Primary 5 Science Practice Paper 5

TuitionGoWhere Practice Paper — Science Primary 5

Answer Key — Diversity (Topic Focus)

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Section A — Multiple Choice (20 marks)

1. (B) — Biodiversity refers to the variety of living organisms (plants, animals, fungi, microorganisms) in a given area or ecosystem. It is not limited to just animals or just plants.

2. (B) — A habitat is the natural home or environment in which an organism lives. It provides the organism with food, water, shelter, and space to survive.

3. (B) — A polar bear has a thick layer of fat (blubber) under its skin that insulates it against the extreme cold of the Arctic. Thin fur, bright feathers, and large ears for heat loss would not help it survive in a cold environment.

4. (C) — In the food chain Grass → Grasshopper → Frog → Snake, the grass is the producer, the grasshopper is the primary consumer, the frog is the secondary consumer (it eats the grasshopper), and the snake is the tertiary consumer.

5. (C) — Photosynthesis is the process by which plants make food using sunlight, water, and carbon dioxide. It is not a method of seed dispersal. Seeds are dispersed by wind, water, animals, and explosive mechanisms.

6. (B) — Plants of the same species can show variation in height and leaf size depending on environmental conditions such as sunlight, water, and soil nutrients. The number of cells, type of reproduction, and classification as a plant remain the same.

7. (B) — A cactus has deep roots to absorb water from deep underground and thick, fleshy stems to store water. These adaptations help it survive in hot, dry desert conditions. Broad leaves and thin stems would cause the plant to lose water quickly.

8. (B) — Foxes feed on rabbits. If the number of rabbits decreases greatly, there will be less food available for foxes. As a result, the number of foxes is likely to decrease due to starvation or migration.

9. (B) — Growing a new plant from a cutting is an example of asexual reproduction because it does not involve the fusion of male and female reproductive cells. The new plant is genetically identical to the parent plant. Pollination, fertilisation, and seed dispersal are all part of sexual reproduction.

10. (B) — Deforestation (the clearing of forests) is the greatest threat to biodiversity in tropical rainforests because it destroys the habitats of millions of species, leading to population decline and extinction.

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Section B — Short Answer (40 marks)

11. (4 marks — 1 mark per correct adaptation)

Organism	Habitat	One adaptation
Polar bear	Arctic	Thick layer of fat (blubber) under the skin to keep warm / Thick white fur for insulation and camouflage
Fish	Ocean	Gills to breathe underwater / Streamlined body shape to swim efficiently / Fins for movement and balance
Cactus	Desert	Thick, fleshy stem to store water / Spines (modified leaves) to reduce water loss / Deep or widespread roots to absorb water
Eagle	Mountain	Sharp talons (claws) to catch prey / Keen eyesight to spot prey from far away / Strong wings for soaring at high altitudes

Marking note: Accept any reasonable adaptation that is clearly linked to survival in the stated habitat.

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12. (5 marks)

(a) Grass (1 mark)

(b) Any two of: Rabbit, Mouse, Fox, Owl (2 marks — 1 mark each)

(c) The number of owls would decrease (1 mark) because mice are a food source for owls. Without mice, owls would have less food and would either starve or move to another area. (1 mark)

Marking note: The explanation must link the removal of mice to a reduction in the owl's food supply.

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13. (4 marks — 2 marks per valid point)

Sample answer:

• Different plant species provide food and shelter for different types of animals, supporting a wider range of organisms in the ecosystem. (2 marks)
• A variety of plants helps maintain soil health and prevents soil erosion, as different plants have different root systems and nutrient needs. (2 marks)

Other acceptable answers:

• Different plants produce oxygen through photosynthesis, supporting animal life.
• Plant diversity ensures that if one species is affected by disease, other species can still survive, keeping the ecosystem stable.
• Different plants contribute to the water cycle and nutrient cycling in different ways.

Marking note: Award 1 mark for a valid point and 1 mark for a clear explanation. Maximum 4 marks.

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14. (3 marks)

(a) Plant A (in the sunny field) would likely be shorter with broader leaves, OR Plant B (in the shade) would likely be taller and thinner as it grows towards the light. (1 mark)

Accept any reasonable difference related to light availability, such as leaf size, stem thickness, or overall height.

(b) Plant B grows in the shade and receives less sunlight. It grows taller/narrower to reach available light for photosynthesis. Plant A receives plenty of sunlight and does not need to grow as tall. (2 marks)

Marking note: The explanation must connect the difference to the availability of sunlight and the plant's need to carry out photosynthesis.

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15. (2 marks — 1 mark per reason)

Sample answer:

• Every species plays a role in its ecosystem (e.g., as a producer, consumer, or decomposer). Losing one species can affect the entire food web. (1 mark)
• Endangered species may have important uses for humans, such as providing medicine or maintaining ecosystem services like pollination. (1 mark)

Other acceptable answers:

• Biodiversity is important for the balance of nature.
• Once a species becomes extinct, it is lost forever.
• Future generations should have the opportunity to see and learn about these species.

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16. (4 marks)

(a) Leaf Z (thick and fleshy) most likely belongs to a plant in a hot, dry environment. (1 mark) A thick, fleshy leaf can store water, which helps the plant survive in dry conditions where water is scarce. (1 mark)

(b) Leaf X (thin, broad, and flat) most likely belongs to a plant in a shady, wet environment. (1 mark) A thin, broad leaf has a large surface area to capture as much light as possible in low-light conditions, and it does not need to store water because water is readily available. (1 mark)

Marking note: The leaf type must be correctly matched to the environment AND a valid explanation must be given for full marks.

