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