Primary 3 Science · Answers and explanations
Primary 3 Science Revision Paper
Covers all seven Primary 3 Science chapters: living and non-living things, classification, materials, life cycles of plants and animals, properties of magnets and making magnets. Total: 30 marks.
Section A · Multiple choice 10 marks
1. Which of these is a non-living thing?1 mark
(A) A seed(B) A paper boat(C) Bread mould(D) A tadpole
Answer: (B) A paper boatA paper boat does not grow, need food or reproduce. A seed, bread mould and a tadpole are all living things.
2. Which animal group has hair or fur, and the mothers feed their young with milk?1 mark
(A) Mammals(B) Birds(C) Reptiles(D) Fish
Answer: (A) MammalsMammals have hair or fur and mothers feed their young milk. A cat is a mammal.
3. Which of these is a fungus?1 mark
(A) A fern(B) A hibiscus(C) An ant(D) A mushroom
Answer: (D) A mushroomFungi cannot make their own food. Mushrooms, mould and yeast are fungi.
4. Which material is best for making a raincoat?1 mark
(A) Paper(B) Cotton cloth(C) Plastic sheet(D) Sponge
Answer: (C) Plastic sheetA raincoat must be waterproof. Plastic does not let water pass through. Paper, cloth and sponge soak up water.
5. Which of these materials is transparent?1 mark
(A) Wood(B) Glass(C) Cardboard(D) Aluminium foil
Answer: (B) GlassTransparent materials let most light pass through so we can see clearly through them. Glass is transparent.
6. Which is the correct order of the life cycle of a flowering plant?1 mark
(A) seed → young plant → adult plant(B) young plant → seed → adult plant(C) seed → adult plant → young plant(D) adult plant → young plant → seed
Answer: (A) seed → young plant → adult plantA seed grows into a young plant, then an adult plant. The adult plant makes flowers and fruits that contain new seeds.
7. Which animal has a life cycle with four stages: egg, larva, pupa and adult?1 mark
(A) Frog(B) Chicken(C) Grasshopper(D) Butterfly
Answer: (D) ButterflyA butterfly has a pupa stage. A frog, a chicken and a grasshopper each have three stages: egg, young and adult.
8. The south pole of one bar magnet is brought near the north pole of another bar magnet. What will happen?1 mark
(A) They repel(B) They stay still(C) They attract(D) They lose their magnetism
Answer: (C) They attractUnlike poles (north and south) attract each other.
9. Which of these is attracted to a magnet?1 mark
(A) An aluminium can(B) An iron nail(C) A glass bottle(D) A wooden spoon
Answer: (B) An iron nailIron and steel are magnetic materials. Aluminium is a metal but it is not magnetic. Glass and wood are not magnetic either.
10. Mei coils wire around an iron nail and connects it to a battery. How can she make this electromagnet stronger?1 mark
(A) Add more turns of wire(B) Use a shorter wire(C) Use a wooden nail(D) Take away the battery
Answer: (A) Add more turns of wireMore turns of wire, or more batteries, make a stronger electromagnet.
Section B · Fill in the blanks 4 marks
11. Living things take in food, water and to stay alive.1 mark
Answer: airAll living things need food, water and air.
12. An insect has legs and three body parts.1 mark
Answer: 6The three body parts of an insect are the head, thorax and abdomen.
13. A young butterfly that hatches from an egg is called a .1 mark
Answer: caterpillarThe caterpillar (larva) hatches from the egg and eats a lot of leaves to grow.
14. The two ends of a magnet, where the pull is strongest, are called the .1 mark
Answer: polesEvery magnet has a north pole and a south pole at its ends.
Section C · Open-ended questions 16 marks
15. Ravi says, "A toy robot is alive because it moves and makes sounds." Is Ravi correct? Give a reason.2 marks
Answer: No (1 mark). A toy robot does not grow, does not need food, or cannot reproduce (any one, 1 mark).Moving is not enough. A living thing must also grow, need food and water, and reproduce.
16. Sam says, "A mushroom is a plant because it grows from the ground." Is Sam correct? Give a reason.2 marks
Answer: No (1 mark). A mushroom is a fungus. It cannot make its own food, but plants can (1 mark).Plants make their own food using light. Fungi cannot.
17. A sponge and a plastic sheet are used to wipe up spilled water. Which is better? Explain why.2 marks
Answer: The sponge (1 mark). The sponge absorbs water, but the plastic sheet is waterproof (1 mark).Absorbent materials soak up water. Waterproof materials do not.
18. Kai wants to make a bag to carry heavy books. Suggest one material for the bag and give one property that makes it suitable.2 marks
Answer: Property: strong (1 mark). Material: canvas, nylon or leather (1 mark). Accept other suitable pairs, such as a strong material with a matching property.The bag must not tear when it carries heavy books, so the material must be strong.
19. Mei says, "A tadpole looks like an adult frog." Is she correct? Give one difference between a tadpole and an adult frog.2 marks
Answer: No (1 mark). A tadpole has a tail, but an adult frog does not (or a tadpole lives in water, but an adult frog lives on land and in water) (1 mark).The tadpole looks unlike the adult frog. A frog has three stages: egg, tadpole and adult.
20. State one difference between the life cycle of a butterfly and the life cycle of a grasshopper.2 marks
Answer: The butterfly has a pupa stage but the grasshopper does not (1 mark). The young grasshopper (nymph) looks like a small adult, but a caterpillar does not look like an adult butterfly (1 mark). Accept any two correct differences.A butterfly has 4 stages. A grasshopper has 3 stages.
21. Magnet X has its poles marked N and S. Magnet Y has no marks. Mei brings the N pole of Magnet X near one end of Magnet Y. The end of Magnet Y is pushed away. What pole is that end of Magnet Y? Explain.2 marks
Answer: It is a north pole (1 mark). Like poles repel (1 mark).Only like poles repel. N repels N, so the end that was pushed away must be a north pole.
22. Raj wants to find out if more turns of wire make a stronger electromagnet. What should he change, and what should he keep the same? Give one thing he should keep the same.2 marks
Answer: Change: the number of turns of wire (1 mark). Keep the same: the nail, or the number of batteries, or the type of clips (any one, 1 mark).This is a fair test. Only one variable is changed.
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