Page 19 - Focus PT3 2020 Science ( BI Version )

Science PT3 Chapter 2 Cell as the Basic Unit of Life
Observations:

Blue-black
Green
region (starch present)
White
Brown
region
(starch absent)
Figure 2.21 Sketches of the variegated leaf before and after the test for starch
Form
Form
1 Discussion:
1. A variegated leaf is a leaf with different colours (pigments) on it.
2. Starch is present only in the green region of the leaf that contains chlorophyll.
3. No starch is formed in the non-green region of the leaf due to the absence of chlorophyll.

Conclusion:
The hypothesis is accepted. Chlorophyll is essential for photosynthesis.

Eksperimen 2.1
Experiment 2.4
Eksperimen 2.1
Problem statement: Does photosynthesis require water?
Hypothesis: Water is essential for photosynthesis.
Aim: To investigate whether water is essential for photosynthesis.
Manipulated variable: Presence of water
Responding variable: Colour change of iodine on the leaf
Constant variable: Type of plants Plant P Plant Q
Materials and apparatus: Two similar potted green plants, water,
boiling tube, white tile, Bunsen burner, tripod stand, wire gauze, forceps, Figure 2.22 The set-up of
apparatus
dropper, ethanol, hot water and iodine solution.
Procedure:
1. Two similar potted green plants are exposed to sunlight.
2. Plant P is watered every day whereas plant Q is not watered.
3. After one week, a leaf is plucked from each plant and then tested for the presence of starch.
Observations:
Presence of Observation for the
Leaf Inference
water test for starch
The leaf turns Photosynthesis takes place in the presence of
Plant P Yes
blue-black water.
Photosynthesis does not take place in the
Plant Q No No change
absence of water.
Discussion:
Starch is present in the leaf of plant P that is watered every day whereas starch is absent in the leaf of plant Q
that is not watered.
Conclusion:
The hypothesis is accepted. Water is essential for photosynthesis.

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