Everything Life Sciences Grade 10

FACT

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• Primary consumers: part of the food made available by plants is consumed by primary
  consumers known as herbivores. The energy gained is converted to body heat or used
  to grow, reproduce, etc. Energy loss also occurs in the expulsion of undigested food
  by excretion.


• Secondary consumers: carnivores and omnivores consume the primary consumers
  using the energy obtained to grow, move, respire etc.


• Tertiary consumers: may be the major predators of an ecosystem, and feed on the
  producers and secondary consumers with some energy passed on and some lost as
  with other levels of the food chain.


• Decomposers: A final link in any food chain are the decomposers which break down
  the organic matter of the tertiary consumers and release the nutrients into the soil.
  They also break down plants, herbivores and other dead organic matter.

The flow of energy in an ecosystem can be explained in the form of a chain, web or pyramid.

Food chain DUMMY

Afood chain is a series of nutrient and energy changes that moves through a chain of or-

ganisms. It always begins with a producer and terminates with decomposers. Below is an

example of a simple food chain in a grassland. Thearrowsshow the movement of energy

from one organism to another.

green plant→impala→leopard→bacteria

producer→primary consumer→secondary consumer→decomposer

Activity:

Activity 1:

Trace afood chainof the vegetables, fruit, cheese, eggs or meat that you had for breakfast or

will have for dinner.

Activity 2:

1. In the food chain shown in the text which of the three organisms is the
   a) Herbivore
   b) Carnivore
   c) Producer


2. Draw in the decomposers in the above food chain. Ensure that the direction of the
   arrows is correct.


3. What organism(s) will feed on the leopard?


4. Construct a new food chain showing at least 4 organisms.


5. Producers use sunlight to manufacture their own food. Write a word equation to de-
   pict this process. [Hint: think of the requirements and outcomes of the process of
   photosynthesis]

278 9.6. Energy flow