3. Give two examples of biotic factors and two examples of abiotic factors in (a) a lake ecosystem (b) a forest ecosystem

**(a) Lake Ecosystem*** **Biotic Factors:** 1. **Phytoplankton:** Microscopic algae and cyanobacteria that form the base of the food web in many lakes. 2. **Fish:** Various species of fish consume other organisms, contributing to energy flow and nutrient cycling.* **Abiotic Factors:** 1. **Water temperature:** Influences the dissolved oxygen levels and the types of organisms that can survive. 2. **Sunlight:** Essential for photosynthesis by phytoplankton, which supports the entire ecosystem.**(b) Forest Ecosystem*** **Biotic Factors:** 1. **Trees:** Dominant producers, providing habitat and food for many other organisms. 2. **Fungi:** Decomposers that break down dead organic matter, releasing nutrients back into the ecosystem.* **Abiotic Factors:** 1. **Soil composition:** Affects the availability of nutrients for plant growth. 2. **Rainfall:** Provides water essential for plant growth and other biological processes.