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Primary 6 PSLE Science Practice Paper 4
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TuitionGoWhere Practice Paper - Science Primary 6 PSLE (Answer Key)
Subject: Science
Level: Primary 6 PSLE
Paper: Practice Paper 4 (Diversity Theme Focus)
Total Marks: 100
SECTION A (56 marks)
Question 1 [2 marks]
Answer: (2) Mould, yeast, mushroom
Explanation: Fungi include moulds, yeasts, and mushrooms. Moss is a non-flowering plant (bryophyte), not a fungus. Bacteria are prokaryotes, not fungi. Ferns are vascular plants.
Question 2 [2 marks]
Answer: (3) Bacteria and Protists | Fungi
Explanation: Group X contains Bacteria (prokaryotes), Amoeba and Paramecium (protists) — all are microorganisms but from different kingdoms. Group Y contains Mushroom, Yeast, Mould — all are fungi. Option (1) is incorrect because both groups are microorganisms. Option (2) is incorrect because yeast is unicellular. Option (4) is incorrect because fungi are decomposers, not producers.
Question 3 [2 marks]
Answer: (2) Bala and Cindy
Explanation:
- Ali is incorrect: Not all bacteria are harmful; many are beneficial (e.g., gut bacteria, decomposers, yogurt production).
- Bala is correct: Bacteria are microscopic and can only be seen under a microscope.
- Cindy is correct: Bacteria reproduce asexually by binary
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TuitionGoWhere Practice Paper - Science Primary 6 PSLE (Answer Key)
Subject: Science
Level: Primary 6 PSLE
Paper: Practice Paper 4 (Diversity Theme Focus)
Total Marks: 100
SECTION A (56 marks)
| Question | Answer | Explanation |
|---|---|---|
| 1 | (2) | Mould, yeast, and mushroom are all fungi. Moss is a non-flowering plant. Bacteria are prokaryotes. Fern is a non-flowering plant. |
| 2 | (3) | Group X contains Bacteria (prokaryotes) and Protists (Amoeba, Paramecium). Group Y contains Mushroom, Yeast, Mould — all fungi. |
| 3 | (2) | Bala: Bacteria are microscopic. Cindy: Bacteria reproduce by binary fission. Ali is wrong (some bacteria are beneficial). Devi is wrong (bacteria lack a nucleus). |
| 4 | (3) | Both plant and animal cells have a nucleus. Plant cells have cell walls and chloroplasts; animal cells do not. Both have cell membranes and cytoplasm. |
| 5 | (3) | Frog is a vertebrate (amphibian). Earthworm (annelid), grasshopper (insect), snail (mollusc) are invertebrates. |
| 6 | (2) | Backbone → Vertebrate → Hair/fur → Mammal. Mammals give birth to live young (except monotremes). |
| 7 | (2) | Flowering plants (angiosperms) produce seeds enclosed in fruits. They reproduce by seeds, not spores. They are vascular and have true roots. |
| 8 | (1) | The ovary develops into the fruit after fertilisation. The ovule develops into the seed. |
| 9 | (1) | Correct sequence: Seed → Seedling → Adult plant → Flower → Fruit → Seed. |
| 10 | (3) | Ferns and mosses are non-flowering plants that reproduce by spores. Bacteria reproduce by binary fission; yeast by budding; mould by spores. |
| 11 | (1) | View A: Rod-shaped bacteria. View B: Yeast budding. View C: Mould with hyphae and sporangia. |
| 12 | (2) | Butterfly (insect), spider (arachnid), earthworm (annelid) are all invertebrates. Others contain vertebrates. |
| 13 | (3) | Four-organism chains (producer + 3 consumers): Grass→Grasshopper→Frog→Hawk; Grass→Grasshopper→Snake→Hawk; Grass→Rabbit→Snake→Hawk; Grass→Mouse→Snake→Owl. (4 chains) |
| 14 | (2) | Thick, waxy cuticle reduces water loss. Large leaves increase transpiration. Shallow roots access less water. Bright flowers attract pollinators. |
