English

You will develop these skills

• Use abstract nouns.

• Use the passive voice (present simple tense).

• Use countable and uncountable nouns.

• Use vocabulary of soil and plant topics.

Ecology is the relationship between plants, animals and the environment. In nature, living organisms depend on each other for life. Therefore, every organism in our environment is important in one way or the other. For example, mosquitoes are a direct threat to humans because they transmit diseases like malaria. However, the same mosquitoes and their larvae are a source of food to some fish, and fish are essential in our diet. Everything is interconnected, and when something happens to one organism, it has an effect on other organisms.

The composition and contents of soil

Read about the composition of soil

Soil is often called the ‘skin of the Earth’. It is the loose upper layer of the Earth’s surface, where plants grow. Soil is made up of a mixture of organic material (decayed plants and animals) and broken bits of rocks and minerals. It can take up to 1 000 years for just 2 cm of soil to form.

Factors that help to form soil include:

• Living organisms: This includes organisms such as plants, animals, fungi and bacteria.

• Topography: This is the shape or slope of the surface of land where the soil is forming.

• Climate: The climate and weather forming affect how the soil forms.

• Core material: The core material is the minerals and rocks that are slowly disintegrating to form the soil.

Grammar focus

Abstract nouns

Nouns can be abstract or concrete. Concrete nouns are tangible. This means that you can experience them with your five senses: you can touch them, hear them, feel them, taste them or smell them. Abstract nouns refer to intangible things, such as feelings, ideals, concepts and qualities.

Example: I have a dream. ‘Dream’ is an abstract noun because you cannot taste it, see it, feel it, hear it or smell it.Here are other examples of abstract nouns:

• beauty

• bravery

• courage

• enthusiasm

• hatred

• intelligence

Activity 1: Change adjectives to abstract nouns

Complete the following sentences by changing the adjective in brackets into an abstract noun.

1. He is a man of ______ . (courageous)

2. The people in this part of the country live in ______ . (poor)

3. ______ to animals is a punishable offence. (cruel)

4. The man showed great _____ of character. (strong)

5. I have great ______ in welcoming you. (pleasing)

Activity 2: Label a diagram

When we draw a diagram to explain something, we must make sure that the diagram is easy to understand. Using labels helps the reader to identify the different parts of the diagram.

1. In your group, use the diagram on page 44 to discuss the composition of the Earth’s surface.

2. Working alone, do research and draw a diagram to show the different parts of the Earth’s crust.

3. Label your diagram.

Read about the composition of soil

Soil is made up of several things, such as inorganic materials (silica, silicate and oxides), as well as living organisms, bacteria, air, water and organic matter.

Many different bacteria, algae and fungi do important jobs that make life possible. Without these basic forms of life, more complex life forms could not survive. Bacteria help to break down the organic matter in the soil. Air in the soil provides oxygen for living organisms.

When plants decay, they break down in the soil to form rotting organic matter called humus. This increases the nutrients available for more plants to grow.

Soil contains all the nutrients needed by plants to survive. Some areas, such as deserts, have very poor soils. In these areas, it is difficult for plant life to take hold. Tropical rain forests also have poor soils. This is because most of the nutrients have already been taken out of the soil by the plants.

Activity 3: Understand the composition of soil

Grammar focus

Passive voice

We use the passive voice to show interest in the person or object that is experiencing an action, rather than the person or object that is performingthe action. In the reading on the composition of soil, there are several sentences where the passive voice is used, for example: Soil is made up of several things. In the active voice, this sentence would be: Several things make up soil. Can you find more sentences in the passive voice?

Activity 4: Write a description of the composition of soil

Copy the following paragraph into your exercise book and fill in the blanks. Plants obtain _______ from the soil. Soil is the outer, loose layer that covers the surface of the _______. Soil quality depends, not only on the chemical composition of the soil, but also on the _______ (regional surface features) and the presence of _______ organisms. The four major components of soil are _______ mineral matter, _______ matter, water and air. Soil is the base of life on Earth because it has most of the important _______ in which plants need to grow. Those plants in turn feed animals and _______. Soil is also where much of our fresh _______ is stored. Fresh water travels through the soil being _______ as it goes. It often ends up in underground _______ called aquifers, where we can get it when we need it.

Soil erosion

Read about soil erosion

Soil erosion occurs when the topsoil disappears for some reason. Erosion can occur naturally as a result of wind or water, or as a result of human activities. It becomes a problem when human activity causes erosion to occur much faster than under natural conditions.

Soil plays a very important role in supporting life on Earth. When soil is eroded, it affects the ecology of the area where erosion has occurred. Plants use soil, not only for nutrients, but also to anchor themselves in the ground using their roots. Many animals, fungi and bacteria rely on soil as a place to live.

