1

2

Natural Science: The Scientific Method Use this format to follow the scientific method for your experiments

Question to investigate What will my experiment answer? __________________________________

_____________________________________________________________

Hypothesis What do I think the results of this experiment will be? ___________________

_____________________________________________________________

Materials What do I need to conduct this experiment? __________________________

_____________________________________________________________

Method How will I conduct this experiment?

Step 1 ________________________________________________________

Step 2 ________________________________________________________

Step 3 ________________________________________________________

Step 4 ________________________________________________________

Step 5 ________________________________________________________

Results and conclusions What are the results of my experiment?

_____________________________________________________________

____________________________________________________________

Was my hypothesis correct? [ ] Yes [ ] No

Discussion How can the results of my experiment be used? _______________________

What other questions does my investigation raise? _____________________

3

Technology: The design process

Use this format to follow the design process for your technology projects

Investigate What must my product do? _________________________________________________

_______________________________________________________________________

Design and plan Specifications: What are the specifications? (E.g. instructions, design brief)

Constraints: What are the constraints? (E.g. materials, time, tools)

Materials: What materials am I going to use? ___________________________________

Equipment: What tools do I have? What tools will I need? _________________________

Final drawing (What will my product look like?)

How am I going to make my product?

Step 1________________________________________________________________

Step 2________________________________________________________________

Step 3________________________________________________________________

Evaluate Does my product work properly? [ ] Yes [ ] No

Does my product look like my drawing? [ ] Yes [ ] No

How can I make my product better? __________________________________________

4

Natural Sciences & Technology Grade 6 Term 2

Strand 2 Natural Sciences: Matter and Materials

Technology: Processing

Plants make food that we eat and put oxygen into the air that we breathe. We and other

animals would not be able to live without plants.

Live and living Processing

Photosynthesis

Plants and food

Plants and air

Nutrients in food

Food groups

Nutrition

Balanced diets

Food processing

Need for food

processing

Methods for processing

food

Ecosystems and food

Different ecosystems

Living and non-living things in

ecosystems

Food webs

5

Unit 1 – Photosynthesis: Plants and food

Lesson 1 The word photosynthesis is derived (comes from) from different words. The word ‘photo’ is

the Greek word for light and ‘synthesis’ is the Greek word for putting together.

Photosynthesis is the using of light to put things together.

The process by which plants make food is called photosynthesis.

Photosynthesis takes place mainly in the leaves of green plants.

All green plants contain a substance called chlorophyll.

Chlorophyll gives the leaves and other parts of the plant their

green colour. Chlorophyll, in the leaves, absorbs energy from

sunlight. The leaves are thin and flat, so the plant can easily

absorb the sunlight.

Plants also need other substances to make their food. Plants absorb a gas called carbon

dioxide, from the air, through their leaves. Plants absorb water through their roots.

During photosynthesis, plants use the energy from the sunlight, carbon dioxide gas from

the air and water to make glucose sugar. Plants also produce oxygen during

photosynthesis. Oxygen is a very important gas which living things need to stay alive.

How does photosynthesis occur?

Plants use chlorophyll, sunlight, water and carbon dioxide to make food.

1. Chlorophyll captures the sunlight energy.

2. This energy spilt the water into hydrogen and oxygen.

3. The oxygen is released into the air.

4. The hydrogen is used with the carbon dioxide to make glucose (sugars).

5. The sugars are moved from the leaves to other parts of the plants where they are

stored.

6. The water in the plant veins carries the sugars. When the sugars reach the storage

parts they are changed into starch.

6

Plants can store the starch in these places:

Leaves (cabbage, spinach, lettuce)

Fruit (apples, banana, peaches)

Stem (sugar cane)

Seeds (wheat or mealies)

Flowers (broccoli and cauliflower)

Roots (carrots or beetroot)

Activity 1 – Draw and write about how plants make food 1. Draw a sunflower plant in your workbooks.

2. Add the following labels to your drawing:

roots

water

stem

leaves

flower

sunlight

carbon dioxide

oxygen

3. Draw arrows to show where the water, carbon dioxide and oxygen enter the plant.

4. Explain how a plant makes food, using your drawing as a guide.

Hint – Start your explanation at the roots

New words Photosynthesis – process in which plants make their own food from carbon dioxide and

water using: light energy from the sun.