| 15 | (4) | Amphibians have moist skin, lay eggs in water, are cold-blooded. Group A: Reptiles. Group B: Birds. Group C: Mammals. |
| 16 | (3) | The cell has chloroplasts (photosynthesis) and mitochondria (implied, though not shown) for respiration. All living cells respire. |
| 17 | (3) | Many microorganisms are useful (e.g., yeast in baking, bacteria in yoghurt, decomposers). Not all cause disease. Viruses are smaller than bacteria. Microorganisms live in diverse habitats. |
| 18 | (2) | Larva (wriggler) lives in water and breathes through a siphon tube at the posterior end. Pupa also lives in water but breathes through trumpets. |
| 19 | (3) | Fungi are heterotrophs (saprotrophs); they do not photosynthesise. They reproduce by spores, feed on decaying matter, and can be unicellular (yeast) or multicellular (mould, mushroom). |
| 20 | (2) | Seeds but no flowers → Non-flowering plant (cone-bearing), i.e., gymnosperms (conifers). Ferns and mosses do not produce seeds. |
| 21 | (3) | Bacteria (Y): No nucleus (prokaryote), cell wall of peptidoglycan, no chloroplasts, heterotrophic. W = Plant. X = Fungus (chitin cell wall, saprotrophic). Z = Animal (no cell wall). |
| 22 | (1) | Standard taxonomic hierarchy: Kingdom → Phylum → Class → Order → Family → Genus → Species. |
| 23 | (2) | Energy transfer = (10 J / 100 J) × 100% = 10%. Each level shows ~10% transfer. |
| 24 | (2) | Mushroom (fungus) is a decomposer. Earthworm is a detritivore. Caterpillar is a herbivore. Eagle is a carnivore. |
| 25 | (2) | Palisade mesophyll cells are densely packed with chloroplasts for maximum light absorption. |
| 26 | (3) | Viruses are non-cellular, smaller than bacteria, cannot reproduce independently, and lack a nucleus. |
| 27 | (1) | Pyramid shows 10,000 grass (producers) > 100 grasshoppers (primary consumers) > 10 frogs (secondary) > 1 hawk (tertiary). Producers outnumber primary consumers. |
| 28 | (3) | Structural adaptation: physical feature (cactus spines reduce water loss). Others are behavioural adaptations. |
SECTION B (44 marks)
Question 29 [3 marks]
(a) Cell A: Animal cell
Cell B: Plant cell
(b) Chloroplasts contain chlorophyll to trap light energy for photosynthesis (to make food/glucose).
(c) Cell wall (or chloroplasts or large central vacuole) — any one structure present in Cell B but not Cell A.
Question 30 [3 marks]
(a) Bacterium / Bacteria (accept: prokaryote)
(b) No nucleus (genetic material in cytoplasm) and cell wall made of peptidoglycan (not cellulose or chitin).
(c) Binary fission — the cell divides into two identical daughter cells.
Question 31 [4 marks]
(a) Fungi (or Mould / Yeast)
(b) Saprotrophic nutrition — they secrete enzymes onto dead/decaying matter to break it down externally, then absorb the digested nutrients.
(c) Decomposers break down dead organisms and waste, recycling nutrients (mineral salts) back into the environment for plants to reuse.
(d) Yeast — used in bread-making (fermentation produces CO₂ to make dough rise) or beer/wine production.
Question 32 [3 marks]
(a) Vertebrates — they have a backbone.
(b) Group P: Mammals (have hair/fur, produce milk).
Group Q: Birds (have feathers, lay eggs).
(c) Bat — it has hair/fur and gives birth to live young (mammal), but it can fly (unlike most mammals).
Question 33 [4 marks]
(a) Ovule
(b) Anther — produces pollen grains (male gametes).
(c) Pollination — transfer of pollen from anther to stigma.
(d) Fruit — protects the seeds and aids in seed dispersal (by wind, water, animals, or splitting).
Question 34 [4 marks]
(a) Fern — reproduces by spores (on underside of fronds), has vascular tissue, no seeds/flowers.
