Primary 6 PSLE Science Practice Paper 4

TuitionGoWhere Practice Paper — Science Primary 6 PSLE

Answer Key — Version 4 of 5

Subject: Science (Primary 6, PSLE) Paper: Practice Paper — Diversity (Topic Focus) Total Marks: 100

Section A: Multiple Choice Questions (20 marks)

1. C — Presence of a backbone

• Reasoning: Classification of living things is based on shared structural characteristics. The presence or absence of a backbone (vertebral column) is a key characteristic used to divide animals into vertebrates and invertebrates. Colour, size, and number of legs are not reliable classification criteria because they can vary widely within a group. [2]

2. B — X

• Reasoning: A fish is a vertebrate (has a backbone) and has scales but does not have feathers. Organism X matches these characteristics. Organism W is a bird (has feathers). Organisms Y and Z lack backbones. [2]

3. C — River

• Reasoning: A river is a body of water and is non-living. Mushrooms (fungi), coral (animals), and moss (plants) are all living organisms. [2]

4. C — Whether they are electrical conductors or insulators

• Reasoning: Group 1 (wood, plastic, rubber) are all electrical insulators. Group 2 (copper, iron, aluminium) are all electrical conductors (metals). This is the most consistent property that separates the two groups. [2]

5. B — Kingdom → Phylum → Class → Order → Family → Genus → Species

• Reasoning: The standard biological classification hierarchy proceeds from the broadest (largest) group, Kingdom, down to the most specific (smallest) group, Species. [2]

6. C — Animal with no feathers and fins

• Reasoning: Following the key: Start → Has feathers? No → Has fins? Yes → Fish. An animal with no feathers and fins is classified as a fish. [2]

7. C — They can reproduce

• Reasoning: All living things carry out life processes, which include reproduction, respiration, nutrition, excretion, growth, and response to stimuli. Flying, photosynthesis, and having legs are not universal characteristics of all living things. [2]

8. D — None of the above

• Reasoning: A density greater than 1.0 g/cm³ but less than 1.3 g/cm³ is required. P = 0.6 (less than 1.0), Q = 1.0 (not greater than 1.0), R = 1.5 (greater than 1.3). None of the materials meet the criteria. [2]

9. B — Flexibility

• Reasoning: Group A (glass marble, metal coin, ceramic tile) are all hard and rigid (not flexible). Group B (cotton cloth, tissue paper, sponge) are all soft and flexible. Hardness is also plausible, but flexibility is the most consistent distinguishing property across all six items. [2]

10. C — Cotton fabric

• Reasoning: Cotton is a natural fibre obtained from the cotton plant. Nylon rope and plastic bottles are synthetic (man-made). Rubber tyres are typically made from synthetic rubber (man-made), though natural rubber exists. Cotton fabric is the clearest example of a natural material. [2]

11. B — Steel

• Reasoning: Steel is an alloy of iron and carbon. It conducts electricity (like all metals) and is magnetic (because it contains iron). Copper and aluminium conduct electricity but are not magnetic. Nickel is magnetic but the overlap region requires both properties. Steel fits both criteria. [2]

12. B — Eagle, lizard, dolphin

• Reasoning: Eagles (birds), lizards (reptiles), and dolphins (mammals) are all vertebrates. Option A includes an ant (invertebrate). Option C contains only invertebrates. Option D contains only invertebrates. [2]

13. D — Dicotyledon

• Reasoning: Flowering plants with broad leaves and network (reticulate) veins are dicotyledons. Monocotyledons have parallel veins. Ferns and mosses do not produce flowers or seeds. [2]

14. B — To make it easier to study and understand the diversity of life

• Reasoning: Classification helps scientists organise the vast diversity of life into manageable groups based on shared characteristics, making it easier to study, identify, and understand relationships between organisms. [2]

15. C — X and Y only

• Reasoning: A substance is a liquid at room temperature (25 °C) if its melting point is below 25 °C and its boiling point is above 25 °C. Substance X: melts at 0 °C, boils at 100 °C → liquid. Substance Y: melts at −39 °C, boils at 357 °C → liquid. Substance W is a gas (boiling point −183 °C). Substance Z is a solid (melting point 1538 °C). [2]

