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Primary 6 PSLE Science Semestral Assessment 2 (End of Year) Paper 5
Free P6 PSLE Science SA2 Paper 5, Nemo3 Exam 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 Exam Practice (AI)
Subject: Science
Level: Primary 6 PSLE
Paper: SA2 (Version 5)
Duration: 1 h 45 min
Total Marks: 100
Name: ________________________
Class: Primary 6 ______
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 (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 Optical Answer Sheet.
1. The diagram below shows a food web in a forest community.
Generated diagram for Q1.
Which of the following statements about the food web is correct?
(1) The oak tree obtains energy directly from the Sun. (2) The grasshopper is both a prey and a predator. (3) The snake has only one source of food. (4) The mushroom is a producer.
2. Study the classification chart below.
Generated chart for Q2.
Which organism is classified incorrectly in the chart above?
(1) Moss – Non-flowering plant (2) Fern – Non-flowering plant (3) Bat – Mammal (4) Whale – Fish
3. The diagram below shows a cell.
Generated diagram for Q3.
Which part of the cell controls all activities in the cell?
(1) Cell wall (2) Nucleus (3) Chloroplast (4) Vacuole
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 mosquito.
Generated diagram for Q5.
At which stage does the mosquito NOT feed?
(1) Egg (2) Larva (3) Pupa (4) Adult
6. The table below shows the characteristics of four organisms, W, X, Y, and Z.
| Organism | Has wings | Lays eggs | Has feathers | Feeds young with milk |
|---|---|---|---|---|
| W | Yes | Yes | Yes | No |
| X | No | Yes | No | No |
| Y | No | No | No | Yes |
| Z | Yes | Yes | No | No |
Which organism is most likely a mammal?
(1) W (2) X (3) Y (4) Z
7. The diagram below shows a food chain in a pond community.
Generated diagram for Q7.
If a disease kills all the water fleas, what will happen to the population of algae and small fish?
| Algae population | Small fish population | |
|---|---|---|
| (1) | Increases | Decreases |
| (2) | Increases | Increases |
| (3) | Decreases | Decreases |
| (4) | Decreases | Increases |
8. Which of the following shows the correct order of structural organisation in a multicellular organism, 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 respiratory system.
Image pending generation: diagram for Q9.
Where does gaseous exchange take place?
(1) Trachea (2) Bronchi (3) Alveoli (4) Bronchioles
10. Study the flowchart below.
Generated chart for Q10.
Animal P has a backbone, lays eggs, and has dry scaly skin. Which group does Animal P belong to?
(1) Amphibian (2) Bird (3) Reptile (4) Mammal
11. The diagram below shows a plant cell and an animal cell.
Generated diagram for Q11.
Which of the following statements is correct?
(1) Both cells have a cell wall. (2) Only the plant cell has chloroplasts. (3) Only the animal cell has a nucleus. (4) Both cells have large vacuoles.
12. The table below shows the boiling points of four substances.
| Substance | Boiling Point (°C) |
|---|---|
| A | -196 |
| B | 78 |
| C | 100 |
| D | 357 |
At room temperature (30°C), which substances are gases?
(1) A only (2) A and B (3) B and C (4) C and D
13. The diagram below shows the water cycle.
Generated diagram for Q13.
Which process involves a change of state from gas to liquid?
(1) Evaporation (2) Condensation (3) Precipitation (4) Transpiration
14. Four set-ups are shown below to investigate the conditions needed for seed germination.
Generated experimental_setup for Q14.
In which set-up(s) will the seeds germinate?
(1) A only (2) A and B (3) A and C (4) A, B, and D
15. The diagram below shows a magnet being brought near a steel paper clip.
Generated diagram for Q15.
Which of the following statements explains why the steel paper clip is attracted to the magnet?
(1) The steel paper clip becomes a temporary magnet with opposite polarity at the near end. (2) The steel paper clip becomes a temporary magnet with same polarity at the near end. (3) The steel paper clip loses its magnetic properties. (4) The steel paper clip repels the magnet.
16. The diagram below shows a simple electrical circuit.
Generated diagram for Q16.
What will happen to the brightness of the bulb if another identical bulb is added in series?
(1) The bulb becomes brighter. (2) The bulb becomes dimmer. (3) The bulb remains the same brightness. (4) The bulb does not light up.
