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Primary 6 PSLE Science Practice Paper 1
Free P6 PSLE Science Practice Paper 1, Nemo3 AI version, with questions, answers, and PSLE-focused practice for Singapore students.
These static practice materials are generated from the site's syllabus and paper-generation workflow, with source and model context shown so students and parents can evaluate the material before use.
Questions
TuitionGoWhere Practice Paper - Science Primary 6 PSLE
TuitionGoWhere Practice Paper (AI)
Subject: Science
Level: Primary 6 PSLE
Paper: Practice Paper 1 (Version 1 of 5)
Duration: 1 h 45 min
Total Marks: 100
Name: ________________________
Class: ________________________
Date: ________________________
Instructions to Candidates
- Do not open this booklet until you are told to do so.
- Follow all instructions carefully.
- Answer all questions.
- For Section A, shade your answers on the Optical Answer Sheet (OAS) provided.
- For Section B, write your answers in the spaces provided in this booklet.
- The number of marks is given in brackets [ ] at the end of each question or part question.
- The total marks for this paper is 100.
Section A: Multiple-Choice Questions (56 marks)
Questions 1 to 28 carry 2 marks each. For each question, four options are given. Choose the correct answer and shade the corresponding oval (1, 2, 3, or 4) on the OAS.
1. The diagram below shows a food web in a forest ecosystem.
Generated diagram for Q1.
Which of the following statements about the food web is correct?
(1) The grasshopper is both a prey and a predator. (2) The snake has only one source of food. (3) The hawk is a primary consumer. (4) The decomposers obtain energy directly from the grass.
2. Study the classification chart below.
Generated chart for Q2.
Which of the following organisms is classified incorrectly in the chart above?
(1) Moss – Non-flowering plant (2) Mushroom – Non-flowering plant (3) Butterfly – Invertebrate (4) Frog – Vertebrate
3. The diagram below shows a cell.
Generated diagram for Q3.
Which part, A, B, C, D, E, or F, controls all activities in the cell?
(1) A (2) B (3) C (4) D
4. Four students made the following statements about microorganisms.
| Student | Statement |
|---|---|
| Ali | All microorganisms are harmful. |
| Bala | Yeast is a microorganism used in making bread. |
| Cindy | Bacteria can only be seen with a microscope. |
| Devi | Mould is a type of bacteria. |
Which two students made correct statements?
(1) Ali and Bala (2) Bala and Cindy (3) Cindy and Devi (4) Ali and Devi
5. The diagram below shows the life cycle of a flowering plant.
Generated diagram for Q5.
Which process occurs immediately after pollination?
(1) Germination (2) Fertilisation (3) Seed dispersal (4) Fruit formation
6. The table below shows the characteristics of four organisms, W, X, Y, and Z.
| Organism | Has feathers | Lays eggs | Has scales | Breathes through lungs |
|---|---|---|---|---|
| W | Yes | Yes | No | Yes |
| X | No | Yes | Yes | No |
| Y | No | No | No | Yes |
| Z | No | Yes | No | Yes |
Which organism is most likely a bird?
(1) W (2) X (3) Y (4) Z
7. The diagram below shows a food chain.
Grass → Grasshopper → Frog → Snake → Hawk
If a disease kills most of the grasshoppers, what will most likely happen to the frog population?
(1) It will increase. (2) It will decrease. (3) It will remain the same. (4) It will increase then decrease.
8. Which of the following shows the correct order of structural organisation in living things, from simplest to most complex?
(1) Cell → Tissue → Organ → Organ system → Organism (2) Tissue → Cell → Organ → Organ system → Organism (3) Cell → Organ → Tissue → Organ system → Organism (4) Organism → Organ system → Organ → Tissue → Cell
9. The diagram below shows the human digestive system.
Generated diagram for Q9.
In which part does most absorption of digested food take place?
(1) A (2) C (3) D (4) E
10. Study the flowchart below.
Generated chart for Q10.
A material is non-living, not made of metal, and not transparent. What is the material?