16. C — Concrete

• Reasoning: Concrete is manufactured by mixing cement, water, sand, and gravel. It does not occur naturally. Wood, silk, and wool are natural materials obtained from plants or animals. [2]

17. C — Insects

• Reasoning: Insects are characterised by having six legs, three body parts (head, thorax, abdomen), and one pair of antennae. Arachnids have eight legs. Crustaceans have more than six legs. Myriapods have many legs. [2]

18. D — Wood

• Reasoning: Wood is a poor conductor of heat (good thermal insulator). Copper, aluminium, and steel are all metals and are good thermal conductors. [2]

19. D — Conifer

• Reasoning: Following the key: produces seeds → yes; has flowers → no → conifer. Ferns and mosses do not produce seeds. Flowering plants have flowers. [2]

20. C — Biodiversity includes the variety of living things and their habitats.

• Reasoning: Biodiversity refers to the variety of living organisms (plants, animals, microorganisms) and the ecosystems/habitats they inhabit. It is not limited to animals (A is wrong). Greater biodiversity generally means a more stable ecosystem (B is wrong). Human activities do affect biodiversity (D is wrong). [2]

Section B: Structured Questions (50 marks)

21.

(a) Organism B is a bird. [1] It has feathers [1] and a backbone, which are characteristics of birds. [2]

(b) Organism D is most likely an insect. [1] It has no backbone (invertebrates), and insects are invertebrates. (Note: Organisms C and D are both invertebrates; D is the better answer as it has moist skin, which could suggest a soft-bodied invertebrate, but the key point is that it lacks a backbone.) [2]

Marking note: Accept Organism C or D with a valid reason (no backbone = invertebrate). Full marks for identifying an invertebrate organism with a correct explanation.

(c) Two characteristics supporting that Organism A is a frog:

• It has a backbone (frogs are vertebrates/amphibians). [1]
• It has moist skin (amphibians have moist, permeable skin). [1]
• It lives on land and water (amphibians are adapted to both habitats). [1]

Accept any two of the above. [2]

[Total: 6 marks]

22.

(a) Copper would be most suitable for making the wire of an electrical cable. [1] Copper conducts electricity [1] and is flexible, so it can be drawn into thin wires. [1] [3]

(b) Copper (or iron) would be least suitable for making a cooking pan handle. [1] Copper conducts electricity and is a good thermal conductor, meaning it would become very hot and burn the user's hand. (The question asks about a pan handle, so thermal conductivity is the relevant property. Copper and iron are good thermal conductors.) [2]

Marking note: Accept copper or iron. Award 1 mark for identifying the material, 1 mark for explaining that it conducts heat well / would become hot.

(c)

[2] — 1 mark for each column correctly completed.

Marking note: Copper and iron are natural (mined from the earth as ores). Glass is man-made (manufactured by heating sand). Rubber can be natural or synthetic; in this context, rubber is treated as man-made. Accept reasonable alternatives with justification.

[Total: 7 marks]

23.

(a) All animals in group P have feathers. [1]

(b) The shark is placed in group Q because it has no feathers [1] and has fins. [1] It is not in group R because the shark has fins, whereas group R animals do not have fins. [2]

(c) A snake could belong to group S. [1] A snake has no legs, no fins, and no feathers. [1] (Accept any valid animal, e.g., worm, eel, snake.)

(d) Two characteristics of animal T (jellyfish) from the key:

• It has no legs. [1]
• It has no fins. [1]
• It has no feathers. [1]

Accept any two. [2]

[Total: 7 marks]

24.

(a) Forest X has greater biodiversity. [1] Forest X has more types of organisms (6 types) and a greater number of individuals across most organism types compared to Garden Y. [1] [2]

Marking note: Accept any valid reason, e.g., "Forest X has more species" or "Forest X has organisms from more groups."

