The correct option is 1 and 3 only.
Explanation
In an aquatic ecosystem, organisms are functionally classified based on their nutritional roles. Producers (Autotrophs) synthesize their own food using sunlight (photosynthesis), whereas Consumers (Heterotrophs) depend on other organisms for energy.
- 1. Phytoplankton: Correct. Phytoplankton are microscopic, free-floating organisms (e.g., algae, diatoms) found in the photic zone of aquatic bodies. They possess chlorophyll and perform photosynthesis, acting as the major primary producers in the ecosystem.
- 2. Zooplankton: Incorrect. Zooplankton are microscopic animals (e.g., protozoa, crustaceans) that feed on phytoplankton or other zooplankton. They function as primary consumers (herbivores) or secondary consumers, not producers.
- 3. Higher aquatic plants: Correct. These are macroscopic plants, also known as macrophytes (e.g., Hydrilla, Lotus, Water Hyacinth). Like terrestrial plants, they perform photosynthesis and serve as producers in the aquatic food web.
Key Takeaway: In aquatic food chains, phytoplankton and macrophytes are autotrophic producers, while zooplankton are heterotrophic consumers that link producers to higher trophic levels like nekton (fish).