(1) Metal (2) Glass (3) Plastic (4) Wood
11. Which of the following is a structural adaptation of a cactus plant to survive in the desert?
(1) It has deep roots to absorb water. (2) It stores water in its stem. (3) It opens its stomata at night. (4) It has a waxy cuticle on its leaves.
12. The diagram below shows a pyramid of numbers for a food chain.
Generated diagram for Q12.
Which of the following statements about the pyramid is correct?
(1) There are more frogs than grasshoppers. (2) The snake is a primary consumer. (3) Energy decreases at each higher level. (4) The grass is a secondary consumer.
13. Which of the following groups contains only vertebrates?
(1) Shark, frog, snake, eagle (2) Earthworm, snail, spider, crab (3) Jellyfish, starfish, octopus, squid (4) Butterfly, beetle, grasshopper, mosquito
14. The diagram below shows a plant cell and an animal cell.
Generated diagram for Q14.
Which of the following structures is found in the plant cell but not in the animal cell?
(1) Cytoplasm (2) Nucleus (3) Chloroplast (4) Cell membrane
15. A student observed four organisms and recorded their characteristics in the table below.
| Organism | Body covering | Breathing method | Reproduction |
|---|---|---|---|
| A | Scales | Gills | Lays eggs |
| B | Feathers | Lungs | Lays eggs |
| C | Hair | Lungs | Gives birth |
| D | Moist skin | Lungs and skin | Lays eggs |
Which organism is an amphibian?
(1) A (2) B (3) C (4) D
16. The diagram below shows the water cycle.
Generated diagram for Q16.
Which process in the water cycle involves a change of state from gas to liquid?
(1) Evaporation (2) Condensation (3) Precipitation (4) Transpiration
17. Which of the following is NOT a function of the skeletal system?
(1) Protects internal organs (2) Produces blood cells (3) Helps in movement (4) Removes waste from the body
18. The diagram below shows a food web in a pond ecosystem.
Generated diagram for Q18.
How many food chains are there in this food web?
(1) 2 (2) 3 (3) 4 (4) 5
19. Which of the following statements about bacteria is correct?
(1) All bacteria cause diseases. (2) Bacteria are multicellular organisms. (3) Bacteria reproduce by binary fission. (4) Bacteria can only survive in warm conditions.
20. The diagram below shows a seedling growing in a pot of soil.
Generated diagram for Q20.
The roots grow downwards towards water. This is an example of:
(1) Phototropism (2) Hydrotropism (3) Geotropism (4) Thigmotropism
21. Which of the following shows the correct path of air through the human respiratory system?
(1) Nose → Trachea → Bronchi → Lungs → Alveoli (2) Nose → Bronchi → Trachea → Lungs → Alveoli (3) Nose → Trachea → Lungs → Bronchi → Alveoli (4) Nose → Lungs → Trachea → Bronchi → Alveoli
22. The table below shows the boiling points of four substances.
| Substance | Boiling point (°C) |
|---|---|
| W | -196 |
| X | 20 |
| Y | 78 |
| Z | 100 |
At room temperature (30°C), which substance(s) is/are in the gaseous state?
(1) W only (2) W and X only (3) W, X, and Y only (4) All of them
23. Which of the following is a behavioural adaptation?
(1) A polar bear has thick fur. (2) A chameleon changes its colour. (3) Birds migrate to warmer countries in winter. (4) A cactus has spines instead of leaves.
24. The diagram below shows the cross-section of a flower.
Generated diagram for Q24.
Which part produces pollen grains?
(1) A (2) B (3) C (4) D
25. A student wants to find out if light is needed for photosynthesis. He sets up two set-ups as shown.
Generated experimental_setup for Q25.
Which variable is the changed variable (independent variable) in this experiment?
(1) Type of plant (2) Presence of light (3) Duration of experiment (4) Amount of water
26. Which of the following organisms carries out decomposition?
(1) Grass (2) Rabbit (3) Mushroom (4) Hawk
27. The diagram below shows a human tooth.
Generated diagram for Q27.
Which part, A, B, C, D, or E, contains nerves and blood vessels?
