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Primary 3 Science Systems Quiz
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Primary 3 Science Quiz - Systems: Answer Key
Total Marks: 50 | Suggested marking: award full marks only when the expected depth is shown; accept scientifically correct wording different from the key.
Answer 1.
Answer: (b) root — 2 marks.
Teaching note: Roots grow down into the soil. They soak up water and hold the plant firmly so it does not fall over. Leaves make food, flowers grow into fruits, and fruits hold seeds — none of these absorb water from the soil.
Common mistake: Choosing "leaf" because leaves also touch water when it rains. The main water-absorbing part is always the root.
Answer 2.
Answer: (c) heart — 2 marks.
Teaching note: The heart is a strong muscle that squeezes again and again to push blood through blood vessels to every part of the body. Blood carries oxygen and nutrients. The lungs help us breathe, the brain controls the body, and the stomach digests food.
Answer 3.
Answer: (d) nose — 2 marks.
Teaching note: The nose detects smells. Each sense organ detects a different thing: ears hear sounds, eyes see light, skin feels touch and temperature. Smelling the durian before seeing it shows the nose at work.
Answer 4.
Answer: (b) leaf — 2 marks.
Teaching note: Leaves are green because they contain a substance that traps sunlight. Using sunlight, air and water, the leaf makes food for the whole plant. (The scientific name of this process is not required at Primary 3.)
Common mistake: Choosing "root" — roots take in water, but they do not make food.
Answer 5.
Answer: (b) mouth → gullet → stomach → intestine — 2 marks.
Teaching note: Food is chewed in the mouth, pushed down the gullet (food pipe), churned and mixed with juices in the stomach, then passes into the intestine where nutrients are taken in. Remember the order by tracing the path down the body.
Answer 6.
Answer: system — 2 marks.
Teaching note: A system is a group of parts that work together to perform a function. Examples: the digestive system breaks down food; a plant's parts work together to keep it alive; a bicycle is a non-living system for moving people.
Answer 7.
Answer:
- (a) stem — 1 mark
- (b) fruit — 1 mark
Teaching note: The stem acts like a straw, carrying water upwards from the roots, and it also holds the plant upright. The fruit develops from the flower and protects the seeds inside until they are ready.
Answer 8.
Answer: Eyes — B; Ears — D; Tongue — A; Skin — C.
Marking: 2 marks for all four correct; 1 mark for two or three correct.
Teaching note: Each sense organ is built to detect one kind of change around us. Matching them correctly shows you know which organ does which job.
Answer 9.
Answer: The leaves would turn pale or yellowish and the plant would look weak (1 mark). This is because leaves need sunlight to make food; without sunlight the plant cannot make enough food and becomes unhealthy (1 mark).
Teaching note: Water alone is not enough. Sunlight is one of the conditions a plant needs to stay green and healthy.
Answer 10.
Answer:
- (a) T — 1 mark
- (b) F — Correction: We breathe in air using our lungs. — 1 mark
Teaching note: The stomach's job is digestion — churning food and mixing it with juices. Breathing is done by the lungs, which take in air rich in oxygen and push out used air.
Answer 11.
Answer: Gills (1 mark). As water flows over the gills, the gills take in the oxygen dissolved in the water (1 mark).
Teaching note: There is air mixed in water too, but it is dissolved. Gills are special organs that remove this dissolved oxygen, just as our lungs remove oxygen from the air.
Answer
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Primary 3 Science Quiz - Systems: Answer Key
Total Marks: 50 | Suggested marking: award full marks only when the expected depth is shown; accept scientifically correct wording different from the key.
Answer 1.
Answer: (b) root — 2 marks.
Teaching note: Roots grow down into the soil. They soak up water and hold the plant firmly so it does not fall over. Leaves make food, flowers grow into fruits, and fruits hold seeds — none of these absorb water from the soil.
Common mistake: Choosing "leaf" because leaves also touch water when it rains. The main water-absorbing part is always the root.
Answer 2.
Answer: (c) heart — 2 marks.
Teaching note: The heart is a strong muscle that squeezes again and again to push blood through blood vessels to every part of the body. Blood carries oxygen and nutrients. The lungs help us breathe, the brain controls the body, and the stomach digests food.
Answer 3.
Answer: (d) nose — 2 marks.
Teaching note: The nose detects smells. Each sense organ detects a different thing: ears hear sounds, eyes see light, skin feels touch and temperature. Smelling the durian before seeing it shows the nose at work.
Answer 4.
Answer: (b) leaf — 2 marks.
Teaching note: Leaves are green because they contain a substance that traps sunlight. Using sunlight, air and water, the leaf makes food for the whole plant.
Common mistake: Choosing "root" — roots take in water, but they do not make food.
Answer 5.
Answer: (b) mouth → gullet → stomach → intestine — 2 marks.
