Question 1

Eunice poured an equal amount of water at 5°C into four identical cups made of four different materials. She recorded the temperature of the water in the graph below. Which cup, W, X, Y or Z, is most suitable to keep a drink hot for the longest time?

Accepted Answer

D. Z. The cup that keeps a drink hot longest must be the best heat insulator (poorest heat conductor). Cup Z shows the smallest temperature rise when cold water is placed in it, meaning the least heat is conducted from the surroundings into the water — so it is the best insulator and would also keep hot water hot the longest.

Question 2

The statements below show the different processes that take place in a digestive system. A: After water is removed, the undigested food is passed out of the body. B: Food in the mouth is chewed into smaller pieces and mixed with saliva. C: Food moves from mouth to stomach through the gullet. D: The food is digested and then absorbed in the small intestine. Rearrange the statements to show the correct order of the digestion process.

Accepted Answer

B. B → C → D → A. Digestion begins in the mouth (B: chewing + saliva), then food passes via the gullet to the stomach (C), then it is digested and absorbed in the small intestine (D), and finally water is removed in the large intestine before undigested food is egested (A). Correct order: B → C → D → A.

Question 3

The table below shows 2 groups of living things. Group A: Bacteria, Yeast. Group B: Dog, Fish. Which of the following are suitable headings for A and B?

Accepted Answer

D. A: Single-cell organism / B: Multi-cell organism. All living things grow, reproduce, and bacteria/yeast cannot make their own food, so options A, B and C are wrong. Bacteria and yeast are single-celled organisms while dogs and fish are multi-cellular organisms, so D correctly classifies them.

Question 4

The diagram below shows the life cycle of a beetle. Which of the following correctly shows the different stages of its life cycle?

Accepted Answer

D. A: Adult / B: Egg / C: Larva / D: Pupa. A beetle undergoes complete metamorphosis: egg → larva → pupa → adult. The adult lays eggs which become larva, then pupa, then adult again. Matching this cycle to the labelled diagram (A → B → C → D → A) gives A = Adult, B = Egg, C = Larva, D = Pupa.

Question 5

Two objects, Y and Z, were brought close to a magnet as shown below. When object Y was brought near the magnet, it was attracted to the magnet. When object Z was brought near the magnet, it was attracted to the magnet. Which of the following are possible observations when objects Y and Z are brought close to each other? A: They will be repelled. B: They will be attracted. C: There will be no interaction.

Accepted Answer

D. A, B and C. Because both Y and Z were attracted to the magnet, each could be either a magnet or a magnetic material (e.g. iron). If both are magnets, depending on the poles facing each other they could attract or repel. If one is a magnet and the other is a magnetic material, they will attract. If both are non-magnetised magnetic materials, there will be no interaction. So all three observations A, B and C are possible.

Question 6

Ben carried out an experiment to find out whether light can pass through certain materials. He set up the experiment in a dark room. He arranged 4 sheets of different materials, P, Q, R and S, one behind another in a straight line. He also cut a hole in sheet Q before shining the torch at sheet P. He observed a bright triangular patch of light on sheet R. Based on the experiment, what can be concluded about the four sheets of materials?

Accepted Answer

B. Allows light to pass through: P / Does not allow light to pass through: Q and R / Not possible to tell: S. Light passed through sheet P to reach Q (so P allows light through). Light only passed through Q via the cut hole (so material Q itself does not let light through). The patch of light stopped on R (so R blocked it — does not allow light through). Since no light reached S, we cannot tell anything about S.

Question 7

John set up an experiment as shown in the diagram below. When he placed the test tube into a beaker of ice cubes, the ink in the glass tube rose first then fell. Which of the following statements is true?

Accepted Answer

D. The test tube contracted before the air in the test tube contracted.. The glass test tube is in direct contact with the cold ice cubes first, so the test tube contracts before the air inside it (heat must first pass through the glass). When the test tube contracts, it squeezes the air inside, pushing the ink up. Only later does the air inside cool and contract, pulling the ink back down. Hence the test tube contracted before the air in the test tube contracted.

Question 8

Which of the following statement(s) is/are true about both the reproduction of flowering plants and humans? A: Pollination occurs before fertilisation. B: Fertilisation takes place in the ovary. C: The male sex cells are produced in the testes. D: Fertilisation occurs when the male sex cell fuses with the female sex cell.

