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Science PT3 Chapter 2 Cell as the Basic Unit of Life

2.2 Respiration and Photosynthesis

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Respiration
1. All living things need energy to carry out various activities and life processes.
2. Food is the primary supplier of energy.
3. The process of breakdown of food to release energy is called respiration.
4. Animals and plants absorb oxygen and release carbon dioxide into the air.
5. Respiration can be divided into two, namely: Form 1
(a) External respiration (breathing) is the Oxygen
exchange of gases between organisms and the Carbon dioxide
Form 1
environment.
(b) Internal respiration (cellular respiration) is
the process of oxidation and breakdown of
glucose to produce energy in living cells. Diagram 2.8 External respiration

C H O + 6O 6CO + 6H O + Energy (ATP)
12
6
2
2
6
2
Glucose Oxygen Carbon Water
dioxide
Photosynthesis
1. Photosynthesis is the process by which green plants produce glucose and oxygen
from water and carbon dioxide with the presence of sunlight and chlorophyll.

Light
6CO + 6H O C H O 6 + 6O
2
12
2
6
2
Carbon Water Chlorophyll Glucose Oxygen
dioxide
2. Chlorophyll is the green pigment that is found in the chloroplast of green plant
cells.
3. Chlorophyll helps to absorb light energy Sunlight
during the photosynthesis. Oxygen
4. Glucose synthesised is stored in the form
of starch in all parts of the plant.
Carbon
dioxide Glucose
(sugar)

Water and mineral
Water and mineral
Diagram 2.9 Photosynthesis in plants

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02 Ranger Science Ting.1.indd 29 30/03/2022 11:27 AM