Glucose - type of sugar used as an energy source for many living organisms.

Chlorophyll – a substance that makes plant green.

Carbon dioxide – a gas in the air that plants need for photosynthesis.

Oxygen – a gas in the air that living things need.

7

Summary Plants make glucose sugar, mainly in their leaves, through a process called

photosynthesis. Plants use sunlight, carbon dioxide and water to make their food. Plants

change glucose to starch and store it in different parts of the plant. Starch changes iodine

solution from brown-yellow to blue-black.

=================================================================== Lesson 2 Plants store food as starch Plants make more glucose than they can immediately use. Plants change some of the

glucose sugar they make in their leaves into starch. The starch is the food that the plant

keeps in reserve. Plants store the starch in their leaves, stems, roots, flowers, fruits and

seeds. There is a lot of starch in potatoes, maize and grains like wheat.

Activity 2 Comparing sugar and starch Aim

- To compare the appearance, taste and solubility of glucose and starch.

Materials: You will need:

Glucose powder

Maize flour (maizena)

2 beakers of water

Teaspoons

Method Steps 1 – Look at the texture and colour of the glucose sugar

and the starch.

Step 2 – Taste the glucose sugar and the starch.

Step 3 – Stir a teaspoon of glucose sugar into a beaker of cold water.

Step 4 – Stir a teaspoon of starch into another beaker of cold water.

Question – Describe how the glucose sugar and the starch are different in colour,

Taste and solubility. Record your results in a table, like the one below.

8

Glucose Starch

Colour

Taste

Solubility

REMINDER: Work in groups of 5 or 6. Your teacher will provide the following items for Lesson 3

1. a small amount of cooked rice

2. 2 tablespoons of flour

3. a potato

4. a slice of bread

5. some cooking oil

6. a boiled egg

7. a piece of cheese

8. an apple

================================================================= Lesson 3 Testing foods for starch We will experiment to find out which foods contain starch.

Iodine solution can be used to test for starch.

Starch turns yellow/brown iodine solution to a blue /black colour.

Activity 3 Aim - To test different foods for starch.

If the food contains starch, the yellow/brown iodine will turn blue /black.

Materials You will need: Iodine solution

Plastic droppers

9

A small amount of cooked rice, flour, a potato, a slice of bread, some cooking oil,

A boiled egg, a piece of cheese and an apple

Method Steps 1 – Put a few drops of iodine on each piece of food

Step 2 – Check the colour of the iodine solution after 1 to 2 minutes.

Question – State which foods contain starch.

Draw the following table to record your results.

Food Contains starch Does not contain starch

================================================================ Lesson 4 Read the two case studies below and answer the questions that follow

Case Study 1

The mystery of the holes in the leaves

Many Delicious Monster leaves have holes in them. These holes form as the leaf develops. The leaves can then withstand strong winds without getting damaged. (Think about banners and flags that sometimes have slits in them which allow the wind to pass through the material without ripping it.) Another reason is so that the sunlight can pass through the leaves. This means that the big leaves at the top of the plant do not block out the sunlight for the leaves underneath.

10

Activity 4 1) Explain, using your own words, why Delicious Monster plants have holes in their leaves.

2) List 3 important nutrients plants cannot make themselves.

New words: Starch – storage product in plant.

Solubility – ability to dissolve.

Nutrients – substances in food that are important for growth or good health.

====================================================================

Unit 2: Plants and Air

Lesson 5 Plants play a very important role in keeping the amount of carbon dioxide and oxygen in

the Earth’s atmosphere constant.

During photosynthesis, plants use carbon dioxide from the air and give off or release

oxygen into the air.

All living organisms like humans and animals use the oxygen that the plants release.

We breathe in oxygen from the air around us. We breathe out carbon dioxide into the air.

Plants absorb this carbon dioxide for photosynthesis.

Did you know? If we plant more trees we can help fight pollution and global warming.

Case Study 2

Why do plants need fertiliser? If plants make their own food, then why do they need plant food or fertiliser? Plants need some nutrients that they cannot make themselves. The most important of these are nitrogen, potassium and phosphorus. Plants get these nutrients from the soil. The nutrients dissolve in the water and plants absorb the water and the nutrients through their roots.