The atmosphere is affected because changes in the soil affect the rate at which gases, such as carbon dioxide, are released into the air. The quality of water is affected because the soil helps to filter and clean our water.

Activity 5: Describe the process of soil erosion

Write sentences about what will happen if too many goats are allowed to graze on a hillside. Make sure you organise your sentences in the right order.

Read about the effects of soil erosion

When the topsoil is eroded from an area, the area loses its most nutrient-rich layer, and therefore the ability of the soil to produce crops is reduced.

When the organic matter that is found within the top layer of soil is removed, the soil can no longer ‘hold’ water. This means that the area is more susceptible to extreme weather conditions such as droughts. As the soil is eroded and runs down to waterways, river banks can be eroded, causing rivers to break their banks during heavy rains. This causes flooding and more damage to the surrounding area.

Wind can also cause soil erosion by moving topsoil. Wind can also damage young seedlings by blasting them with sand and other small particles. Wind can uncover and expose some seedlings, while at the same time covering other seedlings with too much soil.

Soil erosion can be caused by human activities such as over-farming and overgrazing, or by natural phenomena such as wind. Over-farming occurs when farmers use their land too extensively without giving it time to rest and replenish. Instead of rotating crops so that the nitrogen is replenished in the soil, some farmers exhaust the land.

Overgrazing occurs when farmers keep too many animals for the available vegetation. All the vegetation is eaten by the animals. There are no roots left to hold the soil together, and no leaves to make humus. This leaves the land bare and exposed to wind and rain. In East Africa this is a serious concern, especially in the highland areas of Rwanda and Burundi.When land is over-farmed, the soil quality deteriorates. Poor-quality soil also means that farmers need to use artificial fertilisers, which can contaminate underground water.

When soil from farmers’ fields is carried away by water, it carries with it the contaminants. This runoff pollutes drinking water and disturbs the ecosystems of lakes and wetlands. This is harmful for the fish and wildlife that depend on these waters for their food and habitat.

Activity 6: Identify the stages of soil erosion

Look at the pictures below and then match each one to the correct sentence.

1. All the vegetation has been eaten, the land is overgrazed and there is nothing to stop soil erosion. The land becomes a desert.

2. When the land cannot sustain the cattle, sheep and goats are grazed there instead.

3. The soil is fertile and lots of plants grow in it.

4. Cattle are grazed and the smaller plants are eaten.

Plants

In the next section, you will learn more about plants.

Activity 7: Identify the ratio of plants to other species on Earth

The pie chart below shows the different kingdoms of living species on Earth.

1. Which is the largest species of living organisms on Earth?

2. Which is the smallest group of organisms?

3. Which is the second smallest group of organisms?

4. To which group do human beings belong?

Read about the parts of a plant

Plants can be big or small, from giant trees to tiny patches of moss. The study of plants is called botany. The main parts of a plant are the roots, the stem, the leaves and the flower. Each part has a different function.

The lower part of a plant is made up of roots. The roots are the underground part of the plant, and consist of the tap root, lateral roots and the root hairs. The plant anchors itself in the soil by its roots. Roots also absorb water and mineral nutrients (salts and other small organic molecules) from the soil.

The branches, leaves, fruits and flowers of a plant are supported by the stem. A plant can be divided into two main parts:

• the lower part (root system)

• the upper part (shoot system).

Transpiration of water and nutrients from the roots is done by the stem.

Activity 8: Label a plant

Go into the school grounds or surrounding area, and pick a small plant. Bring it back into the classroom, draw it and label it. Make sure you include the functions of each part.

Read about the importance of plants

The production of food for the plant is done by the leaves through the process of photosynthesis. Carbon dioxide from the air is taken into the plant by the leaves. The carbon dioxide mixes with water that has come from the air and the roots. Energy from the sun helps this process and turns the water and carbon dioxide into glucose. Glucose is the plant’s food and gives it energy to grow. During the process of photosynthesis, the plant breathes out oxygen into the atmosphere. This is very important, because oxygen is needed by human beings in order to survive. The great rainforests of central Africa are part of the ‘lungs’ of the planet.

The flower of a plant is responsible for its reproduction. A flower is made up of the sepals, petals, stamen and pistil.

Plants are an extremely important part of the ecosystem. Not only do they provide food for human beings, but they also harbour animals, birds and insects, providing food and shelter for them.

Activity 9: Ask and answer questions

Take turns to ask each other the following questions and supply the correct responses.