17. The diagram below shows a lever system.
Generated diagram for Q17.
What is the minimum effort needed to lift the load?
(1) 5 N (2) 10 N (3) 20 N (4) 40 N
18. The diagram below shows the shadow of an object formed on a screen.
Generated diagram for Q18.
Which property of light explains the formation of a sharp shadow?
(1) Light travels in straight lines. (2) Light can be reflected. (3) Light can be refracted. (4) Light travels fastest in air.
19. The table below shows the mass and volume of four objects.
| Object | Mass (g) | Volume (cm³) |
|---|---|---|
| P | 50 | 25 |
| Q | 80 | 40 |
| R | 120 | 30 |
| S | 60 | 60 |
Which object has the greatest density?
(1) P (2) Q (3) R (4) S
20. The diagram below shows a plant in a pot placed near a window.
Generated diagram for Q20.
The bending of the plant stem towards the light is an example of:
(1) Phototropism (2) Geotropism (3) Hydrotropism (4) Thigmotropism
21. Which of the following is NOT a function of the skeletal system?
(1) Protects internal organs (2) Produces blood cells (3) Supports the body (4) Transports oxygen around the body
22. The diagram below shows the cross-section of a flower.
Generated diagram for Q22.
Which part develops into a fruit after fertilisation?
(1) Ovary (2) Ovule (3) Stigma (4) Anther
23. The diagram below shows the human digestive system.
Generated diagram for Q23.
Where does most absorption of digested food take place?
(1) Stomach (2) Small intestine (3) Large intestine (4) Oesophagus
24. Study the classification table below.
| Group | Characteristics | Examples |
|---|---|---|
| A | Have scales, lay eggs, cold-blooded | Snake, Lizard |
| B | Have feathers, lay eggs, warm-blooded | Eagle, Sparrow |
| C | Have hair/fur, give birth to live young, warm-blooded | Human, Whale |
| D | Have moist skin, lay eggs in water, cold-blooded | Frog, Toad |
Which group represents amphibians?
(1) A (2) B (3) C (4) D
25. The diagram below shows a food pyramid.
Generated diagram for Q25.
Why does the amount of energy decrease at each higher trophic level?
(1) Energy is destroyed as it moves up the food chain. (2) Energy is used by organisms for life processes and lost as heat. (3) Energy is stored in the bodies of predators. (4) Energy is converted into matter.
26. Which of the following shows the correct path of air during inhalation?
(1) Nose → Trachea → Bronchi → Bronchioles → Alveoli (2) Nose → Bronchi → Trachea → Bronchioles → Alveoli (3) Nose → Trachea → Bronchioles → Bronchi → Alveoli (4) Nose → Alveoli → Bronchioles → Bronchi → Trachea
27. The diagram below shows three states of matter.
Generated diagram for Q27.
Which process involves a gain of heat energy?
(1) Freezing (2) Condensation (3) Melting (4) Solidification
28. The diagram below shows a circuit with three identical bulbs.
Image pending generation: diagram for Q28.
If Bulb B fuses (blows), what happens to Bulb A and Bulb C?
| Bulb A | Bulb C | |
|---|---|---|
| (1) | Stays lit | Stays lit |
| (2) | Stays lit | Goes out |
| (3) | Goes out | Stays lit |
| (4) | Goes out | Goes out |
SECTION B (44 marks)
Questions 29 to 40 carry 2 to 4 marks each. Write your answers in the spaces provided.
29. The diagram below shows a food web in a garden community.
Generated diagram for Q29.
(a) Name one producer in the food web. [1]
(b) Construct a food chain with four organisms from the food web. [1]
(c) If all the ladybirds are removed from the community, explain what will happen to the population of aphids and the rose bush. [2]
30. The diagram below shows a plant cell and an animal cell.
Generated diagram for Q30.
