Q4. Assertion: the RQ of fats is less than 1. Reason: in the oxidation of tripalmitin, 145 O are consumed for 102 CO evolved. Are both true, and does the reason explain the assertion?
Both are true, and the reason explains the assertion: RQ = 102 ÷ 145 = about 0.7 (NCERT page 164).
Q5. Why does NCERT say that a measured RQ seldom matches a single substrate exactly?
Because respiratory substrates in living organisms are often more than one; pure proteins or fats are never used as respiratory substrates (NCERT page 164).
Q6. Arrange carbohydrates, fats and proteins in increasing order of RQ.
Fats (0.7) < proteins (about 0.9) < carbohydrates (1.0) (NCERT pages 163–164).
Q7. On which factor does the RQ depend, according to NCERT?
On the type of respiratory substrate used during respiration (NCERT page 163).
Q8. A tissue uses 100 mL of O: 40 mL of it oxidises carbohydrate and 60 mL oxidises fat. Using NCERT’s values (carbohydrate 1.0, fat 0.7), find the CO evolved and the RQ.
CO = 40 × 1.0 + 60 × 0.7 = 40 + 42 = 82 mL, so RQ = 82 ÷ 100 = 0.82, between the values for fat and carbohydrate, as expected when the substrates are more than one (NCERT page 164).