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Primary 5 Science Semestral Assessment 2 (End of Year) Paper 2
Free P5 Science SA2 Paper 2, LongCat Exam version, with questions, answers, and syllabus-aligned practice for Singapore students.
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TuitionGoWhere Practice Paper - Science Primary 5
SA2 (Version 2 of 5) — Answer Key
Section A: Multiple Choice (10 marks)
| Qn | Answer | Marks | Notes |
|---|---|---|---|
| 1 | (B) The variety of living organisms in an environment | 1 | Biodiversity refers to the range of different species, not just animals or plants alone. |
| 2 | (B) The natural home or environment of an organism | 1 | A habitat includes all the conditions an organism needs to survive. |
| 3 | (B) Whether they can make their own food | 1 | Classification is based on biological characteristics, not superficial traits like colour or sound. |
| 4 | (C) Plants | 1 | Plants are producers that carry out photosynthesis using sunlight. |
| 5 | (C) Frog | 1 | Frogs are amphibians and have a backbone. Spiders, earthworms, and snails are invertebrates. |
| 6 | (D) Omnivore | 1 | Omnivores eat both plants and animals. Herbivores eat only plants; carnivores eat only animals. |
| 7 | (B) Mushroom | 1 | Mushrooms are fungi that break down dead organic matter, acting as decomposers. |
| 8 | (B) It ensures a balanced and stable ecosystem | 1 | Biodiversity supports ecosystem stability through food webs and ecological balance. |
| 9 | (B) It has gills for breathing | 1 | Gills allow fish to extract oxygen from water — a key structural adaptation for aquatic life. |
| 10 | (C) A producer | 1 | Food chains always begin with producers (e.g., plants) that convert sunlight into food energy. |
Section B: Short Answer (20 marks)
11. (4 marks)
(a) (2 marks)
- Producer: Flowering plant (1 mark)
- Consumers: Butterfly, earthworm, bird (1 mark — all three must be named for the mark)
(b) (2 marks)
- The flowering plant is a producer because it can make its own food (1 mark) through photosynthesis using sunlight, water, and carbon dioxide (1 mark).
- Accept: Any valid explanation that the plant produces its own food / carries out photosynthesis.
12. (3 marks)
(a) (2 marks)
- Group X: Birds (1 mark)
- Group Y: Mammals (1 mark)
(b) (1 mark)
- Accept any one valid feature:
- Birds have wings/beaks; mammals do not.
- Birds have hollow bones; mammals have solid bones.
- Mammals nurse their young with milk; birds do not.
- Birds have a beak; mammals have teeth.
13. (3 marks)
(a) (1 mark)
- Small fish is the secondary consumer.
- Reasoning: Algae (producer) → Water flea (primary consumer) → Small fish (secondary consumer) → Heron (tertiary consumer).
(b) (2 marks)
- The heron population would decrease (1 mark) because herons depend on small fish as a food source, so less food would be available (1 mark).
- Accept: Herons would have less food and may die or move away.
14. (4 marks)
(a) (1 mark)
- The hard, dark shell provides protection from predators (camouflage in dark forest floor / physical defence).
- Accept: Any valid advantage — camouflage, protection from being eaten, protection from injury.
(b) (1 mark)
- The bright colouring may serve as a warning to predators that the beetle is poisonous or tastes bad (aposematism).
- Accept: Warning colouration / deterring predators.
(c) (2 marks)
- The two beetles have different adaptations that allow them to survive in different ways (1 mark), reducing direct competition for the same resources and allowing both species to coexist in the same forest (1 mark).
- Accept: Any valid explanation of how different survival strategies reduce competition.
15. (3 marks)
(a) (2 marks)
- Habitat P (Forest) has greater biodiversity (1 mark) because it has a higher number of species recorded (105–120 species) compared to Habitat Q (62–85 species) (1 mark).
(b) (1 mark)
- Accept any one valid reason:
- Deforestation / habitat destruction
- Pollution
- Climate change
- Human development / urbanisation
- Overgrazing
- Introduction of invasive species
Section C: Structured / Longer Response (20 marks)
16. (6 marks)
(a) (2 marks)
- Working: (15 + 17 + 16) ÷ 3 = 48 ÷ 3 = 16 (1 mark for correct working, 1 mark for correct answer)
- Average = 16 animal species
(b) (2 marks)
- Area A has a higher biodiversity of animal species (1 mark) compared to Area B, which has far fewer species (average of about 5) (1 mark).