Q. What are the functions of the roots of a plant?

A. The functions of the roots are _______ .

Q. What is the function of the stem of a plant?

A. The function of the stem is _______ .

Q. What is the function of the leaves of a plant?

A. The function of the leaves is _______ .

Q. What is the function of the flower of a plant?

A. The function of the flower is _______ .

Activity 10: Explore your environment

Reread the texts about plants and their importance to humans.

1. Make a list of plants in your environment at school.

2. Why do you think we need plants in our lives?

3. Do you think plants can be harmful to humans? Explain your answer.

4. Describe the relationship between plants and the environment.

5. Compare your answers with those of your friends. Discuss your answers with the rest of your class.

Activity 11: Identify sentences in the passive voice

There are a number of passive sentences in the readings about plants. For example: Transpiration of water and nutrients from the roots is done by the stem. The underlined words show the object being used to start the sentence. Find three more sentences from the passage that are written in the passive voice.

Grammar focus

Countable and uncountable nouns

Countable nouns are things we can count using numbers. They have a singular and a plural form. For example: one dog, two dogs.

Uncountable nouns are the things that we cannot count with numbers. For example: rice, tea, water. We always refer to these nouns in the singular. We do not talk about many rices!

Read about types of plants

There are over 280 000 different plants on Earth, but we can divide these into 4 main groups:

mosses, ferns, conifers and flowering plants.Mosses are land plants, but they do not have seeds or flowers. Mosses reproduce with spores. Mosses do not have stems or large roots to transport water and nutrients, so they live in moist environments and are smaller than other land plants.

Ferns make up the second group of land plants. These plants have vessels that transport water and nutrients from roots to leaves, and sugars from leaves to roots. Ferns do not have flowers.

Conifers produce seeds that are contained within a cone. Seeds are a great evolutionary development, because they are multicellular and contain nutrition for the new, developing plant, all within a protective coat.

Flowering plants represent the most widespread group of plants on Earth. Flowering plants are found in most habitats, from deserts to the polarregions. Flowering plants include species of trees, grasses, shrubs and herbs. The flower attracts many animals which assist in pollination, making the process of pollination more efficient. The seed develops in an ovary, which becomes a fruit. The fruit serves to help seed dispersal, as animals eat the seeds. Birds and mammals may deposit the seeds a long way from the original plant.

There are 8 000 species of grasses, which are plants with small flowers. Grasses provide food for many grazing animals, including buffalo and zebra. Grasses can provide food such as grains like rice, wheat and corn.

Activity 12: Make notes

When we are studying information, it is useful to make notes. When we make a note, we write a brief phrase about the most important points of what we are reading. This helps us to know what is important and must be learned.

Reread the passage ‘Read about types of plants’ and make notes on the most important information. Include any mathematical information that is relevant.

Activity 13: Discuss plants that are useful to humans

In your group, discuss the different plants that are useful to humans. See if you can group them into trees, shrubs, flowers, grasses and herbs.

Activity 14: Classify plant types

Look at the following pictures and answer the questions that follow.

1. Classify each of the plants as a tree, a flowering plant, a shrub, a herb or a grass.

2. Match the following names of the plants with the correct description.

Activity 15: Conduct a survey

Do you know the answers to the following questions?

• How many kinds of plants live around you?

• Which plants are common and which are rare?

• What is the average tree size?

• When do the plants flower?

You can answer these questions by conducting a plant diversity survey. In order to do this, you will need to complete the following steps:

1. Choose an area of your neighbourhood in which to conduct the survey.

2. Mark out the area to be surveyed. An area of 2 m by 2 m is sufficient.

3. In your notebook, write down the names of all the different types of plants in your survey area. Count how many of each species there are, and make a note of your findings.

4. Create your statistics. Add up the total number of plants and then calculate each type of plant as a percentage of the total.

5. Calculate the average number of each plant type.

6. Draw a table showing the different classes and species of plants found.

7. In class, discuss your findings and describe any interesting facts that emerged from your survey. Talk about what types of plants you saw and also what you did not see. Use ‘why’ questions to get answers from each other.

Vocabulary, pronunciation and spelling

Activity 16: Use your dictionary

Assessment

1. Find at least five abstract nouns in this unit, for example ‘cultivation’ (from the verb ‘cultivate’) and ‘importance’ (from the adjective ‘important’). (5 marks)

2. Choose the most appropriate meaning for each of the following words.

a) cultivate

to grow plants

to plant

to have crops for food

to grow plants and animals for food

b) root cropss

tems rich in carbohydrates

substitute for cereals

underground crops

crops with roots

c) harbour

bring

shelter

cause

train (3 marks)

3. Explain the importance of humans to both plants and soil. (2 marks)

4. In your own words, describe how human activities cause soil erosion. Use examples and illustrations. (10 marks)Total (20)