4. What is respiration?
The chemical process in which energy is
released from the breaking down of food is
called respiration.
• Where does
respiration take
place?
Respiration occur
in the body cells.
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5. How does respiration take part?
• Respiration requires oxygen. Oxygen
oxidises the glucose in the body cells to
release energy.
• Carbon dioxide and water
vapour are the waste products
in respiration:
Gucose Oxygen Energy Carbon Water
dioxide vapour
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7. Experiment to find the difference in oxygen content
between inhaled and exhaled air.
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8. What gas is needed for respiration?
• Responding- Contents of air in the boiling tube
• Constant- The presence of living organisms
• Manipulated- The position of mercury thread
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9. Result
• The mercury thread of A and B moves
towards the boiling tubes.
• While the mercury thread at boiling tube C
does not change.
Conclusion:
Oxygen is needed by animals and plants
during respiration.
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10. Do organisms release carbon dioxide during
respiration?
• Responding - Contents of air in the boiling tube
• Constant - The presence of living organisms
• Manipulated -The colour change carbonate indicator
(bicarbonate indicator)
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11. Result
The hydrogen carbonate indicator in tube
X and Y change from red to yellow while
yellow,
the hydrogen carbonate indicator in tubes
Z does not change.
Conclusion
Organisms release carbon dioxide during
respiration.
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18. Summary so far :
Humans require chemical energy to carry out life processes.
This energy is obtained when sugars from digested food are
broken down during respiration.
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21. Combustion
Combustion is the burning of substances
in air.
The substance (fuel), reacts rapidly with
oxygen to produce heat and light.
Combustion is a chemical
process because during
this process new
substances are formed.
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22. Conditions for combustion
Combustion can only occur when these three
conditions are satisfied, that is, the presence of:
a. a substance that can burn, or a fuel (2 types)
i. Carbon
ii. Hydrocarbon
b. Oxygen
c. Heat to warm the fuel
until it reaches ignition
temperature.
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23. The combustion of carbons
The combustion of
carbons like firewood,
charcoal and coal
produces carbon
dioxide and energy in
the form of heat and
light
Carbon + oxygen
Carbon dioxide + energy
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24. The combustion of hydrocarbons
The combustion of hydrocarbons which are
compounds of hydrogen and carbon, produces
carbon dioxide, water and energy in the form of
heat and light.
Examples of hydrocarbons:
1. Kerosene
2. Petrol
3. Diesel
4. wax. yschow88@smkbpj(a) 24
25. The combustion of hydrocarbons
Hydrocarbon + oxygen Carbon dioxide + Water + energy
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28. Substances that Pollute the Air
• Air pollution occurs when air contains
pollutants.
• Pollutants are harmful substances that are
released into the environment. released
into the environment.
• Air pollution is the result of the acts of
human. yschow88@smkbpj(a) 28
29. Thinning of the ozone layer
• Chlorofluorocarbon (CFC)
form aerosol cans,
refrigerators, air
conditioners and
electronic factories.
• Destroys the ozone layer
in Earth's atmosphere
• Ultraviolet light causes
cataracts and skin cancer
and skin cancer
yschow88@smkbpj(a) 29
30. Acid Rain
• Nitrogen dioxide, nitrogen monoxide and sulphur
dioxide dissolve in rain drops to form acid rain.
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34. • Nowadays many of our surrounding peoples are live in suffering of
health problems such as lung cancer, asthma, skin disease,
impaired of eye-sight and etc
• Accidents and breath problems increases due to air pollution such
as haze
• Ways to keep the air clean:
i. Plant more trees at surrounding
Ii. Stop deforestation
Iii. Encourage habit of recycling by discarding materials made from
wood, plastic, glasses and tin
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35. Ways to keep the air clean
iv. Practice car-pooling or prefer walking of short
distance instead of driving
v. Practice using solar energy.
vi. Do not smoke
vii. Avoid open burning of waste products, such as rubbish
and plastics
yschow88@smkbpj(a) 35