11

Do plants need oxygen?

What about plants? Do they breathe? Yes, they do. The correct term for this breathing is

‘respiration’. In darkness, plants only respire. In light (such as sunlight), plants respire and they carry out photosynthesis.

Some differences between respiration and photosynthesis

Respiration Photosynthesis

It takes place in all living plant cells. It only takes place in cells that have chlorophyll.

Chlorophyll gives the cells a green colour.

It occurs in light and dark conditions. It only occurs in light.

Oxygen is used and carbon dioxide and water are

released.

Carbon Dioxide and water are used and Oxygen

is released.

How does this help human beings? Humans cannot produce oxygen and without oxygen, humans cannot survive. Carbon

Dioxide is a poisonous gas that, in large quantities, can kill human beings.

Respiration uses only a little oxygen and releases very little carbon dioxide.

Photosynthesis uses a lot of carbon dioxide and releases a lot of oxygen.

The relationship between these two processes means that plants create more oxygen than

they use and use more carbon dioxide than they release.

Follow this link if you would like to learn more: https://ilovelearningscience.wordpress.com/2015/05/14/photosynthesis-vs-respiration/

12

Revision Activity 1. Use the words in the box to complete the sentences.

Carbon

dioxide

Oxygen Starch Sunlight Photosynthesis Water Leaves Glucose

a. A plant makes food in its ___________ through the process of ______________.

b. A plant uses the energy in ___________ as well as _____________ and

____________ to make ___________ which can be changed into _____________ and

stored.

c. A plant gives off ____________ into the air which is used by people and animals.

Complete the following:

1. What is photosynthesis?

2. Where does photosynthesis in the plant mainly take place?

3. Explain why it takes place there.

4. Name three things that plants need from their environment for photosynthesis to take

place.

5. As what do plants store their food?

Summary Plants use up carbon dioxide and give off oxygen during photosynthesis. Animals and

humans breathe in oxygen and breathe carbon dioxide.

====================================================================

Unit 3 – Nutrients in food: Food groups The main food groups and their function

Lesson 6

Living organisms need food to grow and stay healthy.

There are 7 life processes that every living thing needs: energy to feed, breathe, move,

grow, excrete, sense things and to reproduce.

13

People and animals get their energy from the food they eat. Everything you eat contains

nutrients. Nutrients are substances in food that keep your body healthy. Foods can be

grouped according to their functions in your body and the main nutrients they supply. Most

natural foods contain a mixture of more than one nutrient group.

The four main food groups are:

• Carbohydrates – for energy

• Proteins – for growth and repair

• Fats and oils – for storing energy and insulation

• Vitamins and minerals – for building bones and teeth and maintaining a healthy

immune system.

Carbohydrates Carbohydrates give living organisms energy. Carbohydrates are used by the body to keep

it warm and to provide all the energy it needs for growth and movement. Without

carbohydrates you will be too tired to walk, run, and dance or even to think. Carbohydrate

foods contain sugars and starch.

We find sugary carbohydrates in fruits, honey, dried fruits, cold drinks, etc.

Sugar gives our body’s quick energy. Sugary foods do not have all the important nutrients

in them that our bodies need.

We find starch in foods such as maize meal, potatoes,

rice, bread, pasta and some fruits.

Starch releases energy more slowly into our bodies so

the energy lasts longer. Starch is the most common

form of carbohydrate in our diet.

14

Proteins Living organisms need proteins to build and repair their bodies and for

growth. Proteins also help living things fight sicknesses and they help

the immune system fight of infections. Proteins also make up part of

the red blood cells, which are responsible for carrying oxygen from the

lungs to the rest of the body. Muscles and organs are mostly made up

of proteins. Proteins are part of everything in the human body, such as

bones, hair, skin and nails.

It is important to get proteins from a variety of foods such as: meat, fish, eggs, nuts, and

beans. Eating the right amount of protein is important to help repair any tissues that are

damaged through normal use over the years. Proteins give the body strength and are very

important for muscle growth.

