Primary 6 PSLE Science Practice Paper 1

TuitionGoWhere Practice Paper - Science Primary 6 PSLE (Answer Key)

Subject: Science
Level: Primary 6 PSLE
Paper: Practice Paper 1 (Version 1 of 5)
Total Marks: 100

Section A: Multiple-Choice Questions (56 marks)

1. Answer: (1) The grasshopper is both a prey and a predator.

Explanation: In the food web, the grasshopper eats grass (making it a predator/consumer) and is eaten by the frog (making it prey).
Marks: 2

2. Answer: (2) Mushroom – Non-flowering plant

Explanation: Mushrooms are fungi, not plants. Fungi do not make their own food and reproduce by spores. They belong to a separate kingdom from plants.
Marks: 2

3. Answer: (4) D

Explanation: The nucleus (D) controls all activities in the cell as it contains genetic material (DNA) that directs cell functions.
Marks: 2

4. Answer: (2) Bala and Cindy

Explanation: Bala is correct – yeast is a microorganism (fungus) used in bread-making for fermentation. Cindy is correct – bacteria are microscopic and require a microscope to be seen. Ali is incorrect – not all microorganisms are harmful (e.g., yeast, probiotics). Devi is incorrect – mould is a fungus, not bacteria.
Marks: 2

5. Answer: (2) Fertilisation

Explanation: In the life cycle of a flowering plant, after pollination (transfer of pollen to stigma), fertilisation occurs (fusion of male and female gametes in the ovule).
Marks: 2

6. Answer: (1) W

Explanation: Birds have feathers, lay eggs, and breathe through lungs. Organism W matches all these characteristics. X has scales and breathes through gills (fish). Y gives birth to live young and has hair (mammal). Z lays eggs but has no feathers or scales (could be amphibian or reptile).
Marks: 2

7. Answer: (2) It will decrease.

Explanation: Grasshoppers are the food source for frogs. If grasshoppers decrease, frogs have less food, leading to a decrease in the frog population.
Marks: 2

8. Answer: (1) Cell → Tissue → Organ → Organ system → Organism

Explanation: This is the correct hierarchical organisation: cells form tissues, tissues form organs, organs form organ systems, and organ systems form an organism.
Marks: 2

9. Answer: (3) D

Explanation: The small intestine (D) is where most absorption of digested food takes place, due to its large surface area from villi and microvilli.
Marks: 2

10. Answer: (3) Plastic

Explanation: Following the flowchart: non-living → not metal → not transparent → Plastic. Wood would also fit but is not an option.
Marks: 2

11. Answer: (2) It stores water in its stem.

Explanation: Storing water in the stem is a structural (physical) adaptation. Deep roots (1) is also structural but storing water in the stem is a more distinctive cactus adaptation. Opening stomata at night (3) is a physiological/behavioural adaptation. Waxy cuticle (4) is structural but on leaves (cacti have spines, not leaves).
Marks: 2

12. Answer: (3) Energy decreases at each higher level.

Explanation: In any ecological pyramid, energy decreases at each successive trophic level (typically ~10% transfer). The pyramid shows numbers, but the energy principle still applies.
Marks: 2

13. Answer: (1) Shark, frog, snake, eagle

Explanation: All are vertebrates (have backbones). Group 2 are invertebrates (no backbone). Group 3 are invertebrates. Group 4 are insects (invertebrates).
Marks: 2

14. Answer: (3) Chloroplast

Explanation: Chloroplasts are found in plant cells (for photosynthesis) but not in animal cells. Cytoplasm, nucleus, and cell membrane are found in both.
Marks: 2

15. Answer: (4) D

Explanation: Amphibians have moist skin, breathe through lungs and skin, and lay eggs in water. Organism D matches all these characteristics.
Marks: 2

16. Answer: (2) Condensation

Explanation: Condensation is the change of state from gas (water vapour) to liquid (water droplets). Evaporation is liquid to gas. Precipitation is liquid/solid falling. Transpiration is evaporation from plants.
Marks: 2

17. Answer: (4) Removes waste from the body

Explanation: The excretory system (kidneys) removes waste. The skeletal system protects organs, produces blood cells (in bone marrow), and helps movement (with muscles).
Marks: 2

18. Answer: (3) 4

Explanation: The food chains are: (1) Algae → Water flea → Small fish → Large fish → Kingfisher, (2) Algae → Water flea → Small fish → Kingfisher, (3) Algae → Water flea → Large fish → Kingfisher, (4) Algae → Small fish → Large fish → Kingfisher.
Marks: 2

19. Answer: (3) Bacteria reproduce by binary fission.

Explanation: Bacteria reproduce asexually by binary fission (splitting into two). Not all bacteria cause diseases (many are beneficial). Bacteria are unicellular, not multicellular. Bacteria can survive in various conditions (extremophiles).
Marks: 2

20. Answer: (2) Hydrotropism

Explanation: Hydrotropism is growth response to water (roots growing towards water). Phototropism is response to light. Geotropism is response to gravity. Thigmotropism is response to touch.
Marks: 2