(c) (2 marks)
- Greater plant diversity provides more types of food and shelter for animals (1 mark), which supports a greater variety of animal species (higher animal biodiversity) (1 mark).
- Accept: More plant types → more habitats/food sources → more animal species can survive.
17. (6 marks)
(a) (2 marks)
- Accept any two: Mudskipper, crab, monitor lizard, bird (1 mark each; max 2 marks)
(b) (2 marks)
- The special roots of mangrove trees provide shelter / a habitat for small fish and crabs (1 mark), protecting them from predators and strong currents (1 mark).
- Accept: Roots provide hiding places / breeding grounds / attachment surfaces.
(c) (2 marks)
- Accept any two valid effects (1 mark each):
- Loss of habitat for organisms that depend on mangroves
- Decrease in biodiversity / species extinction
- Disruption of food chains and food webs
- Loss of breeding grounds for fish and other aquatic organisms
- Reduced coastal protection (mangroves protect shorelines)
18. (6 marks)
(a) (2 marks)
- Accept any two: Rabbit, mouse, fox, owl, frog, snake, grasshopper (1 mark each; max 2 marks)
- Note: Grass is a producer, not a consumer.
(b) (2 marks)
- Owl occupies two different trophic levels (1 mark). Owl is a secondary consumer when it eats the mouse, and a tertiary consumer when it eats the snake (which is also a tertiary consumer eating the frog) (1 mark).
- Alternative acceptable answer: Frog — primary consumer when eating grasshopper (actually secondary consumer: grass → grasshopper → frog), and then becomes prey for owl/snake. Award marks if reasoning is valid.
- Clarification for marking: Owl eats mouse (secondary consumer position: grass → mouse → owl) and eats snake/frog (tertiary consumer position: grass → grasshopper → frog → owl). Award 2 marks for correct organism with valid explanation.
(c) (2 marks)
- If all frogs were killed, the owl would lose one of its food sources (1 mark). The owl population may decrease because there is less food available, or the owl would have to rely more on other prey such as mice (1 mark).
- Accept: Owl population decreases; owl switches to other prey.
19. (4 marks)
(a) (3 marks)
- Both students have valid points (1 mark). A garden can have high biodiversity if many different species are planted and maintained (1 mark), but a desert also has biodiversity because organisms have adapted to survive in harsh conditions — biodiversity is not just about the number of species but also about the variety of adaptations and ecological roles (1 mark).
- Alternative marking: Award 3 marks if the student clearly explains that biodiversity depends on the variety of living organisms in an environment, and both gardens and deserts can have biodiversity in different ways.
- Accept: Agreement with Ali only (max 2 marks) or Bala only (max 2 marks) if well-explained.
(b) (1 mark)
- Accept any one valid adaptation:
- Cacti store water in their stems
- Camels store fat in their humps for energy
- Desert foxes have large ears to dissipate heat
- Some desert animals are nocturnal to avoid daytime heat
- Desert plants have deep roots to reach underground water
20. (5 marks)
(a) (1 mark)
- Total = 200 + 85 + 30 + 50 = 365 species
(b) (1 mark)
- Mammals have the least number of species (30 species).
(c) (2 marks)
- Accept any two valid reasons (1 mark each):
- Protects habitats from destruction
- Prevents species from becoming extinct
- Maintains food chains and food webs
- Preserves genetic diversity
- Provides areas for organisms to breed and grow
- Maintains ecological balance
(d) (1 mark)
- Accept any one valid action:
- Plant more trees or create a school garden
- Reduce, reuse, and recycle to reduce pollution
- Do not litter in natural areas
- Learn about and raise awareness of local wildlife
- Create habitats (e.g., insect hotels) in the school garden
- Avoid disturbing animals and plants in the school environment
END OF ANSWER KEY
Mark Summary
| Section | Marks |
|---|---|
| Section A (Q1–10) | 10 |
| Section B (Q11–15) | 20 |
| Section C (Q16–20) | 20 |
| Total | 50 |