1. Gr 9 Second term
How plants work

2. Plants produce there own food (glucose) by photosynthesis
Carbon dioxide + Water(+ light energy) Glucose+Oxygen
[ in the presence of chlorophyl]

3. Plants:
Light energy  potential energy
Animals get
energy from
plants
Predators and other
meat eating animals get
their energy from
animals that originally
got it from plants.

4. Photosynthesis
Carbon dioxide +Water(+ light energy)Glucose + Oxygen
Energy is taken up during photosynthesis. It is
therefore an example of an endothermic
chemical reaction.

5. Functions of plants:
Plants supply food to
humans and all other animals.
Plants remove carbon dioxide
from the atmosphere.
Plants release oxygen to the
atmosphere.

6. Many medicines are made
from plants
Wood from plants are
used to make furniture
and to build houses.
Wood is used
as a fuel.
Plants supply shelter/habitat
to animals.

7. Parts of the plant
roots
stem
leaves
Flower / fruits

8. Functions of the organs of a plant:
Roots
a) Root hair cells absorp water
and minerals from the soil.
b) Roots anchor the plant in
the soil.

9. Stems
a) Keep the plant up straight for sunlight to reach the leaves.
b) Stems contain small tubes that transport water and
dissolved minerals (called xylem) from the roots to the rest
of the plant and food (transported in phloem) from the
leaves to the rest of the plant.

10. Leaves
-Leaves are specialised organs for photosynhesis.
They produce food (simple sugars/glucose)
that the plant needs for it’s life processes
(MRS GREN).
Leaves are green because
the cellscontain a molecule or colour
pigment called chlorophyll (in the chloroplasts).

11. The palisade cells are specialised cells for photosynthesis.
They are found in the top layer of a leaf.
The xylem, which
transports water and
dissolved minerals and
the phloem, which
transports food
around the plant,
form the veins of a leaf

12. Stomata are little holes which are found mainly on
the bottom of a leaf. Exchange of three gasses
namely carbon dioxide, oxygen and water vapour
takes place through the stomata.

13. Flowers
Specialised organs for reproduction. They contain
both male (anthers) and female (carpel)
parts that are responsible for sexual reproduction in
plants.

14. What do plants need to grow well?
Seeds need oxygen, water and warmth
to germinate.
Plants need carbon
dioxide, water, sunlight, soil with a
specific pH and minerals ( such as
phosphates, potassium, nitrogen
and magnesium) to grow well

15. Farmers and gardeners add fertilizers or compost to
the soil to supplement the amount of minerals. The
use of too many fertilizers can damage the
environment. We call this process eutrophication.

16. The burning of fossil fuels
result in the release of sulphur
dioxide and nitrogen oxide.
These two oxides react with
the water in rain drops to
form sulphuric and nitric acid.
As a result of this the pH of
rain drops and the rain
becomes very acidic. It can be
as acidic as vinegar. Acid rain
is harmful to metal, soil, stone
and plants.

17. What happens to the glucose (sugar) that is made during
photosynthesis?
As previously said, glucose(sugar) is made during
photosynthesis. The plant uses it for it’s own life
processes.
The phloem transports it through the plant. Excess
glucose is binded together to form starch.
The starch is stored in the plant, mainly by the
roots.Starch in a photosynhesising plant can already be
detected in the leaves.

18. Test for starch
Method Reason
Step 1: Put a leaf To break down
in boiling water for the cell walls so
about 5 chemicals can
minute, until it is enter the cell.
soft.
To remove the green
Step 2: Put pigment (chlorophyl).
the leaf in a This is for us, to more
test tube clearly see a colour
with ethanol change when we
for a while. add iodine.

19. Test for starch
Method Reason
To make it soft
Step 3: Rinse the
again.
leaf in water.
Step 4: Spread the To stain any
leaf out on a white starch, if
tile/saucer/petri present. Turns
dish. blue/black if
starch is
Step 5: Drop a few present. Stays
drops of iodine on yellow/brown
the leaf if no starch is
present.

20. A leaf covered with iodine turns black due
to the presence of starch

21. Is light needed for photosynhesis?
If plants are kept in a dark cupboard for longer than
24 hours they do not have anymore stored starch in
their leaves. The starch is broken down into sugar.
The plant uses the sugar for it’s own life processes
(MRS GREN).

22. Plan an investigation to determine if sunlight is
needed for photosynhesis.
Aim of the investigation
To determine if sunlight is needed for photosynthesis.

23. A. The planning of an investigation consists of the
following steps:
a) Find the variables.
b) Formulate a hypothesis for the investigation.
c) Write down the method, step-by-step, that you
are going to follow.
d) How are you going to record your results?
e) Which safety measures will you have to keep in
mind?
f) What do you predict (think) your results are
going to be? Explain your answer by using
scientific knowledge.

24. Is oxygen released during photosynthesis?

25. a) What are the variables in this investigation?
b) Formulate a hypothesis for the investigation.
c) Write down the method, step-by-step, that
they are going to follow.
d) How do we know that the gas released is
oxygen?
e) Why is the release of oxygen during
photosynthesis so important?
f) Study the above figures. Write down the
results and the conclusion for this
investigation.

26. Water in plants
Plants need water for :
a) Transport of substances to and through
the plant.
b) Cooling down the plant.
c) Supporting the soft parts, to keep them
firm and upright.

27. d) Photosynthesis
e) Chemical reactions in the plant cells.

28. Water enters the plant through the specialised root hair cells.
It moves through the roots, stems and leaves in the xylem.
Water evaporates from the surface of the leaf through the
stomata. This type of evaporation from the leaves is called
transpiration.

29. Adaptations of plants to reduce the loss of water:
a) Closing of the stomata: At night or at times when it
is very hot, windy or dry.
b) Waxy layer on top of the leaf: Serves as a waterproof
layer to minimise evaporation.
Eg. Succulents

30. c) Hairs on the leaf: The hairs trap a layer of moist air
against the leaf.
d) Stomata are situated at the bottom of a leaf: This
reduces evaporation/transpiration from the leaf.
e) Reducing the surface area of
the leaf: To reduce evaporation
E.g. Cactus thorns are rolled up
leaves. Leaves of plants in
warm areas tend to be small
while leaves that grow in the
shade are big.