Primary 6 PSLE Science Semestral Assessment 2 (End of Year) Paper 4

TuitionGoWhere Practice Paper — Science Primary 6 PSLE

SA2 Version 4 of 5 — Answer Key

Section A: Multiple Choice Questions (10 marks)

1. B — Whether they have feathers, scales, or fur

Classification is based on observable physical characteristics. Body covering (feathers, scales, fur) is a standard taxonomic feature used to group animals.

2. C — Earthworm

The key shows that X has no feathers and no fins. An earthworm fits this description (no feathers, no fins). A frog has no feathers or fins but is an amphibian; however, among the options, earthworm is the best fit as it is a simple invertebrate without fins or feathers.

3. C — Number of legs

Number of legs is a characteristic used to classify animals, not plants. Plants are classified by features such as presence of flowers, root type, leaf venation, and seed type.

4. B — Mushrooms do not make their own food.

Moss and ferns are plants that make their own food by photosynthesis. Mushrooms are fungi and do not photosynthesise — they obtain food from decaying matter. This is the fundamental difference.

5. C — Copper

Copper is a metal and a good conductor of heat. Plastic, wood, and rubber are insulators (poor conductors of heat).

6. B — Rubber band, glass rod, wooden stick

All three are non-metals and poor conductors of electricity. The other options contain metals (iron, aluminium, copper, silver, gold, carbon in the form of graphite) which are good conductors.

7. B — Pure substances

Matter is classified into pure substances and mixtures. Pure substances can be further divided into elements and compounds. Solids and liquids are states of matter, not a classification alongside mixtures.

8. C — They respond to changes in their surroundings.

All living things respond to stimuli. Not all living things can fly (A), have backbones (B), or live on land (D).

9. A — Iron filings are magnetic but sand is not.

A magnet attracts magnetic materials such as iron. Sand (silicon dioxide) is non-magnetic and will not be attracted.

10. C — They do not need food for energy.

Living things need food for energy, growth, and repair. Non-living things do not require food. Options A, B, and D are characteristics of living things.

Section B: Short-Answer Questions (20 marks)

11. (3 marks)

(a) Has legs (1 mark)

P and Q both have legs (Yes), while R and S do not have legs (No).

(b) Organism R (2 marks: 1 for identifying R, 1 for explanation)

R has a backbone, no legs, and lives in water. These characteristics match those of a fish. Fish have backbones (vertebrates), use fins instead of legs for movement, and live in water.

12. (3 marks)

(a) (2 marks)

Steel (a metal) is a good conductor of heat. Glass is a poor conductor (insulator) in this context — correction: Glass is actually a poor conductor of heat. The correct classification is:

Good conductors of heat	Poor conductors of heat
Steel key	Plastic ruler
	Glass marble
	Rubber eraser

(1 mark for each correct column with all items correct)

(b) (1 mark) Example: A wooden/plastic handle on a cooking pot — poor conductors of heat prevent the handle from getting hot, so the user does not burn their hand.

Accept any valid example with correct explanation linking poor conductivity to the use.

13. (2 marks)

(a) Organism B (1 mark)

The bat has a backbone (Yes at Step 1) but no feathers (No at Step 2), so it is classified as Organism B.

(b) Snail / Tortoise / Crab (1 mark — accept any valid organism with a shell and no backbone)

Organism C has no backbone but has a shell. A snail fits this description.

14. (3 marks)

(a) (2 marks) Example: A transparent magnetic material is not common, but accept a student reasoning that a material could be both magnetic and transparent — however, in practice, most magnetic materials are opaque. Award marks for valid reasoning.

Alternative acceptable answer: A steel (iron-coated) transparent material — e.g., a thin steel mesh that allows some light through. Award 1 mark for a reasonable material and 1 mark for explanation.

Best answer: There is no common material that is both fully magnetic and fully transparent. The overlapping region may be empty. Award 2 marks if the student states this with reasoning.

(b) (1 mark) A copper coin is not magnetic. Copper is a good conductor of electricity, which makes it useful for electrical wiring.

Award 1 mark for both parts correct.

15. (3 marks)

(a) (2 marks) Substance W — It has a boiling point of 100°C, is soluble in water, and conducts electricity (likely a salt solution or water with dissolved ions). Pure water boils at 100°C.

Award 1 mark for identifying W and 1 mark for linking the boiling point of 100°C to water.

(b) (1 mark) Substance Y — It has a high boiling point (357°C), does not dissolve in water, and conducts electricity. These are typical properties of a metal (e.g., mercury boils at 357°C).

Accept identification of Y with any one correct property as reason.

16. (3 marks)

(a) Monocotyledon (1 mark)

Monocotyledons typically have parallel venation in their leaves.

