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Primary 3 Science Semestral Assessment 1 (Mid-Year) Paper 4
Free P3 Science SA1 Paper 4, Exam version, with questions, answers, and syllabus-aligned practice for Singapore students.
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Primary 3 Science SA1 Examination 2026
TuitionGoWhere Practice Paper - Version 4 ANSWER KEY
Duration: 75 minutes
Total Marks: 100
Section A: Multiple Choice Questions (25 marks)
| Question | Answer | Topic |
|---|---|---|
| 1 | B | Diversity of Living and Non-living Things |
| 2 | B | Life Cycles |
| 3 | C | Diversity of Materials |
| 4 | B | Plant Systems |
| 5 | C | Diversity of Materials |
| 6 | C | Diversity of Living and Non-living Things |
| 7 | C | Life Cycles |
| 8 | D | Plant Systems |
| 9 | B | Diversity of Materials |
| 10 | B | Life Cycles |
| 11 | B | Diversity of Living and Non-living Things |
| 12 | A | Life Cycles |
| 13 | B | Plant Systems |
| 14 | B | Diversity of Materials |
| 15 | C | Life Cycles |
| 16 | B | Plant Systems |
| 17 | C | Diversity of Materials |
| 18 | B | Life Cycles |
| 19 | B | Plant Systems |
| 20 | B | Diversity of Materials |
| 21 | D | Life Cycles |
| 22 | B | Plant Systems |
| 23 | B | Diversity of Materials |
| 24 | B | Life Cycles |
| 25 | B | Plant Systems |
Section B: Short Answer Questions (45 marks)
26. (4 marks)
(a) Which can make own food and how (2 marks):
- Rose plant can make its own food. (1 mark)
- It uses sunlight, water and air (carbon dioxide) to make food in its leaves through photosynthesis. (1 mark)
(b) One difference between mushroom and rose plant (1 mark):
- Rose plant can make its own food, but mushroom cannot. / Rose plant has leaves and roots, but mushroom does not. / Rose plant is green, but mushroom is not.
(c) What all four living things have in common (1 mark):
- They all need water/air/food to survive. / They can all grow and reproduce. / They are all living things.
27. (6 marks)
(a) Two materials that float (1 mark):
- Wood and Cork
(b) Material not to use and why (2 marks):
- Iron should not be used. (1 mark)
- Iron conducts heat, so the handle would become very hot and burn the chef's hand. (1 mark)
(c) Best material for submarine window and reason (2 marks):
- Glass would be best. (1 mark)
- Glass is transparent so people can see through it, and it does not conduct heat (helps with insulation). (1 mark)
(d) Why cork floats and iron sinks (1 mark):
- Cork is less dense than water so it floats, while iron is denser than water so it sinks. / Cork is lighter than water for the same volume.
28. (6 marks)
(a) What insect is this (1 mark):
- Butterfly (or Moth)
(b) Names of each stage (2 marks):
- Stage 1: Egg (0.5 mark)
- Stage 2: Larva / Caterpillar (0.5 mark)
- Stage 3: Pupa / Chrysalis (0.5 mark)
- Stage 4: Adult butterfly (0.5 mark)
(c) Stage where body structure changes completely (1 mark):
- Stage 3 / Pupa stage
(d) Why insect eats a lot during Stage 2 (2 marks):
- The larva needs to store energy for the pupa stage when it cannot eat. (1 mark)
- It needs nutrients to grow and develop into an adult butterfly. (1 mark)
29. (6 marks)
(a) Names of labelled parts (2 marks):
- A: Flower (0.5 mark)
- B: Leaves (0.5 mark)
- C: Stem (0.5 mark)
- D: Roots (0.5 mark)
(b) Part not found on a fern and why (2 marks):
- Part A / Flower (1 mark)
- Ferns do not produce flowers; they reproduce using spores instead of seeds. (1 mark)
(c) Part to plant in soil and why (2 marks):
- Seeds (from Part A / Flower / Fruit) should be planted. (1 mark)
- Seeds contain the embryo that will grow into a new plant when given water and warmth. (1 mark)
- Accept: Roots/stem cuttings for vegetative propagation
30. (5 marks)
(a) Two animals that undergo complete metamorphosis (1 mark):
- Mosquito and Frog
(b) Why mosquito larvae found in water (2 marks):
- Mosquito eggs are laid in water and larvae live in water. (1 mark)
- Mosquito larvae breathe through special tubes and need water to survive until they become adults. (1 mark)
(c) Difference between dragonfly and mosquito life cycles (2 marks):
- Dragonfly undergoes incomplete metamorphosis (3 stages: egg → nymph → adult). (1 mark)
- Mosquito undergoes complete metamorphosis (4 stages: egg → larva → pupa → adult). (1 mark)
31. (5 marks)
(a) Electrical conductors (1 mark):
- Copper wire, Iron nail, Aluminium foil
(b) Why bulb didn't light up with wooden stick (1 mark):
- Wood is an electrical insulator/non-conductor, so electricity cannot flow through it.
(c) Would rubber be an electrical conductor (2 marks):
- No, rubber would not be an electrical conductor. (1 mark)
- Rubber is similar to plastic and wood, which are non-conductors. / Rubber is used to insulate electrical wires, which shows it does not conduct electricity. (1 mark)
(d) Example of conductor and non-conductor used together (1 mark):
- Electrical wires have a metal (conductor) core covered by rubber or plastic (non-conductor) coating. / Power plug has metal pins (conductor) and plastic body (non-conductor).
