In an ecosystem,
(1) cycling of energy and nutrients is a coupled process.
(2) cycling of energy is an independent process.
(3) movement of energy is unidirectional.
(4) both macro and micro consumers are necessary .
Choose the correct option for statement/s which complete / s the above statement.

Options

A. only 1
B. only 3
C. 1 and 3 both
D. only 4

Answer

To solve the question regarding the statements about energy and nutrient cycling in an ecosystem, let's analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement 1: Cycling of energy and nutrients is a coupled process.**
- This statement is **correct**. In an ecosystem, the cycling of energy and nutrients is indeed a coupled process. Energy flows through the ecosystem while nutrients are recycled. The energy flow supports the cycling of nutrients, and both processes are essential for maintaining ecosystem functionality.

**Hint:** Consider how energy supports life processes and how nutrients are recycled through various trophic levels.

2. **Statement 2: Cycling of energy is an independent process.**
- This statement is **incorrect**. The cycling of energy is not independent; it is closely linked to the cycling of nutrients. Energy transfer involves various organisms and processes that also depend on nutrient availability.

**Hint:** Think about how energy transfer affects and is affected by the availability of nutrients in an ecosystem.

3. **Statement 3: Movement of energy is unidirectional.**
- This statement is **correct**. Energy moves in a unidirectional flow in an ecosystem, starting from producers (like plants) and moving up through various trophic levels to consumers (herbivores and carnivores) and finally to decomposers. Energy does not cycle back to the producers; it dissipates as heat.

**Hint:** Remember the flow of energy in food chains and how it does not return to the source.

4. **Statement 4: Both macro and micro consumers are necessary.**
- This statement is **incorrect**. While both macro (larger consumers) and micro (smaller decomposers) consumers play roles in ecosystems, the statement implies that both are necessary for the cycling process. However, the essential role of decomposers (micro consumers) is critical, but macro consumers can vary in necessity depending on the ecosystem.

**Hint:** Consider the roles of different types of consumers in nutrient cycling and energy flow.

### Conclusion:
Based on the analysis:
- Correct statements are **1** and **3**.
- The correct option that completes the statement is **option 3: first and third both**.

### Final Answer:
The correct option is **3 (first and third both)**.