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Primary 3 Science Systems Quiz

Free P3 Science Systems quiz, Ox Exam version, with questions, answers, and syllabus-aligned practice for Singapore students.

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Primary 3 Science From Real Exams Generated by Ox Alpha Updated 2026-08-27

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Questions

Primary 3 Science Quiz - Systems

Name: ______________________ Class: ________ Date: ______________ Score: ________ / 40

Duration: 45 minutes | Total Marks: 40

Instructions:

Answer ALL 20 questions.
For multiple-choice questions, write the letter of the correct answer in the bracket provided.
Marks for each question are shown in brackets [ ].
Write your answers neatly in the spaces given.
Check your work before handing in.

Section A (Questions 1–5): Choose the correct answer. Each question carries 1 mark. [5 marks]

Question 1.

Which part of a plant takes in water and mineral salts from the soil?

(a) Leaf (b) Root (c) Flower (d) Fruit

Answer: ( ______ ) [1 mark]

Question 2.

Mei Ling smelled a sweet fragrance as she walked past a pot of flowers. Which sense organ did she use?

(a) Eye (b) Ear (c) Nose (d) Tongue

Answer: ( ______ ) [1 mark]

Question 3.

Which organ in the human body pumps blood to all parts of the body?

(a) Brain (b) Heart (c) Stomach (d) Lungs

Answer: ( ______ ) [1 mark]

Question 4.

A bulb will light up only when the electric circuit is __________.

(a) open (b) closed (c) broken (d) missing a bulb

Answer: ( ______ ) [1 mark]

Question 5.

Which part of a plant holds it upright and carries water from the roots to the leaves?

(a) Root (b) Stem (c) Flower (d) Seed

Answer: ( ______ ) [1 mark]

Section B (Questions 6–10): Write your answers in the spaces given. Each question carries 2 marks. [10 marks]

Question 6.

Match each plant part to its job. Write the correct letter in each blank. [2 marks]

Plant part	Job
Roots	A. Makes food for the plant
Stem	B. Becomes a fruit
Leaves	C. Takes in water from the soil
Flower	D. Carries water to the leaves

Roots: ______ Stem: ______ Leaves: ______ Flower: ______

Question 7.

Write True or False for each statement. [2 marks]

(a) The lungs take in air when we breathe. ________

(b) The stomach pumps blood around the body. ________

Question 8.

Study the electric circuit below.

Image pending generation: diagram for Q8.

Will the bulb light up? Give a reason for your answer. [2 marks]

Answer: ________________________________________________

Question 9.

Ahmad accidentally touched a hot pan and pulled his hand away very quickly.

(a) Which sense organ detected the heat? [1 mark]

Answer: ________________________________________________

(b) Which body part carried out the action of pulling away? [1 mark]

Answer: ________________________________________________

Question 10.

Fill in each blank with the correct word. [2 marks]

Water is taken in by the (a)______________ and travels up the (b)______________ to reach the leaves.

Section C (Questions 11–15): Write your answers in the spaces given. Each question carries 2 marks. [10 marks]

Question 11.

Study the flowering plant below.

Image pending generation: diagram for Q11.

Write the name of each part marked A to D. [2 marks]

A: ______________ B: ______________ C: ______________ D: ______________

Question 12.

Give two reasons why a plant needs its roots. [2 marks]

Reason 1: ________________________________________________

Reason 2: ________________________________________________

Question 13.

Study the two circuits below. Both bulbs are of the same type and both circuits are closed.

Image pending generation: diagram for Q13.

Which bulb will be brighter? Explain your answer. [2 marks]

Answer: ________________________________________________

Question 14.

Match each sense organ to what it detects. Write the correct letter in each blank. [2 marks]

Sense organ	Detects
Eye	A. Sound
Ear	B. Smell
Nose	C. Light (things we see)
Skin	D. Taste

Eye: ______ Ear: ______ Nose: ______ Skin: ______

Question 15.

Siti tied her tomato plant to a wooden stick because the plant kept bending over.

Which part of the plant was Siti helping, and what is the job of this part? [2 marks]

Answer: ________________________________________________

Section D (Questions 16–20): Explain your answers clearly. Each question carries 3 marks. [15 marks]

Question 16.

