The energy flow in an ecosystem is not cyclic because being an energy pyramid, it moves from the producers at the bottom of the pyramid up to a point where it cannot be used by living things anymore. It is either used by the organisms in the ecosystem or it is lost to the atmosphere. For example, energy stored in cow = energy stored in grass – (energy for cow’s activities + energy lost to the atmosphere).
Nutrient movement refers to the chemical energy in form of carbohydrates, fats, protein, and other nutrients are distributed among producers, consumers and decomposers. It just about how nutrients flow from one energy level to the other in the ecosystem.
Under this topic, we shall consider the following: food pyramid, pyramid of numbers, pyramid of biomass, and pyramid of energy. In any natural community, the number of individuals at the lower part of the food chain or web is greater than those above. Producers are therefore greater than primary consumers, and secondary consumers less in number than the primary consumers. This number reduces till the terminal group of organism is reached which have no predators depending on them for food. When these numbers are diagrammatically represented, a pyramid of numbers is obtained.
EVALUATION (POST YOUR ANSWERS IN THE BOX BELOW FOR DISCUSSION)
- Explain the following with a typical example: Food Chain, Food Web, and trophic level.
- Why is the energy flow in the ecosystem not cyclic.
- What is nutrient movement?
- Write a short note on energy flow.
- State two the differences between pyramid of numbers and the pyramid of energy.
- Define the term (i) consumers (ii) producers.
- Sketch a diagram of typical food web
- Classify the following organisms: cow, bacteria, green plants, herbivores, fungi, and man into producer, primary, secondary and tertiary consumer.
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