1. And things that plants get up to..

2. KS3 Plants KS3 Sc1 Science Green plants as organisms
3) Pupils should be taught:
that plants need carbon dioxide, water and light for photosynthesis, and produce biomass and oxygen
to summarise photosynthesis in a word equation
that nitrogen and other elements, in addition to carbon, oxygen and hydrogen, are required for plant growth
the role of root hairs in absorbing water and minerals from the soil
that plants carry out aerobic respiration.

3. KS4 Double award (Sc2)
Students should be taught
about similarities and differences in structure between plant and animal cells
the reactants in, and products of, photosynthesis
that the rate of photosynthesis may be limited by light intensity, carbon dioxide concentration or temperature
how the products of photosynthesis are utilised by the plant
the importance to healthy plant growth of the uptake and utilisation of mineral salt
the hormonal control of plant growth and development, including commercial application
how plants take up water and transpire
the importance of water in the support of plant tissues
that substances required for growth and reproduction are transported within plants.

4. What is photosynthesis?
Plants make their own food by photosynthesis.
This process is a chemical reaction that uses light energy.
light energy
The word photosynthesis comes
from the Greek language:
“photo” means “light”
“synthesis” means “putting together”
Photosynthesis just means “putting together with light”.
What do green plants “put together” to make their food?

5. Photosynthesis: raw materials
The raw materials for photosynthesis come from the air and the soil.
What are these raw materials called?
What else do plants need to turn
carbon dioxide
and water into food?
carbon
dioxide
water

6. Photosynthesis: energy for the reaction
Photosynthesis is a chemical reaction between carbon dioxide and water.
Energy is needed for this reaction to take place.
Where do plants get this energy from?
light energy
carbon
dioxide
water

7. carbon dioxide water Photosynthesis takes place in plant cells light
with chloroplasts.
Chloroplasts contain the green chemical called chlorophyll.
Chlorophyll absorbs the energy from sunlight that allows carbon dioxide and water to react.
What are the products of this reaction?
light
energy
chlorophyll
carbon
dioxide
water

8. carbon dioxide oxygen oxygen glucose glucose
Glucose is the useful product for plants.
Some glucose is used straightaway by plant cells, some is converted to starch for storage and later used for food.
Oxygen is the ‘waste’ product. This gas is transported out of the leaf into the air.
Why is this important for humans and other living things?
light
energy
chlorophyll
carbon
dioxide
oxygen
oxygen
glucose
glucose
water

11. Photosynthesis: summary
Summarize the process of photosynthesis in one sentence.
Photosynthesis is a chemical reaction
that takes place in the chloroplasts
in green plant cells, where light energy
is used to convert carbon dioxide and water
into glucose and oxygen.
Photosynthesis is a chemical reaction which means it can also be summarized in a word equation.
What is the word equation for this vital chemical reaction?

12. Photosynthesis: word equation
light energy
carbon
dioxide
water
glucose
oxygen
chlorophyll
light
energy
chlorophyll
carbon
dioxide
oxygen
glucose
water

13. Photosynthesis: word equation activity

14. Photosynthesis: chemical formulae?
Photosynthesis is a chemical reaction involving molecules.
glucose
light energy
chlorophyll
carbon
dioxide
water
oxygen 6 6 6
CO2
H2O
C6H12O6 O2
The chemical formula of a glucose molecule is C6H12O6.
What are the chemical formulae of the simple molecules that make up carbon dioxide, water and oxygen?

15. Photosynthesis and respiration
Only green plants photosynthesize,
but respiration occurs in the cells of all living things to release energy.
Photosynthesis
(energy needed)
glucose
light energy
chlorophyll
carbon
dioxide
water
oxygen
Respiration
(energy released)
carbon
dioxide
glucose
oxygen
water
Compare the reactants, products and energy results of these two chemical reactions. How are they connected?

16. Photosynthesis and respiration
How will the amounts of oxygen and carbon dioxide in the air vary over 24 hours?
amount of
oxygen
amount
of gas
in the air
amount of
carbon dioxide
12 a.m p.m a.m.
What overall effect do photosynthesis and respiration have on the levels of oxygen and carbon dioxide in the air?