Oils and fats Oils and fats provide energy to living organisms. Oils and

fats give more energy than any other food type. They

store energy in the form of body fat. These body fats

form protective layers inside the body, to protect the

organs and provide insulation (keep heat in). Foods

such as nuts, avocado pears and sardines contain

healthy oils and fats. Oils are liquid fats made from plants

and fish and they provide important nutrients. Eating too

much red meat, chocolates, cakes and cooking fat is not

healthy as they contain saturated fat which is not a

healthy fat.

Activity 6 1. Why is it useful to know which foods contain starch?

2. Name one advantage of eating foods that contain starch?

3. Does bread contain starch? Give a reason to support your answer.

4. What substance is used to test for starch?

5. Why is this substance used for a starch investigation?

15

Vitamins and minerals Vitamins and minerals work together with carbohydrates, proteins and fats to help our

bodies grow and develop normally.

Our bodies need vitamins and minerals to help us build strong teeth and bones, have good eyesight and a healthy immune system. The immune system fights germs and stops us from getting sick.

Activity 7 Draw a table with two columns, in your workbooks.

Sort the following foods into carbohydrates or proteins:

• Eggs, beans, bread, meat, cool drinks, maize meal, potatoes, nuts, lentils, chicken,

fish, pasta, honey, dried fruit, sugar, etc.

You can draw examples of the different foods or use pictures from magazines.

New words: Nutrient – important parts of food needed by the body for energy and good health.

Diet – the different foods a person or animal eats.

Food groups – the main types of food.

Immune system – a system in the body that protects it from diseases and germs.

Insulation – protect something from loss of heat or damage.

Carbohydrates Proteins

16

Important vitamins

Vitamin Function Foods that contain the vitamin

A Helps you see at night

Helps your body fight infection

Carrots, pumpkin, butter, liver

B Helps make energy, proteins and red

blood cells, plus many other functions

Cereals, brown rice, meat, vegetables

C Helps fight infections Green vegetables, oranges, guavas

D Helps makes strong bones Margarine, eggs, our bodies make

vitamin D when we are exposed to

sunlight.

E Protects the skin Spinach and other green leafy

vegetables, carrots, avocado pears,

butter

K Helps to stop bleeding Spinach, broccoli and other dark green

vegetables

Important minerals

Mineral Function Foods that contain the vitamin

Calcium Makes teeth and bones strong Dairy foods such as milk, yoghurt,

cheese and green leafy vegetables

Iron Helps make red blood cell which carry

oxygen around your body and gives

you energy.

Red meat, green leafy vegetables,

beans

Zinc Helps you grow Meat, fish and poultry

REMINDER Bring into class a variety of food labels or packaging (can foods, cereals, pasta, etc.) for lesson 10 and lesson 11 ====================================================================

17

Lesson 7 Food additives Most food that comes in a package such as a tin, bottle, box or

sealed plastic packet, is processed food. Most processed or

manufactured foods have added salt (sodium) and sugar as well

as other food additives such as preservatives, flavourants and

colorants.

Flavourants – and MSG (flavour enhancer) which improve the taste

Preservatives – (sodium nitrite and sodium nitrate) makes food last longer

Colorants – makes food look appetising or good enough to eat.

Activity 8 What are E numbers? E numbers are codes for chemicals that can be used as food additives.

Many food additives have E numbers.

E 100 – 199 are colorants

E 200 – 299 are preservatives

E 600 – 699 are flavouring

Tartrazine, a yellow colorant, is also called E102. Look for E numbers on packets of jelly,

puddings, sweets and chips.

Sulphur dioxide is also called E220. It is a common preservative in fruit juices and dried

fruit.

Monosodium glutamate (MSG) is a savoury flavourant also known as E621

====================================================================

18

Lesson 11 Labels on food packaging

Activity 10 Labels on food packaging (Choose three different food labels)

Aim

To read the nutritional information on food labels and to identify the nutrients.

Materials – You will need

(a variety of food labels) packets, tinned food, cereals, pasta, etc.

Read the list of ingredients on the food labels for the additives.

Questions Look at the labels on the packaged items of food:

1. List the three main food groups of your 3 items that you have selected.

2. List the nutrients that are listed for your products. 3. List the food additives for your products.

====================================================================

Unit 4 – Nutrition Lesson 12 Healthy eating The selection of foods you eat every day makes up your diet. A balanced diet contains

enough food from all four food groups, as well as water and fibre, to keep you healthy. We

need to eat the correct amounts of carbohydrates, proteins, fats, vitamins and minerals.

