MakingFood

Page
1

Slide 1

The World of Plants

Standard Grade Biology

Slide 2

World of Plants is divided into:

A- Introducing plants

B- Growing plants (Pollination, Fertilisation, Asexual reproduction)

C- Making food

Slide 3

Plants- the first link

Plants are the link between the energy in the sun being converted into a form which animals can eat and get the energy to survive…

The process by which plants do this is called:

Photosynthesis

All living things respire all the time to release energy from their food in a process called:

Respiration

Slide 4

Plant survival

Plants make their own food, glucose, by photosynthesis.

It only happens during the daytime when there is light available.

This happens in plant cells containing the chemical chlorophyll (green-coloured) which traps the light energy.

The plants have captured light energy and turned it into a store of chemical energy (glucose).

Raw materials

Products

More on the uses for glucose shortly…

Slide 5

Is light needed for photosynthesis?

Take a de-starched geranium plant (24h in dark).

Cover part of a leaf with some tin foil (this prevents light getting through).

Leave the plant in sunlight for a few hours.

Test the leaf for starch.

Slide 6

Is carbon dioxide needed for photosynthesis?

Take a de-starched geranium plant

Enclose it in a plastic bag with a chemical that absorbs carbon dioxide. (e.g. soda lime or sodium hydroxide pellets).

Leave the plant in sunlight for a couple of hours.

Test the leaf for starch.

Slide 7

Questions:

Which parts of the leaf do you think will go blue- black?

Why do parts that were not covered contain starch?

Is light needed for photosynthesis?

Slide 8

Is carbon dioxide needed for photosynthesis?

Questions:

Does the leaf contain starch? Why/ why not?

Has the plant carried out photosynthesis?

What would be your control plant’s conditions?

(Hint: a control plant should have everything it needs for photosynthesis including carbon dioxide).

CO2 is converted into glucose by photosynthesis.

Slide 9

Mans’ uses of plant glucose