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Primary 3 Science Semestral Assessment 2 (End of Year) Paper 2

Free P3 Science SA2 Paper 2, Exam version, with questions, answers, and syllabus-aligned practice for Singapore students.

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Primary 3 Science From Real Exams Generated by Claude Sonnet 4 Updated 2026-08-17

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Primary 3 Science SA2 Examination 2026 (Version 2) - Answer Key

TuitionGoWhere Assessment Paper

Duration: 75 minutes
Total Marks: 100


Section A: Multiple Choice Questions (25 marks)

1 mark each

QAnswerExplanation
1(C)Living things are not always soft (e.g., shells, bones). All living things need air, can reproduce, and can grow.
2(B)Goldfish and Fern are living things (made of living cells). Pencil and plastic bottle are non-living.
3(B)A coconut (seed) is living because it can grow into a new plant - a characteristic of living things.
4(B)Glass is transparent, allowing light to pass through, making it suitable for spectacle lenses.
5(C)Cork and plastic bottle cap both float, making them suitable for a floating toy boat.
6(C)Mosquito egg, larva (wriggler), and pupa (tumbler) all live in water. Only the adult flies.
7(C)Cockroach nymphs look like smaller versions of adults (incomplete metamorphosis).
8(B)Frog: tadpole has tail in water → grows legs → tail disappears → adult lives on land.
9(D)Roots hold the plant firmly in the ground (anchoring function).
10(B)Plants release oxygen during photosynthesis.
11(A)Leaves are green because they contain chlorophyll, a green pigment needed for photosynthesis.
12(B)Plants need water, sunlight, and carbon dioxide to make food through photosynthesis.
13(C)Stems transport water and minerals from roots to other parts of the plant.
14(D)Skin can detect pressure, temperature, pain, and texture (touch sense).
15(C)The nose detects smells, including the strong smell of durian.
16(C)Playing computer games for 6 hours straight is unhealthy - too much screen time and no physical activity.
17(C)Muscles work with the skeletal system (bones) to allow movement.
18(B)The doctor uses ears to listen through the stethoscope.
19(C)Copper wire is NOT magnetic - only iron, steel, nickel, and cobalt are magnetic.
20(B)A magnet's strength is greatest at its poles (North and South ends).
21(A)S pole of P faces N pole of Q - opposite poles attract each other.
22(B)When a magnet breaks, each piece becomes a complete magnet with both N and S poles.
23(C)Magnetic pencil cases use magnets to keep the lid closed.
24(C)Stroking a steel object with a magnet in one direction repeatedly magnetizes it.
25(C)Steel can be magnetized because it contains iron. Copper, aluminium, and rubber cannot.

Section B: Short Answer Questions (45 marks)

26. (4 marks)

(a) Living things in the table: Coral and Venus flytrap (2m)

  • They both need water and can reproduce, which are characteristics of living things
  • (Award 1m for each correct organism identified)

(b) A robot is NOT a living thing because: (2m)

  • It does not need air, food, or water to survive
  • It cannot reproduce/make baby robots on its own
  • It cannot grow
  • It is not made of living cells (Accept any 2 valid reasons)

27. (4 marks)

(a) Rubber is good for making tyres because: (2m)

  • It is flexible - can change shape and return to original form (1m)
  • It has good grip - prevents slipping (1m)
  • It is waterproof - works in rain
  • It is durable/strong

(b) Metal is used for cooking pots instead of plastic because: (2m)

  • Metal can withstand high temperatures without melting (1m)
  • Plastic would melt when heated on a stove (1m)
  • Metal conducts heat well for cooking

28. (5 marks)

(a) Mosquito goes through complete metamorphosis: (2m)

  • It has 4 distinct stages: egg, larva, pupa, and adult (1m)
  • There is a pupa stage where complete transformation occurs (1m)

(b) The nymph stage of a cockroach is different from the larva stage of a mosquito because: (2m)

  • The cockroach nymph looks like a smaller version of the adult (1m)
  • The mosquito larva (wriggler) looks completely different from the adult (1m)
  • Cockroach nymph lives on land, mosquito larva lives in water

(c) Mosquito eggs need to be laid in or near water because: (1m)

  • The larva and pupa stages live in water
  • The larvae need water to survive and develop

29. (4 marks)

(a) Correct order: (2m) Seed → GerminationSeedlingAdult plant with flowers → Seed (in fruit) (0.5m for each correct placement)

(b) It is important for plants to produce seeds because: (2m)

  • Seeds allow plants to reproduce (1m)
  • Seeds can grow into new plants, continuing the species (1m)
  • Seeds can be dispersed to new places for plant survival

30. (5 marks)

(a) Name of the process: Photosynthesis (1m)

(b) The plant gets carbon dioxide from: The air (1m)

(c) The oxygen produced: (1m)

  • Is released into the air
  • Animals and humans use it for breathing

(d) Plants need to carry out this process because: (2m)

  • To make food (glucose) for energy and growth (1m)
  • Without photosynthesis, plants cannot make their own food and will die (1m)

31. (4 marks)

(a) Conclusion from the experiment: (2m)

  • Plants need fresh water (not salt water) to stay healthy (1m)
  • Salt water is harmful to plants (1m)

(b) Plant B had wilted leaves because: (2m)

  • Salt water prevents the plant from absorbing water properly (1m)
  • The salt draws water OUT of the plant cells, causing them to lose water and wilt (1m)
  • The plant could not get the water it needed to survive

32. (5 marks - 1m for each correct row)

