Question

Assertion: Glycolysis is the first step of respiration in which glucose completely breaks into CO₂ and H₂O.

Reason : In glycolysis process, net gain of ATP is twenty four molecules.

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not correct explanation of A

(c) A is true but R is false

(d) A and R are false

Answer 1

Correct option (d) A and R are false

Explanation:

Glycolysis is the process of breakdown of glucose or similar hexose sugar into two molecules of pyruvic acid through a series of enzyme mediated reactions, releasing energy (ATP) and reducing power (NADH₂). It is the first step of respiration, which occurs inside the cytoplasm and is independent of O₂. In glycolysis, two molecules of ATP are consumed during double phosphorylation of glucose to form fructose 1. 6 diphosphate. Four molecules of ATP are produced in the conversion of 1, 3-diphosphoglycerate to 3-phosphoglycerate and phosphenol pyruvate to pyruvate whereas, two molecules of NADH₂ are formed during oxidation of glyceraldehyde 3- phosphate to 1, 3-diphosphoglycerate. Since, each NADH is equivalent to 3 ATP, so net gain in glycolysis is 8 ATP.