1.11 To understand the natural balance between living organisms

Natural sciences

Ecosystems and the environmental balance

Educator section

Memorandum

Assignment 18:

Bryophytes (mosses) are extremely adaptable;

Mosses are extremely adaptable, because they survive in a variety of environments. Mosses are even able to adapt to different climatic regions. They can adapt to moist environments, dry environments and even to dark environments. Some of the tough species are even found in the crevices on volcanoes.

a) It is very dense and can seal the wound so that no germs can enter; it was found in abundance and was easy to obtain.

b) Human influence: Extermination of animals

Natural disasters; droughts; floods

True or false:

7.

(a) True

(b) True

(c) False

(d) As soon as the seeds germinate, the rats invade the sugar plantations and eat the seeds

(e) Simultaneous means one at a time and not everything together.

Leaner section

Content

Activity: to understand the natural balance between living organisms and available sources [lo 2.3]

1. FOOD WEBS

A link in one chain is often joined to other links in other chains. Isolated food chains are very rare in nature. An interconnected series of food chains is called a food web.

Study the above example of a food web showing links between various food chains. The herbivores are eaten by both the carnivores and omnivores.

Energy, however, is lost each time one organism is eaten by another. The plant provides energy for the buck to run or breathe. That energy is no longer available to another organism.

The shorter a food chain, the greater the number of organisms able to live in a fixed area.

Identify as many food chains as possible in the illustration on the previous page and illustrate them by means of words and arrows:

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(a) Harmony in the ecosystem

In a natural ecosystem living organisms live in harmony. Plants and animals are both affected by the environment and also influence it in turn. There is a natural balance between the available resources and the organisms which rely on it.

(i) Growth of plants of the same species in different conditions

The climate in a particular region determines the type of vegetation. Plants from the same species grow and develop differently under different climatic conditions.

Sometimes, when walking in a forest or along a river, you will find yourself walking on a dense green “carpet”. This “carpet” clings to the ground and is called moss. It grows in a variety of places, amongst others on barks, branches of plants and even on dead logs. It is also found on damp soil near rivers or lakes and some kinds of moss also grow on rocks and cement. This plant species consists of more that 350 000 different plants.