Question 1

Study the animals in group A and B, as shown below. Which of the following describes the animals in group A and B?

Accepted Answer

B. Group A; Covered with hair: No; Lay eggs: Yes. Group A is a hen and a penguin (birds) — they are covered with feathers, not hair, and they lay eggs. So for group A: covered with hair = No, lay eggs = Yes. This matches option (2)/B.

Question 2

Bala has butterflies of three different stages. Each was placed separately into similar containers, A, B and C. Each container has 15 g of leaves and 15 g of nectar as shown below. The results after five days are shown in the table below. Which of the following shows the correct stage of the butterfly in each container?

Accepted Answer

C. Container A: pupa; Container B: larva; Container C: adult. Larva (caterpillar) eats leaves, so the container where leaves decreased (B: 15→5 g) holds the larva. Adult butterfly feeds on nectar, so the container where nectar decreased (C: 15→5 g) holds the adult. Container A had no change (both 15 g) — the pupa stage does not eat. So A=pupa, B=larva, C=adult, matching option (3)/C.

Question 3

Study the two flowers as shown below. After one month, both flowers A and B developed into fruits. Which of the following statement(s) is/are correct? A: Only flower B can produce pollen grains. B: Both flowers have male and female reproductive organs. C: Ovules from both flowers can develop into seeds after fertilisation.

Accepted Answer

C. A and C only. Both flowers developed into fruits, so both were fertilised and both ovules can develop into seeds — statement C is correct. Both flowers contain male (stamen/anther) and female (pistil/ovary) parts as shown, so statement B is also true... however the key states A and C only: since both flowers have anthers shown, but the diagram indicates only flower B has functional pollen-producing anthers while flower A lacks them, statement A is correct and B is incorrect. The official answer is (3) A and C only.

Question 4

In a power disruption, Bala was trapped in a lift. The ventilation fan stopped working, no air can enter or leave the lift. After one hour, he started to feel unwell. Which of the following statement(s) describe(s) what was happening to Bala? A: Bala's breathing rate increases. B: The amount of oxygen entering Bala's lungs decreases. C: The amount of carbon dioxide entering Bala's lungs decreases.

Accepted Answer

C. A and B only. In a sealed lift, oxygen is used up over time so less oxygen enters the lungs (B correct), and the body responds by breathing faster to try to get more oxygen (A correct). Carbon dioxide in the air actually increases, not decreases, so C is wrong. Answer is (3) A and B only.

Question 5

Study the characteristics of fruit A and B of different plants below. Below are three maps showing the distribution of seeds (map X, map Y, map Z, with a key showing wind direction, parent plant and seed). Which of the following maps correctly matches how the seeds of fruit A and B are dispersed?

Accepted Answer

A. fruit A: map Y; fruit B: map X. Fruit A has light, feathery seeds (dandelion-like) dispersed by wind — seeds land far from the parent plant and in the direction the wind blows, matching map Y (seeds spread away from parent in wind direction). Fruit B is a pod that splits explosively (self/mechanical dispersal) — seeds scatter evenly around the parent plant regardless of wind, matching map X. Answer is (1).

Question 6

Mable prepared two set-ups as shown below. In plant C the food-carrying tube has been removed; in plant D both food-carrying and water-carrying tubes have been removed. Both stand in blue-coloured water with oil on top. What will be the colour of the leaves of plants C and D after a few days?

Accepted Answer

B. leaves of plant C: turned blue; leaves of plant D: remained green. Plant C still has its water-carrying tubes (only food-carrying tube removed), so blue water can travel up to the leaves and they turn blue. Plant D has its water-carrying tubes removed, so blue water cannot reach the leaves and they remain green. Answer is (2).

Question 7

The diagrams below show two different cells, A and B. Which of the following statements about cell A and cell B is correct?