21. Answer: (1) Nose → Trachea → Bronchi → Lungs → Alveoli

Explanation: Air enters through the nose, passes through the trachea, branches into bronchi, enters the lungs, and reaches the alveoli for gas exchange.
Marks: 2

22. Answer: (2) W and X only

Explanation: At 30°C, substances with boiling points below 30°C are gases. W (-196°C) and X (20°C) are gases. Y (78°C) and Z (100°C) are liquids at 30°C.
Marks: 2

23. Answer: (3) Birds migrate to warmer countries in winter.

Explanation: Migration is a behavioural adaptation (action/behaviour). Thick fur (1), colour change (2 - physiological), and spines (4) are structural adaptations.
Marks: 2

24. Answer: (3) C

Explanation: The stamen (C) consists of the anther (produces pollen) and filament. The anther produces pollen grains.
Marks: 2

25. Answer: (2) Presence of light

Explanation: The changed (independent) variable is the one deliberately changed – presence vs absence of light. Other variables (plant type, duration, water) are kept constant (controlled variables).
Marks: 2

26. Answer: (3) Mushroom

Explanation: Mushrooms are fungi (decomposers) that break down dead organic matter. Grass is a producer, rabbit is a consumer, hawk is a consumer.
Marks: 2

27. Answer: (3) C

Explanation: The pulp cavity (C) contains nerves and blood vessels. Enamel (A) is the hard outer layer. Dentine (B) is beneath enamel. Gum (D) and jaw bone (E) are supporting structures.
Marks: 2

28. Answer: (3) Organisms interact with both living and non-living components of their environment.

Explanation: Organisms interact with biotic (living) factors (other organisms) and abiotic (non-living) factors (light, water, temperature, soil).
Marks: 2

Section B: Open-Ended Questions (44 marks)

29.

(a) Grass → Aphid → Ladybird → Sparrow (or Grass → Aphid → Sparrow → Cat) [1]
Marking note: Any valid 4-organism chain from the web. Arrows must show energy flow direction.

(b) Aphid population will increase because there are fewer ladybirds to eat them. Sparrow population may decrease because they lose one food source (ladybirds), though they still have aphids. [2]
Mark breakdown: 1 mark for aphid increase with reason; 1 mark for sparrow decrease with reason.

(c) Decomposers break down dead organisms and waste, returning nutrients to the soil for plants to use. [1]
Key concept: Nutrient recycling.

30.

(a) Cell wall and chloroplast (or large vacuole) [1]
Marking note: Any two correct structures: cell wall, chloroplast, large central vacuole.

(b) Chloroplast contains chlorophyll which traps light energy for photosynthesis. [1]
Key concept: Photosynthesis site.

(c) Animal cells do not need a rigid cell wall for support because they have other support systems (skeletons, exoskeletons) or live in environments where turgor pressure is not needed. The flexible cell membrane allows animal cells to change shape for movement and phagocytosis. [1]
Key concept: Structural difference related to function.

31.

(a) A: Birds, B: Fish, C: Mammals, D: Amphibians [2]
Mark breakdown: 0.5 marks each, or 1 mark per pair.

(b) Whales are mammals because they have hair (at birth), breathe through lungs, give birth to live young, and feed young with milk. Living in water is a habitat, not a classification criterion. [1]
Key concept: Classification based on characteristics, not habitat.

(c) Both lay eggs in water / both have aquatic young stages / both are cold-blooded. [1]
Accept any valid similarity.

32.

(a) Complete metamorphosis [1]

(b) Larva

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TuitionGoWhere Practice Paper - Science Primary 6 PSLE (Answer Key)

Subject: Science
Level: Primary 6 PSLE
Paper: Practice Paper 1 (Version 1 of 5)
Total Marks: 100

Section A: Multiple-Choice Questions (56 marks)

Section B: Open-Ended Questions (44 marks)

29. Garden Food Web

(a) Grass → Aphid → Ladybird → Sparrow
OR Grass → Aphid → Sparrow → Cat
OR Grass → Aphid → Ladybird → Sparrow → Cat (5 organisms, but "with four organisms" means 4 organisms in the chain, so 3 arrows)
Acceptable answer: Grass → Aphid → Ladybird → Sparrow [1]

(b) Aphids: Population will increase because there are fewer ladybirds to eat them (less predation).
Sparrows: Population will decrease because one of their food sources (ladybirds) is gone, and although aphids increase, sparrows may not be able to eat enough aphids to compensate / sparrows lose a food source.
Marking points: [1] Aphids increase (less predators). [1] Sparrows decrease (less food / lost food source).