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Section C — Structured / Longer Response (40 marks)

17. (9 marks)

(a) "Biodiverse" means having a wide variety of living organisms (plants, animals, fungi, microorganisms) in an area. (1 mark)

(b) Two human activities: (2 marks — 1 mark each)

• Farming (clearing land for agriculture)
• Logging (cutting down trees for wood)
• Building roads

Accept any two from the passage.

(c) Deforestation could lead to extinction because: (4 marks — 2 marks per reason, max 2 reasons)

• Animals lose their habitats (places to live, hide, and raise their young). Without shelter and space, they cannot survive. (2 marks)
• Animals lose their food sources. When plants are removed, herbivores lose their food, and this affects the entire food chain, including carnivores. (2 marks)
• Animals may be unable to find mates if their population becomes too small and scattered, leading to a decline in reproduction. (2 marks)
• Animals may be exposed to predators or harsh weather without the protection of the forest canopy. (2 marks)

Marking note: Award 2 marks for each well-explained reason. The reason must be clearly linked to extinction.

(d) Two actions: (2 marks — 1 mark each)

• Reduce the use of paper and wood products / Recycle paper to reduce the demand for logging.
• Support organisations that protect rainforests.
• Raise awareness about the importance of rainforests.
• Buy products that are certified as sustainably sourced.
• Reduce consumption of products linked to deforestation (e.g., certain palm oil products).

Accept any two reasonable actions.

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18. (8 marks)

(a) (2 marks — 0.5 mark per correct order)

Stage	Order
Seed dispersal	4
Germination	1
Flowering	2
Seed formation	3

(b) Seed dispersal is important because: (2 marks)

• It reduces competition between the parent plant and the offspring for resources such as light, water, and nutrients. (1 mark)
• It allows the plant species to spread to new areas, increasing the chances of survival of the species. (1 mark)

(c) Two ways seeds can be dispersed: (4 marks — 2 marks per method with example)

• By wind: Seeds are light and may have wing-like or parachute-like structures that allow them to be carried by the wind. Example: Dandelion / Angsana. (2 marks)
• By animals: Seeds may have hooks or barbs that attach to animal fur, or they may be contained in fleshy fruits that animals eat and later excrete. Example: Rambutan / Begonia / Mimosa. (2 marks)
• By water: Seeds are buoyant and can float on water to new locations. Example: Coconut. (2 marks)
• By explosive mechanism: The fruit bursts open when ripe, scattering seeds away from the plant. Example: Balsam / Rubber tree. (2 marks)

Marking note: Award 1 mark for naming the method and 1 mark for a correct example. Accept any valid method and example.

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19. (7 marks)

(a) Pond 1 has greater biodiversity. (1 mark) This is because Pond 1 has many different types of water plants, insects, and small fish, while Pond 2 has very few organisms. (1 mark)

(b) Factory waste could have reduced biodiversity in Pond 2 by: (3 marks)

• The waste may have polluted the water, making it toxic or reducing the oxygen levels in the water, causing organisms to die. (1.5 marks)
• The waste may have made the water muddy, blocking sunlight from reaching underwater plants. Without sunlight, plants cannot carry out photosynthesis and die, which affects the entire food chain. (1.5 marks)

Other acceptable points:

• The waste may have changed the pH of the water, making it unsuitable for many organisms.
• The waste may have introduced harmful chemicals that directly killed organisms.

Marking note: Award 1.5 marks for each well-explained point (1 mark for the point, 0.5 mark for the explanation).

(c) If the factory stops releasing waste, the biodiversity in Pond 2 is likely to increase over time. (1 mark) The water quality would gradually improve, allowing plants to grow again. As plants return, animals that depend on them for food and shelter would also return, increasing the number of species in the pond. (1 mark)

Marking note: The prediction must be linked to an improvement in water quality and the return of organisms.

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20. (9 marks)

(a) Mangrove (1 mark)

(b) Two reasons why the mangrove supports more bird species than the oil palm plantation: (4 marks — 2 marks per reason)

• Mangroves have a greater variety of plants, which provide more types of food (fruits, seeds, nectar, insects) and nesting sites for different bird species. (2 marks)
• Mangroves have a more complex habitat structure (trees, roots, water, mud) that provides shelter and breeding grounds for a wider range of bird species, whereas oil palm plantations have a uniform structure with little variety. (2 marks)
• Mangroves support a rich food web with many insects, fish, and other organisms that birds feed on, while oil palm plantations have fewer types of organisms due to the use of pesticides and the lack of plant diversity. (2 marks)

Marking note: Award 2 marks for each well-explained reason. The reason must clearly contrast the mangrove with the oil palm plantation.

(c) Urban parks still have more bird species than oil palm plantations because: (2 marks)

• Urban parks usually have a greater variety of plants (trees, shrubs, flowers, grass) compared to oil palm plantations, which have only one type of plant. This variety provides more food sources and habitats for different bird species. (1 mark)
• Urban parks may have water features (ponds, fountains) and feeding areas that attract birds, while oil palm plantations are often treated with chemicals that reduce the number of insects and other food sources for birds. (1 mark)

Marking note: The answer must compare urban parks with oil palm plantations and explain why the greater plant/environmental diversity in parks supports more bird species.

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End of Answer Key

Total: 100 marks