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Primary 6 PSLE Science Semestral Assessment 2 (End of Year) Paper 3
Free P6 PSLE Science SA2 Paper 3, Nemo3 Exam version, with questions, answers, and PSLE-focused practice for Singapore students.
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TuitionGoWhere Practice Paper - Science Primary 6 PSLE (Answer Key)
TuitionGoWhere Exam Practice (AI)
Subject: Science
Level: Primary 6 PSLE
Paper: SA2 Version 3
Total Marks: 100
BOOKLET A (56 marks)
1
Answer: (1) Mould, yeast, mushroom
Marks: 2
Explanation: Mould, yeast, and mushroom are all fungi. Fern and moss are non-flowering plants. Bacteria and viruses are microorganisms but not fungi. Algae are plant-like protists.
2
Answer: (3) Feed on dead or living organisms | Feed on dead or living organisms
Marks: 2
Explanation: Group X (Bacteria, Amoeba, Paramecium) are microorganisms that obtain food by feeding on other organisms (heterotrophic). Group Y (Mushroom, Mould, Yeast) are fungi, which are saprotrophs that feed on dead and decaying matter. Neither group makes its own food.
3
Answer: (3) Some microorganisms are useful in food production.
Marks: 2
Explanation: Yeast is used in bread making and brewing. Bacteria are used in yoghurt, cheese, and fermented foods. Not all microorganisms are harmful (many are beneficial), most cannot be seen with the naked eye, and all microorganisms need air, water, and food to survive.
4
Answer: (3) Cell wall
Marks: 2
Explanation: Plant cells have a cell wall made of cellulose, chloroplasts, and a large central vacuole. Animal cells lack a cell wall, chloroplasts, and have only small vacuoles. Both have a nucleus, cytoplasm, and cell membrane.
5
Answer: (4) Devi
Marks: 2
Explanation: Bacteria are prokaryotic microorganisms classified in their own domain (Bacteria). They are neither plants (no chloroplasts, different cell wall composition), nor animals (unicellular, no ingestion), nor fungi (different cell wall, no chitin).
6
Answer: (1) P
Marks: 2
Explanation: Organism P has a cell wall and chloroplasts (photosynthetic) but does not reproduce by spores or feed on decaying matter — characteristics of a flowering plant. Q and R have chitin cell walls, reproduce by spores, and feed on decaying matter — fungi. S lacks a cell wall — likely an animal.
7
Answer: (3) They can move from place to place.
Marks: 2
Explanation: Not all living things move from place to place (locomotion). Plants are living but are generally fixed in one place. All living things need air, food, water; can reproduce; and respond to stimuli.
8
Answer: (3) Fungi
Marks: 2
Explanation: Following the flowchart: Does not make own food → feeds on dead/decaying matter → Fungi. Fungi are saprotrophs that reproduce by spores.
9
Answer: (2) Bird, fish, mammal
Marks: 2
Explanation: Birds, fish, and mammals are all vertebrates (have backbones). Frog is a vertebrate but earthworm is an invertebrate. Insect, spider, crab are arthropods (invertebrates). Snail, jellyfish, starfish are invertebrates.
10
Answer: (2) Birds
Marks: 2
Explanation: The animal has feathers, wings, beak, lays eggs, and has two legs with claws — all characteristic features of birds. Mammals have hair/fur and produce milk. Reptiles have dry scaly skin. Amphibians have moist skin.
11
Answer: (3) Mammals feed their young with milk.
Marks: 2
Explanation: This is a defining characteristic of mammals. Not all winged animals are birds (e.g., bats are mammals, insects have wings). Not all egg-layers are reptiles (birds, monotremes, amphibians, fish lay eggs). Amphibians have moist skin, not dry scaly skin.
12
Answer: (4) Z
Marks: 2
Explanation: Animal Z has hair/fur, breathes with lungs, and gives birth to live young — all mammalian characteristics. W has scales and lays eggs (reptile). X has moist skin and metamorphosis (amphibian). Y has feathers and lays eggs (bird).