(c) Decomposers break down dead organisms and waste materials, returning nutrients to the soil for plants to use. / They recycle nutrients in the ecosystem. [1]

30. Plant Cell vs Animal Cell

(a) Cell wall and chloroplasts (or large central vacuole)
Any two: Cell wall, Chloroplasts, Large central vacuole [1 each, max 2]

(b) Function of chloroplasts: Contain chlorophyll to trap light energy for photosynthesis. / Site of photosynthesis. [1]
Function of cell wall: Gives the cell a fixed/regular shape and provides support/protection. / Prevents cell from bursting when it absorbs water. [1]

31. Human Respiratory System

(a) Part X: Alveolus / Alveoli (air sac) [1]

(b) The alveoli have:

• Thin walls (one cell thick) for fast diffusion of gases.
• Large surface area (many alveoli) for efficient gas exchange.
• Moist lining for gases to dissolve.
• Dense network of capillaries for transport of gases.
  Any two features with explanation: [1] Feature, [1] How it helps.
  Example: Thin walls → short diffusion distance for oxygen and carbon dioxide. [1]
  Large surface area → more space for gas exchange. [1]

32. Water Cycle

(a) Process A: Evaporation (from water bodies)
Process B: Condensation (forming clouds) [1 each]

(b) The water cycle ensures a continuous supply of fresh water for living things. / It distributes water around the Earth. / It purifies water through evaporation and condensation. [1]

(c) Transpiration is the loss of water vapour from the leaves of plants. It adds water vapour to the atmosphere, contributing to condensation and precipitation. / It helps pull water up from the roots (transpiration pull). [1]

33. Magnetism

(a) Repel [1]
Reason: Like poles (North-North) repel each other. [1]

(b) Method: Stroke the steel bar with a magnet in one direction repeatedly (stroking method).
OR Place the steel bar in a solenoid and pass direct current through it (electrical method).
OR Induction method (bring magnet near, then remove).
Acceptable: Stroke with a magnet in one direction many times. [1]

(c) Test: Bring the rod near some iron nails/paper clips. If it attracts them, it is magnetised.
OR Suspend the rod freely; if it comes to rest in a North-South direction, it is magnetised.
OR Bring a known magnet near; if it repels one end, it is magnetised (repulsion is the only sure test).
Best answer: Bring a known magnet near; if there is repulsion, the rod is magnetised. [1]

34. Heat and Temperature

(a) Conduction [1]
Explanation: Heat travels through the solid metal rod from the hotter end to the colder end by vibration of particles. [1]

(b) Material Y [1]
Reason: It has the lowest temperature after 5 minutes, meaning it conducts heat the slowest / is the poorest conductor of heat / best insulator. [1]

(c) The handles will not get hot easily / will remain cool, preventing the user from getting burnt. / It is a poor conductor of heat / good insulator. [1]

35. Light and Shadows

(a) Light travels in straight lines. [1]
Explanation: The opaque object blocks the light, forming a shadow behind it because light cannot bend around the object. [1]

(b) The shadow will become larger / bigger. [1]
Reason: When the object is moved closer to the light source, it blocks more light rays, casting a larger shadow on the screen. [1]

(c) Use a point source of light / smaller light source / move the screen further away from the object.
To get a sharp shadow: Use a point source of light (or move the light source further from the object). [1]

36. Electrical Systems

(a) Circuit B [1]
Reason: It is a closed circuit with no gaps / the switch is closed, allowing electric current to flow. [1]

(b) The bulbs in Circuit A are connected in series. [1]
Explanation: In a series circuit, the current is the same through all components. When one bulb fuses (breaks), the circuit becomes open and current cannot flow, so the other bulb goes out. [1]

(c) Advantage: If one bulb fuses, the other bulbs will still light up / each bulb can be controlled independently / each bulb receives the full voltage and shines at maximum brightness. [1]

37. Forces

(a) Gravitational force (or weight) [1]

(b) The reading on the spring balance decreases. [1]
Reason: The water exerts an upward upthrust (buoyant force) on the object, opposing its weight, so the net force pulling down on the spring balance is less. [1]

(c) Frictional force [1]
Direction: Acts opposite to the direction of motion / backwards (against the pulling force). [1]

38. Matter

(a) Solid [1]
Reason: It has a fixed volume and a fixed shape / definite shape and volume. [1]

(b) Gas [1]
Reason: It has no fixed volume and no fixed shape / takes the shape and volume of its container / can be compressed. [1]

(c) Melting [1]
Process: The solid gains heat, particles vibrate faster and break free from their fixed positions to become a liquid. [1]

39. Photosynthesis Experiment

(a) Carbon dioxide [1]

(b) Oxygen [1]

(c) Test: Place a glowing wooden splint into the gas collected.
Observation: The glowing splint relights / bursts into flame. [1]
This confirms the gas is oxygen.

40. Adaptations

(a) Structural adaptation: Webbed feet / Streamlined body shape / Waterproof feathers / Wings modified as flippers / Thick layer of fat (blubber) under skin. [1]
Any one.

(b) Behavioural adaptation: Huddling together in groups to keep warm / Migrating to warmer areas (though penguins don't migrate far, they move) / Taking turns to be on the outside of the huddle. [1]
Acceptable: Huddling together to reduce heat loss.

(c) The thick layer of fat (blubber) acts as an insulator, reducing heat loss from the penguin's body to the cold surroundings / keeping the penguin warm. [1]

End of Answer Key