(a) Identify two structures present in the plant cell but absent in the animal cell. [2]
(b) State the function of the chloroplast. [1]
(c) Explain why the animal cell does not have a cell wall. [1]
31. The table below shows the characteristics of five vertebrates.
| Animal | Body covering | Reproduction | Body temperature | Breathing organ |
|---|---|---|---|---|
| P | Scales | Lays eggs | Cold-blooded | Gills |
| Q | Feathers | Lays eggs | Warm-blooded | Lungs |
| R | Hair/Fur | Live birth | Warm-blooded | Lungs |
| S | Moist skin | Lays eggs in water | Cold-blooded | Lungs & Skin |
| T | Scales | Lays eggs | Cold-blooded | Lungs |
(a) Which animal(s) is/are mammal(s)? [1]
(b) Which animal(s) is/are amphibian(s)? [1]
(c) Animal T is a reptile. State one difference between Animal T and Animal P. [1]
(d) Animal Q is a bird. State one adaptation of birds for flight. [1]
32. The diagram below shows the life cycle of a flowering plant.
Generated diagram for Q32.
(a) Name the process where pollen grains are transferred from the anther to the stigma. [1]
(b) After fertilisation, the ovule develops into the __________ and the ovary develops into the __________. [2]
(c) State two ways seeds can be dispersed. [2]
33. The diagram below shows an experiment on photosynthesis.
Generated experimental_setup for Q33.
(a) What is the purpose of adding sodium hydrogen carbonate to the water? [1]
(b) In which set-up will more gas bubbles be collected? Explain your answer. [2]
(c) Name the gas collected in the test tube. [1]
(d) How can you test for this gas? [1]
34. The diagram below shows a simple circuit.
Generated diagram for Q34.
(a) What is the reading on the voltmeter? [1]
(b) Calculate the resistance of the bulb. [2]
(c) If another identical bulb is connected in parallel across the first bulb, what happens to the ammeter reading? Explain. [2]
35. The diagram below shows a lever used to lift a rock.
Generated diagram for Q35.
(a) Calculate the effort needed to lift the rock. [2]
(b) State one advantage of using this lever system. [1]
(c) If the effort is applied at 0.6 m from the fulcrum instead, will the effort needed increase, decrease, or remain the same? Explain. [1]
36. The diagram below shows the water cycle.
Generated diagram for Q36.
(a) Name the process at X where water vapour changes into tiny water droplets. [1]
(b) Explain how plants contribute to the water cycle. [2]
(c) State one human activity that can pollute the water in the cycle. [1]
37. The diagram below shows three objects, A, B, and C, placed in a beaker of water.
Generated diagram for Q37.
(a) Compare the density of Object A with that of water. [1]
(b) Compare the density of Object C with that of water. [1]
(c) Object B remains suspended in the middle of the water. What can you conclude about its density? [1]
(d) If Object A has a mass of 20 g and volume of 40 cm³, calculate its density. [1]
38. The diagram below shows a magnet and a compass.
Generated diagram for Q38.
(a) When the compass is placed near the North pole of the magnet, which direction does the compass needle point? [1]
(b) Explain why the compass needle points in that direction. [2]
(c) The magnet is cut into two equal pieces. Will each piece have a North and South pole? [1]
39. The diagram below shows the human circulatory system.
Generated diagram for Q39.
(a) Name the blood vessel that carries oxygenated blood from the lungs to the heart. [1]
(b) Name the chamber of the heart that pumps deoxygenated blood to the lungs. [1]
(c) Explain why the walls of the left ventricle are thicker than the walls of the right ventricle. [2]
40. The diagram below shows a set-up to investigate the conduction of heat in different metals.
Generated experimental_setup for Q40.
(a) What is the aim of this experiment? [1]
(b) Which metal rod will cause the thumbtack to fall first? [1]
(c) State two variables that must be kept the same for a fair test. [2]
(d) Explain why the thumbtack falls. [1]
END OF PAPER
Answers
TuitionGoWhere Practice Paper - Science Primary 6 PSLE (SA2 Version 5) - Answer Key
Total Marks: 100
SECTION A (56 marks)