(b) (2 mark) Any two of the following:

• Presence or absence of flowers
• Type of root system (tap root or fibrous root)
• Venation pattern of leaves (parallel or reticulate)
• Number of cotyledons in the seed
• Whether the plant is woody or herbaceous

(1 mark each, maximum 2 marks)

Section C: Structured / Long-Answer Questions (20 marks)

17. (6 marks)

(a) (4 marks) Sample dichotomous key:

1a. Has backbone ─────────────────────────── Go to 2
1b. No backbone ──────────────────────────── Go to 5

2a. Has feathers ──────────────────────────── Bird
2b. No feathers ───────────────────────────── Go to 3

3a. Has scales ────────────────────────────── Lizard
3b. No scales ─────────────────────────────── Go to 4

4a. Has moist skin, 4 legs ────────────────── Frog
4b. No moist skin ─────────────────────────── (none in this set)

5a. Has 6 legs ────────────────────────────── Go to 6
5b. Does not have 6 legs ──────────────────── Go to 7

6a. Feeds on other insects ────────────────── Ant
6b. Feeds on plants ───────────────────────── Beetle

7a. Has 8 legs ────────────────────────────── Spider
7b. Does not have 8 legs ──────────────────── Go to 8

8a. Has a shell ───────────────────────────── Snail
8b. Has 10 legs, lives in water ────────────── Crab

Marking scheme: Award 1 mark for each correctly separated pair/groups (up to 4 marks). The key must use observable characteristics from the table and correctly separate all 8 organisms. Deduct marks if organisms are misclassified or if the key is incomplete.

(b) (2 marks) Vertebrates: Lizard, Frog, Bird

These organisms have backbones. (1 mark for listing all three correctly, 1 mark for stating that they have backbones/are vertebrates.)

Common mistake: Students may forget that frogs and fish are vertebrates because they do not have obvious external bones. Award partial credit (1 mark) if only 2 of 3 are listed.

18. (6 marks)

(a) (3 marks) Circuit diagram should include:

• A battery/power source (1 mark)
• A bulb or ammeter in series (1 mark)
• The test material connected in the circuit with a gap/switch (1 mark)

Expected diagram description: A simple series circuit with a battery, connecting wires, a bulb, and a gap where the test material is inserted. If the material is a conductor, the bulb lights up; if it is an insulator, the bulb does not light up.

(b) (2 marks)

(1 mark for each column correct. All three metals must be in Conductors; both non-metals in Insulators.)

(c) (1 mark) Metals have free electrons that can move easily through the material, carrying electric current.

Accept equivalent wording: "Metals contain delocalised/mobile electrons that allow electricity to flow."

19. (5 marks)

(a) (2 marks) The garden has a greater diversity of organisms. It contains 5 different types of organisms (insects, plants, birds, frogs, and no fish or crabs), while the pond has 6 types. Correction: The pond has 6 types (insects, fish, plants, birds, frogs, crabs) and the garden has 4 types (insects, plants, birds, frogs — no fish, no crabs).

The pond has greater diversity because it has 6 different types of organisms compared to 4 types in the garden. (1 mark for correct habitat, 1 mark for using data as evidence.)

(b) (2 marks) Fish need water to survive — they breathe through gills that extract dissolved oxygen from water. The garden habitat does not have a body of water, so fish cannot survive there. The pond provides the aquatic environment that fish need.

(1 mark for mentioning water/aquatic habitat, 1 mark for linking to fish survival/breathing.)

(c) (1 mark) Example: Plant more flowering plants to attract insects and birds / Add a small pond to attract frogs and fish / Create a compost area to attract decomposers.

Accept any reasonable suggestion that would increase the variety of organisms.

20. (6 marks)

(a) (4 marks — 2 marks per sorting method)

Sorting method 1:

Property used: Magnetic vs non-magnetic

• Group A (Magnetic): Steel ball bearing, aluminium coin* (*aluminium is NOT magnetic — correction below)
• Group B (Non-magnetic): Marble, cork, plastic bead, wooden cube, rubber ball, feather

Corrected:

• Group A (Magnetic): Steel ball bearing
• Group B (Non-magnetic): Marble (glass), cork, plastic bead, wooden cube, aluminium coin, rubber ball, feather

(1 mark for valid property, 1 mark for correct grouping)

Sorting method 2:

Property used: Floats in water vs sinks in water

• Group A (Floats): Cork, plastic bead*, wooden cube, feather
• Group B (Sinks): Marble (glass), steel ball bearing, aluminium coin, rubber ball

(1 mark for valid property, 1 mark for correct grouping)

Alternative acceptable methods: Hard/soft, natural/synthetic material, transparent/opaque, flexible/rigid, etc.

(b) (2 marks) Steel ball bearing would be attracted to the magnet. Steel contains iron, which is a magnetic material. The other objects (glass, cork, plastic, wood, aluminium, rubber, feather) are non-magnetic and would not be attracted.

(1 mark for identifying steel ball bearing, 1 mark for explanation involving magnetic material/iron content.)

Mark Summary