(1) A (2) B (3) C (4) D
28. Which of the following statements about the environment and organisms is correct?
(1) Organisms do not affect their environment. (2) Only animals interact with their environment. (3) Organisms interact with both living and non-living components of their environment. (4) Non-living components do not affect organisms.
Section B: Open-Ended Questions (44 marks)
Questions 29 to 40 carry the marks shown. Write your answers in the spaces provided.
29. The diagram below shows a food web in a garden ecosystem.
Generated diagram for Q29.
(a) Write down one food chain from the food web with four organisms. [1]
(b) If all the ladybirds are removed from the garden, explain what will happen to the population of aphids and sparrows. [2]
(c) State the role of decomposers in this ecosystem. [1]
30. The diagram below shows a plant cell and an animal cell.
Generated diagram for Q30.
(a) Identify two structures found in the plant cell but not in the animal cell. [1]
(b) State the function of the chloroplast. [1]
(c) Explain why animal cells do not have a cell wall. [1]
31. Study the classification table below.
| Group | Characteristics | Examples |
|---|---|---|
| A | Body covered with feathers; breathe through lungs; lay eggs with hard shells | Eagle, Penguin, Sparrow |
| B | Body covered with scales; breathe through gills; lay eggs in water | Goldfish, Shark, Salmon |
| C | Body covered with hair/fur; breathe through lungs; give birth to live young | Human, Whale, Bat |
| D | Moist skin; breathe through lungs and skin; lay eggs in water | Frog, Toad, Salamander |
(a) Name the vertebrate groups A, B, C, and D. [2]
(b) A whale lives in water but is classified in Group C. Explain why. [1]
(c) State one similarity between Group B and Group D. [1]
32. The diagram below shows the life cycle of a mosquito.
Generated diagram for Q32.
(a) Name the type of metamorphosis shown by the mosquito. [1]
(b) State one difference between the larva and the adult mosquito. [1]
(c) The larva lives in water and breathes through a siphon tube. Explain how this is an adaptation for its survival. [1]
(d) Suggest one way to control the mosquito population at the larva stage. [1]
33. The diagram below shows a food pyramid for a forest ecosystem.
Generated diagram for Q33.
(a) If the producers capture 10,000 kJ of energy from the sun, how much energy is available to the tertiary consumers? [1]
(b) Explain why only about 10% of energy is transferred from one trophic level to the next. [2]
(c) Why are there usually fewer organisms at higher trophic levels? [1]
34. The diagram below shows an experiment to investigate the conditions needed for germination.
Generated experimental_setup for Q34.
(a) Which two set-ups should be compared to find out if water is needed for germination? [1]
(b) Based on the set-ups, state the three conditions necessary for seed germination. [1]
(c) In Set-up C, the seeds did not germinate. Explain why. [1]
35. The diagram below shows the human circulatory system.
Generated diagram for Q35.
(a) Name the blood vessel that carries oxygenated blood from the heart to the rest of the body. [1]
(b) State the function of the valves in the heart. [1]
(c) Explain why the left ventricle has a thicker muscular wall than the right ventricle. [2]
36. The table below shows the characteristics of five organisms.
| Organism | Makes own food | Has chlorophyll | Reproduces by spores | Body made of hyphae |
|---|---|---|---|---|
| P | Yes | Yes | No | No |
| Q | No | No | Yes | Yes |
| R | Yes | Yes | Yes | No |
| S | No | No | No | No |
| T | No | No | Yes | No |
(a) Which organism(s) is/are fungi? [1]
(b) Which organism(s) is/are plants? [1]
(c) Organism S has a nucleus but no cell wall. Which group of living things does it most likely belong to? [1]
37. The diagram below shows a cross-section of a leaf.
Generated diagram for Q37.
(a) Name the part labelled B and state its function. [1]
(b) Explain how the guard cells control the opening and closing of the stoma. [2]
(c) Water vapour escapes from the leaf through the stomata. Name this process. [1]
38. A student conducted an experiment to find out how the amount of light affects the rate of photosynthesis. She placed a water plant in a beaker of water at different distances from a lamp and counted the number of bubbles produced per minute.
