Download NS/Tech - Tom Newby School

1
Natural Sciences and Technology
Grade 6
Term 1
Index
Unit 1: Photosynthesis: Plants and food
5
Unit 2: Plants and air
10
Unit 3: Nutrients in food: Food groups
12
Unit 4: Nutrition
18
Unit 5: Food processing
24
Unit 6: Methods for food processing
26
Unit 7: What is an ecosystem?
29
Unit 8: Ecosystems and food webs
32
Unit 9: Food webs
34
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
Does my product look like my drawing? [
[
] Yes
] No
[
] No
How can I make my product better? __________________________________________
4
Natural Sciences & Technology
Grade 6
Term 1
Strand 1
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
Nutrients in
food
Food
groups
Nutrition
Food
processing
Ecosystems
and food
Balanced
diets
Need for
food
processing
Different
ecosystems
Plants and
air
Methods for
processing
food
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.
Plants can store the starch in these places:
6
 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
Vocabulary
Photosynthesis
Glucose
Chlorophyll
Carbon dioxide
Oxygen
A process through which plants make their own food from carbon
dioxide and water using light energy from the sun.
A type of sugar used as an energy source for many living organisms.
A substance that makes plant green.
A gas in the air that plants need for photosynthesis.
A gas in the air that living things need.
Summary
7
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
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.
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.
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
It takes place in all living plant cells.
Photosynthesis
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 Carbon Dioxide and water are used and Oxygen
released.
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-vsrespiration/
12
Revision Activity
1. Use the words in the box to complete the sentences.
Carbon
Oxygen
Starch
Sunlight
Photosynthesis
Water
Leaves
Glucose
dioxide
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.
2. What is photosynthesis?
3. Where does photosynthesis in the plant mainly take place?
4. Explain why it takes place there.
5. Name three things that plants need from their environment for photosynthesis to take
place.
6. 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
carbohydrate in our diet.
common
form
of
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.
Carbohydrates
Proteins
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.
Vocabulary
Nutrients
Diet
Food groups
Immune system
Insulation
The important parts of food needed by the body for energy and good
health.
The different foods a person or animal eats.
The main types of food.
The system in the body that protects it from diseases and germs.
The ways or things that protect prevent loss of heat or cold.
16
Important vitamins
Vitamin
A
Function
Helps you see at night
Foods that contain the vitamin
Carrots, pumpkin, butter, liver
Helps your body fight infection
B
Helps make energy, proteins and red Cereals, brown rice, meat, vegetables
blood cells, plus many other functions
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
Calcium Makes teeth and bones strong
Foods that contain the vitamin
Dairy foods such as milk, yoghurt,
cheese and green leafy vegetables
Iron
Helps make red blood cell which carry Red meat, green leafy vegetables,
oxygen around your body and gives beans
you energy.
Zinc
Helps you grow
Meat, fish and poultry
REMINDER
Bring 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
====================================================================
Lesson 11
18
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:
Breakfast
Lunch
Afternoon snack
Supper
1 cup cereal
Two slices bread
One apple
One cup rice
Half a cup milk
Two teaspoons
One bread roll
Four fish fingers
margarine
One slice large
cooked in two
Half a cup baked
cheese
teaspoons of oil
beans
20 peanuts
Half a cup pumpkin
One banana
Half a cup cabbage
Small glass of grape
juice
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
====================================================================
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) Research one of the following diseases to identify the food that causes it.

Hypertension (high blood pressure)

Heart disease

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
24

Pellagra

Scurvy

Rickets

Goitre

Osteoporosis

Kwashiorkor
Vocabulary
Evaluate
Diabetes
Obesity
Kwashiorkor
To look at the facts carefully and form your own conclusion.
A disease in which the body cannot control blood sugar levels.
To be extremely overweight.
A 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 mealie 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.
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.
27
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.
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.
28
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.
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.
29
Activity 18
Method of processing
Drying
•
•
Advantages
Stops micro-organisms
from growing.
Keeps most nutrients.
•
•
Refrigerating
•
Slows growth of microorganisms.
Freezing
•
Prevent growth of micro- •
organisms by low
temperature and
unavailability of water.
Nutrients not usually
lost.
Micro-organisms cannot •
grow in salty water.
Process does not
destroy nutrients.
Prevents growth of
•
micro-organisms.
No loss of nutrients.
•
Adding salt
•
•
Pickling
•
•
•
Disadvantages
Can cause loss of some
nutrients – especially
vitamin C.
Dry weather conditions
are needed for drying
food.
There is a slow loss of
some nutrients with
time.
Unintended defrosting
can reduce product
quality.
Increases salt content of
food.
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:
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.
30
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
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.
31
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.
====================================================================
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.
32
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.
====================================================================
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.
33
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?
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.
34
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.
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.
35
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.
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.
36
•
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.
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
====================================================================