Ravi put a small plant with its roots into a jar of red-coloured water. After a few hours, he saw that the leaves had turned slightly red.

(a) What does this experiment show about the function of the stem? [2 marks]

Answer: ________________________________________________

(b) Name the plant part that took in the coloured water. [1 mark]

Answer: ________________________________________________

Question 17.

Study the circuit below.

Image pending generation: diagram for Q17.

What will happen to the bulb when the switch is closed? Explain your answer. [3 marks]

Answer: ________________________________________________

Question 18.

During a race, Wei Ming noticed that his heart beat faster and he breathed faster than usual.

Explain why his heart and lungs worked harder during the race. [3 marks]

Answer: ________________________________________________

Question 19.

A wire in Kai Xun's torch circuit broke. He found four materials at home: an iron nail, a plastic ruler, a copper wire and a rubber band.

Which material can he use to fix the circuit so that the bulb lights up again? Explain why the other materials cannot be used. [3 marks]

Answer: ________________________________________________

Question 20.

The parts of a plant work together as a system to keep the plant alive.

Explain how the roots, the stem and the leaves work together. [3 marks]

Answer: ________________________________________________

END OF QUIZ

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Answers

Primary 3 Science Quiz - Systems: Answer Key

Total Marks: 40

Answer 1.

(b) Root [1 mark]

Teaching note: Roots grow underground and take in water and mineral salts from the soil. Leaves make food, flowers become fruits, and fruits hold seeds. Common mistake: choosing "leaf" — leaves take in air, not water from the soil.

Answer 2.

(c) Nose [1 mark]

Teaching note: The five sense organs are: eyes (sight), ears (hearing), nose (smell), tongue (taste) and skin (touch). A smell is always detected by the nose.

Answer 3.

(b) Heart [1 mark]

Teaching note: The heart works like a pump. It pushes blood to all parts of the body. The brain controls the body, the stomach digests food, and the lungs help us breathe.

Answer 4.

(b) Closed [1 mark]

Teaching note: Electricity can only flow around a complete, unbroken loop. When the circuit is closed, the bulb lights up. An open or broken circuit has a gap, so electricity cannot flow.

Answer 5.

(b) Stem [1 mark]

Teaching note: The stem holds the plant upright and carries water from the roots up to the leaves. Roots take in water; seeds grow into new plants.

Answer 6.

Roots: C, Stem: D, Leaves: A, Flower: B [2 marks]

Marking: ½ mark for each correct match; all four correct needed for full marks.

Teaching note: Learn each part's job — roots take in water (C), the stem carries the water upwards (D), leaves make food (A), and the flower develops into a fruit (B). Common mistake: swapping A and D — making food happens in the leaves, not the stem.

Answer 7.

(a) True [1 mark]

(b) False [1 mark]

Teaching note: The lungs take in air when we breathe, so (a) is true. The heart, not the stomach, pumps blood. The stomach's job is to churn and break down food.

Answer 8.

No, the bulb will not light up. [2 marks]

Marking: Correct decision (no) — 1 mark; correct reason — 1 mark.

Reason: There is a gap in the wire, so the circuit is not complete. Electricity cannot flow all the way around the loop to the bulb.

Expected visual (Q8-fig1): a loop with one battery, one bulb, and a clear break in the top wire. Students must spot the gap.

Common mistake: saying "the battery is flat" — the picture shows a working battery; the real problem is the broken loop.

Answer 9.

(a) Skin [1 mark]

(b) His hand (the muscles in his hand/arm pulled it away) [1 mark]

Teaching note: The skin is the sense organ that detects heat, touch and pain. After the skin detects the heat, the body responds by moving the hand away quickly. Detecting is done by the sense organ; responding is done by the moving body part.

Answer 10.

(a) roots [1 mark]

(b) stem [1 mark]

Teaching note: This describes the water path in a plant: soil → roots (take in water) → stem (carries water up) → leaves (use


<stage3_quiz_answers_md>
# Primary 3 Science Quiz - Systems: Answer Key

**Total Marks: 40**

## Answer 1.
**(b) Root** [1 mark]

Teaching note: Roots grow underground and take in water and mineral salts from the soil. Leaves make food; flowers become fruits.