Generated experimental_setup for Q38.
The results are shown in the table below.
| Distance from lamp (cm) | Number of bubbles per minute |
|---|---|
| 10 | 48 |
| 20 | 32 |
| 30 | 18 |
| 40 | 8 |
| 50 | 2 |
(a) What is the relationship between the distance from the lamp and the rate of photosynthesis? [1]
(b) Explain why the rate of photosynthesis changes with distance from the lamp. [2]
(c) State one other factor that affects the rate of photosynthesis. [1]
39. The diagram below shows a food web in a marine ecosystem.
Generated diagram for Q39.
(a) The whale feeds on both zooplankton and small fish. What does this tell you about the whale's position in the food web? [1]
(b) If overfishing causes the large fish population to decrease drastically, explain how this will affect the shark population and the zooplankton population. [2]
(c) State one way humans can have a positive impact on this marine ecosystem. [1]
40. The diagram below shows the reproductive parts of a flowering plant.
Generated diagram for Q40.
(a) Name the process where pollen grains are transferred from the anther to the stigma. [1]
(b) Describe what happens after the pollen grain lands on the stigma until fertilisation occurs. [2]
(c) After fertilisation, the ovary develops into the fruit and the ovule develops into the seed. State one function of the fruit. [1]
End of Paper
Answers
TuitionGoWhere Practice Paper - Science Primary 6 PSLE (Answer Key)
Subject: Science
Level: Primary 6 PSLE
Paper: Practice Paper 1 (Version 1 of 5)
Total Marks: 100
Section A: Multiple-Choice Questions (56 marks)
1. Answer: (1) The grasshopper is both a prey and a predator.
Explanation: In the food web, the grasshopper eats grass (making it a predator/consumer) and is eaten by the frog (making it prey).
Marks: 2
2. Answer: (2) Mushroom – Non-flowering plant
Explanation: Mushrooms are fungi, not plants. Fungi do not make their own food and reproduce by spores. They belong to a separate kingdom from plants.
Marks: 2
3. Answer: (4) D
Explanation: The nucleus (D) controls all activities in the cell as it contains genetic material (DNA) that directs cell functions.
Marks: 2
4. Answer: (2) Bala and Cindy
Explanation: Bala is correct – yeast is a microorganism (fungus) used in bread-making for fermentation. Cindy is correct – bacteria are microscopic and require a microscope to be seen. Ali is incorrect – not all microorganisms are harmful (e.g., yeast, probiotics). Devi is incorrect – mould is a fungus, not bacteria.
Marks: 2
5. Answer: (2) Fertilisation
Explanation: In the life cycle of a flowering plant, after pollination (transfer of pollen to stigma), fertilisation occurs (fusion of male and female gametes in the ovule).
Marks: 2
6. Answer: (1) W
Explanation: Birds have feathers, lay eggs, and breathe through lungs. Organism W matches all these characteristics. X has scales and breathes through gills (fish). Y gives birth to live young and has hair (mammal). Z lays eggs but has no feathers or scales (could be amphibian or reptile).
Marks: 2
7. Answer: (2) It will decrease.
Explanation: Grasshoppers are the food source for frogs. If grasshoppers decrease, frogs have less food, leading to a decrease in the frog population.
Marks: 2
8. Answer: (1) Cell → Tissue → Organ → Organ system → Organism
Explanation: This is the correct hierarchical organisation: cells form tissues, tissues form organs, organs form organ systems, and organ systems form an organism.
Marks: 2
9. Answer: (3) D
Explanation: The small intestine (D) is where most absorption of digested food takes place, due to its large surface area from villi and microvilli.
Marks: 2
10. Answer: (3) Plastic
Explanation: Following the flowchart: non-living → not metal → not transparent → Plastic. Wood would also fit but is not an option.