ActionSense OrganHow it helps
Looking at vegetablesEyesSee if vegetables look fresh (not wilted or brown)
Smelling soupNoseDetect if the soup smells good/ready
Tasting foodTongueCheck if food has enough salt/seasoning
Feeling breadSkinFeel the texture (soft or hard)
Listening to waterEarsHear the sound of boiling (bubbling sound)

33. (4 marks)

(a) Regular exercise is important for children because: (2m)

  • It keeps the body healthy and strong (1m)
  • It helps maintain a healthy weight (1m)
  • It strengthens bones and muscles
  • It improves mood and energy (Any 2 for 2m)

(b) Two other healthy habits children should have: (2m)

  • Eating a balanced diet with fruits and vegetables (1m)
  • Getting enough sleep (8-10 hours) (1m)
  • Drinking enough water
  • Maintaining good personal hygiene (Any 2 for 2m)

34. (5 marks)

(a) The iron filings formed this pattern because: (2m)

  • They were attracted to the magnet's magnetic field (1m)
  • The iron filings aligned along the magnetic field lines (1m)

(b) The iron filings are most concentrated: (2m)

  • At the poles (North and South ends) of the magnet (1m)
  • Because the magnetic force is strongest at the poles (1m)

(c) Plastic filings would NOT form the same pattern because: (1m)

  • Plastic is not a magnetic material and would not be attracted to the magnet

35. (5 marks)

(a) Completed table: (2m)

ObjectMaterialPrediction: Magnetic?
Paper clipSteelYes
EraserRubberNo
NailIronYes
RingGoldNo
PinSteelYes

(Award 0.5m for every 2 correct predictions)

(b) Some metals are not attracted to magnets because: (2m)

  • Only certain metals are magnetic: iron, steel, nickel, and cobalt (1m)
  • Other metals like gold, copper, aluminium, and brass are not magnetic (1m)

(c) How Kamal can clean up spilled pins and paper clips: (1m)

  • Move the magnet over the floor to attract and pick up all the pins and paper clips at once

Section C: Word Problems (30 marks)

36. (8 marks)

(a) Metal or Plastic would be best for making a slide: (4m)

For Metal:

  • It is very strong - can support many children (1m)
  • It is smooth - children can slide down easily (1m)
  • It is waterproof - will not be damaged by rain (1m)
  • (1m for clearly stating the choice)

For Plastic:

  • It is waterproof - will not be damaged by rain (1m)
  • It is smooth - children can slide down easily (1m)
  • It is medium cost - more affordable than metal (1m)
  • (1m for clearly stating the choice)

(b) For strong, waterproof benches with limited budget: (2m)

  • Use concrete for the base/structure (strong and low cost) (1m)
  • The rough surface is acceptable for bench seats, or add wooden/plastic seat tops (1m)
  • Alternative: Use wood treated with waterproof coating

(c) Wood would NOT be best for an outdoor slide because: (2m)

  • It is NOT waterproof - will rot when exposed to rain (1m)
  • It may get splinters which can hurt children (1m)
  • It is only medium strength

37. (8 marks)

(a) Animals that go through complete metamorphosis: Animal A (Frog) and Animal B (Butterfly) (3m)

  • Animal B has 4 distinct stages: egg, caterpillar (larva), chrysalis (pupa), butterfly (adult) (1m)
  • There is a pupa/chrysalis stage where the animal transforms completely (1m)
  • The young (caterpillar/tadpole) looks completely different from the adult (1m)

Note: Frog metamorphosis is sometimes considered a special case but still "complete" as tadpole looks very different from adult.

(b) Animal C (Dragonfly) goes through incomplete metamorphosis: (2m)

  • The nymph looks like a small version of the adult (1m)
  • There is no pupa stage (1m)

(c) Two changes as tadpole becomes adult frog: (3m)

  • Tail disappears (1m)
  • Grows four legs (1m)
  • Develops lungs to breathe air instead of gills (1m)
  • Skin changes to allow life on land

38. (7 marks)

(a) Comparing Plot A and Plot B - effect of fertilizer: (2m)

  • Plot A (with fertilizer) grew taller (35 cm) than Plot B (without fertilizer, 25 cm) (1m)
  • Conclusion: Fertilizer helps plants grow taller/better (1m)

(b) Plot C grew less even with fertilizer because: (2m)

  • Plot C was only watered every 3 days (not enough water) (1m)
  • Plants need regular water to absorb the nutrients from fertilizer and to carry out photosynthesis (1m)

(c) Prediction for Plot D (no sunlight, with water and fertilizer): (3m)

  • The plant would NOT grow well / would be weak and yellow (1m)
  • This is because plants need sunlight for photosynthesis to make food (1m)
  • Without sunlight, the plant cannot make food even if it has water and fertilizer (1m)

39. (7 marks)

(a) As thickness increases, the number of paper clips picked up: (2m)

  • Decreases (1m)
  • The thicker the material, the fewer paper clips can be picked up (1m)

(b) The steel sheet result (0 paper clips) is explained by: (2m)

  • Steel is a magnetic material that absorbs/redirects the magnetic force (1m)
  • The steel sheet blocked the magnetic field from reaching the paper clips (1m)
  • The magnetic force was attracted to the steel sheet instead of passing through

(c) Two conclusions about magnetic force: (3m)

  • Magnetic force can pass through non-magnetic materials like paper, cardboard, plastic, and wood (1m)
  • Magnetic force gets weaker as the distance (thickness) increases (1m)
  • Magnetic force cannot pass through magnetic materials like steel (1m)

Mark Summary

SectionMaximum Marks
Section A: MCQ25
Section B: Short Answer45
Section C: Word Problems30
Total100

Answer Key for TuitionGoWhere P3 Science SA2 2026 Version 2