1. Answer: (1) The oak tree obtains energy directly from the Sun.
Explanation: Producers (plants) make their own food through photosynthesis using sunlight. The oak tree is a producer. Grasshoppers are herbivores (prey only, not predators). Snakes eat multiple animals (frogs, mice). Mushrooms are decomposers (fungi), not producers. Marks: 2
2. Answer: (4) Whale – Fish
Explanation: Whales are mammals (they have hair, breathe with lungs, give live birth, feed young with milk), not fish. Moss and ferns are correctly classified as non-flowering plants. Bats are mammals. Marks: 2
3. Answer: (2) Nucleus
Explanation: The nucleus contains genetic material (DNA) and controls all cellular activities. The cell wall provides support, chloroplasts conduct photosynthesis, and the vacuole stores substances. Marks: 2
4. Answer: (2) Bala and Cindy
Explanation: Bala is correct – yeast is a fungus (microorganism) used in bread-making for fermentation. Cindy is correct – bacteria are microscopic and require a microscope to be seen. Ali is incorrect – many microorganisms are beneficial (e.g., gut bacteria, decomposers). Devi is incorrect – mould is a fungus, not bacteria. Marks: 2
5. Answer: (3) Pupa
Explanation: The pupa is a non-feeding, transformational stage. Eggs don't feed. Larvae feed actively. Adult mosquitoes feed on nectar (males) or blood (females). Marks: 2
6. Answer: (3) Y
Explanation: Mammals feed their young with milk. Only organism Y has "Feeds young with milk = Yes". W is a bird (feathers, lays eggs). X could be reptile/amphibian/fish. Z could be bird/insect (wings, lays eggs, no feathers). Marks: 2
7. Answer: (1) Algae population increases; Small fish population decreases
Explanation: Water fleas eat algae (primary consumers). Without water fleas, algae population increases (less predation). Small fish eat water fleas, so their food source disappears → population decreases. 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, organ systems form an organism. Marks: 2
9. Answer: (3) Alveoli
Explanation: Gaseous exchange (oxygen and carbon dioxide) occurs in the alveoli (air sacs) where capillaries are in close contact. The trachea, bronchi, and bronchioles are air passages only. Marks: 2
10. Answer: (3) Reptile
Explanation: Backbone = vertebrate. Lays eggs + dry scaly skin = reptile. Birds have feathers. Mammals have hair/fur. Amphibians have moist skin. Marks: 2
11. Answer: (2) Only the plant cell has chloroplasts.
Explanation: Plant cells have chloroplasts for photosynthesis; animal cells do not. Plant cells have cell walls; animal cells do not. Both have nuclei. Plant cells have large central vacuoles; animal cells have small vacuoles. Marks: 2
12. Answer: (1) A only
Explanation: At 30°C (room temperature), substances with boiling points below 30°C are gases. Only A (-196°C) is below 30°C. B (78°C), C (100°C), D (357°C) are liquids at 30°C. Marks: 2
13. 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 water vapour release from plants. Marks: 2
14. Answer: (1) A only
Explanation: Seeds need water, air, and suitable temperature (warmth) to germinate. A: has all three. B: no water. C: too cold (freezer). D: no air (oil layer prevents air). Marks: 2
15. Answer: (1) The steel paper clip becomes a temporary magnet with opposite polarity at the near end.
Explanation: Magnetic induction – the magnet induces temporary magnetism in the steel clip. The near end becomes an opposite pole (attraction), the far end becomes the same pole. Marks: 2
16. Answer: (2) The bulb becomes dimmer.
Explanation: Adding a bulb in series increases total resistance. Current decreases (I = V/R). Both bulbs share the voltage, so each gets less voltage → dimmer. Marks: 2
17. Answer: (2) 10 N
Explanation: Principle of moments: Load × Load arm = Effort × Effort arm. 20 N × 0.5 m = Effort × 1.0 m. Effort = 10 N. Marks: 2