19

Water and fibre Many foods contain a lot of water, especially fresh vegetables

and juicy fruits. Fruits and vegetables are also high in fibre. Fibre

is the part of plant food that you cannot digest, but it is good for

your digestive system. Grains like oats and whole wheat are

also high in fibre. It prevents you from suffering from

constipation and can protect you from diabetes or heart

problems.

Junk food and fast food Junk food is food that is high in sugar, high in fat and high in salt. It usually contains very

little protein and lots of food additives. Junk food gives you energy, but does not feed your

body well. Examples of junk foods are sweets, biscuits, ice cream, fizzy drinks, crisps and

fast foods.

Fast food Fast food is fried food or takeaway food. It is quickly prepared (often pre-prepared) and

highly processed. Examples of fast food are French fries (potato chips), pies, hot dogs,

burgers, fried chicken and pizzas.

20

Activity 12 Nadiema wrote a list of all the foods she ate for one day. Look at her list and answer the questions that follow:

1. How many servings of these foods did Nadiema have?

a. Grains group

b. Dairy group

c. Meat, fish and beans

d. Vegetables and fruits

e. Fats and oils.

2. Was Nadiema’s diet balanced on this day? Give a reason for your answer.

3. List the foods that she should eat:

a. More of

b. Less of

====================================================================

Breakfast 1 cup cereal

Half a cup milk

Lunch Two slices bread

Two teaspoons

margarine

Half a cup baked

beans

One banana

Afternoon snack One apple

One bread roll

One slice large

cheese

20 peanuts

Supper One cup rice

Four fish fingers

cooked in two

teaspoons of oil

Half a cup pumpkin

Half a cup cabbage

Small glass of grape

juice

21

Lesson 13 The Traffic Light Diet Red: stop and think twice Eat these foods only in small amounts. These foods include junk food and fast foods. They

include:

- Sweets, hamburgers, chips and fizzy drinks.

Orange: be careful/ pause Eat a little bit of these foods every day. These foods include fat or sugar-rich foods like:

- Butter, eggs, cheese, bacon and red meat.

Green: go for it Add plenty of fresh fruits and vegetables to your diet. These foods include:

- Fish, milk and yogurt, whole-wheat bread, fresh fruits and vegetables.

22

Activity 13 Read the following case study and answer the following questions about Natalie’s diet.

Natalie’s diet Natalie is a 12 year old girl and is in Grade 6.

This is what she ate yesterday. It is similar to what she eats every day.

Do you think that she is eating a balanced diet?

Breakfast Lunch Supper Toast and jam Bread roll with ham Chips and burger

1. List the items Natalie ate for breakfast, lunch and supper.

2. List the food groups that are missing from each meal.

3. Work out which is the most important missing food group for each meal.

Add one food item to each meal to improve Natasha’s diet.

4. Suggest two healthy meal options for Natalie’s breakfast, lunch and supper.

(Refer to the traffic light diet)

==================================================================== Lesson 14 Diseases related to diet What you eat is important for your health, especially as you grow older.

Some diseases are the result of a poor diet.

Other diseases can be managed by a good diet.

23

Tooth decay Tooth decay is caused by bacteria (germs) that feed on sugars on your teeth. The bacteria

make acids that cause holes (cavities) in your teeth. If you eat a lot of sugary foods you

increase your chances of tooth decay.

Diabetes Diabetes is a condition of high blood sugar. Some people are born with diabetes.

Type 2 diabetes can be caused by eating too many sugary foods and drinking too many

fizzy sweet drinks. People with diabetes have to be very careful about what they eat.

They have to inject themselves with insulin in order to keep their blood sugar levels

correct.

Obesity Obesity is the condition of being unhealthily overweight.

It is caused by eating too much food (especially food high

in sugars and fats) as well as doing too little exercise.

Obesity can lead to disease like:

Diabetes (often caused by eating too much sugar)

Heart disease (often caused by eating too much fat)

Hypertension or high blood pressure

Activity 14 Researching diet-related diseases Create an information poster by researching the following:

1) Choose one of the following diseases.

Research the disease to identify the food that causes it.