Teaching note: Food is chewed in the mouth, pushed down the gullet (food pipe), churned and mixed with juices in the stomach, then passes into the intestine where nutrients are taken in.
Answer 6.
Answer: system — 2 marks.
Teaching note: A system is a group of parts that work together to perform a function. Examples: the digestive system breaks down food; a plant's parts work together to keep it alive.
Answer 7.
Answer:
- (a) stem — 1 mark
- (b) fruit — 1 mark
Teaching note: The stem acts like a straw, carrying water upwards from the roots, and holds the plant upright. The fruit develops from the flower and holds the seeds inside.
Answer 8.
Answer: Eyes — B; Ears — D; Tongue — A; Skin — C.
Marking: 2 marks for all four correct; 1 mark for two or three correct.
Teaching note: Each sense organ is built to detect one kind of change around us.
Answer 9.
Answer: The leaves would turn pale or yellowish and the plant would look weak (1 mark). This is because leaves need sunlight to make food; without sunlight the plant cannot make enough food and becomes unhealthy (1 mark).
Teaching note: Water alone is not enough. Sunlight is one of the conditions a plant needs to stay green and healthy.
Answer 10.
Answer:
- (a) T — 1 mark
- (b) F — Correction: We breathe in air using our lungs. — 1 mark
Teaching note: The stomach's job is digestion — churning food and mixing it with juices. Breathing is done by the lungs.
Answer 11.
Answer: Gills (1 mark). As water flows over the gills, the gills take in the oxygen dissolved in the water (1 mark).
Teaching note: There is air mixed in water too, but it is dissolved. Gills remove this dissolved oxygen, just as our lungs remove oxygen from the air.
Answer 12.
Answer:
- A: flower — 0.5 mark
- B: leaf — 0.5 mark
- C: stem — 0.5 mark
- D: roots — 0.5 mark
Teaching note: The flower is at the top, the leaf is the flat green part, the stem is the upright middle part, and the roots are below the soil.
Answer 13.
Answer: The thick, fleshy stem stores water (1 mark), so the cactus has water to use during long dry periods when it does not rain (1 mark).
Teaching note: The cactus also has no broad leaves, so it loses much less water than a plant with broad leaves. Accept any answer about storing water or reducing water loss.
Answer 14.
Answer: gullet — 2; mouth — 1; intestine — 4; stomach — 3.
Marking: 2 marks for all four correct; 1 mark for two or three correct.
Teaching note: Trace the path: mouth (1) → gullet (2) → stomach (3) → intestine (4).
Answer 15.
Answer: A fish uses gills to take in oxygen dissolved in water, while a human being uses lungs to take in oxygen from the air (2 marks).
Teaching note: Accept either the different body parts (gills vs lungs) or the different source (water vs air), but both parts give full marks.
Answer 16.
Answer:
- (a) The amount of sunlight (light) the plants received — 1 mark
- (b) Plant P grew healthy with green leaves; Plant Q turned pale or yellowish and grew weakly — 2 marks
- (c) Plants need sunlight to make food and stay healthy — 1 mark
Teaching note: Only one condition was changed (sunlight); water, plant type and pot size were kept the same. The conclusion must link sunlight to the plant's health.
Answer 17.
Answer:
- A: mouth — 1 mark
- B: gullet (food pipe) — 1 mark
- C: stomach — 1 mark
- D: intestine — 1 mark
Teaching note: Follow the food path down the body: mouth at the top, gullet down the chest, stomach in the upper belly, intestine coiled in the lower belly.
Answer 18.
Answer (any four clear steps):
- The roots take in water and mineral salts from the soil. (1 mark)
- The stem carries the water up to the leaves and holds the plant upright. (1 mark)
- The leaves use sunlight, air and the water to make food for the plant. (1 mark)
- The parts work together as a system, so the plant gets water and food and can grow. (1 mark)
Teaching note: Award the final mark only if the answer shows the parts working together, not just listed separately.
Answer 19.
Answer:
- (a) Skin — 1 mark
- (b) Nerves carried the message and the muscles moved her hand away — 1 mark
- (c) Pulling her hand away quickly stopped the heat from hurting her skin further, preventing a serious burn or injury — 2 marks
Teaching note: The skin detects heat, the nerves send the message, and the muscles act. Quick responses protect the body from harm.
Answer 20.
Answer (accept similar points):
Similarities:
- Both are systems made of different parts working together. (1 mark)
- Both need air (oxygen) to stay alive. (1 mark)
Differences:
- A plant makes its own food using sunlight, while a human must eat food. (1 mark)
- A plant has parts like roots, stem and leaves, while a human has organs like the heart, lungs and stomach. (1 mark)
Teaching note: Any two valid similarities and two valid differences earn full marks; each point must compare both systems.
END OF ANSWER KEY