13
Answer: (1) Bacteria | Yeast | Mould
Marks: 2
Explanation: View A shows rod-shaped single cells (typical bacteria). View B shows oval cells with buds (yeast budding reproduction). View C shows thread-like hyphae with spores (mould structure).
14
Answer: (2) Yeast used in bread making
Marks: 2
Explanation: Yeast ferments sugar to produce carbon dioxide, which causes bread dough to rise. Salmonella causes food poisoning, viruses cause diseases, mould on spoiled food indicates spoilage.
15
Answer: (3) Frog
Marks: 2
Explanation: The frog eats grasshoppers (predator) and is eaten by snakes (prey). Grass is a producer. Grasshopper is a primary consumer (prey only in this chain). Eagle is a top predator.
16
Answer: (3) Producer → Consumer → Decomposer
Marks: 2
Explanation: Energy flows from producers (plants) to consumers (herbivores, then carnivores) to decomposers (bacteria, fungi) which break down dead matter and recycle nutrients.
17
Answer: (4) The population of snakes may decrease.
Marks: 2
Explanation: Grasshoppers are prey for frogs and snakes. Fewer grasshoppers → less food for frogs and snakes → their populations may decrease. Plants may increase (less herbivory). Mice are not directly affected.
18
Answer: (3) They break down dead organisms and waste, returning nutrients to the environment.
Marks: 2
Explanation: Decomposers (bacteria, fungi) are saprotrophs that externally digest dead organic matter and absorb nutrients, recycling them back into the ecosystem for producers to use.
19
Answer: (3) Dicotyledon
Marks: 2
Explanation: The plant has broad leaves with network (reticulate) veins, a taproot system, flowers with 5 petals (multiple of 4 or 5), and seeds in a fruit — all characteristics of dicotyledons. Monocots have parallel veins, fibrous roots, flower parts in multiples of 3.
20
Answer: (2) Broad, flat leaves that float on water
Marks: 2
Explanation: Water lilies have broad floating leaves to capture sunlight on the water surface. Deep roots (1) are for dry habitats. Thick waxy leaves (3) and spines (4) are adaptations to reduce water loss in dry (xerophytic) habitats.
21
Answer: (3) Egg, larva, and pupa
Marks: 2
Explanation: Mosquito eggs are laid in water. Larvae (wrigglers) and pupae (tumblers) are aquatic stages. Only the adult mosquito is terrestrial and flies.
22
Answer: (4) By photosynthesis
Marks: 2
Explanation: Photosynthesis is the process by which plants make food, not a method of seed dispersal. Wind, water, and animals are the three main agents of seed dispersal.
23
Answer: (3) By splitting action (explosive dispersal)
Marks: 2
Explanation: The pod-like fruit that splits open when dry, flinging seeds away, is characteristic of explosive dispersal (e.g., pea, bean, rubber tree).
24
Answer: (4) Digestion of food is completed in the small intestine.
Marks: 2
Explanation: Digestion starts in the mouth (starch), continues in the stomach (protein), and is completed in the small intestine (all nutrients). The small intestine absorbs digested nutrients. The large intestine absorbs water.
25
Answer: (3) Alveoli
Marks: 2
Explanation: Gaseous exchange (oxygen in, carbon dioxide out) occurs in the alveoli (air sacs) where the walls are one cell thick and surrounded by capillaries. The trachea and bronchi are air passages.
