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Primary 6 PSLE Science Semestral Assessment 2 (End of Year) Paper 5

Free P6 PSLE Science SA2 Paper 5, Qwen3.7 Exam version, with questions, answers, and PSLE-focused practice for Singapore students.

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Primary 6 PSLE Science From Real Exams Generated by Qwen3.7 Plus Updated 2026-08-17
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Answers

TuitionGoWhere Practice Paper - Science Primary 6 PSLE (Version 5)

Answer Key and Marking Scheme

Section A (28 marks)

QnAnswerQnAnswer
11152
24161
31172
42182
52193
62202
72213
83222
93233
102242
112252
122264
134272
141283

Section B (28 marks)

29. (a) They have a backbone / vertebral column. [1] (b) A spider does not have a backbone. [1] It is an invertebrate. [1] Teaching Note: Group A represents vertebrates. Group B represents invertebrates. The key distinguishing feature is the presence of a backbone.

30. (a) Cabbage [1] (b) The population of caterpillars will increase. [1] Because there is less competition for food (cabbage) from snails. [1] Teaching Note: Removing one consumer (snail) reduces competition for the producer (cabbage), allowing the other consumer (caterpillar) to thrive initially.

31. (a) Leaf B [1] (b) It has a small surface area to reduce water loss through transpiration. [1] It has a thick waxy coating to prevent water loss. [1] Teaching Note: Adaptations for dry environments focus on water conservation. Small surface area and waxy cuticles are key features.

32. (a) Forest Y [1] Because the number of individuals is more evenly distributed among the species, indicating a more balanced ecosystem. [1] Alternative Answer: Forest Y has higher biodiversity because it supports a more stable population of different species, whereas Forest X is dominated by a few species. (b) It makes the ecosystem more resistant to diseases and environmental changes. [1] If one species dies out, others can take its place in the food web. [1] Teaching Note: Biodiversity provides resilience. A monoculture (low diversity) is vulnerable to collapse if a specific threat targets the dominant species.

33. (a) Tube B [1] (b) The boiled water has no dissolved oxygen. [1] The layer of oil prevents oxygen from the air from dissolving into the water. Seeds need oxygen to germinate. [1] Teaching Note: Germination requires water, warmth, and oxygen. Tube C lacks oxygen.

34. (a) The Sun [1] (b) The population of tuna will decrease. [1] Because there will be fewer small fish for the tuna to eat as the small fish population decreases due to lack of zooplankton. [1] Teaching Note: Energy flows up the food chain. A decrease at a lower level causes a decrease at higher levels due to food scarcity.

35. (a) Anther [1] (b) The stigma is sticky to trap pollen grains. [1] This allows pollination to occur. [1] Teaching Note: The stigma is part of the female reproductive organ (pistil) and is adapted to catch pollen.

36. (a) Algae →\rightarrow Dragonfly larva →\rightarrow Frog →\rightarrow Heron [2] Accept any valid chain starting with a producer (Algae or Water lily) and ending with a top consumer. Arrows must be in the correct direction. (b) They can make their own food through photosynthesis. [1]

37. (a) It has humps to store fat (which can be converted to water/energy). OR It has long eyelashes to keep sand out of its eyes. [1] (b) The thick fur traps a layer of air. [1] Air is a poor conductor of heat, so it reduces heat loss from the body to the cold environment. [1] Teaching Note: Adaptations for cold environments focus on heat retention. Fur/fat acts as insulation.

38. (a) Virus [1] (b) It has no nucleus. [1] It reproduces by binary fission. [1] Teaching Note: Bacteria are prokaryotes (no nucleus). Viruses are non-living and need a host. Fungi have nuclei and reproduce by spores/budding.

39. Decomposers break down dead organisms and waste materials. [1] This releases nutrients (such as nitrogen and minerals) back into the soil. [1] Plants then absorb these nutrients to grow, completing the nutrient cycle. [1] Teaching Note: Decomposers are the recyclers of the ecosystem. Without them, nutrients would remain locked in dead matter.

40. (a) Because there are the most producers (grass) to support the consumers above them. [1] Energy is lost at each trophic level, so fewer organisms can be supported at higher levels. [1] (b) The population of grass will decrease. [1] If birds are eaten by a new predator, the bird population decreases. [1] This leads to an increase in the grasshopper population (less predation), which then eats more grass. [1] Teaching Note: This tests understanding of trophic cascades. Removing a top predator often leads to an explosion of primary consumers and a decline in producers.