Primary 4 Science Semestral Assessment 2 (End of Year) Paper 4

TuitionGoWhere Practice Paper - Science Primary 4

SA2 Answer Key — Version 4 of 5

Total Marks: 50

Section A: Multiple Choice Questions (10 marks)

1. C — A potted plant is a living thing. Plastic bottles, wooden chairs (made from trees but no longer alive), and metal spoons are non-living.

2. B — All living things can grow. Not all living things can fly, are green, or live on land (e.g., fish live in water).

3. C — A fish has fins to move in water, while a bird has feathers and wings. Fish breathe through gills, not lungs, and most fish lay eggs.

4. C — A river is non-living. Caterpillars, mushrooms, and frogs are all living things.

5. C — Living things need food, water, and air to survive. Sunlight is needed by plants but not all living things directly; soil is not required by all living things.

6. B — Plants can make their own food through photosynthesis. Animals and fungi cannot make their own food.

7. B — Living things can reproduce (produce young). Size, location, and visibility are not reliable distinguishing features.

8. C — Not all living things are visible to the naked eye (e.g., bacteria). This is NOT a characteristic of all living things.

9. C — Cats and dogs are both mammals that feed their young with milk. They do not have feathers, do not breathe through gills, and do not lay eggs.

10. B — Biodiversity refers to the variety of different types of living things in an area.

Section B: Short Answer Questions (20 marks)

11. (2 marks) Any two of the following (1 mark each):

• They can grow.
• They need food and water.
• They can reproduce.
• They respond to changes in their surroundings.
• They breathe / respire.
• They can move (in some way).

Marking note: Accept any valid characteristic of living things. Do not accept "they are big" or "they are visible."

12. (2 marks) — ½ mark per correct classification

Marking note: Clouds are non-living (made of water droplets). Grass and butterflies are living. Rocks are non-living.

13. (3 marks)

(a) (1 mark) Any one valid difference, e.g.:

• Animal X has scales while Animal Y has fur.
• Animal X breathes through gills while Animal Y breathes through lungs.
• Animal X lives in water while Animal Y lives on land.
• Animal X lays eggs while Animal Y gives birth to live young.

(b) (2 marks) Both Animal X and Animal Y are living things because:

• They both need food and water to survive (1 mark).
• They both can reproduce / produce young (1 mark).

Accept other valid characteristics: they grow, they respond to changes, they breathe.

Marking note: Students must give two distinct reasons. Award 1 mark per valid reason.

14. (4 marks)

(a) (1 mark) The student found 3 living things (ant, flower, worm).

Marking note: Stone and puddle of water are non-living.

(b) (3 marks) Award 1 mark for naming a valid living thing (ant, flower, or worm) and 2 marks for two valid reasons.

Example answer (ant):

• It can move from place to place (1 mark).
• It needs food and water to survive (1 mark).

Example answer (flower):

• It can grow (1 mark).
• It can reproduce / produce seeds (1 mark).

Marking note: Accept any valid characteristic of living things. Reasons must be specific to the organism chosen.

15. (4 marks)

(a) (1 mark) Grass is the producer.

(b) (1 mark) Snake is the top consumer.

(c) (2 marks) If all the grasshoppers disappeared, the frog population would decrease (1 mark) because frogs depend on grasshoppers as a food source / frogs would not have enough food to eat (1 mark).

Marking note: Students must state the direction of change (decrease) AND give a reason related to food/dependency for full marks.

Section C: Structured / Extended Response Questions (20 marks)

16. (4 marks)

(a) (2 marks) The nature reserve has high biodiversity (1 mark) because there are many different types of living things (plants, insects, birds, and fish) living in the same area (1 mark).

Marking note: Award 1 mark for identifying high biodiversity and 1 mark for explaining the variety.

(b) (2 marks) — 1 mark per reason Any two of the following:

• It helps maintain a balanced ecosystem so that each organism has a role to play.
• It ensures that there is enough food for different animals in the food chain.
• It helps living things adapt to changes in the environment.
• It provides resources (medicine, food, materials) for humans.
• It keeps the environment healthy and stable.

Marking note: Accept any reasonable answer related to ecosystem balance, food chains, or environmental health.

17. (4 marks)

(a) (2 marks) Group A animals (eagle, sparrow, penguin) are birds that can fly or have feathers and live mainly on land/in the air (1 mark), while Group B animals (goldfish, shark, whale) are aquatic animals that live in water (1 mark).

Marking note: Accept any valid distinction — e.g., "Group A are birds, Group B are fish/sea animals" or "Group A can fly, Group B swim."

(b) (2 marks) A whale is a living thing because it breathes through lungs, gives birth to live young, and feeds its young with milk (any 1 valid characteristic, 1 mark). One characteristic it shares with other mammals is that it is warm-blooded / it has fur or hair (some whales have small amounts) / it feeds its young with milk (1 mark).

Marking note: Students may be surprised that whales are mammals. Award marks for any valid mammalian characteristic.

18. (4 marks)

(a) (2 marks) Organism 1 is a plant (1 mark) because it is green, rooted in soil, and makes food using sunlight (photosynthesis) (1 mark).

Marking note: The key evidence is that it "makes food using sunlight" — this is unique to plants.

(b) (2 marks) Organism 4 is still a living thing because:

• It can grow (1 mark).
• It can reproduce / produce young (1 mark).

Accept other valid reasons: it needs food and water, it responds to changes, it breathes.

Marking note: Students should understand that not all living things move from place to place (e.g., barnacles, corals, some molluscs). Award 1 mark per valid reason.

19. (4 marks)

(a) (2 marks) Organism P is most likely a bird (1 mark) because it has feathers (1 mark).

Marking note: Feathers are unique to birds. This is the key identifying feature.

(b) (2 marks) Organism Q is most likely a reptile (e.g., a lizard or crocodile) or an amphibian (e.g., a frog) (1 mark).

Evidence from the table:

• It lays eggs (1 mark).
• It is cold-blooded (not warm-blooded) (1 mark).

Marking note: Accept "reptile" or "amphibian" as the answer. Students must cite two pieces of evidence from the table for full marks. Award 1 mark for the identification and 1 mark for citing two valid pieces of evidence.

20. (4 marks)

(a) (2 marks) — ⅔ mark per living thing (accept any 3) Any three of the following: mudskippers, crabs, mangrove trees, algae, water snakes, kingfishers, monitor lizards.

Marking note: Fallen leaves (detached from tree), muddy water, and rocks are non-living. Do not award marks for these.

(b) (2 marks) — 1 mark per valid explanation Any two of the following:

• Food dependence: Kingfishers eat mudskippers and crabs, so the birds depend on these animals for food. If the fish and crabs disappeared, the kingfishers would have less food.
• Habitat dependence: Mangrove trees provide shelter and nesting sites for kingfishers and monitor lizards.
• Oxygen and carbon dioxide exchange: Mangrove trees and algae produce oxygen that animals need, while animals produce carbon dioxide that plants need.
• Nutrient cycling: Fallen leaves from mangrove trees decompose and provide nutrients for algae and small organisms, which are then eaten by crabs and mudskippers.

Marking note: Accept any reasonable explanation showing interdependence. Award 1 mark per valid, distinct explanation.

END OF ANSWER KEY