26
Answer: (1) Nose → Trachea → Bronchi → Bronchioles → Alveoli
Marks: 2
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TuitionGoWhere Practice Paper - Science Primary 6 PSLE (Answer Key)
TuitionGoWhere Exam Practice (AI)
Subject: Science
Level: Primary 6 PSLE
Paper: SA2 Version 3
BOOKLET A (56 marks)
| Question | Answer | Explanation |
|---|---|---|
| 1 | (1) | Mould, yeast, and mushroom are all classified as fungi. Fern and moss are non-flowering plants. Bacteria and viruses are microorganisms but not fungi. Algae are plant-like protists. |
| 2 | (3) | Group X (Bacteria, Amoeba, Paramecium) are microorganisms that feed on dead or living organisms (heterotrophic). Group Y (Mushroom, Mould, Yeast) are fungi which are decomposers feeding on dead or decaying matter (saprotrophic). Neither group makes its own food. |
| 3 | (3) | Some microorganisms are useful in food production (e.g., yeast in bread/beer, bacteria in yogurt/cheese). Not all are harmful (1), most cannot be seen with the naked eye (2), and they need air, water, and food to survive (4). |
| 4 | (3) | The cell wall is a rigid structure made of cellulose found in plant cells but absent in animal cells. Nucleus, cytoplasm, and cell membrane are present in both. |
| 5 | (4) | Devi is correct. Bacteria are prokaryotic microorganisms classified in their own domain (Bacteria/Monera), distinct from plants, animals, and fungi. They have cell walls (peptidoglycan, not cellulose), some can move, but they reproduce by binary fission, not spores. |
| 6 | (1) | Organism P has a cell wall and chloroplasts (photosynthesises) but does not reproduce by spores or feed on decaying matter. This matches a flowering plant. Q and R are fungi (cell wall, spores, saprotrophic). S is an animal (no cell wall). |
| 7 | (3) | Not all living things can move from place to place (locomotion). Plants are living but generally fixed in one place. All living things need air, food, water; can reproduce; and respond to stimuli. |
| 8 | (3) | Following the flowchart: Does not make own food (No) → Feeds on dead/decaying matter (Yes) → Fungi. Reproduction by spores is a characteristic of fungi. |
| 9 | (2) | Vertebrates have a backbone. Bird, fish, and mammal are all vertebrate classes. Frog (amphibian) and snake (reptile) are vertebrates, but earthworm is an invertebrate. Insect, spider, crab are arthropods (invertebrates). Snail (mollusc), jellyfish (cnidarian), starfish (echinoderm) are invertebrates. |
| 10 | (2) | The features described (feathers, wings, two legs with claws, beak, lays eggs) are defining characteristics of Birds. |
| 11 | (3) | Mammals are defined by the presence of mammary glands to feed young with milk. (1) Bats (mammals) and insects have wings. (2) Birds, monotremes, amphibians, fish, reptiles lay eggs. (4) Amphibians have moist, permeable skin; reptiles have dry, scaly skin. |
| 12 | (4) | Animal Z has hair/fur, breathes with lungs, and gives birth to live young – characteristics of Mammals. W is a reptile, X is an amphibian, Y is a bird. |
| 13 | (1) | View A: Rod-shaped single cells = Bacteria. View B: Oval cells with buds = Yeast (budding reproduction). View C: Thread-like structures (hyphae) with spores = Mould. |
| 14 | (2) | Yeast is used in bread making (fermentation produces CO2 to make dough rise). Salmonella, cold viruses, and spoilage mould are harmful. |
| 15 | (3) | Frog eats grasshopper (predator) and is eaten by snake (prey). Grass is a producer. Grasshopper is prey (to frog) but not a predator (eats plants). Eagle is a top predator only. |
| 16 | (3) | Energy flows: Producer (makes food) → Consumer (eats producer/other consumers) → Decomposer (breaks down dead matter). |
| 17 | (4) | Grasshoppers are prey for frogs, spiders, birds. If grasshoppers decrease, their predators (frogs, snakes via frogs/birds) have less food, so populations may decrease. Plants may increase (less herbivory). Mice are not directly linked to grasshoppers. |