Hypertension (high blood pressure)

Heart disease

24

Diabetes

Obesity

Tooth decay

2) Choose one of the following diseases. Research the disease to identify which lack of food, vitamin or mineral causes it.

Beriberi

Pellagra

Scurvy

Rickets

Goitre

Osteoporosis

Kwashiorkor

New words:

Evaluate – look at the facts carefully and form your own conclusion.

Diabetes – disease in which the body cannot control blood sugar levels.

Obesity – being overweight.

Kwashiorkor – form of malnutrition caused by too little protein in the diet.

====================================================================

Unit 5: Food processing Lesson 15 What is food processing? Food processing is the process of turning raw plant and animal materials into food

products. Most people buy food products from supermarkets. Most food processing takes

place in factories, rather

than kitchens.

25

Why is food processed? Plant crops only grow in certain seasons. Consumers want safe, nutritious, convenient and

inexpensive food throughout the year.

Food is processed for the following reasons:

To make it edible and ready to eat, or quick and easy to prepare.

To make it last longer

To improve its nutrient value

Food is processed for our eating convenience

Fortified foods Unless vitamins and minerals are added, foods can lose some of their nutrients during

processing. The more food is processed, the less nutritious it becomes.

Fortified foods are foods that have had vitamins and minerals added to them to raise or

restore their nutrient content for example: folic acid, iron and B vitamins are added to

breakfast cereals and mielie meal. Iodine is added to salt.

Activity 15 1) Match the processed foods to their raw material. Think of 3 examples of your own.

Raw materials Food products

26

2) Evaluate why the foods were processed. Copy and complete the table with the examples

in question 1.

To make it edible To make it last longer To improve its nutrient

value

Summary Food is processed to make it safe to eat, to make it last longer and to

make its nutrients last.

====================================================================

Unit 6: Methods for food processing Lesson 16 Methods for processing food

Look at the following images.

The meat has been prepared by slicing the leg of beef with a butcher’s blade.

The mayonnaise has been made by combing eggs with oil and vinegar and beating them together.

The beetroot has been cooked before being bottled.

27

Meat mayonnaise Beetroot

Three food products: Preparing, combining and cooking are three ways of processing food.

• Preparing involves processes such as shelling, peeling, slicing or chopping.

• Combining is the mixing together of two or more ingredients.

• Cooking involves heat. It includes methods such as boiling, baking, steaming, roasting and frying.

Activity 16 Identify some methods of food processing Research and identify the difference between boiling, baking, steaming, roasting, toasting and

frying.

Design a poster to present your information.

Ways of preserving food. Food does not last long before going rotten. It goes stale, or it spoils as moulds and bacteria start

to grow on it and break it down. Treating food to make it last longer is called preserving. Food is

often processed to preserve it, or make it last longer. Heating (cooking) kills bacteria. Freezing,

pickling, drying or salting (adding lots of salt) stops bacteria from growing on the food. Pickling is

the process of preserving food in salt water or vinegar. (Salt water is called brine)

Did you know? Pasteurisation is the process of heating milk to make it last longer. It was invented by French scientist Louis Pasteur.

28

Ways of preserving food.

Hot and spicy atchar Atchar is a South African Indian relish that is made with green

mangoes and chillies.

The name comes from the Hindi word for pickle - atchar.

Activity 17 Identify ways of preserving food 1. Copy and complete the table below.

Table - Examples of food preserving

Processed food Main method of preserving Extra examples

Gherkins

Biltong

Dried peaches

Frozen peas

2. Read about atchar.

2.1 State what the word atchar means.

2.2 List what South African atchar is made from.

Fermenting Fermenting is a method of food

processing that uses yeast or

bacteria. These bacteria are the good

guys, not the bad ones! The yeasts or

bacteria multiply as they feed on the

food and change the starches or

sugars into acids or alcohol.

29

Fermenting improves the nutritional value of the food or beverage. The yeasts or bacteria

themselves are nutritious and they partly digest the food. Yoghurt, amasi, ginger beer and

sorghum beer are all made using the fermentation process.

Drying food

When food is dried, water is removed from it. Drying completely

changes the taste and texture of food. For example, dried fruit is

smaller than fresh fruit and tastes sweeter. When water is removed,

micro-organisms are unable to grow. Some types of dried fruit need to

have water added again before you can eat them, for example pasta.

