The deficiencies of micronutrients not only affects growth of plants, but also vital functions such as photosynthetic and mitochondrial electron flow. Among the list given below, which group of three elements shall affect the most, both photosynthetic and mitochondrial electron transport ?

Options

A. Cu, Mn, Fe
B. Co, Ni, Mo
C. Mn, Co, Ca
D. Ca, K, Na

Answer

To determine which group of three elements affects both photosynthetic and mitochondrial electron transport, we need to analyze the roles of the given micronutrients in these processes.

### Step-by-Step Solution:

1. **Identify the Micronutrients**: The question provides a list of micronutrients. For this analysis, we will consider copper (Cu), manganese (Mn), and iron (Fe).

2. **Role of Copper (Cu)**:
- Copper is a vital micronutrient that plays a crucial role in redox reactions.
- It is involved in electron transport chains, particularly in oxidative phosphorylation, which is essential for both photosynthesis and respiration.

3. **Role of Manganese (Mn)**:
- Manganese is another important micronutrient that serves as a cofactor for various enzymes.
- It is particularly important in the Krebs cycle (also known as the citric acid cycle), which is a critical part of cellular respiration.

4. **Role of Iron (Fe)**:
- Iron is a key component of cytochromes, which are proteins involved in electron transport chains.
- It plays a significant role in both photosynthesis (specifically in the light reactions) and respiration.

5. **Conclusion**:
- The combination of copper, manganese, and iron is essential for both photosynthetic and mitochondrial electron transport.
- Therefore, the group of three elements that affects both processes the most is **Copper (Cu), Manganese (Mn), and Iron (Fe)**.

### Final Answer:
The group of three elements that shall affect the most, both photosynthetic and mitochondrial electron transport is **Copper (Cu), Manganese (Mn), and Iron (Fe)**.