| 18 | (3) | Decomposers (bacteria, fungi) break down dead organisms and waste, returning nutrients to the environment for producers to reuse. |
| 19 | (3) | Broad leaves with network (reticulate) veins, taproot system, flower parts in 4s/5s, seeds in fruit → Dicotyledon. Monocots have parallel veins, fibrous roots, flower parts in 3s. |
| 20 | (2) | Water lilies have broad, flat leaves that float on water to capture sunlight. They don't need deep roots for water (1), thick waxy leaves are for xerophytes (3), spines are for cacti (4). |
| 21 | (3) | Mosquito eggs are laid in water; larvae (wrigglers) and pupae (tumblers) are aquatic. Only the adult is terrestrial/flying. So Egg, larva, and pupa live in water. |
| 22 | (4) | Photosynthesis is the process of making food, not a method of seed dispersal. Wind, water, and animals are standard dispersal agents. |
| 23 | (3) | A pod that splits open when dry to scatter seeds describes explosive dispersal (splitting action). Examples: pea, bean, rubber tree. |
| 24 | (4) | Digestion starts in the mouth, continues in stomach, and is completed in the small intestine where most absorption of nutrients occurs. Large intestine absorbs water (2, 3 incorrect). |
| 25 | (3) | Gaseous exchange (O2 in, CO2 out) occurs in the alveoli (air sacs) due to thin walls and rich capillary network. |
| 26 | (1) | Correct anatomical path: Nose → Trachea → Bronchi → Bronchioles → Alveoli. |
| 27 | (1) | During respiration, cells use oxygen and produce carbon dioxide. Hence exhaled air has less O2 (16% vs 21%) and more CO2 (4% vs 0.04%). Nitrogen is inert. Water vapour increases due to moist respiratory surfaces. |
| 28 | (3) | Running is vigorous exercise requiring more oxygen/nutrients, increasing heart rate the most. Sleeping, reading, sitting are low activity. |
BOOKLET B (44 marks)
29
(a) Both have a cell wall. (Accept: Both are living things / made of cells)
(b) Organism A is single-celled (unicellular) with no nucleus (prokaryotic); Organism B is multi-cellular with a nucleus (eukaryotic). (Accept: A has flagellum/moves, B is fixed/has chloroplasts)
(c) Bacteria (or Monera / Prokaryotes)
30
(a) Flowering plants and Non-flowering plants.
(b) Fern (or Moss / Non-flowering plant that reproduces by spores).
(c) Pine tree / Conifer / Cypress / Ginkgo (any gymnosperm example).
31
(a) Food chain 1: Grass → Grasshopper → Frog → Hawk (or Grass → Grasshopper → Bird → Hawk, etc.)
Food chain 2: Shrubs → Aphid → Ladybird → Bird → Hawk (or Trees → Caterpillar → Bird → Hawk, etc.)
(Must start with producer, arrows show energy flow, min 3 organisms)
(b) The aphid population will increase. Ladybirds are predators of aphids. With no ladybirds, fewer aphids are eaten, so their population rises (until limited by food/other predators).
32
(a) Plant cell (has cell wall, chloroplasts, large central vacuole).
(b) Nucleus.
(c) Contain chlorophyll to trap light energy for photosynthesis (make food).
(d) No. Mitochondria are too small to be seen under a light microscope / not shown in simplified diagrams. Plant cells have mitochondria for respiration (release energy).
33
(a) Y (No nucleus = prokaryote = bacterium; peptidoglycan cell wall).
(b) X (Has nucleus, chitin cell wall, no chloroplasts, saprotrophic = fungus).
(c) W (Has nucleus, cellulose cell wall, chloroplasts, autotrophic = plant).
(d) Z (Has nucleus, no cell wall, no chloroplasts, heterotrophic = animal).
34
(a) Diffusion (of oxygen from alveoli into blood / carbon dioxide from blood into alveoli).
(b) Alveoli have: (1) Thin walls (one cell thick) for short diffusion distance; (2) Large surface area (many alveoli); (3) Rich blood supply (dense capillary network) / Moist lining for gases to dissolve. (Any two)
(c) Haemoglobin in red blood cells binds to oxygen to form oxyhaemoglobin for transport.
