Unit18_EnergyFlow_and_FoodWebs_IGCSE_Year10 (1).pptx

Energyflow Question/Answers

1. Unit 18: Organisms and Their Environment IGCSE Biology (0610) – Year 10 Topic: Energy Flow and Food Webs

2. Introduction to Ecology Ecology is the study of how living organisms interact with each other and their environment. The environment includes both living (biotic) and non-living (abiotic) components. Energy flow is the key factor linking organisms within an ecosystem.

3. Energy Flow in Ecosystems The main source of energy for life on Earth is the **Sun**. Plants (producers) convert light energy into chemical energy by photosynthesis. Energy is passed along the food chain when one organism eats another. Energy is lost at each stage as heat, movement, or waste.

4. The Roles in the Ecosystem Producers: Plants that make food using sunlight. Consumers: Animals that eat plants or other animals. - Primary consumers: eat plants (herbivores) - Secondary consumers: eat other animals (carnivores) - Tertiary consumers: top predator s Decomposers: Bacteria and fungi that break down dead material, returning nutrients to the soil.

5. Food Chains A food chain shows how energy is transferred from one organism to another. Example: Grass → Grasshopper → Frog → Snake → Eagle The arrows show the **direction of energy flow**.

6. Food Webs A food web consists of many interconnected food chains. It shows how organisms are interdependent within an ecosystem. If one species is removed, it affects the entire web. Food webs provide a more realistic picture of feeding relationships.

7. Energy Loss in Food Chains Only about **10%** of energy is transferred to the next trophic level. Energy is lost through: - Respiration (heat loss) - Movement - Undigested material - Excretion This limits the length of food chains.

8. Trophic Levels A trophic level is a position of an organism in a food chain. Example: - 1st level: Producer - 2nd level: Primary consumer - 3rd level: Secondary consumer - 4th level: Tertiary consumer Energy decreases as we move up the trophic levels.

9. Importance of Decomposers Decomposers break down dead plants and animals. They release nutrients back into the soil for reuse by producers. They play an essential role in nutrient cycling and maintaining ecosystem balance.

10. Summary – Energy Flow and Food Webs Energy flows from the sun to producers and through consumers. Food chains and food webs show feeding relationships. Energy decreases along trophic levels due to losses. Decomposers recycle nutrients back into the ecosystem.