Q4. Why is ATP called the energy currency of the cell?
The energy released by oxidation cannot be used directly; it is trapped in ATP, which is broken down whenever and wherever energy is needed (NCERT page 154).
Q5. Assertion: plants need no specialised respiratory organs. Reason: each living cell of a plant lies quite close to the surface. Are both true, and does the reason explain the assertion?
Both are true, and the reason is one of the explanations NCERT gives, along with each part managing its own needs and the low demand for gas exchange (NCERT pages 154–155).
Q6. Name the cytoplasmic pathway described by NCERT that partially oxidises glucose without directly using oxygen, and its product.
Glycolysis, which breaks glucose down to pyruvic acid (NCERT page 155).