35
(a) Water-crowfoot (or Hydrilla / Elodea / any submerged aquatic plant).
(b) Narrow / finely divided / dissected leaves to reduce water resistance / prevent tearing by currents; No / reduced stomata on leaves; Flexible stems to move with water; Air spaces (aerenchyma) in stems/leaves for buoyancy/gas exchange. (Any one)
(c) Floating leaves (broad, flat, waxy upper surface, stomata on upper surface only) to absorb sunlight / exchange gases with air; Long, flexible leaf stalks to reach water surface. (Any one)
36
(a) Stigma (receives pollen).
(b) Anther (produces pollen).
(c) Ovary (develops into fruit after fertilisation).
(d) Ovule (develops into seed after fertilisation).
37
(a) Germination.
(b) Air (oxygen), Water, Warmth (suitable temperature). (All three required)
(c) The seed leaves (cotyledons) store food / provide nutrients for the seedling until the first true leaves can photosynthesise.
38
(a) Circulatory system (heart, blood vessels, blood).
(b) Heart (pumps blood).
(c) Arteries carry oxygenated blood away from heart (except pulmonary artery); Veins carry deoxygenated blood back to heart (except pulmonary vein). Arteries have thicker, more muscular walls; higher pressure. Veins have valves; lower pressure. (Any one difference)
(d) Capillaries have walls one cell thick to allow exchange of substances (oxygen, nutrients, waste) between blood and cells by diffusion.
39
(a) Evaporation (water changes from liquid to gas/vapour).
(b) Condensation (water vapour changes to liquid droplets).
(c) Heat gain (from surroundings/sun) causes evaporation; Heat loss (to cooler air) causes condensation.
(d) The water cycle ensures continuous supply of fresh water (rain) for living things; distributes water globally; regulates climate/temperature. (Any one)
40
(a) Shadow is formed when light is blocked by an opaque/translucent object. Light travels in straight lines.
(b) Move the torch closer to the object (or move object closer to torch / move screen further away).
(c) The shadow becomes sharper / less fuzzy (smaller penumbra) because the light source acts more like a point source / rays are more parallel. (Or: Shadow size increases if screen distance fixed).
41
(a) Repel (Like poles face each other: North-North or South-South).
(b) Attract (Unlike poles face: North-South).
(c) Stroke the steel rod with a magnet (stroking method) using one pole, in one direction, repeatedly. (Or: Electrical method - coil wire around rod, pass DC current).
(d) Heat the magnet / Hammer the magnet / Drop it repeatedly / Store it incorrectly (e.g., N-pole to N-pole). (Any one)
42
(a) Gravitational potential energy → Kinetic energy + Heat energy + Sound energy.
(b) Some kinetic energy is converted to heat and sound energy due to friction (air resistance, ramp surface) / not all GPE converts to KE.
(c) Increase the height of the ramp (more GPE) / Use a smoother ramp/ball (less friction) / Use a heavier ball (more GPE). (Any one)
43
(a) Circuit A: Bulbs are brighter. (Series vs Parallel: In parallel, each bulb gets full battery voltage; in series, voltage is shared).
(b) Circuit B (Parallel). In parallel, if one bulb fuses, the other circuit path remains closed. In series (A), one fused bulb breaks the only path.
(c) Add more batteries in series / Use batteries with higher voltage / Use bulbs with lower resistance (higher wattage). (Any one)
44
(a) C (Copper is a good conductor of heat; metal spoon transfers heat fast from hot soup to hand).
(b) A (Plastic/Wood is a poor conductor of heat / good insulator; handle stays cool).
(c) Conduction (Heat travels through the solid spoon from hotter end to cooler end).
(d) Air is a poor conductor of heat (good insulator). The air pockets in the handle reduce heat transfer by conduction.
End of Answer Key