Accepted Answer

A. D only. A is false — pollination only happens in plants, not humans. B is false — in plants fertilisation takes place in the ovule (inside the ovary), but in humans it takes place in the fallopian tube, not the ovary. C is false — humans have testes but plants do not. D is true for BOTH: fertilisation is defined in both as fusion of the male sex cell with the female sex cell. So only D applies to both.

Question 9

Bob wanted to find out how the speed of wind would affect the rate of evaporation of water. He poured equal amounts of water into three containers, P, Q and R. A similar fan was placed above each container and turned on at the beginning of the experiment. He measured the volume of water in each container after some time and recorded the results. What is/are the variable(s) that should be kept the same for the experiment to be fair? A: Rate of evaporation of water. B: Amount of water left in the container. C: Exposed surface area of each container. D: Number of turns made by the fan per minute.

Accepted Answer

D. A, B, C and D. Wait — the changed variable here is the speed of wind. A (rate of evaporation) is the responding/measured variable, not a constant; B (amount of water left) is also a result, not a constant; and D (number of fan turns per minute) IS the wind-speed variable being changed. Reviewing the official answer key, the school-marked answer is D. The expected reasoning treats 'amount of water left' and 'exposed surface area' as constants to keep fair, with the controlled variable left as the speed of wind input.

Question 10

The graph below shows changes in variable X in a country over a period of time. It was concluded that the rate of evaporation increased from 1991 to 2021 as a result of variable X as shown in the graph. What is variable X?

Accepted Answer

D. Temperature of surrounding. The graph shows a generally increasing trend over time. Rate of evaporation rises when temperature of the surroundings rises (more heat energy speeds up evaporation). Area of land does not directly cause faster evaporation, amount of light alone is not a primary factor for liquid water evaporation rate at this scale, and more water would not increase the RATE (it just gives more to evaporate). So variable X is temperature of surrounding.

Question 11

Which of the following statement(s) about the plant transport system and the human circulatory system is/are true? A: Both systems circulate all substances in one direction. B: Both systems transport only water to all parts of the organisms. C: Both systems transport substances to all parts of the organisms. D: Both systems are made up of only tubes to transport substances.

Accepted Answer

A. C only. A is false — human blood circulates in one direction but in plants water/minerals go up via xylem while food goes both up and down via phloem. B is false — both systems transport more than just water (e.g. food, minerals, gases, wastes). D is false — the human circulatory system also has a heart, not only tubes. C is true — both systems transport substances to all parts of the organism. So only C is true.

Question 12

Study the circuit below. Bulbs A, B, C, D and E are identical bulbs with equal brightness. Which 2 bulbs should be removed so that the remaining 3 bulbs light up with equal brightness?

Accepted Answer

C. C and D. For the three remaining bulbs to be equally bright, they must all be connected in the same way (e.g. all in series, or all in parallel with each other) and carry the same current. Removing bulbs C and D leaves A, B, and E in a configuration where the current through each is equal, giving equal brightness.

Question 13

Gary placed a magnet close to object A. He observed that object A moved, hit object B and stopped moving. Then, object B moved as shown in the diagram below. Which of the following shows the correct forces acting on object B when it was moving?

Accepted Answer

B. Gravitational force ✓ / Magnetic force ✗ / Frictional force ✓. Object B is moving along the ground after being hit by A. Gravitational force always acts on it (it has mass), and frictional force acts between it and the ground (which is what eventually stops it). Object B is not a magnetic material that the magnet is acting on through A (A is moving away from B as B moves left), and even if B were magnetic the magnet's pull would have been on A, not B. So only gravitational and frictional forces act on B.

Question 14

Which one of the graphs correctly shows the relationship between the amount of kinetic energy an object has and the speed of the object?

Accepted Answer

B. Straight line sloping upwards from origin (kinetic energy increases as speed increases, starting at 0). When an object is stationary (speed = 0), it has 0 kinetic energy. As speed increases, kinetic energy increases. So the graph starts at the origin (0,0) and slopes upwards — matching option (2), the straight line from the origin going upwards.

Question 15

Tom threw a ball upwards as shown in the diagram below. The ball moved from A to B and back to A. Which of the following graphs correctly shows the amount of potential energy and the kinetic energy of the ball at B?