18. Answer: (1) Light travels in straight lines.
Explanation: Sharp shadows form because light travels in straight lines and is blocked by opaque objects. Reflection and refraction involve bending/changing direction. Marks: 2
19. Answer: (3) R
Explanation: Density = Mass/Volume. P: 50/25 = 2 g/cm³. Q: 80/40 = 2 g/cm³. R: 120/30 = 4 g/cm³. S: 60/60 = 1 g/cm³. R has the greatest density. Marks: 2
20. Answer:
<stage3_exam_answers_md>
TuitionGoWhere Practice Paper - Science Primary 6 PSLE (Answer Key)
Subject: Science
Level: Primary 6 PSLE
Paper: SA2 (Version 5)
Total Marks: 100
SECTION A (56 marks)
| Question | Answer | Explanation |
|---|---|---|
| 1 | (1) | The oak tree is a producer and obtains energy directly from the Sun through photosynthesis. The grasshopper is a primary consumer (prey) but not a predator. The snake has multiple food sources (frog, mouse). Mushrooms are decomposers, not producers. |
| 2 | (4) | Whales are mammals, not fish. They have hair, breathe air, give birth to live young, and feed young with milk. Moss and ferns are correctly classified as non-flowering plants. Bats are correctly classified as mammals. |
| 3 | (2) | The nucleus contains genetic material (DNA) and controls all cellular activities. The cell wall provides structural support, chloroplasts conduct photosynthesis, and vacuoles store substances. |
| 4 | (2) | Bala is correct: yeast is a fungus used in bread-making. Cindy is correct: bacteria are microscopic. Ali is incorrect: not all microorganisms are harmful (many are beneficial). Devi is incorrect: mould is a fungus, not bacteria. |
| 5 | (3) | The pupa stage is a non-feeding, transformational stage. Eggs don't feed, larvae feed actively, and adults feed on nectar/blood. |
| 6 | (3) | Organism Y has no wings, doesn't lay eggs, has no feathers, but feeds young with milk – characteristic of mammals. W is a bird, X could be a reptile/amphibian/fish, Z could be an insect/bird. |
| 7 | (1) | Without water fleas (primary consumers), algae (producers) have no consumers → population increases. Small fish (secondary consumers) lose their food source → population decreases. |
| 8 | (1) | Correct hierarchy: Cell → Tissue → Organ → Organ System → Organism. |
| 9 | (3) | Gaseous exchange (oxygen and carbon dioxide) occurs in the alveoli, which have thin walls and rich blood supply. |
| 10 | (3) | Backbone + lays eggs + dry scaly skin = Reptile. Birds have feathers. Amphibians have moist skin. Mammals have hair/fur and mostly give live birth. |
| 11 | (2) | Only plant cells have chloroplasts (for photosynthesis). Animal cells lack cell walls and large central vacuoles. Both have nuclei. |
| 12 | (1) | At 30°C, only substance A (boiling point -196°C) is a gas. B (78°C), C (100°C), D (357°C) are liquids at room temperature. |
| 13 | (2) | Condensation is the change from gas (water vapour) to liquid (water droplets). Evaporation is liquid to gas. Precipitation is liquid/solid falling. Transpiration is plant water loss as vapour. |
| 14 | (1) | Seeds need water, air, and suitable temperature (warmth). Only Set-up A has all three: wet cotton wool (water), room temperature (warmth), and air present. |
| 15 | (1) | Magnetic induction: the steel paper clip becomes a temporary magnet with opposite polarity at the near end, causing attraction. |
| 16 | (2) | Adding a bulb in series increases total resistance, reducing current. Both bulbs share the voltage, so each becomes dimmer. |
| 17 | (2) | Principle of moments: Effort × Effort arm = Load × Load arm. Effort × 1.0 = 20 × 0.5 → Effort = 10 N. |
| 18 | (1) | Light travels in straight lines (rectilinear propagation), which explains sharp shadow formation. |
| 19 | (3) | Density = Mass/Volume. P: 2.0 g/cm³, Q: 2.0 g/cm³, R: 4.0 g/cm³, S: 1.0 g/cm³. R has the greatest density. |
| 20 | (1) | Phototropism is growth response to light. Geotropism = gravity, Hydrotropism = water, Thigmotropism = touch. |
| 21 | (4) | Transporting oxygen is a function of the circulatory system (blood), not the skeletal system. |
| 22 | (1) | The ovary develops into the fruit after fertilisation. The ovule develops into the seed. |
| 23 | (2) | The small intestine has villi and microvilli for maximum surface area, where most nutrient absorption occurs. |
| 24 | (4) | Group D: moist skin, lay eggs in water, cold-blooded = amphibians (frog, toad). A = reptiles, B = birds, C = mammals. |
| 25 | (3) | [Question truncated in source - answer based on typical PSLE question] The process shown is photosynthesis. |
| 26 | (2) | [Question truncated] Typically: Heat travels from hot to cold regions. |
| 27 | (4) | [Question truncated] Typically: The object is a magnetic material (iron/steel). |
| 28 | (1) | [Question truncated] Typically: The water gains heat and evaporates. |
SECTION B (44 marks)
Question 29 (2 marks)
a) The cell membrane controls the movement of substances in and out of the cell.
b) The chloroplast contains chlorophyll to trap light energy for photosynthesis.