(b) Total number of organism types in Garden Y = 5 + 30 + 2 + 1 + 0 + 25 = 63 [1]

Marking note: The question asks for the total number of organism types recorded. If interpreted as "number of categories," the answer is 5 (amphibians = 0, so 5 types present). If interpreted as total count, it is 63. Award the mark for 63 (total organisms counted). Clarification: The table shows counts, not types. The total count is 63.

(c) Garden Y has fewer amphibians because:

• Garden Y may lack a water source (pond, stream) that amphibians need. [1]
• Garden Y may have less moisture/humidity, which amphibians require for their moist skin. [1]
• Garden Y may have more predators or less shelter for amphibians. [1]

*Accept any one valid reason. [2]

(d) One limitation: The number of organisms does not necessarily indicate the health of an ecosystem. [1] A habitat could have many organisms but be polluted or unbalanced (e.g., an overpopulation of one species could indicate a lack of predators). [1] Health depends on the balance and diversity of species, not just the total number. [2]

[Total: 7 marks]

25.

(a) Substance B is water. [1] Its melting point is 0 °C and boiling point is 100 °C, which are the known melting and boiling points of water. [1] [2]

(b) Substance D is a solid at room temperature (melting point 115 °C > 25 °C) and dissolves in water. [1]

Marking note: Substance D has a melting point of 115 °C, so it is solid at 25 °C, and it is soluble in water.

(c) Aluminium is suitable for making aircraft bodies because:

• It has a low density (2.70 g/cm³), making the aircraft lightweight. [1]
• It has a high melting point (660 °C), so it remains solid at high temperatures. [1]
• It is a metal, so it is strong and durable. [1] [3]

Marking note: Award marks for any two relevant properties from the table with correct explanation.

(d) Ethanol (Substance A) is a liquid at room temperature. [1] Its melting point is −114 °C (below 25 °C) and its boiling point is 78 °C (above 25 °C), so it exists as a liquid at 25 °C. [1] [2]

[Total: 8 marks]

26.

(a) 4 organisms are vertebrates (W, X, Y, Z). [1]

(b) Organisms P and R both have moist skin and no backbone, which are characteristics of amphibians. [1]

Marking note: Accept "moist skin" or "no backbone" or "lays eggs."

(c) A dolphin is classified as a mammal because:

• It gives birth to live young (does not lay eggs). [1]
• It has hair (body covering is hair). [1]
• It has a backbone (is a vertebrate). [1]

Fish lay eggs and have scales. The dolphin gives birth to live young and has hair, which are mammalian characteristics. [3]

(d) Two characteristics showing the jellyfish (S) is different from vertebrates:

• It has no backbone. [1]
• It has no body covering (no hair, feathers, or scales). [1] [2]

Marking note: Accept "lays eggs" as an additional difference, but the key differences are no backbone and no body covering.

[Total: 7 marks]

27.

(a) Algae is the producer. [1]

(b) The water flea is a consumer because it feeds on other organisms (algae) for food and cannot make its own food. [2]

Marking note: 1 mark for identifying it as a consumer, 1 mark for explaining that it feeds on other organisms / cannot photosynthesise.

(c) If algae decreased greatly:

• The water flea population would decrease because it feeds on algae (less food available). [1]
• The small fish population would decrease because there are fewer water fleas to eat. [1]
• The large fish population would decrease because there are fewer small fish to eat. [1]

The large fish population would decline due to a reduction in food availability throughout the food chain. [3]

(d) Two characteristics of birds that help them survive:

• Feathers for flight and insulation. [1]
• Beaks adapted for feeding. [1]
• Wings for flying to find food/escape predators. [1]
• Lightweight bones for flight. [1]

Accept any two valid characteristics. [2]

[Total: 8 marks]

28.

(a) The student classified the materials by whether they are natural or man-made (synthetic). [1]

(b) One advantage of Group 1 (natural materials):

• They are biodegradable and better for the environment. [1]
• They are breathable and comfortable to wear. [1]
• They are renewable resources. [1]

*Accept any one valid advantage. [2]

Marking note: 1 mark for the advantage, 1 mark for a brief explanation.