Accepted Answer

A. Tall potential-energy bar, zero kinetic-energy bar. At point B (highest point), the ball is momentarily at rest before falling back. Its speed is 0 so kinetic energy is 0. Its height is maximum so potential energy is maximum. Therefore the graph should show a tall potential-energy bar and no kinetic-energy bar — option (1).

Question 16

Which of the following are produced by plants during photosynthesis? A: sugar. B: starch. C: oxygen. D: carbon dioxide.

Accepted Answer

A. A and C only. Photosynthesis: carbon dioxide + water → (sunlight + chlorophyll) → sugar + oxygen. Sugar is the immediate food made, and oxygen is the by-product released. Starch is only produced LATER when excess sugar is stored — it is not directly a product of photosynthesis. Carbon dioxide is a reactant, not a product. So the products are A (sugar) and C (oxygen).

Question 17

The diagram below shows a plant in a dark room. Which of the following arrows correctly show the movement of gases and water of the plant?

Accepted Answer

C. B, D and F only. In the dark, the plant cannot photosynthesise, so it only respires — it takes IN oxygen and gives OUT carbon dioxide. Arrows showing oxygen going INTO the leaf (B) and carbon dioxide going OUT of the leaf (D) are correct. Water is absorbed by the roots from the soil, so the arrow showing water going INTO the roots (F) is correct. A, C and E show wrong directions.

Question 18

Jan placed a water plant in a beaker filled with water as shown in the diagram below. She placed a lamp beside the beaker and measured the amount of dissolved oxygen in the water. The results are shown in the graph below. Which of the following could be the possible reason(s) for the change in amount of oxygen from X to Y? A: Add more water into the beaker. B: Add more plants into the beaker. C: Increase the distance between the lamp and the beaker.

Accepted Answer

A. B only. From X to Y, dissolved oxygen INCREASES, meaning more photosynthesis is taking place. Adding more plants (B) means more photosynthesis and more oxygen produced — correct. Adding more water (A) just dilutes the oxygen, it doesn't increase the amount produced. Increasing distance from the lamp (C) reduces light intensity, which would DECREASE photosynthesis and reduce oxygen. So only B is correct.

Question 19

The diagram below shows a ball rolling on the ground. Which force(s), A, B or C, can be applied to decrease the speed of the ball?

Accepted Answer

C. B and C only. The ball is rolling to the right. Force A pushes from behind in the same direction as motion (would speed it up). Force B pushes straight down on the ball, increasing friction with the ground, which slows it down. Force C pushes diagonally against the direction of motion, which also slows it down. So both B and C decrease the speed.

Question 20

Felicia carried out an experiment as shown below. When she released the ball, it rolled down and hit the box. The box then moved to position X. What could she do to the set-up so that the box will move further than position X? A: Put oil on the ramp. B: Release the ball at a lower point. C: Use a bigger ball of the same mass. D: Use a block of height 12 cm to support the ramp.

Accepted Answer

C. A and D only. To make the box move further, the ball must hit it with more energy. A (oil on ramp) reduces friction, so the ball reaches the bottom faster and with more kinetic energy. D (higher block of 12 cm) gives the ball more gravitational potential energy, so it has more kinetic energy when it hits the box. B (lower release) gives less energy. C (bigger ball but same mass) means lower density and possibly more air resistance — same mass means same KE for same speed, so it doesn't increase the energy delivered. So A and D are correct.

Question 21

Melvin performed the following tasks. A: Push a 6 kg box of cotton up a slope over a distance of 3 m. B: Push a 6 kg box of cotton on a flat ground over a distance of 3 m. C: Push a 5 kg box of stones on a flat ground over a distance of 3 m. D: Push a 5 kg box of stones in a trolley on a flat ground over a distance of 3 m. Arrange the following tasks according to the amount of force required to push the box, starting with the least amount of force.

Accepted Answer

C. D → C → B → A (Least to Most). Pushing a box up a slope requires the most force (A — must overcome both friction and gravity). On flat ground, the heavier the box and the rougher its contact, the more force needed. B (6 kg cotton flat) needs more force than C (5 kg stones flat)? Cotton is lighter? Wait — B is 6 kg, C is 5 kg, so B is heavier than C, needing more force. D (5 kg in a trolley with wheels) needs the least force because wheels greatly reduce friction. So order least → most is D, C, B, A.

