Question 1

Which of the following is the correct function of a system in our body?

Accepted Answer

4. Respiratory — takes in and gives out air. The respiratory system takes in air (oxygen) and gives out air (carbon dioxide). The muscular system enables movement (not shape support — that is the skeletal system), the digestive system breaks down food, and the circulatory system transports oxygen (not carbon dioxide only) and nutrients.

Question 2

Which of the following does not reproduce by spores?

Accepted Answer

2. rose plant. Rose plant is a flowering plant that reproduces by seeds. Mushrooms, bread mould (fungi) and bird's nest fern (non-flowering plant) all reproduce by spores.

Question 3

Which of the following characteristics can be used to differentiate between amphibians and mammals?

Accepted Answer

1. body covering. Amphibians have moist smooth skin while mammals have fur/hair. Both groups can have 4 legs, eat varied foods, and have life cycles with similar number of stages, so body covering reliably differentiates them.

Question 4

For an adult plant to produce fruits, which process(es) must take place?

Accepted Answer

3. pollination and fertilisation. Pollination (transfer of pollen) is followed by fertilisation (fusion of male and female gametes); the fertilised ovary then develops into the fruit. Germination occurs only after the seed is dispersed.

Question 5

Study the food web with organisms A, B, C and D. Which of the following organism is a food producer?

Accepted Answer

2. B. A producer has only outgoing arrows (it is eaten by others but does not eat anything). Organism B has arrows pointing only out (to A and D) and none pointing in, so it is the producer.

Question 6

The diagram shows the stages in the life cycle of a butterfly. . Which of the following correctly describes the organism at stages Y and Z? [Table: (1) Y does not look like adult, Z lives in water; (2) Y lives on land, Z does not look like adult; (3) Y lives in water, Z able to fly; (4) Y unable to fly, Z looks like adult]

Accepted Answer

2. Y: lives on land / Z: does not look like adult. Y is the caterpillar (larva) which lives on land and feeds on leaves; Z is the pupa, which does not look like the adult butterfly. Both stages cannot fly, ruling out options 3 and 4.

Question 7

The diagram shows a pond habitat. . Which of the following statements is true?

Accepted Answer

2. There are five populations in the habitat altogether.. A population is all members of one species in a habitat. The habitat shows 5 different species/populations: caterpillars, butterflies, land plants, water plants and fish. A habitat has only one community.

Question 8

Scientists have observed that the increase in Earth's air temperature in recent years has slowed down. Which of the following could have contributed to the improvement?

Accepted Answer

4. An increase in the use of alternative energy sources like solar, wind and running water. Alternative energy sources do not release carbon dioxide / greenhouse gases when used, so they reduce the rate of global warming. The other options all increase greenhouse gas emissions or reduce trees that absorb carbon dioxide.

Question 9

Tim, Suriah and Joanne observed the following cells, A, B and C, and made the following statements. . Tim: Both cell A and C are animal cells as they do not have chloroplast. Suriah: Both cell B and C are plants cells as they have cell walls. Joanne: Only cell B can make food. Which statement(s) is/are true?

Accepted Answer

3. Suriah and Joanne only. Cell C has a cell wall (hexagonal shape) so it is a plant cell even without chloroplast — Tim is wrong. Both B and C are plant cells (have cell wall) — Suriah is correct. Only B has chloroplasts, so only B can make food — Joanne is correct.

Question 10

Mrs Lim prepared three different set-ups, A, B and C to find out if seeds will germinate under different conditions. Identical seeds were used in the set-up. The different conditions in the three set-ups were shown below. . In which set-ups will the seeds germinate?

Accepted Answer

1. A and B only. Seeds need water, oxygen and a suitable temperature to germinate (light is NOT required). Set-up A has all three needed conditions, set-up B has all three plus light, but set-up C lacks suitable temperature, so seeds in C will not germinate.

Question 11

Jessica conducted an experiment with the following set-ups. . What are the likely changes in the amount of gases after a few hours? [Table options shown]

Accepted Answer

4. X: decrease in carbon dioxide / Y: increase in carbon dioxide / Z: increase in carbon dioxide. In X (light): plant photosynthesises more than it respires → takes in CO2 (decrease) and gives out O2. In Y (dark): plant only respires → takes in O2 and gives out CO2 (increase). In Z (dark, plant + fish): both respire → both take in O2 and give out CO2 (increase). Option 4 matches.

