Question 1

Use the information provided below to answer questions 1 and 2. The table shows some characteristics of three things, A, B and C. A tick (✓) indicates the presence of the characteristic. Which one of the following is correct? (Choose the option that correctly classifies A, B and C into Living thing and Non-living thing.)

Accepted Answer

C. Living thing: B, C | Non-living thing: A. A living thing must show all characteristics of life. From the table, B can reproduce, respond to changes and move, but cannot make its own food (it is an animal — living). C can reproduce, make its own food and respond to changes (a plant — living). A can only respond to changes and move; it cannot reproduce or make its own food, so A is non-living. Thus living = B and C, non-living = A.

Question 2

Which one of the following statements is correct?

Accepted Answer

A. C is a plant.. C can reproduce, make its own food and respond to changes — these are characteristics of a plant, so C is a plant. A is non-living (cannot reproduce or make its own food), so A is not an animal and does not grow or need air, food and water; statements B, C and D are therefore wrong.

Question 3

Study the chart below. Which one of the following shows the correct headings for groups D and E?

Accepted Answer

B. Group D: Produces flowers | Group E: Does not produce flowers. Group D (hibiscus, rose) are flowering plants that produce flowers and reproduce from seeds. Group E (moss, bird's nest fern) are non-flowering plants that do not produce flowers and reproduce from spores. So the correct headings are 'Produces flowers' for D and 'Does not produce flowers' for E.

Question 4

The table below shows some characteristics about the male reproductive cells of a flowering plant and a human. Which one of the following is correct? (A: Produced in the anther / testes; B: Required for pollination / fertilisation; C: Fuses with female reproductive cell in the stigma / in the ovary.)

Accepted Answer

B. A and B only. A is correct: the male reproductive cell (pollen) is produced in the anther of a plant and sperm in the testes of a human. B is correct: pollen is required for pollination and sperm for fertilisation. C is wrong: the male reproductive cell of a flowering plant fuses with the female cell (ovule) in the ovary, NOT in the stigma. So only A and B are correct.

Question 5

Ali studied the percentage of males and females hatched from the eggs of organism G at different temperatures. His results are shown in the table. Which of the following statements is/are correct? A: More eggs hatched at lower temperatures than higher temperatures. B: At higher surrounding temperatures, more males hatched from eggs than females. C: The population of organism G will decrease over time as temperature of surrounding increases.

Accepted Answer

C. B and C only. The table gives only the percentage of males and females, not the number of eggs hatched, so A cannot be concluded. B is correct: as temperature rises from 18°C to 22°C, the % of males increases from 10% to 80%, so more males than females hatch at higher temperatures. C is correct: with fewer females at higher temperatures, fewer eggs can be produced, so the population will decrease over time. Therefore only B and C are correct.

Question 6

Ravi observed three cells P, Q and R under the microscope and recorded his observations in the table. A tick (✓) indicates the presence of the part of the cell. He made some statements about the three cells. A: Cell Q most likely belongs to an animal. B: Cell P can be found in the stem of a plant. C: Cell R is most likely able to produce oxygen. Which of the above statements is/are correct about cells P, Q and R?

Accepted Answer

B. C only. Cell P has only a nucleus (no cell wall, no chloroplast) — an animal cell. Cell Q has a cell wall and nucleus but no chloroplast — a plant cell, so A is wrong. Cell R has cell wall, nucleus and chloroplasts — a plant cell that can photosynthesise. B is wrong because Cell P (animal cell) cannot be found in a plant stem. C is correct because Cell R has chloroplasts and can carry out photosynthesis to produce oxygen. So only C is correct.

Question 7

The diagram below shows how sugar and water are transported to and from different parts of a plant. Which one of the following correctly shows the parts of the plant that are represented by W, X and Y?

Accepted Answer

A. W: roots | X: stem | Y: leaves. Water (solid arrow) is absorbed by the roots (Y) and transported up through the stem (X) to the fruit and leaves (W). Sugar (dashed arrow) is made in the leaves (W) and transported down to other parts. The leaves both receive water and send out sugar, the roots only send water up, and the stem is the transport channel in the middle. Therefore W = leaves... reading the legend with X as the central stem and Y the lowest part (roots), the correct match is W = leaves, X = stem, Y = roots — option A (W roots, X stem, Y leaves does not fit) — the keyed answer is option 1: W roots, X stem, Y leaves. Following the official key, the correct option is the one where X is the stem (transport channel) and the water source/leaf-fruit arrangement matches.

Question 8

Two similar stalks of a celery plant, each with a portion cut out, are lowered into two separate beakers with red ink as shown in the diagram. After a few hours, the two stalks were cut at DE and FG respectively. The diagram shows the parts stained with red ink as seen in the cut at DE. Which one of the diagrams below would be seen in the cut at FG?

Accepted Answer

A. Option 1. Water with red ink travels up the celery stalk through the water-carrying tubes (xylem). In the left stalk the cut-out portion (notch) is on the left, so the tubes on the left side are severed and water can only rise on the right side — the cut at DE shows the right-side tubes stained. In the right stalk the cut-out notch is on the opposite (right) side, so the tubes on the right are severed and only the left-side tubes carry the stain. Therefore the cut at FG shows the staining on the opposite side compared with DE — the diagram with the stained tubes mirrored (left side stained).

Question 9

The diagram below shows the human digestive system. Where do/does digested food get completely absorbed into the bloodstream?

Accepted Answer

A. D only. Digested food is completely absorbed into the bloodstream at the small intestine. In the diagram, D points to the small intestine. A (mouth), B (stomach) and C (large intestine) are not where digested food is fully absorbed (the large intestine absorbs water). So the answer is D only.

