Plants are essential for survival of human beings and animals.
They provide food, regulate air as well as protect the environment.
look at the following pictures.
Describe each picture above.
Predict what you are going to learn.
11.1: Identification of the importance of plants
Activity 11.1: identifying the importance of plants in the locality
What to do
1. Visit the school farm or farms around the school.
2. Observe and record the types of plants grown in your local area.
3. Use a table like the one shown below to group the crops that you have identified according to their uses.
Plants that are cultivated by human beings are generally known as crops.
A crop is a plant that is grown for its usefulness.
The following are reasons why crops are important.
(a) Human food (food crop)
(b) Animal feeding
(c) Medicinal plants
(d) Cash crops
(e) Protection of environment
Human food Crops that are grown for human food are called food crops.
When eaten, these plants supply nutrients to the body.
Activity 11.2: Grouping plants into various food groups
Fill in the following table appropriately.
• Give at least five examples in each case.
• Use your XO laptop or books in the library.
Types of Food Crops
These are crops grown for their grains.
They include rice, barley, wheat, oats, maize, sorghum, millet among others.
(ii) legumes These crops mainly produce their seeds in pods.
These include: peas, green grams, beans, groundnuts, black beans, french beans and groundnuts.
(iii) Fruits These include:
pawpaw, oranges, mangoes, bananas, pineapples, passion fruits, pears, apples, avocado and many others.
Fruits have two scars, unlike seeds which have one scar.
(iv) vegetables These include: spinach, kales, cabbages, broccoli, lettuce, cauliflower, egg plant, onions,
tomatoes and many others.
These are plants that store food in their roots (root tubers) or stem (stem tubers).
a) Root tubers include: carrots, cassava, turnips, radish, beetroot, arrow roots, sweet potatoes and others. b) Stem tubers include: yams and Irish / English potatoes.
Activity 11.3: identifying cash crops
(i) Observe various types of plants grown in your locality.
(ii) Write down the names of the crops.
(iii) Identify crops that are sold to earn income (cash crops). (iv) Compare your findings with those of your friend.
(v) Research from books more cash crops.
These are crops grown mainly for sale. The farmer sells the crops to industries for processing.
Cash crops can be grouped as shown in table 11.1 on page 137.
Table 11.1: Cash crops.
Practice Activity 11.1
Match the plants with their products.
Activity 11.4: identifying importance of plants
Describe what is happening in the following pictures.
Both wild and domestic animals feed on plants. Most domestic animals feed on grass, leaves of trees and grains. Animals such as chickens and ducks feed on grains and leaves of plants.
Some animals feed on fruits and plants.
Medicinal plants Extracts from some trees, shrubs and herbs have been used traditionally to treat known diseases.
Medicines that come from plant parts are called herbal medicines. The following pictures show some medicines from plants.
Practice Activity 11.2
1.Using the Browse Activity, research medicinal plants in Rwanda.
You can also search for information from books in the school library. 2.Copy the following table in your notebooks. From your research findings,
fill in 8 examples of medicinal plants and what they cure.
Protection of the environment
Look at the following picture
How are the plants shown in the picture protecting the environment? Plants are very important to the environment.
Plants protect the environment from drought by acting as rain attracting zones.
Roots of trees hold the soil particles together. Soil erosion is minimised.Trees act as a windbreak.
They protect the environment from the dangers of the wind.
11.2: Common importance of trees on the environment
Look at the following pictures.
(a) Which place looks beautiful? Why?
(b) Outline the benefits of trees in Place A:
(i) to the farmer and his or her neighbours (ii) t o Rwanda.
(c) Imagine you are an agricultural officer. Write down short notes that you will give to farmer in Place B in order to encourage him to plant trees on his farm.
(i) improves weather conditions of a place Trees produce moisture during transpiration. This moisture forms rain clouds.
This explains why places that have dense forests record high rainfall.
Trees also act as windbreaker by slowing down the speed of the wind.
(ii) Control soil erosion The roots of trees hold soil particles together. This prevents top soil from being washed away by water.
The leaves of trees also form a canopy.
The canopy acts like a shade that reduce the intensity of rain drops falling on the soil.
(iii) Recycle air through photosynthesis Plants require carbon dioxide to make food through photosynthesis.
When they use carbon dioxide they release oxygen, which is then used by animals.
Name 3 human activities that give out carbon dioxide.
How do animals produce carbon dioxide?
(iv) Shelter for wild life and birds Many wild animals live in forests. Forests provide a safe hiding place for the animals.
