Primary 3 Science Human System Quiz

Answer Key: Primary 3 Science Quiz - Human System

Total Marks: 20

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Section A: Multiple Choice (Questions 1 – 10)

1 mark each

1. (b) Skin

• Explanation: The skin is a sense organ that detects touch, pressure, heat, cold, and pain. The heart, lungs, and stomach are internal organs, not sense organs.
• Common mistake: Students may think the hand is a sense organ, but the hand is a body part that contains the sense organ skin.

2. (b) Eyes

• Explanation: The eyes are the sense organs for sight. They detect light and allow us to see shapes, colours, and movement.
• Common mistake: Students may confuse the function of eyes and ears.

3. (c) Nose

• Explanation: The nose detects smells in the air. This is the sense of smell.
• Common mistake: Students may think the tongue detects smell, but the tongue detects taste.

4. (c) Skin

• Explanation: The skin can detect temperature, including hot and cold. This is part of the sense of touch.
• Common mistake: Students may think the nose or ears detect temperature.

5. (b) Sweet

• Explanation: The tongue can detect five basic tastes: sweet, sour, salty, bitter, and umami. Loud, bright, and hard are not tastes.
• Common mistake: Students may confuse taste with other senses like hearing (loud) or sight (bright).

6. (c) Hand

• Explanation: The hand is not a sense organ. It is a body part that contains the sense organ skin. The ear, eye, and nose are sense organs.
• Common mistake: Students may think the hand is a sense organ because we use it to touch.

7. (c) Skin

• Explanation: When you touch something, the skin on your hand detects the texture (softness). This is the sense of touch.
• Common mistake: Students may say "hand" instead of "skin". The hand is the body part, but the skin is the sense organ.

8. (d) Tongue

• Explanation: The tongue detects taste. Sour is one of the tastes the tongue can detect.
• Common mistake: Students may think the nose detects sour, but the nose detects smell, not taste.

9. (b) Ears

• Explanation: The ears detect sound waves in the air. Hearing a bird singing means the ears are working.
• Common mistake: Students may think the eyes are used because they see the bird, but the question asks about hearing the sound.

10. (c) Flying

• Explanation: Humans have five senses: sight, hearing, smell, taste, and touch. Flying is not a sense; it is an action.
• Common mistake: Students may think flying is a sense because birds can fly, but the question asks about human senses.

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Section B: Matching and Fill-in-the-Blanks (Questions 11 – 15)

1 mark each

11. Matching:

Sense Organ	Sense
Eyes	Sight
Ears	Hearing
Nose	Smell
Tongue	Taste

• Explanation: Each sense organ is responsible for a specific sense. Eyes detect light (sight), ears detect sound (hearing), nose detects chemicals in the air (smell), and tongue detects chemicals in food (taste).
• Marking: Award 1 mark for all four correct matches. If any are wrong, award 0 marks.

12. ears

• Explanation: The ears are the sense organs for hearing. They detect sound waves.
• Common mistake: Students may write "ear" (singular) which is acceptable, but "ears" is more accurate as we have two.

13. tongue

• Explanation: The tongue contains taste buds that detect different flavours in food and drink.
• Common mistake: Students may write "mouth" but the specific sense organ for taste is the tongue.

14. touch

• Explanation: The skin is the sense organ for touch. It can detect pressure, temperature, pain, and texture.
• Common mistake: Students may write "feel" which is similar but "touch" is the correct scientific term for this sense.

15. eyes

• Explanation: To tell if a flower is red, you need to see its colour. The eyes are the sense organs for sight, which detects colour.
• Common mistake: Students may think the nose can detect colour, but the nose only detects smell.

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Section C: Short Answer Questions (Questions 16 – 20)

1 mark each

16. Any one of the following pairs:

• Eyes – Sight

• Ears – Hearing

• Nose – Smell

• Tongue – Taste

• Skin – Touch

• Explanation: Each sense organ has a specific sense it provides. Students need to name one sense organ and its corresponding sense correctly.

• Marking: Award 1 mark only if both the sense organ and sense are correct. If only one is correct, award 0 marks.

17. Accept any reasonable answer, such as:

• To feel if something is hot or cold (to avoid getting hurt).

• To feel pain (to know when we are injured).

• To feel the texture of objects (to know if something is soft or hard).

• Explanation: The sense of touch helps us interact with and understand our environment. It also protects us from danger.

• Marking: Award 1 mark for a valid reason related to the sense of touch.

18. Eyes

• Explanation: Seeing words on a board requires the sense of sight, which uses the eyes. If the eyes are not working well, a person cannot see clearly.
• Common mistake: Students may say "brain" which is involved in processing, but the question asks for the sense organ.

19. Yes. / Yes, because the tongue can taste sweetness even when the eyes are closed.

• Explanation: Taste is detected by the tongue, not the eyes. Closing your eyes does not affect your ability to taste.
• Marking: Accept "Yes" with any reasonable explanation. Award 0 marks for "No" or for "Yes" without explanation.

20. Sight, Hearing, Smell, Taste, Touch (in any order)

• Explanation: Humans have five main senses. Each sense is linked to a specific sense organ.
• Marking: Award 1 mark for all five senses listed correctly. Award 0 marks if any are missing or incorrect.

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End of Answer Key