Organisms which are associated with first as well as third trophic level are

Options

A. Macrophytes
B. Phytoplanktons
C. Chemoautotrophs
D. Insectivorous plants

Answer

To answer the question "Organisms which are associated with first as well as third trophic level are," we need to understand the concept of trophic levels in an ecosystem.

### Step-by-Step Solution:

1. **Understand Trophic Levels**:
- Trophic levels represent the position of organisms in a food chain. The first trophic level consists of producers (like plants), the second level consists of primary consumers (herbivores), and the third level consists of secondary consumers (carnivores).

2. **Identify Organisms in the Options**:
- We need to analyze the given options: macrophytes, phytoplankton, chemotrophs, and insectivorous plants.

3. **Evaluate Each Option**:
- **Macrophytes**: These are large aquatic plants. They primarily act as producers and are associated with the first trophic level but do not consume other organisms, so they do not belong to the third trophic level.
- **Phytoplankton**: These are microscopic plants that float in water. They are producers and occupy only the first trophic level, thus not associated with the third trophic level.
- **Chemotrophs**: These organisms obtain energy through chemical processes. They are also producers and do not belong to the third trophic level.
- **Insectivorous Plants**: These plants are autotrophic (produce their own food) but can also digest insects for nutrients. This means they can function as producers (first trophic level) and can also act as consumers (third trophic level) when they digest insects.

4. **Conclusion**:
- The only organisms that can be associated with both the first and third trophic levels are **insectivorous plants**. Therefore, the correct answer is option four.

### Final Answer:
The organisms which are associated with the first as well as third trophic level are **insectivorous plants**.