1. In This Section We Will Study The Following Topics:
PLANTS FOR FOOD
In This Section We Will Study The Following Topics:
Humans eat plants for food.
Plants make their own food.
Plant storage organs.
Why do plants store food?
Fertilisers.
Plant nutrients.
Herbicides, pesticides and weed control.
Toxins in the food chain.
What do plants need to grow well?
How do greenhouses work?
Organic farming.

2. This is one of the 7 life processes (remember Mrs Nerg?).
WHAT ARE WE EATING?
Nutrition.
This is one of the 7 life processes (remember Mrs Nerg?).
Nutrition is about feeding.
All organisms need food to grow.
Plants can make their own food by photosynthesis.
Animals need to eat other plants and animals to get food.

3. FOOD FROM PLANTS All our food comes from plants.
This is because only plants can use sunlight to make food. The Sun is the start of any food chain.
When plants photosynthesise they make glucose. This glucose is used to make cellulose for cell walls and is stored as starch.
It is also used to make proteins for growth and repair.
PHOTOSYNTHESIS EQUATION.
Carbon Dioxide +
Water
Sunlight
Glucose
Oxygen

4. Plants use photosynthesis to make their own food.
Oxygen
Released into
the atmosphere.
Light
From the sun
Glucose
For biomass
and energy.
Carbon dioxide
From the air.
Water
From the soil.
Plants use this glucose for respiration.

5. FOOD FOR HUMANS
Humans eat plants and animals for food. Some humans do not eat animals.
They are called VEGETARIANS.
If we eat only plants then we can survive well but we have to eat all of the different parts of plants to make sure we have a healthy diet.
Humans are part of the food chain and the chain can have two links or three.
The arrow shows the direction of energy flow.

6. WHAT PART OF A PLANT DO WE EAT?
Work out which column each of these foods should go into:
Root.
Stem.
Fruit.
Seed.
Leaf.
SUNFLOWER
POTATO
CELERY
TOMATO
LETTUCE
PEAS
CARROT
ORANGE

7. PLANT NUTRIENTS
The plant’s roots do not just absorb water from the soil but also minerals.
These minerals are needed for healthy growth.
Farmers and gardeners have known this for thousands of years and they put plenty of these minerals into the soil to help the plants to grow well.
They use manure.
They use bones that are ground up for specialist plants. They also use blood when planting out new plants. This is an ORGANIC product.
These products are called FERTILISERS and they contain several different chemicals which plants need.

8. WHY DO PLANTS STORE ENERGY?
Seeds need to have an energy store so that can survive before they get leaves. All plants need a store for times when photosynthesis is slow
Some plants are good at converting the sugars made in photosynthesis to oils. SUNFLOWERS make sunflower oil in their seeds.
Potato tubers are able to create new plants.
The plant converts the sugars it has made into starch which is stored in the tuber.
It does this because the starch will not dissolve in the soil (in the ground) whereas the sugar would.

9. ENERGY STORES IN PLANTS
It is often easier to think of these as the parts of the plant that animals like to eat.
Stems and leaves are not as high in energy as roots.
They are often high in protein or starch.
These are the reserves the plant uses for respiration.
Tubers and roots.
These are stores of starch/ glucose.
Nuts and seeds.
These are stores of fats/oils.

10. HOW DO WE GET MORE? Fertilisers help plants to grow.
They provide plants with the correct balance of minerals.
This makes them healthy and makes them grow well.
Organic fertilisers are used by some farmers to increase their crop growth. Manure is an example.
The solid part of a plant (if all of the water was taken away) is called its BIOMASS.
Grapes
Raisins
DRIED OUT IN THE AIR

11. Match up the following words to their correct definition:
WHAT DO THEY MEAN?
Match up the following words to their correct definition:
Nutrients.
Sugar.
Photosynthesis.
Respiration.
Biomass.
A sweet, water-soluble carbohydrate.
A chemical process where sunlight is used
to make sugars.
A chemical process that releases energy
from food. Takes place in the cells.
The mass of an organism (minus the water).
Foods and essential chemicals needed
by living things.

12. FERTILISERS NOT ENOUGH NITROGEN!
A lack of NITROGEN means that the plant grows slowly.
The leaves are pale in colour.
NITROGEN (N)
Helps to make the proteins which are important for growth.

13. FERTILISERS NOT ENOUGH PHOSPHORUS!
A lack of phosphorus means that the plant is stunted.
The leaves are purple in colour.
PHOSPHORUS (P)
Helps to produce a healthy root and stem.

14. FERTILISERS NOT ENOUGH POTASSIUM!
A lack of potassium means that few flowers or fruit are produced The leaves’ edges turn yellow/brown.
POTASSIUM (K)
Helps in the production of flowers and flowering of fruit crops.

15. FERTILISERS NOT ENOUGH MAGNESIUM!
A lack of magnesium means the plant looks yellow or brown and it lacks chlorophyll. It can’t photosynthesise because of the lack of chlorophyll.
MAGNESIUM (Mg)
Helps in the production of chlorophyll.

16. MINERALS Plants need different minerals for different reasons.
Match up each mineral to show how it affects plant growth.
Magnesium.
Nitrogen.
Phosphorus.
Potassium.
The plant cannot make proteins, so the
growth is slow and the leaves are pale.
The plant cannot make chlorophyll or seeds
so the leaves are pale.
The plant cannot make fruit or flowers.
The plant cannot make roots so the
leaves turn purple.