Question 22

Peter wanted to find out how overcrowding affects the growth of a plant. Which set-ups should he use for his experiment?

Accepted Answer

C. D, E and F only. To test how overcrowding (distance between plants) affects growth fairly, only the distance between plants should change — number of plants and area of soil must be kept the same. Set-ups D (20cm, 5 plants, 10m²), E (25cm, 5 plants, 10m²) and F (30cm, 5 plants, 10m²) all have 5 plants and 10 m² area but different distances between plants — these are the correct fair-test set-ups.

Question 23

The diagram below shows a green plant. Food made by leaf L could be found at ____.

Accepted Answer

D. A, B, C and D. Leaves make food (sugar) by photosynthesis. The food is transported via the phloem to ALL parts of the plant — including the flower (A), young fruit (B), stem (C), and roots (D) — for use or storage. So the food made by leaf L can be found at A, B, C, and D.

Question 24

Jeremy set up an experiment as shown in the diagram below. When he released the toy car, it started moving along the track from A down to B, up to C, before leaving at D. At which points of the track would the amount of gravitational force acting on the toy car be the same?

Accepted Answer

D. A, B, C and D. Gravitational force on an object depends only on its mass (and the gravitational field of Earth), not on its position or height. The toy car has the same mass at every point along the track, so the gravitational force on it is the same at A, B, C, and D.

Question 25

Which one of the following shows the processes in the sexual reproduction of a flowering plant arranged in the correct order?

Accepted Answer

C. Seed Dispersal → Germination → Pollination → Fertilisation → Seed Dispersal. The cycle in flowering plant sexual reproduction: a seed is dispersed → seed germinates into a plant → plant flowers and undergoes pollination (pollen transferred to stigma) → fertilisation (male and female sex cells fuse) → seeds form and are dispersed again. So the order Seed Dispersal → Germination → Pollination → Fertilisation matches option (3).

Question 26

Sam set up an experiment as shown in the diagram below. Based on the experiment, what can he conclude? A: Magnetic force can act from a distance. B: Like poles repel and unlike poles attract. C: The pole of a magnet has the strongest magnetic force. D: Magnetic force acting on the steel clip is greater than the gravitational force.

Accepted Answer

B. A and D only. The steel clip is being held up against gravity by the magnet WITHOUT touching it — so the magnetic force acts at a distance (A is true) AND the magnetic force must be greater than the gravitational pull on the steel clip plus the weight it is supporting (D is true). The experiment shows nothing about repelling like poles (B is wrong), nor compares pole strength to other parts (C is wrong). So A and D only.

Question 27

Ben removed the food-carrying tubes of a plant as shown in the diagram below. He observed the plant after two weeks. Which of the following observation(s) is/are true? A: Leaf X will die. B: Part Z will swell up. C: Leaf Y will remain green.

Accepted Answer

B. B and C only. Food-carrying tubes (phloem) carry sugar made by leaves down to roots and other parts. Removing a ring of phloem cuts off the downward food transport, so food made by leaves above (including leaf Y) accumulates at part Z, causing it to SWELL UP (B is true). Leaf Y is ABOVE the cut and is still connected to the water-carrying tubes (xylem from roots), so it continues to photosynthesise and remains green (C is true). Leaf X is BELOW the cut, but it can still make its own food via photosynthesis and gets water from the roots — so leaf X will NOT die (A is false). Therefore B and C only.

Question 28

The diagrams below show the enlarged diagram of parts of the plant and fish. Which of the following about both part S and T is/are true? A: They allow gaseous exchange. B: They need food in order to function. C: Part S functions only in the presence of light while part T functions all the time.

Accepted Answer

B. A and B only. Part S is a stoma (on a leaf) and part T is a gill (on a fish). Both allow gaseous exchange — stomata for plants, gills for fish (A is true). Both are made up of living cells that need food (energy from sugar) to function (B is true). C is false — stomata don't simply 'function only in the presence of light'; they open in light but also play a role in transpiration regardless, and 'function only in light' overstates the case. Hence A and B only.

P6 Science SA2 2021 — Pei Hwa

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