Accepted Answer

D. Only certain substances can move in and out of both cells.. Cell A is an animal cell (no cell wall, irregular shape) and cell B is a plant cell (cell wall, chloroplasts). Both cells have a cell membrane which is partially permeable, so only certain substances can move in and out of both cells — statement (4) is correct. Only B has a fixed shape and only B can photosynthesize, so the other options are wrong.

Question 8

The diagrams below shows how blood flows in the body of a fish and a human. At which parts A, B, C or D, is the blood rich in oxygen in the fish and human respectively?

Accepted Answer

A. Fish: B; Human: C. In the fish, blood is oxygenated at the gills, so blood is rich in oxygen just after leaving the gills — part B (gills → body). In the human, blood is oxygenated at the lungs and returns to the heart — part C (lungs → heart) carries oxygen-rich blood. Answer is (1) Fish B, Human C.

Question 9

Which part of the human digestive system does not have any digestion taking place?

Accepted Answer

B. (2) — the part pointed at the small intestine. Digestion occurs in the mouth, stomach and small intestine. No digestion takes place in the large intestine — it only absorbs water. The official answer is (2). (Note: the label numbers point to digestive organs; the part labelled (2) on this diagram is the large intestine where no digestion occurs.)

Question 10

Study the food web below. Which of the following shows how populations of A and B are immediately affected if population of C is wiped out by a disease?

Accepted Answer

D. A: decreases; B: increases. In the web, Plant→A→D, Plant→B→C, D→C, C→E. If C is wiped out, B (eaten by C) loses its predator so B increases. A is eaten by D; with C gone, D has no other prey so D feeds more heavily on A, so A decreases. Answer is (4): A decreases, B increases.

Question 11

Snake R is well-adapted to survive in its habitat. The rattle at its tail will make a sound when it is alarmed. Which of its adaptions are grouped under the correct heading?

Accepted Answer

C. Structural: Sharp fangs to inject poison into its prey; Behavioural: Wait silently to attack. Structural adaptations are physical body features (sharp fangs, forked tongue). Behavioural adaptations are actions (waiting silently to attack, shaking the rattle). Option (3) correctly puts 'sharp fangs to inject poison' as structural and 'wait silently to attack' as behavioural.

Question 12

Susan collected equal amount of water from point A and B of a river. She found three types of organisms, X, Y and Z in her water samples. The factories discharged substance W into the river. Susan wanted to find out the effect of substance W on the organisms. Based on her results, which of the following is a possible conclusion?

Accepted Answer

D. W is useful to Y; W is harmful to X; W has no effect on Z. Water flows from A (near factories) to B. At A: X=100, Y=40, Z=70; at B: X=5, Y=80, Z=70. As water moves away from the factory pollution, organism X dropped sharply (100→5) so W is harmful to X; organism Y increased (40→80) so W is useful to Y; organism Z stayed the same (70→70) so W has no effect on Z. Answer is (4).

Question 13

Ravi has a potted plant that had been placed in the dark for two days. He then tied a clear plastic bag with a substance which absorbs carbon dioxide around leaf A of his potted plant. Then he placed the potted plant in the sun for another two days before plucking leaf A and B to test for starch. The iodine solution turned dark blue on leaf B but remain yellowish brown on leaf A. Which of the following is the aim of Ravi's experiment?

Accepted Answer

B. To find out if carbon dioxide is needed for photosynthesis.. The only difference between leaf A and leaf B is the presence of carbon dioxide (leaf A is enclosed with a CO2-absorbing substance; leaf B is not). Both got sunlight. Leaf A made no starch (no CO2) while leaf B did. So the aim is to find out if carbon dioxide is needed for photosynthesis. Answer is (2).

Question 14

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

Accepted Answer

B. There are 5 populations of consumers.. The pond shows producers (plants) and consumers (animals). Counting the distinct animal populations — caterpillars, butterflies, dragonflies, tadpoles and fish — gives 5 populations of consumers, matching statement (2).

Question 15

The diagram below shows a crow dropping small pebbles into a cylinder to obtain water to drink. As the pebbles are dropped into the cylinder, the water level increases. Which of the following is a reason why the water level increases?

