takes place in the aerobic condition in the mitochondrial matrix of eukaryotic cells.

So the correct option is 'Mitochondria.'

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

The energy-releasing process in which the substrate is oxidised without an external electron acceptor is called?

  1. Aerobic respiration

  2. Glycolysis

  3. Fermentation

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

Fermentation is an anaerobic energy-releasing process where an organic substrate is oxidized without an external inorganic electron acceptor. In contrast, aerobic and anaerobic respiration use an electron transport chain.

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

Aerobic respiration of glucose produces energy _______________.

  1. $637K.Cal$
  2. $640K. Cal$
  3. $686K.cal$
  4. $693K.cal$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The complete aerobic oxidation of one mole of glucose releases approximately 686 kcal of energy under standard biological conditions. This is a standard biochemical constant taught in cellular respiration.

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.