17. How does water enter a plant?
Water is one of the raw materials needed for plants to carry out photosynthesis.
How does water enter a plant?
Water from the soil enters a plant through the roots.
You can’t normally see them but
roots are a very important part of a plant.
Why are roots branched and spread out through the soil?

18. How are roots adapted? water Roots are branched and spread out
for two reasons:
to absorb water (and mineral salts)
from a large amount of soil.
to anchor the plant in the soil.
Taking a closer look, roots are
covered in root hair cells.
Root hair cells have thin walls
and a large surface area to help
them absorb lots of water.
How are roots adapted to their job?
water

20. Why do plants need water?
Water is needed by plants for photosynthesis but this important liquid is also used in many other ways:
to provide dissolved minerals that keep the plants healthy;
to transport substances around the plant;
to keep the plant rigid and upright;
to keep the plant cool;
to allow other chemical reactions to occur in plant cells.
What happens to a plant if it does not get enough water?

21. Tropisms water hydrotropism light phototropism gravity geotropism
Plant responses to light, water and gravity are given
special names.
water
hydrotropism
light
phototropism
gravity
geotropism
Can you work out what the name of each tropism means?
Which parts of a plant respond to these different stimuli?

22. What do different tropisms mean?

23. Phototropism and auxins – light from one side
Why does the shoot bend towards the light when it gets light from one side?
There are more auxins on the shaded side of the shoot,
so the shaded side grows faster making the bright side bend towards the light.
light
light

24. Geotropism and auxins
If a plant is laid on its side, why does the root grow down
and the stem grow up?
Auxins slow down growth on the lower side of the root,
so the root curves down.
Auxins speed up growth on the lower side of the stem,
so the stem curves up.

25. Plant Responses What do plants respond to? Response to light
Contents
Plant Responses
What do plants respond to?
Response to light
Response to gravity
Response to water
Using plant hormones
Summary quiz

26. What are plant hormones used for?
Plant hormones can be used in gardening and
agriculture to control how plants grow and develop.
Plant hormones are naturally-occurring chemicals
but can also be produced synthetically for the following commercial uses:
growing cuttings
killing weeds
ripening fruit

27. Using plant hormones – growing cuttings
A cutting is a part of plant that
is removed from the main shoot.
What does a cutting no longer have, when it is removed from a plant?
A cutting does not have roots and
so has no supply of water or minerals.
Rooting powder contains plant growth hormones. Dip a cutting into rooting powder and the plant hormones stimulate the cutting to grow new roots.
Why does the gardening business use cuttings and rooting powder to grow new plants?

28. Grow your own plant cutting

29. Using plant hormones – killing weeds
A surprising use of plant hormones is for killing weeds.
Why are weeds a problem in farming and gardening?
Weeds are unwelcome plants that compete with the plants being grown by gardeners and farmers.
Many chemicals that are potential weedkillers are toxic
to animals and humans as well as plants.
Why might a weedkiller with plant hormones that only affects plants be a more favourable option?

30. Using plant hormones – killing weeds
Cereal crops like wheat are grasses with narrow leaves.
Most weeds that grow in fields and gardens have broad leaves.
Selective weedkillers contain plant hormones at concentrations that will only affect plants with broad leaves.
What effect will this type of weedkiller have on a field of wheat overgrown with weeds?
These selective weedkillers upset the normal growth of broad-leaved plants and so kill off any weeds.
The growth of cereal crops and grasses is not affected.

31. Using plant hormones – ripening fruit
Fruit is usually ripe and
ready to eat when it is
bought from a greengrocers
or supermarket.
Fruit farmers are able to control when fruit ripens
using plant hormones.
Why is this important for their business?
Fruit has often travelled many miles before being bought from the shops.
Is it better for fruit to be ripe or unripe during a long journey?

32. Using plant hormones – ripening fruit
Fruit that is picked before
it is ripe is usually hard.
There is less chance of unripe fruit being damaged when transported, which
is important to the farmer
and the buyer.
Plant hormones can be sprayed onto unripe fruit during transportation. These hormones ripen fruit in time for its arrival in the shops.
Why is it a good idea to wash fruit before you eat it?