Question 12

The diagram shows the direction of blood flow in some parts of the body. . What do V, W and X represent? [Table options]

Accepted Answer

4. V: heart / W: lungs / X: other parts of the body. Blood leaving the heart to the lungs is rich in CO2; blood returning from the lungs is rich in O2. Blood from heart to other parts of the body is rich in O2; blood returning is rich in CO2. V (receives O2-poor blood from W and sends O2-poor blood to X-bound flow) = heart; W = lungs; X = other parts of the body.

Question 13

The graph below shows the population of squirrels in a forest community over a period of time. [Graph: number of squirrels rises from Jan, peaks at May, then drops sharply, then rises slightly]. Based on the graph above, what could have caused the drop in the squirrel population in May? A. Increase in the amount of food for the squirrels. B. New predator of the squirrels was introduced into the forest. C. Increase in deforestation.

Accepted Answer

3. B and C only. A drop in population can be caused by increased predation (B — more squirrels eaten) or loss of habitat/food due to deforestation (C). An increase in food (A) would increase, not decrease, the population.

Question 14

Amy set up an experiment using four similar leaves, A, B, C and D on the same plant. These leaves have tiny openings on both their upper and lower surfaces. She coated some surfaces of the leaves with oil as shown in the table. . The plant was under bright sunlight for two hours. Amy measured the volume of water loss at regular time intervals. Her results are shown in the graph below. [Graph: water loss greatest for D, then B, then A, then C least]. Based on her results, what can Amy conclude about the tiny openings on the leaves of the plant?

Accepted Answer

2. There are more tiny openings on the lower surfaces.. Leaf B (lower surface open only) loses more water than leaf A (upper surface open only). Since more water escapes through the lower surface, there must be more tiny openings (stomata) on the lower surface.

Question 15

The diagram shows two men on a gondola. . To hold the weight of the gondola, steel cables are used because steel is ____.

Accepted Answer

3. strong. Steel is used for the cables because it is strong enough to bear the weight of the gondola and the workers without breaking. Being magnetic, flexible or waterproof is not relevant to supporting heavy weight.

Question 16

The diagram shows a magnet with an iron ball attracted to it. . Which force(s) is/are acting on the iron ball?

Accepted Answer

4. magnetic and gravitational force. Gravitational force pulls the iron ball downwards. The magnet exerts a magnetic force upwards that attracts the iron ball, balancing gravity so it stays attached. Both forces act on the ball.

Question 17

Diagram 1 shows a toy with a rolled paper tube. When Belle blew air into it, the paper tube straightened as shown in Diagram 2. [Diagram 1: girl with rolled paper tube and mouthpiece; Diagram 2: girl blowing — paper tube straightened out]. Which of the following best explains why the paper tube straightened?

Accepted Answer

1. Air takes up space.. When Belle blew air into the tube, the air filled the inside of the rolled tube and took up space, pushing the paper outwards and unrolling it. This demonstrates that air (a gas) takes up space.

Question 18

Casey conducted an experiment by heating substance S. At the start, S was a solid at 25 °C. After 15 minutes of heating, S reached a temperature of 80 °C as shown. . Based on Casey's experiment, which of the following is possible? [Table: (1) MP 15 / BP 85; (2) MP 20 / BP 80; (3) MP 25 / BP 75; (4) MP 30 / BP 90]

Accepted Answer

4. Melting point 30 °C / Boiling point 90 °C. S started solid at 25 °C (so melting point must be > 25 °C) and ended as liquid at 80 °C (so boiling point must be > 80 °C). Only option 4 satisfies both: MP 30 °C (> 25) and BP 90 °C (> 80).

Question 19

Which one of the following is not an example of energy conversion?

Accepted Answer

1. cooling hot water in a cup. Cooling hot water is heat transfer (loss of heat to surroundings), not energy conversion from one form to another. Toasting converts electrical → heat, climbing converts potential → kinetic, and power station converts various forms → electrical energy.

Question 20

Daniel pasted a sticker on a toy truck. Some air bubbles were trapped under the sticker as shown in Diagram 1. The toy truck was left in the sun. After a few hours, the air bubbles became larger as shown in Diagram 2. [Diagram 1: small bubble; Diagram 2: enlarged bubble]. Which of the following explains why the air bubbles became larger?

Accepted Answer

3. Air expands when heated.. Heat from the sun caused the trapped air to gain heat and expand, so the bubbles became larger. No more air can enter under the sealed sticker; sticker/truck expansion would not enlarge the bubble.

