1. Challenging Mathematics in Primary School National Examination in Singapore
2. Free Exam papers to practice
Tuesday, January 5, 2010
PSLE Science
1. How are ferns different from other green plant?
ans: Ferns reproduce by spores, other green plant reproduce by seeds.
2. What are spores and how do ferns ensure continuity of their kind?
ans: Spores are produced by ferns and fungi for reproduction, and ferns ensure continuity of their kind by producing spores.
3. How do carnivorous plant adapt to ensure survival?
ans: Carnivorous plant can trap insects and small organisms for food.
4. What happens to household refuse after it has been thown into the refuse bin or down the chute?
ans: The household refuse are either sent for incineration at an incinerator or sent to dumping grounds for burial.
5. SAMPLES:
test tube A: saliva and starch
test tube B:boiled saliva and starch
test tube C:distilled water and starch
AFTER IODINE TEST:
A:solution remained unchanged
B:solution turns dark blue
C:solution turns dark blue
a)what is the iodine test used for?
ans: Iodine is used to test for starch.
b)compare test tube A and B. why did the iodine remain unchanged in A?
ans: Saliva has digested starch into sugars.
c)what is the effect of heat on saliva?
ans: The enzyme in starch has been killed (or denatured) by heating.
d)what is the purpose of test tube C?
ans: To act as a control to compare the results with Test tube A and B which contained saliva.
6.
step1:de-starch the plant.
step2:pluck a leaf from the plant and place it in chemical A.
step3:place the leaf in a test tube containing chemical B and place it in a beaker of hot water. step4:remove the leaf from the test tube and wash with chemical A.
step5:place the leaf on a tile and add a few drops of chemical C.
A)how would you de-starch a plant?
ans: Keep the plant in the dark for 48 hours.
B)identify chemicals A,B,C and state their function in the process of testing a leaf for starch.
ans:
A- Boiling water: To kill the leaf
B- Alcohol: Remove the cholorophyll
C- Iodine - Test for starch
7. How does a plant adapt itself to carry out photosynthesis?
ans: The plant grow towards light and has many leaves to increase the surface area to capture more sunlight.
8. Can magnetic force pass through an iron block and attract a steel car?
ans: No. Magnetic force cannot pass through a magnetic object.
9. Is Yeast a Fungi or Micro-organism.
ans: Yeast is both a fungi and a micro-organism.
10. What is the direction of rotation of the Earth around the Sun.
ans: West to East direction
11. Which ball (of different material but same size) will drop to the ground fastest when each drops from 5m height at the same time? A rubber ball, a wooden ball or an iron ball? Or will they reach the ground at the same time?
ans: They will reach the ground at the same time.
12. Which is heavier? A kilogram of Iron or a kilogram of feather?
ans: Both of them are one kilogram, so both are equally heavy.
ans: Ferns reproduce by spores, other green plant reproduce by seeds.
2. What are spores and how do ferns ensure continuity of their kind?
ans: Spores are produced by ferns and fungi for reproduction, and ferns ensure continuity of their kind by producing spores.
3. How do carnivorous plant adapt to ensure survival?
ans: Carnivorous plant can trap insects and small organisms for food.
4. What happens to household refuse after it has been thown into the refuse bin or down the chute?
ans: The household refuse are either sent for incineration at an incinerator or sent to dumping grounds for burial.
5. SAMPLES:
test tube A: saliva and starch
test tube B:boiled saliva and starch
test tube C:distilled water and starch
AFTER IODINE TEST:
A:solution remained unchanged
B:solution turns dark blue
C:solution turns dark blue
a)what is the iodine test used for?
ans: Iodine is used to test for starch.
b)compare test tube A and B. why did the iodine remain unchanged in A?
ans: Saliva has digested starch into sugars.
c)what is the effect of heat on saliva?
ans: The enzyme in starch has been killed (or denatured) by heating.
d)what is the purpose of test tube C?
ans: To act as a control to compare the results with Test tube A and B which contained saliva.
6.
step1:de-starch the plant.
step2:pluck a leaf from the plant and place it in chemical A.
step3:place the leaf in a test tube containing chemical B and place it in a beaker of hot water. step4:remove the leaf from the test tube and wash with chemical A.
step5:place the leaf on a tile and add a few drops of chemical C.
A)how would you de-starch a plant?
ans: Keep the plant in the dark for 48 hours.
B)identify chemicals A,B,C and state their function in the process of testing a leaf for starch.
ans:
A- Boiling water: To kill the leaf
B- Alcohol: Remove the cholorophyll
C- Iodine - Test for starch
7. How does a plant adapt itself to carry out photosynthesis?
ans: The plant grow towards light and has many leaves to increase the surface area to capture more sunlight.
8. Can magnetic force pass through an iron block and attract a steel car?
ans: No. Magnetic force cannot pass through a magnetic object.
9. Is Yeast a Fungi or Micro-organism.
ans: Yeast is both a fungi and a micro-organism.
10. What is the direction of rotation of the Earth around the Sun.
ans: West to East direction
11. Which ball (of different material but same size) will drop to the ground fastest when each drops from 5m height at the same time? A rubber ball, a wooden ball or an iron ball? Or will they reach the ground at the same time?
ans: They will reach the ground at the same time.
12. Which is heavier? A kilogram of Iron or a kilogram of feather?
ans: Both of them are one kilogram, so both are equally heavy.
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