17. MINERALS
There are other important minerals that plants need in very small amounts.
Molybdenum
The leaves become narrow in some plants without this mineral.
Iron
The newer younger leaves are yellow. Tomatoes are prone to this.
Copper
Without this brown spots start to appear on the leaves and the leaves start to die off.
We can use ‘plant food’ for house plants. This helps to correct these problems.
These are tomato plants with an iron problem!

18. KEY WORDS Work out what words these letters should spell: Phtsynthss
Frtlsr
xygn
Crbn dxd
Glucs
nrgy
Chlrplst
Plnt Ntrtn
Mgnsm
Ptssm
Phsphrs
Ntrgn

19. KEY WORD ANSWERS Photosynthesis. Fertiliser. Oxygen. Carbon dioxide.
Glucose.
Energy.
Chloroplast.
Plant Nutrition.
Magnesium.
Potassium.
Phosphorus.
Nitrogen.

20. PESTS
Sometimes we do not want plants to grow. A plant growing in a place where it is not wanted can be called a weed.
We can use chemicals to get rid of weeds, these are called herbicides.
Farmers also find animals destroying their crops. These are a form of pest. When the pest is an insect we use an insecticide. We say that we are using a pesticide to get rid of pests.
Aphids are small insects that feed on roses.

21. COMPETITION FOR RESOURCES
If a person is growing a crop they do not want to waste the resources they have on weeds.
The weeds COMPETE for the resources in the following ways.
LIGHT
The weeds may have broader leaves that grow above other plants and take more light.
CARBON DIOXIDE
The weeds may use up more of the CO2 from the air leaving less for the crop plants.
NUTRIENTS
The root of the weeds will take nutrients from the soil that could go to the crop plants.
WATER
The roots of the weeds will take the available water away from the crop plants.

22. THE GREENHOUSE
Greenhouse gardening or Polytunnel farming allows us to control the factors that affect photosynthesis.
The light, temperature, amount of carbon dioxide and nutrients can be closely monitored.
This means that a high crop yield will be produced.
Because the plants are away from other plants, weeds are less likely to grow.
The numbers of PESTS and INSECTS are also limited.

23. How does the sparrow hawk end up with copper and arsenic in its body?
BIOACCUMULATION
Copper and arsenic are present in the soil near copper mines. Earthworms eat the soil. The copper and the arsenic are not poisonous to earthworms.
Soil containing plant remains.
Earthworm.
Blackbird.
Sparrow hawk.
How does the sparrow hawk end up with copper and arsenic in its body?
The amount of toxin becomes concentrated. As it moves up the food chain it becomes part of the biomass of the next organism. Eventually there will be so much arsenic in the sparrow hawk it will become ill. The toxin will have ACCUMULATED.

24. KEY TERMS Match up the words to their definitions:
This is when something lasts for a long time
in the environment.
Pest.
Bioaccumulation.
This is a poison that kills plants.
Persistent.
This is a poison that kills a pest.
Herbicide.
This is an organism that competes with humans
for food.
Pesticide.
This is when toxins build up in the food chain.

25. ORGANIC FARMING
The amount of herbicides, pesticides and fertilisers added to crops has become very controlled.
These substances are causing environmental problems and many farmers and buyers want crops that are grown only with natural and SUSTAINABLE substances.
There are ways that this can be done:
You could weed the plants rather than using a herbicide.
You could farm plants like peas and plough them back into the soil to improve the nitrogen content.
Grow plants that are more attractive to insects than the crop.
The crop does not get destroyed.

26. SAVE THE ROSES
Biological control can be used to protect crops rather than using chemicals.
Farmers introduce a new organism that will control the pest.
Aphids eat roses, however, the farmer wants to protect them. He introduces ladybirds to the environment and the ladybirds eat the aphids.

27. Fact about Biological Control
SAVE THE ROSES
There are positives and negatives to using biological control, just like there are with using chemical control e.g. herbicides/ pesticides.
Tick the boxes to show whether you think it is positive or negative.
Fact about Biological Control
Positive
Negative
It can be cheaper than chemical pesticides.
It is safe to use on food crops.
It doesn’t remove the pest, it just limits the damage it can do.
The predator may get eaten by another animal.
Suitable predators may not be available for every pest.
There are no poisons left in the environment.
Your predator may get out of control and become the pest.
It only kills the pest, not other organisms.

28. DDT is a persistent poison.
LET’S THINK
DDT is a persistent poison.
Discuss these comments with your classmates.
DDT protects crops from locusts. Locusts can eat tonnes of crops in a short amount of time. DDT stops people from starving.
DDT kills the mosquitoes that cause malaria. This means it saves people’s lives.
DDT has killed many birds. Species will become extinct if we are not careful.
DDT is a persistent poison. This means it stays in the environment for a long time.

29. CHECK YOUR LEARNING. Why do plants store food?
What are the four main nutrients in fertilisers?
Why do we get rid of weeds?
What is a herbicide?
What is bioaccumulation?
Why do greenhouses improve crop yield?
What does farming organically mean?

30. CHECK YOUR LEARNING- ANSWERS.
Plants store food for their seeds and to survive poor weather conditions.
The four main nutrients in fertilisers are:
NITROGEN, PHOSPHORUS, POTASSIUM & MAGNESIUM.
Weeds compete for: LIGHT, NUTRIENTS, WATER & CARBON DIOXIDE.
A herbicide is a chemical that kills weeds and unwanted plants.
Bioaccumulation is the build up of toxins in an organism.
Greenhouses mean that we can control the factors that affect the rate of photosynthesis.
Farming organically means not using chemicals that damage the environment.