Question 21

Kelly sets up the circuit below using materials A, B and C. She does not know whether the materials are electrical conductors or insulators. . Which of the following is possible when Kelly closes the switch? [Table: (1) 1 insulator/1 bulb; (2) 2 insulators/2 bulbs; (3) 2 insulators/1 bulb; (4) 3 insulators/1 bulb]

Accepted Answer

2. 2 insulators / 2 bulbs light up. If A and B are both insulators (2 insulators), no current flows through the A-bulb or B-bulb branches, but the right branch with C (a conductor) still lights its bulb, and the bulb on the main line also lights, giving 2 bulbs lit.

Question 22

Beth set up the electrical circuit below. She set up another similar electrical circuit and added one more battery to it. She observed the brightness of the bulbs in both set-ups. . What was the hypothesis tested in this experiment?

Accepted Answer

3. More batteries will increase the brightness of the bulb.. The only variable changed between the two set-ups is the number of batteries; everything else (lemon juice, bulb) is kept the same. So Beth is testing whether adding more batteries increases the brightness of the bulb.

Question 23

The diagram shows how water changes from one state to another. . Which of the following correctly describes A, B and C? [Table: (1) A liquid, B gas, C heat loss; (2) A liquid, B gas, C heat gain; (3) A gas, B liquid, C heat loss; (4) A gas, B liquid, C heat gain]

Accepted Answer

1. A liquid / B gas / C heat loss. Solid → A → B in sequence: solid (ice) melts to liquid (A), then liquid evaporates to gas (B). C is the reverse arrow from A back to solid (freezing), which involves heat loss. So A = liquid, B = gas, C = heat loss.

Question 24

Ella and her black rabbit were in a dimly lit room. . Which one of the following statements correctly explains why she could see the rabbit's eyes clearly?

Accepted Answer

3. Light was reflected from the rabbit's eyes to Ella's eyes.. We see non-luminous objects when light from a source (the lamp) reflects off them into our eyes. Light from the lamp hit the rabbit's eyes, reflected, and entered Ella's eyes, so she could see them clearly.

Question 25

Delia set up an experiment. . She placed the set-up in a dry place. She recorded the temperature of the air inside the small pot. Her results are shown below. [Table: 0 min — 32 °C; 10 min — 30 °C; 20 min — 29 °C]. What is the reason for the decrease in temperature of the air inside the small pot?

Accepted Answer

1. Water evaporated from the wet sand.. Water from the wet sand evaporates, gaining heat from the surroundings (the air inside the small pot). This loss of heat from the air causes its temperature to drop. This is the principle of evaporative cooling.

Question 26

Study the diagrams below. . The floating globe is easier to spin because it has less ____.

Accepted Answer

2. frictional force. A floating globe has no physical contact with its base, so there is less (almost no) frictional force opposing its motion. The globe on an axle rubs against the axle, producing friction.

Question 27

In an experiment, Fatin measured the lengths of Gina's shadows from two lighted lamp posts, S and T, as Gina walked along a straight path from A to E. [Graph: shadow from lamp post S (dashed) starts at 0 at A and increases linearly to E; shadow from lamp post T (solid) starts long at A, decreases linearly to near 0 at D, then increases slightly at E]. Based on the graph, which one of the following correctly shows the positions of lamp posts S and T?

Accepted Answer

3. S at A, T at D. Shadow length is shortest when the person is right under (closest to) the lamp post and grows longer with distance. Shadow from S is shortest at A → S is at A. Shadow from T is shortest at D → T is at D.

Question 28

Ali used the set-up below to study four types of springs, A, B, C and D. . He placed objects of different mass on each spring and measured the length of the spring. The results are shown in the graph below. [Graph: A barely shortens with mass; B shortens slightly more; C shortens more; D is already shorter at 0 kg and barely changes — basically D = least sensitive to mass]. Using the same set-up, Ali wanted to compare the mass of two apples below. Which spring, A, B, C or D, is the most suitable for his set-up?

Accepted Answer

3. C. Apples have small mass, so the spring must compress noticeably with small mass to distinguish between the two apples. Spring A barely changes (too stiff), spring D is too short to register the small differences (or too sensitive at the high mass range only), spring B changes less than C. Spring C compresses the most noticeably across the small mass range, making it the most suitable for comparing the apples.

P6 Science SA2 2025 — Methodist Girls

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