## Answer 2.
**(c) Nose** [1 mark]

Teaching note: The five sense organs are eyes (sight), ears (hearing), nose (smell), tongue (taste) and skin (touch).

## Answer 3.
**(b) Heart** [1 mark]

Teaching note: The heart works like a pump, pushing blood to all parts of the body.

## Answer 4.
**(b) Closed** [1 mark]

Teaching note: Electricity flows only around a complete, unbroken loop. An open or broken circuit has a gap.

## Answer 5.
**(b) Stem** [1 mark]

Teaching note: The stem holds the plant upright and carries water from the roots up to the leaves.

## Answer 6.
**Roots: C, Stem: D, Leaves: A, Flower: B** [2 marks]

Marking: ½ mark per correct match.

Teaching note: Roots take in water (C); the stem carries water upwards (D); leaves make food (A); the flower develops into a fruit (B).

## Answer 7.
**(a) True** [1 mark]

**(b) False** [1 mark]

Teaching note: The lungs take in air when we breathe. The **heart**, not the stomach, pumps blood; the stomach digests food.

## Answer 8.
**No, the bulb will not light up.** [2 marks]

Marking: Correct decision (no) — 1 mark; correct reason — 1 mark.

Reason: There is a gap in the wire, so the circuit is not complete. Electricity cannot flow around the loop to the bulb.

Common mistake: saying "the battery is flat" — the problem is the broken loop, not the battery.

## Answer 9.
**(a) Skin** [1 mark]

**(b) His hand (the muscles pulled it away)** [1 mark]

Teaching note: The skin detects heat, touch and pain. Detecting is done by the sense organ; responding is done by the moving body part.

## Answer 10.
**(a) roots** [1 mark]

**(b) stem** [1 mark]

Teaching note: Water path: soil → roots (take in water) → stem (carries water up) → leaves (use the water to make food).

## Answer 11.
**A: Roots, B: Stem, C: Leaf, D: Flower** [2 marks]

Marking: ½ mark per correct part name.

## Answer 12.
Reason 1: Roots take in water and mineral salts from the soil. [1 mark]

Reason 2: Roots hold the plant firmly in the ground and keep it upright. [1 mark]

## Answer 13.
**The bulb in Circuit B will be brighter.** [2 marks]

Marking: Correct choice — 1 mark; explanation — 1 mark.

Explanation: Circuit B has two batteries, which give more electricity (more energy) than one battery, so its bulb glows more brightly.

## Answer 14.
**Eye: C, Ear: A, Nose: B** [2 marks]

Note: The skin detects touch and heat, which does not match any listed option. If the fourth organ were the tongue, it would be D (Taste).

## Answer 15.
Siti was helping the **stem**. [2 marks]

Job of the stem: to hold the plant upright and support it (it also carries water from the roots to the leaves).

## Answer 16.
(a) The stem carries water (with dissolved mineral salts) from the roots up to the leaves and other parts of the plant. [2 marks]

(b) **Roots** [1 mark]

Teaching note: The red colour showed the path of the water moving upward through the stem.

## Answer 17.
The bulb will light up. [3 marks]

Explanation: Closing the switch completes the circuit. Electricity can then flow from the battery through the wires and the bulb, so the bulb lights up.

## Answer 18.
During the race, Wei Ming's body needed more energy. [3 marks]

His heart beat faster to pump more blood, carrying oxygen and nutrients to his muscles. He breathed faster so his lungs could take in more oxygen for his body.

## Answer 19.
He can use the **copper wire** (the iron nail would also work, since metals conduct electricity). [3 marks]

The plastic ruler and rubber band cannot be used because plastic and rubber are non-conductors (insulators) — electricity cannot flow through them to complete the circuit.

## Answer 20.
The roots take in water and mineral salts from the soil. [3 marks]

The stem carries the water and mineral salts up to the leaves.

The leaves use the water, sunlight and air to make food for the whole plant. Working together as a system, these parts keep the plant alive.

**END OF ANSWER KEY**