Marks: 2
11. Answer: (2) It stores water in its stem.
Explanation: Storing water in the stem is a structural (physical) adaptation. Deep roots (1) is also structural but storing water in the stem is a more distinctive cactus adaptation. Opening stomata at night (3) is a physiological/behavioural adaptation. Waxy cuticle (4) is structural but on leaves (cacti have spines, not leaves).
Marks: 2
12. Answer: (3) Energy decreases at each higher level.
Explanation: In any ecological pyramid, energy decreases at each successive trophic level (typically ~10% transfer). The pyramid shows numbers, but the energy principle still applies.
Marks: 2
13. Answer: (1) Shark, frog, snake, eagle
Explanation: All are vertebrates (have backbones). Group 2 are invertebrates (no backbone). Group 3 are invertebrates. Group 4 are insects (invertebrates).
Marks: 2
14. Answer: (3) Chloroplast
Explanation: Chloroplasts are found in plant cells (for photosynthesis) but not in animal cells. Cytoplasm, nucleus, and cell membrane are found in both.
Marks: 2
15. Answer: (4) D
Explanation: Amphibians have moist skin, breathe through lungs and skin, and lay eggs in water. Organism D matches all these characteristics.
Marks: 2
16. Answer: (2) Condensation
Explanation: Condensation is the change of state from gas (water vapour) to liquid (water droplets). Evaporation is liquid to gas. Precipitation is liquid/solid falling. Transpiration is evaporation from plants.
Marks: 2
17. Answer: (4) Removes waste from the body
Explanation: The excretory system (kidneys) removes waste. The skeletal system protects organs, produces blood cells (in bone marrow), and helps movement (with muscles).
Marks: 2
18. Answer: (3) 4
Explanation: The food chains are: (1) Algae → Water flea → Small fish → Large fish → Kingfisher, (2) Algae → Water flea → Small fish → Kingfisher, (3) Algae → Water flea → Large fish → Kingfisher, (4) Algae → Small fish → Large fish → Kingfisher.
Marks: 2
19. Answer: (3) Bacteria reproduce by binary fission.
Explanation: Bacteria reproduce asexually by binary fission (splitting into two). Not all bacteria cause diseases (many are beneficial). Bacteria are unicellular, not multicellular. Bacteria can survive in various conditions (extremophiles).
Marks: 2
20. Answer: (2) Hydrotropism
Explanation: Hydrotropism is growth response to water (roots growing towards water). Phototropism is response to light. Geotropism is response to gravity. Thigmotropism is response to touch.
Marks: 2
21. Answer: (1) Nose → Trachea → Bronchi → Lungs → Alveoli
Explanation: Air enters through the nose, passes through the trachea, branches into bronchi, enters the lungs, and reaches the alveoli for gas exchange.
Marks: 2
22. Answer: (2) W and X only
Explanation: At 30°C, substances with boiling points below 30°C are gases. W (-196°C) and X (20°C) are gases. Y (78°C) and Z (100°C) are liquids at 30°C.
Marks: 2
23. Answer: (3) Birds migrate to warmer countries in winter.
Explanation: Migration is a behavioural adaptation (action/behaviour). Thick fur (1), colour change (2 - physiological), and spines (4) are structural adaptations.
Marks: 2
24. Answer: (3) C
Explanation: The stamen (C) consists of the anther (produces pollen) and filament. The anther produces pollen grains.
Marks: 2
25. Answer: (2) Presence of light
Explanation: The changed (independent) variable is the one deliberately changed – presence vs absence of light. Other variables (plant type, duration, water) are kept constant (controlled variables).
Marks: 2
26. Answer: (3) Mushroom
Explanation: Mushrooms are fungi (decomposers) that break down dead organic matter. Grass is a producer, rabbit is a consumer, hawk is a consumer.
Marks: 2
27. Answer: (3) C
Explanation: The pulp cavity (C) contains nerves and blood vessels. Enamel (A) is the hard outer layer. Dentine (B) is beneath enamel. Gum (D) and jaw bone (E) are supporting structures.
Marks: 2
28. Answer: (3) Organisms interact with both living and non-living components of their environment.
Explanation: Organisms interact with biotic (living) factors (other organisms) and abiotic (non-living) factors (light, water, temperature, soil).