(b) Moss — non-vascular, reproduces by spores, no true roots/stems/leaves.
(c) Similarity: Both reproduce by spores (not seeds).
Difference: Ferns have vascular tissue (xylem and phloem); mosses do not have vascular tissue.
Question 35 [4 marks]
(a) Producer — makes its own food through photosynthesis.
(b) Grass → Grasshopper → Frog → Snake → Hawk (or any valid 5-organism chain from the web).
(c) Energy decreases at each trophic level (only ~10% transferred; rest lost as heat, waste, uneaten parts).
(d) Population of grasshoppers increases (less predation by frogs) → grass population decreases (more herbivory).
Question 36 [3 marks]
(a) Structural adaptation — thick, fleshy stem stores water.
(b) Behavioural adaptation — active at night (nocturnal) to avoid daytime heat and reduce water loss.
(c) Spines (modified leaves) — reduce surface area to minimise water loss through transpiration; also deter herbivores.
Question 37 [4 marks]
(a) X: Xylem — transports water and mineral salts from roots to leaves.
Y: Phloem — transports food (sugar) from leaves to all parts of the plant.
(b) Xylem: Dead cells, hollow tubes, thick lignified walls (no cytoplasm/nucleus).
Phloem: Living cells (sieve tubes + companion cells), transport sugars bidirectionally.
(c) Transpiration pull — evaporation of water from stomata creates suction, pulling water up through xylem (cohesion-tension theory).
Question 38 [4 marks]
(a) Decreases — energy is lost as heat (respiration), waste (faeces/urine), and uneaten parts at each transfer.
(b) 100 J — 10% of 1000 J (primary consumer level).
(c) Pyramid of energy — always upright because energy decreases at each level; pyramid of numbers can be inverted (e.g., one tree → many insects).
(d) Shorter food chains — more energy reaches top consumers; less energy lost in transfers.
Question 39 [3 marks]
(a) Virus — non-cellular, protein coat (capsid) enclosing genetic material (DNA/RNA).
(b) Viruses cannot reproduce on their own — they must infect a living host cell and hijack its machinery to replicate.
(c) Vaccination — introduces weakened/dead virus to stimulate antibody production without causing disease.
Question 40 [4 marks]
(a) Insect — 3 body parts (head, thorax, abdomen), 6 legs, 1 pair of antennae, usually 2 pairs of wings.
(b) Arachnid — 2 body parts (cephalothorax, abdomen), 8 legs, no antennae, no wings.
(c) Complete metamorphosis: Egg → Larva → Pupa → Adult (e.g., butterfly, mosquito).
Incomplete metamorphosis: Egg → Nymph → Adult (e.g., grasshopper, cockroach). Nymph resembles small adult.
(d) Mosquito — larvae and pupae live in stagnant water; removing breeding sites breaks the life cycle.
Question 41 [4 marks]
(a) Camouflage — colour/pattern matches surroundings to avoid detection by predators or prey.
(b) Mimicry — harmless species mimics appearance of harmful species (e.g., viceroy butterfly mimics monarch) to deter predators.
(c) Polar bear: Thick fur + fat layer (insulation), white fur (camouflage), padded feet (insulation + grip on ice).
Cactus: Spines (reduce water loss), thick waxy cuticle, fleshy stem (water storage), deep/extensive roots.
(d) Adaptations are inherited traits that enhance survival and reproduction in a specific environment; they arise through natural selection over generations.
Question 42 [4 marks]
(a) Bacteria and Fungi (mould, yeast) — break down dead organic matter.
(b) Carbon cycle: Decomposers release CO₂ through respiration, returning carbon to atmosphere for photosynthesis.
Nitrogen cycle: Decomposers convert organic nitrogen → ammonia (ammonification) → nitrites/nitrates (nitrification) for plant uptake.
(c) Nutrients accumulate in dead matter → soil becomes infertile → plants cannot grow → food chains collapse.
(d) Composting — using decomposers to recycle kitchen/garden waste into nutrient-rich humus for soil fertility.
END OF ANSWER KEY