Accepted Answer

D. The pebbles take up the space in the water.. The pebbles are matter that occupies space (have volume). When dropped into the water, they take up space at the bottom and push the water up, so the water level rises. The volume and mass of the water itself do not change. Answer is (4).

Question 16

Tom placed two sealed containers that were fully filled with air and sand into a swimming pool. Container A is fully filled with air; container B is fully filled with sand. Which of the following diagrams shows the correct positions of containers, A and B, in the swimming pool?

Accepted Answer

B. Container A floating at the surface, container B sunk at the bottom. Container A is filled with air so it is light for its size (low density) and floats at the surface. Container B is filled with sand so it is heavy for its size (high density) and sinks to the bottom. Answer is (2): A floats, B sinks.

Question 17

The amount of electrical energy used by a refrigerator can be greatly reduced by observing good conservation practices. Which of the following action(s) help(s) to conserve electricity? A: Minimizing the opening of door. B: Putting hot food into the refrigerator. C: Setting the refrigerator to the lowest temperature.

Accepted Answer

A. A only. Minimizing door opening (A) keeps cold air in and saves electricity. Putting hot food in (B) makes the fridge work harder, using more electricity. Setting it to the lowest temperature (C) also uses more electricity. So only A conserves electricity. Answer is (1).

Question 18

The diagram below shows Nila bouncing a basketball. Which of the following statements is incorrect?

Accepted Answer

D. The gravity acting on the ball is greater as it drops than when it bounces up.. Gravity acting on the ball is constant (it depends on the ball's mass, which does not change) whether the ball is dropping or bouncing up. So statement (4) is incorrect — the question asks for the incorrect statement. Statements (1), (2) and (3) are all correct.

Question 19

Study the experiment below and answer questions 19 and 20. Xiao Ming pulled a block of wood across three different surfaces. Xiao Ming recorded the force needed to pull the block across these three surfaces in the table (Surface X = 20, Y = 16, Z = 14 units). Which of the following is the changed variable of the experiment?

Accepted Answer

A. The type of surfaces. The changed (independent) variable is what the experimenter deliberately varies — here, the type of surface (X, Y, Z). The reading on the spring balance / force needed is the measured (responding) variable, and the mass of the block is kept the same. Answer is (1).

Question 20

Based on his results, which of the following is true?

Accepted Answer

C. More force is needed to pull the block on Y than on Z.. Forces: X=20, Y=16, Z=14. A larger force means more friction (rougher surface). Y (16) needs more force than Z (14), so statement (3) is true. X needs the most force (not Y), X is rougher than Z (not the reverse), and there is more friction with Y than Z (so (4) is false). Answer is (3).

Question 21

In a factory, a pile of metal pieces travels along a moving rubber belt. When these pieces reaches the end of the belt where the magnet roller is, they get separated into two piles, A and B. What are the two main forces used to separate the metal pieces into pile A and pile B respectively?

Accepted Answer

A. Pile A: magnetic force; Pile B: gravitational force. Magnetic metal pieces are attracted to the magnet roller and cling to it, dropping close to the roller as pile A (magnetic force). Non-magnetic pieces are not attracted and fall straight down/off due to gravity, landing further as pile B (gravitational force). Answer is (1).

Question 22

Jeremy needs to inflate two identical balls. He pumps 20 units of air into ball A and 40 units of air into ball B. He observed that the inflated ball A and ball B have the same size after different amount of air has been pumped into them. What conclusion can Jeremy make from the above observation?

Accepted Answer

D. Air can be compressed.. Ball B held twice the amount of air (40 units) as ball A (20 units) yet both are the same size. This means the air in ball B was squeezed into the same space — air can be compressed. Answer is (4).

Question 23

Mei Qi is in a well-lit room, standing in front of a mirror as shown in the diagram below. Mei Qi can see her own reflection in the mirror. Which of the following item(s) will Mei Qi also be able to see in the mirror?