Marks: 2
Section B: Open-Ended Questions (44 marks)
29.
(a) Grass → Aphid → Ladybird → Sparrow (or Grass → Aphid → Sparrow → Cat) [1]
Marking note: Any valid 4-organism chain from the web. Arrows must show energy flow direction.
(b) Aphid population will increase because there are fewer ladybirds to eat them. Sparrow population may decrease because they lose one food source (ladybirds), though they still have aphids. [2]
Mark breakdown: 1 mark for aphid increase with reason; 1 mark for sparrow decrease with reason.
(c) Decomposers break down dead organisms and waste, returning nutrients to the soil for plants to use. [1]
Key concept: Nutrient recycling.
30.
(a) Cell wall and chloroplast (or large vacuole) [1]
Marking note: Any two correct structures: cell wall, chloroplast, large central vacuole.
(b) Chloroplast contains chlorophyll which traps light energy for photosynthesis. [1]
Key concept: Photosynthesis site.
(c) Animal cells do not need a rigid cell wall for support because they have other support systems (skeletons, exoskeletons) or live in environments where turgor pressure is not needed. The flexible cell membrane allows animal cells to change shape for movement and phagocytosis. [1]
Key concept: Structural difference related to function.
31.
(a) A: Birds, B: Fish, C: Mammals, D: Amphibians [2]
Mark breakdown: 0.5 marks each, or 1 mark per pair.
(b) Whales are mammals because they have hair (at birth), breathe through lungs, give birth to live young, and feed young with milk. Living in water is a habitat, not a classification criterion. [1]
Key concept: Classification based on characteristics, not habitat.
(c) Both lay eggs in water / both have aquatic young stages / both are cold-blooded. [1]
Accept any valid similarity.
32.
(a) Complete metamorphosis [1]
(b) Larva
<stage5_exam_answers_md>
TuitionGoWhere Practice Paper - Science Primary 6 PSLE (Answer Key)
Subject: Science
Level: Primary 6 PSLE
Paper: Practice Paper 1 (Version 1 of 5)
Total Marks: 100
Section A: Multiple-Choice Questions (56 marks)
| Question | Answer | Explanation |
|---|---|---|
| 1 | (1) | The grasshopper eats grass (prey to grass) and is eaten by the frog (predator to frog). |
| 2 | (2) | Mushroom is a fungus, not a plant. It should be classified under fungi, not non-flowering plants. |
| 3 | (4) | Part D is the nucleus, which controls all activities in the cell. |
| 4 | (2) | Bala is correct (yeast is used in bread-making). Cindy is correct (bacteria are microscopic). Ali is wrong (not all microorganisms are harmful). Devi is wrong (mould is a fungus, not bacteria). |
| 5 | (2) | After pollination (transfer of pollen to stigma), fertilisation (fusion of male and female gametes) occurs. |
| 6 | (1) | Organism W has feathers, lays eggs, and breathes through lungs – characteristics of a bird. |
| 7 | (2) | Grasshoppers are the food source for frogs. If grasshoppers decrease, frogs will have less food and their population will decrease. |
| 8 | (1) | Correct hierarchy: Cell → Tissue → Organ → Organ system → Organism. |
| 9 | (3) | The small intestine (D) is where most absorption of digested food takes place. |
| 10 | (3) | Non-living, not metal, not transparent → Plastic. |
| 11 | (4) | A waxy cuticle on leaves (or stems) reduces water loss – a structural adaptation. Storing water in stem (2) is also structural, but (4) is the classic textbook answer for cactus leaves modified to spines with waxy cuticle. Deep roots (1) and opening stomata at night (3) are also adaptations but (4) is most directly about the leaf modification. |
| 12 | (3) | Energy decreases at each higher trophic level (only ~10% transferred). |
| 13 | (1) | Shark (fish), frog (amphibian), snake (reptile), eagle (bird) are all vertebrates. |
| 14 | (3) | Chloroplasts are found only in plant cells (and some protists), not in animal cells. |
| 15 | (4) | Organism D has moist skin, breathes through lungs and skin, lays eggs – characteristics of an amphibian. |
| 16 | (2) | Condensation is the change of state from gas (water vapour) to liquid (water droplets). |
