Q4. At which step of the TCA cycle is GTP made, and what kind of phosphorylation is this?
When succinyl-CoA is converted to succinic acid; it is substrate-level phosphorylation (NCERT page 159).
Q5. Name the mobile carrier that transfers electrons between complexes III and IV, and say where it is.
Cytochrome c, a small protein attached to the outer surface of the inner mitochondrial membrane (NCERT page 160).
Q6. Assertion: the process of ATP synthesis in mitochondria is called oxidative phosphorylation. Reason: the energy of oxidation-reduction, not light, builds the proton gradient used for phosphorylation. Are both true, and does the reason explain the assertion?
Both are true, and the reason explains the assertion (NCERT page 160).
Q7. Explain ETS. (NCERT Exercise 6)
The electron transport system is the chain of carriers in the inner mitochondrial membrane through which electrons from NADH + H and FADH pass to O, forming water: complex I (NADH dehydrogenase) and complex II pass them to ubiquinone, then cytochrome bc (complex III), cytochrome c and cytochrome c oxidase (complex IV). The flow is coupled to ATP synthase (complex V), giving 3 ATP per NADH and 2 per FADH (NCERT pages 159–160).
Q8. What is oxidative phosphorylation? (NCERT Exercise 11)
The synthesis of ATP using the energy of oxidation-reduction in the electron transport system, which builds the proton gradient used by ATP synthase; it is called oxidative phosphorylation because this energy comes from oxidation-reduction, whereas in photophosphorylation light energy builds the gradient (NCERT page 160).
Q9. Give a schematic representation of an overall view of Krebs’ cycle. (NCERT Exercise 5)
Acetyl CoA (2C) + OAA (4C) → citric acid (6C) → isocitrate → α-ketoglutaric acid (5C), releasing CO and NADH → succinyl-CoA (4C), releasing CO and NADH → succinic acid (GTP, then ATP) → fumaric acid (FADH) → malic acid → OAA (NADH), which accepts the next acetyl CoA (NCERT pages 158–159; fumaric acid is beyond the NCERT text: MedlinePlus Genetics, SDHA and FH genes).