More practice questions

4. Q4. At which two steps of glycolysis is ATP used?

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   In the conversion of glucose into glucose-6-phosphate, and of fructose-6-phosphate into fructose 1,6-bisphosphate (NCERT page 156).

5. Q5. Assertion: classical glycolysis does not directly consume O_₂. Reason: its oxidation step transfers reducing equivalents to NAD^⁺ rather than O_₂. Are both true, and does the reason explain the assertion?

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   Both are true, and the reason explains the assertion. NAD^⁺ must still be regenerated so the pathway can continue (NCERT pages 155–157).

6. Q6. Name the three major ways in which cells handle the pyruvic acid from glycolysis.

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   Lactic acid fermentation, alcoholic fermentation and aerobic respiration (NCERT page 157).

7. Q7. Give the schematic representation of glycolysis. (NCERT Exercise 3)

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   Glucose → (ATP used) glucose-6-phosphate → fructose-6-phosphate → (ATP used) fructose 1,6-bisphosphate → DHAP + PGAL (DHAP → PGAL) → 2 × [PGAL → (NAD^⁺ → NADH + H^⁺) BPGA → (ATP made) 3-phosphoglyceric acid → 2-phosphoglycerate → (water lost) PEP → (ATP made) pyruvic acid] (NCERT page 156; see the figure on the page).