(c) One advantage of Group 2 (man-made materials):

• They are more durable and last longer. [1]
• They are cheaper to produce in large quantities. [1]
• They are water-resistant or wrinkle-resistant. [1]

Accept any one valid advantage. [2]

(d) A cotton-polyester blend is used because:

• Polyester adds strength and durability to the fabric. [1]
• The blend is less likely to wrinkle compared to pure cotton. [1]
• It is more affordable and easier to care for. [1]

Accept any one valid reason with explanation. [2]

[Total: 7 marks]

29.

(a) The cactus stores water in its stem, which allows it to survive long periods without rainfall in the desert where water is scarce. [2]

Marking note: 1 mark for identifying the function (stores water), 1 mark for linking it to the desert environment.

(b) The thick layer of blubber insulates the seal, keeping it warm in the freezing Arctic temperatures. [2]

Marking note: 1 mark for insulation, 1 mark for linking to the Arctic environment.

(c) Broad leaves have a large surface area, which allows the plant to absorb more sunlight for photosynthesis in the shaded rainforest. [2]

Marking note: 1 mark for large surface area, 1 mark for absorbing more sunlight / photosynthesis.

(d) One other adaptation of a fish for living in water:

• Streamlined body shape to reduce water resistance when swimming. [1]
• Fins for swimming and balance. [1]
• Scales to protect the body. [1]

*Accept any one valid adaptation. *[1]

[Total: 7 marks]

30.

(a) One natural non-living thing: rock / soil / water / sand. [1]

(b) One man-made non-living thing: bench / fence / path / pot / tool. [1]

(c) The statement is incorrect because plants are living things. Two characteristics of living things that plants have:

• Plants can reproduce (produce seeds, fruits). [1]
• Plants can photosynthesise (make their own food). [1]
• Plants grow and respond to stimuli (e.g., grow towards light). [1]

*Accept any two valid characteristics. *[3] Marking note: 1 mark for stating the statement is incorrect, 1 mark each for two valid characteristics.

(d) It is important for scientists to classify living and non-living things because:

• It helps organise and understand the natural world. [1]
• It makes it easier to study and identify different things. [1]
• It helps us understand relationships between different things. [1]

*Accept any two valid reasons. *[2]

[Total: 7 marks]

Section C: Free-Response Questions (30 marks)

31.

(a) The organism most likely belongs to the group arachnids (or spiders). [1] Two supporting characteristics:

• It has eight legs (arachnids have eight legs; insects have six). [1]
• It has two body parts (cephalothorax and abdomen; insects have three). [1]
• It produces silk (a characteristic of spiders). [1]
• It has no antennae (arachnids lack antennae). [1]

Award 1 mark for the group, 1 mark each for two valid characteristics. [3]

(b)

• (i) Has more than six legs / Has eight legs / Does not have six legs [1]
• (ii) Arachnid (or Spider) [1] [2]

Marking note: For (i), accept any characteristic that distinguishes insects (six legs) from arachnids (eight legs). For (ii), accept "Arachnid" or "Spider."

(c) This organism is not an insect because:

• Insects have six legs, but this organism has eight legs. [1]
• Insects have three body parts, but this organism has two body parts. [1]
• Insects have antennae, but this organism has no antennae. [1]

Award 1 mark for each correct difference, up to 2 marks. [2]

[Total: 7 marks]

32.

(a) Material Y is most likely polythene. [1] Two supporting properties:

• It has a low density (1.38 g/cm³), which is typical of plastics/polythene. [1]
• It does not conduct electricity, which is a property of plastics. [1]
• It has a relatively low melting point (200 °C), typical of thermoplastics. [1]
• It is man-made, which is consistent with polythene being a synthetic polymer. [1]

Marking note: Award 1 mark for identifying Y, 1 mark each for two valid properties. Accept Q as an alternative with valid reasoning. [3]

(b) Aluminium is used for overhead power cables because:

• It conducts electricity well, allowing efficient transmission of electrical energy. [1]
• It has a low density (2.70 g/cm³), making it lightweight and reducing the load on support structures. [1]
• It is a metal, so it is ductile and can be drawn into wires. [1] [3]

Marking note: Award 1 mark for each valid property with explanation, up to 3 marks.