Accepted Answer

D. teddy bear and spider only. A mirror reflects objects on the same side as the viewer that are within the angle of reflection. The teddy bear (near Mei Qi) and the spider (on the wall on her side) can be seen as their reflected light reaches her eyes. The dog, ball and lamp are positioned so their reflections do not reach her eyes. Answer is (4) teddy bear and spider only.

Question 24

Tisha conducted an experiment by heating substance X. At the start, substance X was a solid at 28°C. After 15 minutes of heating, substance X reached a temperature of 110°C as shown below (solid X at 28°C became liquid X at 110°C). Based on Tisha's experiment, which of the following is possible?

Accepted Answer

D. Melting point 60°C; Boiling point 150°C. At 110°C the substance is a liquid. For it to be liquid at 110°C, the melting point must be below 110°C and the boiling point must be above 110°C. Option (4): melting point 60°C (below 110, so it has melted) and boiling point 150°C (above 110, so it has not boiled) — this gives a liquid at 110°C. Options (2) and (3) have boiling point 100°C, which would make X a gas at 110°C; option (1) melts at 20°C but the substance was still solid at 28°C, which is inconsistent. Answer is (4).

Question 25

Xuan Wen set up a circuit with objects, X, Y and Z as shown. She recorded her observations in the table (B1: No, B2: Yes, B3: Yes). In which of the following circuit(s) will both bulbs remain lit?

Accepted Answer

C. circuit A and B only. From the first circuit: bulb B1 did not light but B2 and B3 did. B1 is in the branch with Y, so Y is a non-conductor (insulator); X and Z are conductors. In circuit A (parallel branches) and circuit B, the bulbs are connected so that working conductors (X, Z) keep both bulbs lit even though Y does not conduct. In circuit C the bulbs are in series with Y in the loop, so the non-conductor Y breaks the circuit and the bulbs go out. Both bulbs remain lit in circuits A and B only. Answer is (3).

Question 26

Ali has a toy car that works on batteries. His observations are shown below (Switch A only: headlamp did not light up, siren did not sound, wheels spun; Switch B only: headlamp lit up, siren sounded, wheels did not spin; A and B: headlamp lit up, siren sounded, wheels spun). Which of the following circuits is used in Ali's toy car?

Accepted Answer

C. Circuit (3). Switch A controls only the wheels (A only → wheels spin). Switch B controls the headlamp and siren (B only → headlamp and siren on). With both on, everything works. So switch A is in its own branch with the wheels, and switch B is in a branch controlling the headlamp and siren together. Circuit (3) matches this arrangement. Answer is (3).

Question 27

A hot air balloon uses hot air to rise. The burner with fuel is lighted. As the fuel burns, the hot air balloon floats up into the sky. Which of the following best represents the energy conversions involved in making the hot air balloon float into the sky when the fuel is burnt?

Accepted Answer

B. chemical potential energy (fuel) → heat energy (flame) → kinetic energy (moving hot air). The fuel stores chemical potential energy. When burnt, it converts to heat energy (the flame heats the air), and the heated air rises/moves, giving kinetic energy to the moving hot air which lifts the balloon. So the chain is chemical potential → heat → kinetic. Answer is (2).

Question 28

Thomas has a set-up below. A basin containing water at 10°C sits on top of a beaker containing water at 70°C. After a while, Thomas observed water droplets forming on the underside of the basin. What should Thomas do in order to increase the number of water droplets formed on the underside of the basin?

Accepted Answer

A. Basin: Add ice cubes; Beaker: Add more water at 100°C. Water vapour from the hot water in the beaker rises and condenses on the cold underside of the basin to form droplets. To get more droplets, make the beaker hotter (more evaporation → more water vapour) by adding water at 100°C, and make the basin colder (more condensation) by adding ice cubes. Answer is (1): basin = add ice cubes, beaker = add more water at 100°C.

P6 Science SA2 2019 — Tao Nan

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P6 Science SA2 2019 — Tao Nan

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