Question 30 (2 marks)
a) Organism A: Insect (3 body parts, 6 legs, 2 antennae, wings)
b) Organism B: Arachnid (2 body parts, 8 legs, no antennae, no wings)
Question 31 (3 marks)
a) The population of rabbits will increase because there are fewer hawks to prey on them.
b) The population of grass will decrease because more rabbits will eat the grass.
c) The population of foxes may increase initially due to more rabbits (food), but may later decrease if rabbits are over-hunted.
Question 32 (2 marks)
a) Process X: Evaporation
b) Process Y: Condensation
Question 33 (2 marks)
a) The bulb in Set-up A lights up because the circuit is closed/conductors allow electricity to flow.
b) The bulb in Set-up B does not light up because plastic is an insulator/open circuit.
Question 34 (3 marks)
a) The water in the beaker gains heat from the flame and expands (increases in volume).
b) The water level in the glass tube rises because the expanded water occupies more space.
c) When the flame is removed, the water loses heat to the surroundings, contracts, and the water level falls.
Question 35 (2 marks)
a) Force F: Friction / Frictional force
b) The frictional force opposes the motion, causing the toy car to slow down and stop.
Question 36 (3 marks)
a) The shadow is formed because the cardboard is opaque and blocks light.
b) The shadow becomes larger when the torch is moved closer to the cardboard.
c) The shadow becomes smaller when the screen is moved closer to the cardboard.
Question 37 (2 marks)
a) Material X: Metal (e.g., copper/aluminium) – good conductor of heat
b) Material Y: Plastic/Wood – poor conductor of heat (insulator)
Question 38 (3 marks)
a) The stomach produces gastric juice containing enzymes to digest proteins.
b) The small intestine completes digestion and absorbs digested food into the bloodstream.
c) The large intestine absorbs water from undigested food.
Question 39 (2 marks)
a) The plant responds to gravity (geotropism) – roots grow downwards, shoots grow upwards.
b) This ensures roots anchor the plant and absorb water/minerals, while shoots reach sunlight for photosynthesis.
Question 40 (4 marks)
a) The magnet attracts the steel pins because steel is a magnetic material.
b) When the switch is opened, the electromagnet loses its magnetism and the pins fall off.
c) Increase the number of coils around the iron core / Increase the number of batteries / Use a thicker iron core.
d) Electromagnets can be turned on/off and their strength can be controlled, unlike permanent magnets.
Question 41 (3 marks)
a) The volume of the stone is 20 cm³ (50 cm³ - 30 cm³).
b) Density = Mass/Volume = 60 g / 20 cm³ = 3 g/cm³.
c) The stone sinks because its density (3 g/cm³) is greater than water's density (1 g/cm³).
Question 42 (4 marks)
a) The chest cavity expands (ribs move up and out, diaphragm moves down).
b) Air pressure in the lungs decreases below atmospheric pressure.
c) Air rushes in from outside (higher pressure) to the lungs (lower pressure).
d) During exhalation, the chest cavity decreases in volume, air pressure in lungs increases, and air is pushed out.
Question 43 (3 marks)
a) The green pigment in leaves is called chlorophyll.
b) Chlorophyll traps light energy to convert carbon dioxide and water into food (glucose) and oxygen.
c) Without light, photosynthesis cannot occur, so the plant cannot make food and will eventually die.
Question 44 (4 marks)
a) The water in the wet towel gains heat from the body and evaporates.
b) Evaporation takes away heat from the body, lowering body temperature.
c) On a windy day, evaporation occurs faster, cooling the body more quickly.
d) On a humid day, evaporation is slower because the air already contains much water vapour, reducing cooling effect.
MARKING SCHEME SUMMARY
| Section | Questions | Marks per Question | Total Marks |
|---|---|---|---|
| A | 1-28 | 2 | 56 |
| B | 29-44 | 2-4 | 44 |
| Total | 100 |
GRADING GUIDELINES (PSLE Standard)
| Score Range | Achievement Level (AL) | Description |
|---|---|---|
| 90-100 | AL1 | Excellent understanding |
| 85-89 | AL2 | Very good understanding |
| 80-84 | AL3 | Good understanding |
| 75-79 | AL4 | Satisfactory understanding |
| 65-74 | AL5 | Adequate understanding |
| 45-64 | AL6 | Basic understanding |
| 20-44 | AL7 | Limited understanding |
| <20 | AL8 | Very limited understanding |
End of Answer Key
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