Biology

Preliminary Biology Assessment Task 1: Part B

Experiment - Chlorophyll

Dependent Variable: (1/2 mark)

Measuring the amount of starch present.

Independent Variable: (1/2 mark)

The Colour of leaf

Control group: (1/2 mark)

Green part of leaf

Control Variables: (1/2 mark)

Green part of leaf

Control variables: (1/2 mark)

- type of leaf

- solution (iodine)

- the environment

Aim: To determine whether chlorophyll is necessary for starch transportation

Apparatus:

3 verigated geramun leafs.

Iodine with water dropper

3 pedri dishes

600ml tap water

600ml methylated spirits

Hot plate

2 beakers

Stop watch

Diagram: (2marks)

Vegetated leafDiagram of experiment

Vegetated leaf

R

600ml methylated spirits

Hot plate

Heat

600ml tap water

Pedri dishes

Method:

Collect all apparatus

Measure area of total leaf

Set up the equipment shown in the diagram above , wait till bubbles start to form at the surface

Immediately put the leaf in boiling water for three minutes

While water is boiling , fill up another beaker with the methylated spirits boil it.

Put the leaf immediately in methylated spirits for three minutes

Put the water back on the hot plate re dip the leaf in the boiling after for 1 minute.

Place the soft, clear leaf in a pedri dish and add 5 drops of iodine

Record observations of leaf

Repeat steps 3,5 6- 8 two more times.

Results: (5 marks)

Discussion: (7 mark)

2. Explain why the areas of a leaf stained with iodine indicate where photosynthesis has occurred (2)

- because photosynthesis has occurred in the leaf, starch is therefore present because of the elements light, water, carbon dioxide needed to work photosynthesis to produce starch .There fore the black indication of the iodine presenting the presence of starch is because the important elements of water sunlight and carbon dioxide are present there for indicating photosynthesis.

3....