32. (6 marks)
(a) Tallest and shortest plants (2 marks):
- Tallest: Black pot (1 mark)
- Shortest: Clear (transparent) pot (1 mark)
(b) Why plant in clear pot was shortest (2 marks):
- Light could reach the roots through the clear pot. (1 mark)
- Roots normally grow in darkness, and light may have damaged them or caused algae growth in the soil. (1 mark)
(c) What was kept the same and why important (2 marks):
- Water, sunlight, and soil were kept the same. (1 mark)
- This is important to ensure a fair test so we know any differences are caused by the pot colour only. (1 mark)
33. (7 marks)
(a) Identification of organisms (3 marks):
- Organism A: Flowering plant (e.g., rose, hibiscus, any flowering plant) (1 mark)
- Organism B: Butterfly / Beetle / Any insect with complete metamorphosis (1 mark)
- Organism C: Mushroom / Fungus (1 mark)
(b) How Organism A gets food (1 mark):
- It makes its own food using sunlight, water, and air (carbon dioxide) in its leaves.
(c) How Organism C gets food (1 mark):
- It absorbs nutrients from dead or decaying matter / It breaks down dead wood to get food.
(d) Similarity and difference between A and C (2 marks):
- Similarity: Both cannot move from place to place / Both are living things / Both can reproduce. (1 mark)
- Difference: Organism A can make its own food (has leaves), but Organism C cannot / A is green but C is not / A has roots but C does not. (1 mark)
Section C: Word Problems (30 marks)
34. (8 marks)
(a) Four stages in order (2 marks):
- Egg → Caterpillar (Larva) → Pupa (Chrysalis) → Adult butterfly (0.5 mark each)
(b) Why caterpillars ate so much (2 marks):
- They needed to store energy for the pupa stage when they cannot eat. (1 mark)
- They needed nutrients to grow larger and develop into adult butterflies. (1 mark)
(c) Why caterpillars shed skin several times (1 mark):
- Their skin cannot stretch, so they shed it to allow their body to grow larger. / This is called moulting.
(d) Type of metamorphosis and reason (2 marks):
- Complete metamorphosis (1 mark)
- Because it has 4 stages with a pupa stage where the caterpillar completely transforms. / The young (caterpillar) looks completely different from the adult (butterfly). (1 mark)
(e) Why butterflies lay eggs on citrus plants (1 mark):
- So that when caterpillars hatch, they have food (citrus leaves) to eat immediately.
35. (8 marks)
(a) Strongest and weakest materials (2 marks):
- Strongest: Metal wire (1 mark)
- Weakest: Paper straws (1 mark)
(b) Two reasons metal wire may not be best choice (2 marks):
- Reason 1: Metal wire is harder to cut and shape for students. (1 mark)
- Reason 2: Metal wire is more expensive than other materials. / Metal wire might be too heavy. (1 mark)
(c) Two other properties engineers consider (2 marks):
- Property 1: Cost / Price (1 mark)
- Property 2: Weight / Durability / Resistance to rusting / Flexibility / Weather resistance (1 mark)
(d) Material to replace wooden benches and reason (2 marks):
- Metal / Concrete / Stone / Plastic (1 mark)
- Metal/concrete/stone does not rot when wet and is more durable. / Plastic is waterproof and does not absorb water like wood. (1 mark)
36. (8 marks)
(a) Control plant and why (2 marks):
- Plant A was the control. (1 mark)
- It had all the normal conditions (water, sunlight, air) that plants need to grow, so it can be compared with the other plants. (1 mark)
(b) Why Plant B grew taller despite being in the dark (2 marks):
- Plant B grew taller trying to reach light (etiolation). (1 mark)
- The plant stretched upward searching for sunlight, but it was weak and yellow because it couldn't make food properly. (1 mark)
(c) What Plant D's result tells us (2 marks):
- Plant D had its roots wrapped, blocking air from the roots. (1 mark)
- This shows that plant roots need air to absorb water and stay healthy. / Plants need air/oxygen at their roots. (1 mark)
(d) Is the statement correct and explanation (2 marks):
- No, the statement is not correct. (1 mark)
- Plant D shows that plants also need air at their roots to survive and grow healthily. (1 mark)
37. (6 marks)
(a) Two differences between bird wings and butterfly wings (2 marks):
- Difference 1: Bird wings are covered with feathers, but butterfly wings are thin and covered with tiny scales. (1 mark)
- Difference 2: Birds have 2 wings, but butterflies usually have 4 wings. / Bird wings are larger and stronger. (1 mark)
(b) Similarity and difference between chicken and butterfly life cycles (2 marks):
- Similarity: Both lay eggs / Both start life as eggs. (1 mark)
- Difference: Chicken has 3 stages with no pupa, while butterfly has 4 stages with a pupa stage. / Chick looks like the adult, but caterpillar looks different from butterfly. (1 mark)
(c) Why chick development is different from caterpillar (2 marks):
- The chick grows gradually larger while keeping the same body form (no metamorphosis). (1 mark)
- The caterpillar completely changes its body structure during the pupa stage to become a butterfly (complete metamorphosis). (1 mark)
Marking Summary
| Section | Maximum Marks |
|---|---|
| Section A: MCQ | 25 |
| Section B: Short Answer | 45 |
| Section C: Word Problems | 30 |
| Total | 100 |
End of Answer Key