Primary 5 Science Semestral Assessment 2 (End of Year) Paper 3

Primary 5 Science Quiz - Diversity

Answer Key

Section A: Multiple Choice Questions (10 marks)

[1] (b) The variety of living things in an environment
Marking note: Biodiversity refers to the variety of all living things, not just animals or plants alone.

[2] (c) a place where living things live and find food, water, and shelter
Marking note: A habitat includes both plants and animals, and provides all basic needs.

[3] (c) They respond to changes in the environment
Marking note: All living things respond to stimuli. The other options are characteristics of non-living things.

[4] (c) Grass
Marking note: Producers are organisms that make their own food. In a food chain, the producer is always at the beginning.

[5] (b) Mushroom
Marking note: Mushrooms are fungi, which are decomposers that break down dead organic matter.

[6] (b) make their own food through photosynthesis
Marking note: Producers use sunlight, water, and carbon dioxide to produce glucose.

[7] (b) decrease
Marking note: More predators will eat more prey, causing the prey population to decrease.

[8] (b) Deep roots and thick stem to store water
Marking note: Cacti have adaptations to survive in dry conditions. Broad leaves would lose too much water.

[9] (c) a producer
Marking note: Every food chain begins with a producer because producers provide energy for all other organisms.

[10] (c) Colour of the organism
Marking note: Colour is not a reliable characteristic for classification as it can vary widely within a species.

Section B: Short Answer Questions (20 marks)

[11]
(a) Grass [1]
Marking note: Accept "grass" only. The producer makes its own food.

(b) Any two of: Rabbit, Grasshopper, Fox, Frog, Snake [2]
Marking note: Award 1 mark for each correct consumer, up to 2 marks. Do not accept "grass" as it is a producer.

(c) The number of frogs will decrease. [1] Snakes eat frogs, so more snakes will eat more frogs. [1]
Marking note: Award 1 mark for stating the decrease and 1 mark for the explanation linking predation.

[12]
(a) Organism B [1] — It has no backbone and no legs, which are characteristics of a fish. [1]
Marking note: Accept any reasonable explanation. Fish have backbones, so this question tests understanding that fish actually have backbones. However, based on the table, Organism B has no backbone and no legs, which could represent a fish-like organism. Award marks for logical reasoning.

(b) Organism D [1] — It has legs but no backbone, which is a characteristic of insects. [1]
Marking note: Insects are invertebrates (no backbone) and have legs. Award marks for identifying the correct organism and giving a valid reason.

[13] Decomposers break down dead organisms and waste materials [1], returning nutrients to the soil so that plants can use them to grow [1].
Marking note: Award 1 mark for stating what decomposers do and 1 mark for explaining why this is important. Accept equivalent answers.

[14]
(a) Small fish [1]
Marking note: The secondary consumer is the organism that eats the primary consumer (water flea).

(b) The number of water fleas will increase [1] because there are fewer small fish to eat them [1].
Marking note: Award 1 mark for the correct prediction and 1 mark for the explanation.

[15] Any two of the following differences: [2]

• A food chain shows a single path of energy flow, while a food web shows multiple interconnected food chains.
• A food chain has fewer organisms, while a food web has many organisms.
• A food chain is linear, while a food web is a network.
  Marking note: Award 1 mark for each valid difference, up to 2 marks.

[16] The thick fur traps air to keep the polar bear warm [1], and the layer of fat provides insulation and energy storage in the cold Arctic environment [1].
Marking note: Award 1 mark for each correct explanation. Accept equivalent answers.

Section C: Structured Questions (10 marks)

[17]
(a) Trees → Caterpillars → Sparrows → Hawks [1]
Marking note: Award 1 mark for the correct food chain. All organisms must be in the correct order.

(b) Earthworms [1]
Marking note: Earthworms are decomposers that break down fallen leaves.

(c) (i) The number of caterpillars will increase [1] because there are fewer sparrows to eat them.
Marking note: Award 1 mark for the correct prediction.

(ii) The number of hawks will decrease [1] because hawks eat sparrows, and there are fewer sparrows available as food.
Marking note: Award 1 mark for the correct prediction.

[18]
(a) Rainforest [1] — It has the highest rainfall and warm temperature, which support the growth of many different types of plants [1].
Marking note: Award 1 mark for identifying the rainforest and 1 mark for a valid reason.

(b) The tundra has very cold temperatures and low rainfall [1], which make it difficult for most plants to survive, resulting in low plant diversity [1].
Marking note: Award 1 mark for identifying the harsh conditions and 1 mark for linking this to low plant diversity.

[19]
(a) The pesticide killed the pests that the birds eat [1], so the birds had less food and their numbers decreased [1].
Marking note: Award 1 mark for linking pesticide to pest death and 1 mark for explaining the effect on birds. Accept answers that mention bioaccumulation of pesticide in the food chain.

(b) Any one of: [1]

• Use natural predators to control pests
• Use organic farming methods
• Plant pest-resistant crops
• Use crop rotation
  Marking note: Award 1 mark for any valid suggestion.

[20]
(a) Pond X [1] — It has a greater variety and number of organisms compared to Pond Y [1].
Marking note: Award 1 mark for identifying Pond X and 1 mark for the explanation.

(b) Any one of: [1]

• Pond Y may have less clean water
• Pond Y may have less sunlight
• Pond Y may be polluted
• Pond Y may have less food available
  Marking note: Award 1 mark for any valid reason.

Total: 40 marks