Activity 18

Method of processing Advantages Disadvantages Drying • Stops micro-organisms

from growing. • Keeps most nutrients.

• Can cause loss of some nutrients – especially vitamin C.

• Dry weather conditions are needed for drying food.

Refrigerating • Slows growth of micro-organisms.

• There is a slow loss of some nutrients with time.

Freezing • Prevent growth of micro-organisms by low temperature and unavailability of water.

• Nutrients not usually lost.

• Unintended defrosting can reduce product quality.

Adding salt • Micro-organisms cannot grow in salty water.

• Process does not destroy nutrients.

• Increases salt content of food.

Pickling • Prevents growth of micro-organisms.

• No loss of nutrients.

• Some people are sensitive to some chemical preservation.

Using the table above answer the following questions:

1. What is the difference between food processing and food preservation?

2. Which is more effective to prevent micro-organisms from growing:

30

Freezing or refrigerating? Provide a reason for your answer.

3. What are the disadvantages of pickling and salting food?

4. Do you think fruit can be pickled?

5. Which of the processing methods, mentioned above, do you think is best? Give a reason

for your answer.

====================================================================

Unit 7: What is an ecosystem? Lesson 17 An ecosystem is an area or habitat that contains living and non-living things.

The living and non-living things depend on each other in many different ways.

An ecosystem works like a smooth-running engine, provided people do not interfere with

or harm it.

• The living things are plants, animals and micro-organisms, such as fungi, moulds and

bacteria.

• The non-living things are air, water, sunlight and soil. An ecosystem There are many different ecosystems, such as mountains, grasslands, forests, deserts,

rivers, ponds, wetlands, rocky shores and seas, which all support different kinds of living

things. This term, we will focus on two ecosystems: Rocky Shore and Desert.

Rocky shore ecosystems The rocky shore has a lot of wildlife. It is home to animals such as fish, crabs, jumping sea

lice and slow-moving anemones, sea urchins, sea snails and limpets. The rocky shore

31

ecosystem is also home to animals such as barnacles, limpets and sea anemones, and

plants such as seaweed. At high tide the rocks are covered by water and at low tide the

rocks are exposed to the Sun.

The mussels and barnacles sieve (pronounced: siv) little bits of food from the water when

it washes over them. To protect themselves, they close their shells tightly shut when it is

dry. The limpets eat seaweed. They leave their shells to search for food. Sea birds, such

as seagulls and oysters catchers, catch and then crack open the mussels and limpets.

Activity 20 Draw and label a rocky shore ecosystem.

32

====================================================================

Lesson 18 Desert ecosystems Desert ecosystems are hot and dry. But, the plants

and animals that make up these ecosystems can cope

with the harsh conditions. Tsamma melons are an

essential plant in the Kalahari’s semi-desert

ecosystem. They look like watermelons, although they

are bitter and do not taste very much like

watermelons. For many animals, though, they are an

essential source of water. The melon vines grow quickly after the rains, storing the water in

their fruits.

These ripen during the dry winter season, just when

the animals are getting a little thirsty. Brown hyenas,

gemsbok, ground squirrels, striped mice and weaver

birds all depend on the Tsamma melon plants. The

gemsbok dig up the long fat roots for water. The

rodents eat the seeds. The hyenas help to spread the

seeds in their dung. The seeds are nicely hidden and

protected from the rodents. It all fits together well.

Activity 21 Learn more about the rocky shore and desert ecosystems. 1. Draw a desert ecosystem. Search Google images to help you find information.

2. Use the internet to read about and research the rocky shore and desert ecosystems.

====================================================================

33

Unit 8: Ecosystems and food webs Living and non-living things in ecosystems

Lesson19 Examples of relationships In an ecosystem, there are certain relationships between the living things and non-living

things. Healthy ecosystems are made up of a wide range of plants, animals and habitats

that depend on each other. Unhealthy ecosystems have a plant or animal that overpowers

the ecosystem. Let us illustrate this with three examples.

Earthworms: friends of the soil. Earthworms have been described as the intestines of the

earth. Not only does an earthworm look like part of your

gut but it also acts as the soil’s digestive system.

Earthworms feed on rotting bits of plant and animal matter

in the soil. They break these bits down into simpler

substances, a lot of which go back into the soil.

