Part
A Multiple Choice (30 marks)
2@
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1. B
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2. C
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3. D
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4. A
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5. A
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6. B
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7. B
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8. C
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9. B
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10. D
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11. B
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12. B
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13. D
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14. A
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15. B
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Part B Fill in the blanks (30 marks) 2@
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a. noble
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i.
respiration
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b. glowing
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j. chlorophyll
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c. burning
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k. light
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d. cobalt chloride
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l. chemical
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e. blue
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m. food/ starch
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f. pink
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n. oxygen
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g. higher
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o. respiration
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h. water vapour
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Part C Structured Questions (40 marks)
1.
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(a)
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Iodine solution
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2
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(b)
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The mixture of iodine solution and water is brown in colour
while that of iodine solution and starch solution is dark blue.
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2
2
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(c)
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The
iodine solution cannot enter the leaf cells unless the cells are killed. /
The
colour of the chlorophyll in the leaves affects our observation of the colour
of iodine solution.
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2
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2.
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(a)
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Respiration
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2
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(b)(i)
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Carbon dioxide
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2
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(ii)
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Test
the gas with lime water.
Lime
water will change from colourless to milky. /
Test
the gas with hydrogencarbonate indicator. The indicator will change from red
to yellow.
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1
2
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3.
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(a)
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A plant can be destarched by
keeping it in the dark for at least 24 hours.
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2
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(b)
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In tubes C and D
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2
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(c)
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In tubes A, C and D
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3
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(d)
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Tube A
In the dark, photosynthesis stops.
Only respiration occurs and carbon dioxide
is released.
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1
1
2
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4.
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(a)
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It shows the three conditions
for burning to take place, i.e. fuel, oxygen and a sufficiently high
temperature.
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2
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(b)
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We can remove any one of the three
necessary conditions to put out a fire.
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2
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(c)
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Carbon dioxide is released from the fire
extinguisher.
As carbon dioxide is denser than air,
it sinks and displaces the air around the
fire, hence cuts off the supply of oxygen.
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2
2
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5.
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(a)
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Ÿ Both consume oxygen;
Ÿ Both release energy / carbon dioxide /
water;
Ÿ Both involve the change of the
chemical energy in food into other forms of energy.
(any two or other reasonable answers)
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2
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(b)
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Ÿ A flame exists in burning but not in
respiration;
Ÿ Respiration is a much more complicated
process than burning;
Ÿ Respiration takes place in living cells while
burning takes place in air;
Ÿ The energy from food is released much slower
in respiration than in burning.
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4
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