`NAD^(+)` is reduced in photorespiration inside

Options

A. Mitochondria
B. Mitochondria and peroxisome
C. Mitochondria and chloroplasts
D. Chloroplasts and peroxisomes.

Answer

**Step-by-Step Solution:**

1. **Understanding Photorespiration:**
- Photorespiration is a process that occurs in plants, primarily when the enzyme RuBisCO oxygenates RuBP instead of carboxylating it, leading to the formation of a two-carbon compound.

2. **Role of Glycine:**
- In photorespiration, glycine is produced in the peroxisome and then transported to the mitochondria. Glycine is a key intermediate in this process.

3. **Transport of Glycine:**
- Glycine moves from the peroxisome to the mitochondria, where it undergoes further reactions.

4. **Formation of Serine:**
- In the mitochondria, two molecules of glycine combine with water and NAD⁺ (Nicotinamide adenine dinucleotide) to form serine, ammonia, and carbon dioxide. This reaction is crucial as it involves the reduction of NAD⁺.

5. **Reduction of NAD⁺:**
- During the conversion of glycine to serine, NAD⁺ is reduced to NADH. This is an important step because NADH is a reduced form of NAD⁺ and carries electrons for cellular processes.

6. **Further Reactions in Chloroplasts:**
- After the formation of serine, the process continues when glycerate (derived from the earlier steps) enters the chloroplast. Here, it is phosphorylated to form 3-phosphoglycerate (3-PGA), which is part of the Calvin cycle (C3 cycle).

7. **Final Reduction of NAD⁺:**
- In the chloroplast, NAD⁺ is again reduced during the Calvin cycle, leading to the production of NADH.

8. **Conclusion:**
- Therefore, NAD⁺ is reduced in both the mitochondria and the chloroplast during the processes associated with photorespiration and the Calvin cycle.

**Answer:**
NAD⁺ is reduced in photorespiration inside the mitochondria and the chloroplast.

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