| 17 | (4) | Removing waste is a function of the excretory system, not the skeletal system. |
| 18 | (3) | Food chains: 1) Algae → Water flea → Small fish → Large fish → Kingfisher; 2) Algae → Water flea → Small fish → Kingfisher; 3) Algae → Water flea → Large fish → Kingfisher; 4) Algae → Small fish → Large fish → Kingfisher. (4 chains) |
| 19 | (3) | Bacteria reproduce asexually by binary fission. |
| 20 | (2) | Hydrotropism is growth response to water. Geotropism is response to gravity (roots grow down), but the question specifies "towards water". |
| 21 | (1) | Correct path: Nose → Trachea → Bronchi → Lungs → Alveoli. |
| 22 | (2) | At 30°C: W (-196°C) and X (20°C) are gases (boiling point < 30°C). Y (78°C) and Z (100°C) are liquids. |
| 23 | (3) | Migration is a behavioural adaptation (action/behaviour). Thick fur (1), colour change (2 - physiological/behavioural but often classified as physiological), spines (4) are structural. |
| 24 | (3) | Part C is the stamen (anther and filament); the anther produces pollen grains. |
| 25 | (2) | The changed variable is the presence of light (Set-up A in light, Set-up B in dark). |
| 26 | (3) | Mushroom (fungus) is a decomposer. Grass is a producer, rabbit is a consumer, hawk is a consumer. |
| 27 | (3) | Part C is the pulp cavity, which contains nerves and blood vessels. |
| 28 | (3) | Organisms interact with both biotic (living) and abiotic (non-living) components of their environment. |
Section B: Open-Ended Questions (44 marks)
29. Garden Food Web
(a) Grass → Aphid → Ladybird → Sparrow
OR Grass → Aphid → Sparrow → Cat
OR Grass → Aphid → Ladybird → Sparrow → Cat (5 organisms, but "with four organisms" means 4 organisms in the chain, so 3 arrows)
Acceptable answer: Grass → Aphid → Ladybird → Sparrow [1]
(b) Aphids: Population will increase because there are fewer ladybirds to eat them (less predation).
Sparrows: Population will decrease because one of their food sources (ladybirds) is gone, and although aphids increase, sparrows may not be able to eat enough aphids to compensate / sparrows lose a food source.
Marking points: [1] Aphids increase (less predators). [1] Sparrows decrease (less food / lost food source).
(c) Decomposers break down dead organisms and waste materials, returning nutrients to the soil for plants to use. / They recycle nutrients in the ecosystem. [1]
30. Plant Cell vs Animal Cell
(a) Cell wall and chloroplasts (or large central vacuole)
Any two: Cell wall, Chloroplasts, Large central vacuole [1 each, max 2]
(b) Function of chloroplasts: Contain chlorophyll to trap light energy for photosynthesis. / Site of photosynthesis. [1]
Function of cell wall: Gives the cell a fixed/regular shape and provides support/protection. / Prevents cell from bursting when it absorbs water. [1]
31. Human Respiratory System
(a) Part X: Alveolus / Alveoli (air sac) [1]
(b) The alveoli have:
- Thin walls (one cell thick) for fast diffusion of gases.
- Large surface area (many alveoli) for efficient gas exchange.
- Moist lining for gases to dissolve.
- Dense network of capillaries for transport of gases.
Any two features with explanation: [1] Feature, [1] How it helps.
Example: Thin walls → short diffusion distance for oxygen and carbon dioxide. [1]
Large surface area → more space for gas exchange. [1]
32. Water Cycle
(a) Process A: Evaporation (from water bodies)
Process B: Condensation (forming clouds) [1 each]
(b) The water cycle ensures a continuous supply of fresh water for living things. / It distributes water around the Earth. / It purifies water through evaporation and condensation. [1]
(c) Transpiration is the loss of water vapour from the leaves of plants. It adds water vapour to the atmosphere, contributing to condensation and precipitation. / It helps pull water up from the roots (transpiration pull). [1]
33. Magnetism
(a) Repel [1]
Reason: Like poles (North-North) repel each other. [1]
(b) Method: Stroke the steel bar with a magnet in one direction repeatedly (stroking method).
