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Primary 5 Science Semestral Assessment 2 (End of Year) Paper 1
Free P5 Science SA2 Paper 1, Qwen3.7 Exam version, with questions, answers, and syllabus-aligned practice for Singapore students.
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Questions
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Answers
Answer Key - Science Primary 5 SA2 Practice Paper (Version 1)
Topic Focus: Diversity
Section A (28 marks)
1. (1)
- Reasoning: Bats, whales, and dolphins are all mammals. They give birth to live young, have hair/fur (even if minimal in whales), and feed their young with milk. Penguins are birds; Sharks are fish; Frogs are amphibians.
2. (2)
- Reasoning: According to the key, Q is the organism that has feathers. Having feathers is the defining characteristic of birds.
3. (3)
- Reasoning: Insects have three body parts (head, thorax, abdomen), six legs, and a hard outer covering (exoskeleton). Spiders have 8 legs; Centipedes have many legs; Earthworms have no legs and no hard covering.
4. (2)
- Reasoning: Spines have a very small surface area compared to broad leaves. This reduces the rate of water loss through transpiration, which is crucial for survival in dry environments.
5. (2)
- Reasoning: Polar bears live in freezing environments. A thick layer of fat (blubber) provides insulation to keep them warm, and white fur provides camouflage in the snow.
6. (3)
- Reasoning: Plant Z has spines (reduced leaves to save water), a fleshy stem (to store water), and shallow widespread roots (to absorb rain quickly from a large area). These are classic desert adaptations.
7. (2)
- Reasoning: Producers (plants) make their own food via photosynthesis. This energy is stored in their tissues and passed on to consumers when they are eaten.
8. (3)
- Reasoning: Fungi are not plants; they lack chlorophyll and cannot photosynthesize. They are saprophytes, meaning they obtain nutrients by breaking down dead and decaying organic matter.
9. (2)
- Reasoning: Frogs eat grasshoppers. If the frog population decreases, fewer grasshoppers are eaten, so the grasshopper population will likely increase. Snakes eat frogs, so snake population might decrease, not increase.
10. (3)
- Reasoning: Structural adaptations are physical features of an organism. Webbed feet are a physical structure. Hibernation, colour change (physiological/behavioral mix, but often considered physiological in this context or behavioral response), and migration are behavioral or physiological. Note: In Primary science, webbed feet is the clearest structural example.
11. (2)
- Reasoning: Decomposers break down dead organisms and waste, releasing nutrients (minerals) back into the soil, which plants then use to grow. This recycles nutrients in the ecosystem.
12. (2)
- Reasoning: A streamlined body reduces drag (water resistance), allowing the fish to swim efficiently. Gills are specialized organs that extract dissolved oxygen from water.
13. (2)
- Reasoning: Bees get nectar (food) from flowers, and flowers get pollinated by bees. Both benefit. Ticks harm dogs; Lions eat zebras; Mistletoe takes nutrients from trees (parasitism).
14. (2)
- Reasoning: The organism has six legs (implied by antennae and typical cave dwellers like crickets/beetles, though the prompt says "long antennae" and "feeds on droppings"). Among the options, Insects are the most likely group for small, antennae-bearing creatures in caves. Mammals have fur; Reptiles have scales; Amphibians have moist skin. The description fits an insect (e.g., cave cricket).
Section B (28 marks)
15. (a) Leaf A has a larger surface area than Leaf B. [1] (b) The waxy coating prevents water loss / reduces transpiration. [1] It acts as a waterproof barrier. [1] (c) Leaf A has a large surface area, which would lead to excessive water loss through transpiration in a hot desert, causing the plant to dry out and die. [1]
16. (a) Birds. [1] (b) They have hair/fur. [1] OR They feed their young with milk. [1] (c) Bats give birth to live young [1] and feed their young with milk [1]. Birds lay eggs. Therefore, bats are mammals.
17. (a) Algae. [1] (b) The population of Tadpoles will increase. [1] This is because there are fewer Small Fish to eat them (reduced predation). [1] (c) Energy is lost at each trophic level / food chain level. [1] Only a small amount of energy is passed from Algae to Tadpoles, and even less to Large Fish. Therefore, the ecosystem can support fewer Large Fish than Algae. [1]
18. (a) Camouflage. [1] (b) The foul smell drives away / repels predators. [1] This gives the skunk time to escape / prevents the predator from attacking. [1] (c) Example: Leaf insect / Chameleon / Arctic Fox. [1] Explanation: It blends in with its surroundings (leaves / environment / snow), making it hard for predators to see it. [1]
19. (a) Bacteria and Fungi. [2] (1 mark each) (b) Dead organisms and waste would pile up / accumulate. [1] Nutrients would not be recycled back into the soil, so plants would not get enough nutrients to grow, affecting the whole ecosystem. [1]
20. (a) Frogs live both on land and in water. [1] They use lungs to breathe air on land and moist skin to absorb oxygen from water or when underwater. [1] (b) Lungs. [1] Whales are mammals, and all mammals breathe air using lungs. They need to surface to breathe. [1] (c) Gills have many fine filaments / large surface area [1] to maximize the absorption of dissolved oxygen from water.