Earthworms also mix and aerate the soil as they tunnel

and burrow. Without earthworms, the soil would be hard

and airless.

Lichens: they like clean air. Lichens are those plant-like things that grow

on the bark of trees and on rocks and walls,

as shown in the picture. Some are crusty

and greenish, some are grey and frilly.

Lichens are very fussy about the quality of

the air. The cleaner the air is, the greater

their variety. Lichens play an important role

in making soil. When they grow on rocks

they slowly break down rocks.

People: how they pollute the water (without even thinking about it) Have you ever seen a pond or a river with topping of green slime?

34

The green slime is algae and it can take over the surface of the water very fast.

Algae grow quickly when there is lots of food for it in the water.

Our fertilisers and washing powder detergents are an easy source of food.

At the end of their life cycle, the algae die and rot away. The rotting process uses up all of

the oxygen in the water, leaving none for the fish, which can then all suffocate and die.

Summary An ecosystem is an area where living and non-living things depend on each other in

different ways. There are many kinds of ecosystems. The conditions in an ecosystem

determine which plants and animals live there.

====================================================================

Unit 9: Food webs Lesson 21 What is a food web?

In an ecosystem, plants and animals are connected by their feeding relationship. These

relationships are called a food web.

A food web is made up of a number of linked food chains. A food web is a good way to

show the different

organisms that animals feed

on.

35

Food webs A food web consists of:

• Producers: plants that produce food for themselves, and for animals.

• Consumers: animals, which are herbivores, carnivores and omnivores.

• Decomposers: micro-organisms that break down dead plant and animal matter and

return nutrients to the soil.

Decomposers Decomposers are nature’s recyclers. When plants and animals die, their bodies slowly rot

away and disappear into the soil. Decomposers, such as bacteria and fungi feed on the

remains and break them down. Decomposers play a very important role in an ecosystem,

returning nutrients to the soil.

Activity 20 Draw and label food webs. 1. Identify and draw three food chains that make up the food web in Figure 1.

(Hint: Begin with the plant and follow the arrows.)

2. Look at the rocky shore ecosystem again.

Draw and label a simple food web for this ecosystem.

==================================================================== Lesson 22

Case study: Examine a South African ecosystem under threat.

36

Welcome to Tembe

This ecosystem supports the largest African

elephants together with black and white rhino,

buffalo, leopard, hippo, antelope, eland,

zebra, giraffe, hyena, jackal, nyala, kudu,

waterbuck, reedbuck, the rare suni antelope

and lots of smaller mammals such as bats and

a variety of 340 bird types. Recently the

elephants have begun hiding in the dense sand forests of the Tembe away from poachers.

The area is sandy, dry and ranges from dense woodland to forest to thicket.

This spectacular park is home to approximately 40 of the biggest indigenous elephants.

Sadly it currently faces some challenging threats and concerns.

• The elephants have been fenced in and no longer roam

freely. Fences have been set up to protect them against

the increasing number of poachers in the area. They also

have to protect them from explosives which were planted

during the civil war in Mozambique.

• The area does not have much water. The available water

is not as easy for elephants to reach because of the

fencing.

• The area is overpopulated by elephants that are destroying the plants faster than they are

growing. As a result, the primary habitat and food source within the ecosystem are slowly

being destroyed.

• The existence of animal species such as the dung beetle, lion and wild dog are

threatened. Each of these species contributes to the ecosystem and their presence in the

reserve is necessary.

Activity 21 1. What type of ecosystem is the Tembe Park situated in?

2. What type of bird life is there is Tembe Park?

3. List three animal types that live in this ecosystem.

4. List three plant types that exist in this ecosystem.

5. List three animal species that are at risk in this ecosystem.

37

6. List three animal types that eat plants in Tembe Park?

7. List two ways in which the dung beetle assists in the ecosystem.

8. Briefly suggest how you would control the large numbers of elephants that are

continually increasing.

9. How would you control poaching in the area?

10. Suggest how to solve the challenges regarding water.

11. Why is it important to care for parks like Tembe Elephant Park?

12. Use a page to illustrate and label your impression of Tembe Park. Use the following

words to guide you.

Water Animal types Birds Plants Threatened species

====================================================================