Page 17 - Focus PT3 2020 Science ( BI Version )

Science PT3 Chapter 2 Cell as the Basic Unit of Life

Eksperimen 2.1
Eksperimen 2.1
Experiment 2.1
Problem statement: Does photosynthesis require sunlight?
Hypothesis: Sunlight is essential for photosynthesis.
Formo investigate whether sunlight is essential for photosynthesis.
Aim: T
Form
1 Manipulated variable: Presence of sunlight
Responding variable: Colour change of iodine on the leaf
Constant variable: Type of plants
Plant K
Materials and apparatus: Two similar potted green plants, boiling tube, beaker,
Bunsen burner, tripod stand, wire gauze, forceps, dropper, white tile, ethanol, iodine (In the dark)
solution and hot water.
Procedure:
1. Two similar potted plants are prepared and labelled as plant K and plant L.
2. Plant K is exposed to sunlight whereas plant L is kept in the dark.
3. After one week, a leaf is plucked from each plant and then tested for the presence
of starch.
Plant L
Observations: Figure 2.18
Presence of Observation for
Leaf Inference
sunlight the test for starch
The leaf turns Photosynthesis takes place in the presence of
Plant K Yes
blue-black sunlight.
Photosynthesis does not take place in the dark
Plant L No No change
(absence of sunlight).
Discussion:
1. Starch is present in the leaf of plant K that is exposed to the sunlight whereas starch is absent in the leaf
of plant L that is not exposed to the sunlight.
2. Plant L does not receive sunlight, therefore photosynthesis does not take place.
Conclusion:
The hypothesis is accepted. Sunlight is essential for photosynthesis.

Experiment 2.2
Eksperimen 2.1
Eksperimen 2.1
Problem statement: Does photosynthesis require carbon dioxide?
Hypothesis: Carbon dioxide is essential for photosynthesis.
Aim: To investigate whether carbon dioxide is essential for photosynthesis.
Manipulated variable: Presence of carbon dioxide
Responding variable: Colour change of iodine on the leaf
Constant variable: Type of plants
Materials and apparatus: Two similar potted green plants, bell jars, glass plates coated with vaseline, beaker,
boiling tube, white tile, Bunsen burner, tripod stand, wire gauze, forceps, dropper, ethanol, hot water, iodine
solution and potassium hydroxide solution.
Procedure:
1. Two potted plants are kept in a dark place for two days to remove the starch.
2. The apparatus is set up as shown in Figure 2.19 and kept under the Sun.

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