Lecture Notes: Energy Flow in an Ecosystem

Introduction

• Topic: Energy flow in an ecosystem.
• Source of Energy: The sun.
  • Green plants convert light energy into chemical energy (food) through photosynthesis.
  • Chemical energy is transferred through the food chain: primary -> secondary -> tertiary consumers.

Classification of Organisms in Ecosystems

1. Producers
   • Produce own food via photosynthesis.
   • Examples: Green plants.
2. Consumers
   • Eat other organisms.
   • Classified into three types:
     • Primary Consumers: Eat producers (usually herbivores and omnivores).
     • Secondary Consumers: Eat primary consumers (usually omnivores and carnivores).
     • Tertiary Consumers: Eat secondary consumers (mostly carnivores).
3. Decomposers
   • Break down dead organisms into nutrients.
   • Process: Saprophytism.
   • Examples: Mushrooms, bacteria.

Examples

• Example Food Chain:
  • Green plant (producer) -> Caterpillar (primary consumer) -> Bird (secondary consumer) -> Fox (tertiary consumer).

Food Chain vs. Food Web

• Food Chain

  • Shows feeding relationships and energy flow between organisms.
  • Example: Cabbage -> Snail -> Bird -> Fox.
  • Arrows indicate the flow of energy.

• Food Web

  • Formed by the combination of multiple food chains.
  • Example Food Web:
    • Cabbage eaten by caterpillar, snail, grasshopper.
    • Bird and frog eat caterpillar, snail, grasshopper.
    • Snake eats bird and frog.
  • Arrows indicate energy flow.

Energy Transfer

• Energy is not transferred completely from one organism to another.
• Energy Loss Occurs Through:
  • Movement.
  • Respiration (heat energy loss).
  • Undigested food (feces).

Conclusion

• Summary of concepts: producers, consumers, decomposers, food chains, and food webs.
• Importance of understanding energy flow and energy loss in ecosystems.

End of lecture notes. Be sure to review these concepts and understand the energy relationships within an ecosystem.