Q4. What must happen to amino acids before they enter the respiratory pathway?
They must be deaminated (NCERT page 162).
Q5. Assertion: the respiratory pathway is better called amphibolic than catabolic. Reason: acetyl CoA is withdrawn from the respiratory pathway when the organism needs to make fatty acids. Are both true, and does the reason explain the assertion?
Both are true, and the reason explains the assertion: the pathway is used in synthesis as well as breakdown (NCERT page 162).
Q6. Define catabolism and anabolism.
Breaking down processes within the living organism are catabolism; synthesis is anabolism (NCERT page 162).
Q7. Why do fats and proteins not enter the respiratory pathway at its first step?
They must first be broken down, fats into glycerol and fatty acids and proteins into amino acids, and each product enters at its own point: glycerol as PGAL, fatty acids as acetyl CoA, and amino acids, after deamination, as pyruvate, acetyl CoA or within the Krebs’ cycle (NCERT page 162).