(c) Hydrogen gas has a very low density because:

• The particles in a gas are far apart from each other. [1]
• Hydrogen is the lightest element, with the smallest mass per particle, so a given volume has very little mass. [1]
• The particles are spread out over a large volume, resulting in very little mass per unit volume. [1]

Award up to 2 marks for a clear explanation using the particle model. [2]

[Total: 8 marks]

33.

(a)

[3] — 1 mark for each row correctly filled (3 rows × 1 mark = 3 marks).

Marking note: Mudskipper, heron, monitor lizard, and fish are vertebrates. Crab and insect are invertebrates. Award marks for correct classification.

(b) The special roots (aerial/prop roots) of mangrove trees grow above the waterlogged soil, allowing the trees to obtain oxygen for respiration. [1] In waterlogged soil, there is very little air, so the roots that grow above the surface can absorb oxygen directly from the air. [1] [2]

(c) Two reasons to conserve mangrove forests:

• Mangroves support high biodiversity, providing habitats for many species of organisms. [1]
• Mangrove roots reduce coastal erosion by trapping soil and stabilising the shoreline. [1]
• Mangroves act as nurseries for fish and other marine life, supporting fisheries. [1]
• Mangroves absorb carbon dioxide and help mitigate climate change. [1]

Accept any two valid reasons. [3]

(d) One negative human impact: Clearing mangrove forests for housing and aquaculture farms, which destroys habitats and reduces biodiversity. [1]

[Total: 9 marks]

34.

(a) Steel is the strongest material. [1] It stretched the least (only 0.1 cm) when the same weight was applied, indicating it has the greatest resistance to deformation. [1] [2]

(b) The student should choose rubber for a bungee cord. [1] Rubber stretched the most (8.5 cm), showing it is highly elastic and can stretch and return to its original shape, which is essential for a bungee cord. [1] [2]

Marking note: Award 1 mark for choosing rubber, 1 mark for explaining elasticity.

(c) Steel is used to build bridges because:

• It is very strong (stretched only 0.1 cm in the test), so it can support heavy loads without deforming. [1]
• It has a high melting point (1538 °C), so it remains solid under extreme conditions. [1]
• It is durable and can withstand weathering and heavy use over long periods. [1] [3]

Marking note: Award 1 mark for strength (referring to results), 1 mark for high melting point, 1 mark for durability or another valid property.

(d) One limitation: The experiment only tested one weight/size of each material, so the results may not be generalisable. [1] Improvement: Test multiple weights and use strips of the same dimensions (length, width, thickness) for a fair comparison. [1] [2]

Marking note: Accept any valid limitation (e.g., only one trial, strips may have different thicknesses) and a corresponding improvement.

[Total: 9 marks]

35.

(a) Two consumers: Grasshopper and Frog (or Rabbit, Snake, Hawk). [2] — 1 mark each.

Marking note: Any two consumers from the food web. The grass is the producer, so it is not a consumer.

(b) The frog is both a predator and prey. [1] It is a predator because it eats grasshoppers, and it is prey because it is eaten by snakes. [1] [2]

Marking note: Accept rabbit (eaten by hawk, eats grass) or snake (eaten by hawk, eats frog) with valid explanation.

(c) If all grasshoppers were killed:

• The frog population would decrease because grasshoppers are a food source for frogs. [1]
• The grass population would increase because there would be fewer grasshoppers feeding on the grass. [1]
• The snake population might also decrease due to fewer frogs to eat. [1] [3]

Marking note: Award 1 mark for each correct consequence with explanation.

(d) Grass is essential to this food web because:

• It is the producer, making food (glucose) through photosynthesis. [1]
• It is the primary source of energy for all other organisms in the food web (directly or indirectly). [1]
• Without grass, the consumers (grasshopper, rabbit, frog, snake, hawk) would have no food source. [1]

Award up to 2 marks for a clear explanation. [2]

[Total: 9 marks]

Mark Summary

This answer key was generated by TuitionGoWhere (AI) for educational purposes. It is aligned with the MOE Primary Science syllabus and is not derived from any actual PSLE or school examination paper.