OR Place the steel bar in a solenoid and pass direct current through it (electrical method).
OR Induction method (bring magnet near, then remove).
Acceptable: Stroke with a magnet in one direction many times. [1]
(c) Test: Bring the rod near some iron nails/paper clips. If it attracts them, it is magnetised.
OR Suspend the rod freely; if it comes to rest in a North-South direction, it is magnetised.
OR Bring a known magnet near; if it repels one end, it is magnetised (repulsion is the only sure test).
Best answer: Bring a known magnet near; if there is repulsion, the rod is magnetised. [1]
34. Heat and Temperature
(a) Conduction [1]
Explanation: Heat travels through the solid metal rod from the hotter end to the colder end by vibration of particles. [1]
(b) Material Y [1]
Reason: It has the lowest temperature after 5 minutes, meaning it conducts heat the slowest / is the poorest conductor of heat / best insulator. [1]
(c) The handles will not get hot easily / will remain cool, preventing the user from getting burnt. / It is a poor conductor of heat / good insulator. [1]
35. Light and Shadows
(a) Light travels in straight lines. [1]
Explanation: The opaque object blocks the light, forming a shadow behind it because light cannot bend around the object. [1]
(b) The shadow will become larger / bigger. [1]
Reason: When the object is moved closer to the light source, it blocks more light rays, casting a larger shadow on the screen. [1]
(c) Use a point source of light / smaller light source / move the screen further away from the object.
To get a sharp shadow: Use a point source of light (or move the light source further from the object). [1]
36. Electrical Systems
(a) Circuit B [1]
Reason: It is a closed circuit with no gaps / the switch is closed, allowing electric current to flow. [1]
(b) The bulbs in Circuit A are connected in series. [1]
Explanation: In a series circuit, the current is the same through all components. When one bulb fuses (breaks), the circuit becomes open and current cannot flow, so the other bulb goes out. [1]
(c) Advantage: If one bulb fuses, the other bulbs will still light up / each bulb can be controlled independently / each bulb receives the full voltage and shines at maximum brightness. [1]
37. Forces
(a) Gravitational force (or weight) [1]
(b) The reading on the spring balance decreases. [1]
Reason: The water exerts an upward upthrust (buoyant force) on the object, opposing its weight, so the net force pulling down on the spring balance is less. [1]
(c) Frictional force [1]
Direction: Acts opposite to the direction of motion / backwards (against the pulling force). [1]
38. Matter
(a) Solid [1]
Reason: It has a fixed volume and a fixed shape / definite shape and volume. [1]
(b) Gas [1]
Reason: It has no fixed volume and no fixed shape / takes the shape and volume of its container / can be compressed. [1]
(c) Melting [1]
Process: The solid gains heat, particles vibrate faster and break free from their fixed positions to become a liquid. [1]
39. Photosynthesis Experiment
(a) Carbon dioxide [1]
(b) Oxygen [1]
(c) Test: Place a glowing wooden splint into the gas collected.
Observation: The glowing splint relights / bursts into flame. [1]
This confirms the gas is oxygen.
40. Adaptations
(a) Structural adaptation: Webbed feet / Streamlined body shape / Waterproof feathers / Wings modified as flippers / Thick layer of fat (blubber) under skin. [1]
Any one.
(b) Behavioural adaptation: Huddling together in groups to keep warm / Migrating to warmer areas (though penguins don't migrate far, they move) / Taking turns to be on the outside of the huddle. [1]
Acceptable: Huddling together to reduce heat loss.
(c) The thick layer of fat (blubber) acts as an insulator, reducing heat loss from the penguin's body to the cold surroundings / keeping the penguin warm. [1]
End of Answer Key
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