1. Name 5 animals that live in the forest.
2. Name 3 mammals that live on trees.
3. Name 3 animals that live in trees.
Other importance ways trees help the environment
Activity 11.6: importance of vegetation to the environment
(i) Using your atlas, locate the deserts in Africa. Also locate regions around Rwanda and Congo forest.
(ii) Compare the vegetation found in these two areas.
(iii) Identify the importance of trees to the environment.
Relate them to agents of weather: Wind, rainfall and temperature.
(iv) Name the general importance of trees in your locality.
(v) Write short notes on your findings.
(vi) Present your findings to the rest of the class.
The following are other important ways trees help the environment are:
• Ornamental trees. • Agroforestry.
• Fruit trees. • Timber and fuel.
Practice Activity 11.3
Match the following description of uses of trees to their pictures.
11.3: Effects of afforestation and deforestation on the environment
Activity 11.7: Identifying importance of afforestation, causes of deforestation and effects of deforestation
(i) Visit a planted forest near your school.
(ii) Observe and feel the environment around the forest.
(iii) Visit a place without tress around your school.
(iv) Observe and feel the environment around this place.
(v) When you get back to school discuss in your groups the causes of deforestation,effects of deforestation
and the importance of afforestation.
(vi) Present your findings to the rest of the class.
Importance of afforestation
1. Minimises soil erosion.
2. Beautifies the environment.
3. Promotes air circulation.
4. Provides homes for wild animals.
5. It shields homes and crops from excessive wind and sun.
Fig. 11.10 (a) and (b): A hilly place before and after afforestation.
6. It provides timber, fruits and feeds for cattle.
Causes of deforestation
1. Construction and expansion of roads, towns and cities. 2. Commercial use of trees such as for making paper, making timber, making posts among others uses.
3. Creation of homes for settlement.
4. Creation of agricultural land.
Effects of deforestation
Activity 11.8: debate
Debate on the following topic: Conserving an existing forest is better than planting a new forest in a deforested area
Deforestation leads to:
1. destruction of the natural environment. This can result in drying of rivers and formation of deserts.
2. increased soil erosion.
3. destruction of animal habitats.
4. climate change. These changes include low rainfall and poor air circulation.
5. extinction of some plants.
Prevention of deforestation
Activity 11.9: Planting trees
Plant trees in the school surroundings to maintain the environment. You can also plant trees in your home. Materials needed:
• Piece of land • Tree seedlings • Hoes
• Manure • Spades
What to do:
1. Dig a hole to the desired depth using a hoe.
2. Mix manure and soil that you have dug up from the hole.
3.Plant your seedlings the same depth they were in the nursery seedbed. If the seedlings are in paper tubes,
remove the papers before planting.
4. Compact the soil around the seedlings using your hands.
5. Apply some mulch and then water your seedling.
6. Take care of your seedling until it grows.
When we prevent deforestation, we conserve trees.
Conservation means using a resource in a sustainable way and without wastage.
In order to conserve trees, we need to do the following :
1.Use existing trees properly. For instance we should not cut down trees in order to obtain fuel.
Instead we should prune the branches and use them.
2.The government should regulate harvesting of trees in both natural and planted forests through strict rules.
Laws that punish those who break these rules should be put in place.
3.Elders in the Districts and villages should ensure that when a tree is cut down another tree is planted to
4. There should be recycling of waste paper to avoid cutting down many trees to make new paper.
5 Using alternative sources of fuel for example kerosene, biogas and solar energy for domestic use.
List 5 other things that can help to prevent deforestation.
Revision Activity 11
1. Name two examples of medicinal plants.
2. Identify 3 crops that produce oil. 3. Name three cash crops grown in your District. 4. Explain three ways in which trees help to conserve the environment. 5. Describe briefly how trees recycle air.
6. Explain the meaning of the following terms. (a) Afforestation (b) Deforestation (c) Ornamental plant
7. (a) What is agroforestry?
(b) What characteristics should trees used for agroforestry have? (c) What are the benefits of practising agroforestry?
8. Study the following pictures.
(a) How can the effects of wind shown above be prevented?
(b) Name two effects of deforestation.
9. (a) What are food crops?
(b) Name 5 types of food crops grown in your locality.
10. What is the importance of trees to:
(a) domestic animals.
(b) wild animals.
11.You have been given a tree seedling as your birthday gift. Write an essay on how you will take care of
1. Read the following words in pairs.
• Fibre crops
• Neem tree
2.Spell 3 words while your friend writes them in his or her notebook. Let your friend also spell 3 other words
as you write them in your notebook.
3. Discuss with your friend the meaning of any 3 words in the word list. Refer to notes in your textbook.