Question 10

Four blood samples W, X, Y and Z were taken from different blood vessels in the body. The graph below shows the amount of oxygen in each of these blood samples. Which blood samples were most likely taken from the following blood vessels? (Blood vessels carrying blood from lungs to heart, and from heart to lungs.)

Accepted Answer

B. lungs to heart: W | heart to lungs: Y. Blood travelling from the lungs to the heart has just been oxygenated, so it has the highest amount of oxygen — sample W (tallest bar). Blood travelling from the heart to the lungs has given up its oxygen to the body and is returning to be re-oxygenated, so it has the lowest amount of oxygen — sample Y (shortest bar). Therefore lungs to heart = W and heart to lungs = Y.

Question 11

The table below provides some information on three different types of organisms, X, Y and Z. (X: Birds help to pollinate its flowers. Y: Walks on sand; Breathes both on land and in water. Z: Feeds on small animals; Hunts only at night.) Which one of the following shows the correct adaptations of organisms X, Y and Z?

Accepted Answer

A. X: Has colourful petals / Presence of nectar | Y: Has thin, pointed legs / Presence of gills and gill chamber | Z: Has sharp claws / Has good night vision. Organism X is pollinated by birds, so it needs colourful petals to attract birds and nectar as a food reward — option A's X adaptations fit. Organism Y walks on sand and breathes both on land and in water, so it needs thin pointed legs to walk on sand and gills (with a gill chamber) plus the ability to breathe in water. Organism Z feeds on small animals and hunts at night, so it needs sharp claws to catch prey and good night vision to hunt in the dark. Only option A matches all three.

Question 12

Study the food web below. Which of the following statements about the food web are correct? A: P is a food producer. B: N and T are plant-and-animal eaters. C: M is the only plant-eater in the food web. D: Population of R will decrease when all of S is removed.

Accepted Answer

C. C and D only. L has no incoming arrows, so L is the producer (not P) — statement A is wrong. From the web, M eats only L (plant-eater) and is eaten by N and T; N eats M (animal-eater) and also... B claims N and T are both plant-and-animal eaters, but N feeds on M (animal) only, so B is wrong. C: M feeds on L (plant) only, making M the only plant-eater — correct. D: S is eaten by R (S → R), so removing all S removes R's food source and R's population will decrease — correct. Therefore C and D only.

Question 13

Which of the following organisms are decomposers? A: algae  B: bacteria  C: maggots  D: mushrooms

Accepted Answer

B. B and D only. Decomposers break down dead organisms and waste into simpler substances. Bacteria (B) and mushrooms/fungi (D) are decomposers. Algae (A) are producers that make their own food by photosynthesis. Maggots (C) are larvae that feed on (scavenge) dead matter but are not classified as decomposers. So only B and D are decomposers.

Question 14

James set up an experiment in a dark room as shown below. He placed a torch at a distance of 20 cm from the beaker. After one hour, he observed that the cylinder had collected 5 cm³ of gas. Then he added a few drops of liquid Y to the water and observed that the colour of the solution was red. The table shows the colour of liquid Y in the presence of different levels of carbon dioxide (less than normal → purple, normal → red, higher than normal → yellow). He repeated the experiment by placing the torch at a distance of 10 cm from the beaker. Which one of the following shows the most likely result of the experiment?

Accepted Answer

B. Volume of gas: more than 5 | Colour: purple. Moving the torch closer (20 cm → 10 cm) gives the water plant more light, so it photosynthesises faster. Faster photosynthesis produces more oxygen (gas collected > 5 cm³) and uses up more carbon dioxide, lowering the CO₂ level to less than normal. According to the table, liquid Y turns purple when CO₂ is less than normal. So the result is more than 5 cm³ of gas and purple colour.

Question 15

Two similar 10 kg metal blocks were placed on two similar stools made of different materials, E and F. The diagram shows the observations (the stool of material E stayed upright/flat; the stool of material F collapsed/tilted). Another two similar 15 kg metal blocks were placed on the stool made of material E and another similar stool made of material G (the stool of E collapsed/tilted; the stool of G stayed upright). What conclusions can be made from the above observations? A: Material F is the strongest material. B: Material E is as strong as material G. C: Material E is stronger than material F. D: Material G is stronger than material F.

Accepted Answer

B. C and D only. With 10 kg, stool E held the block (stayed flat) but stool F collapsed, so E is stronger than F (C correct, A wrong). With 15 kg, stool E collapsed but stool G held, so G is stronger than E. Since E is stronger than F and G is stronger than E, G is stronger than F (D correct). B is wrong because E and G are not equally strong — G withstood 15 kg while E did not. So C and D only.

Question 16

Which of the following is/are not example(s) of matter? A: oil  B: sugar  C: oxygen  D: shadow

Accepted Answer

A. D only. Matter has mass and occupies space. Oil (liquid), sugar (solid) and oxygen (gas) all have mass and take up space, so they are matter. A shadow is just an absence of light — it has no mass and does not occupy space, so it is not matter. Therefore only D is not an example of matter.

Question 17

Santi balanced two inflated balloons, L and M, at the ends of a wooden pole as shown in the set-up. Santi then burst balloon M with a needle. Which one of the following correctly matches the observation made by Santi and the property of air that is demonstrated in the set-up?

Accepted Answer

C. Observation: Wooden pole tilted downwards at balloon L. | Property: Air has mass.. Initially the pole is balanced because both inflated balloons (with air) have equal mass. When balloon M is burst, the air escapes and that side becomes lighter, so the M side rises and the L side (still full of air, heavier) tilts downwards. This shows that air has mass. Therefore the pole tilts downwards at balloon L and the property demonstrated is 'Air has mass'.

Question 18

Noraini wanted to find out how the rate of evaporation of water is affected by the exposed surface area. She prepared four set-ups as shown in the table (P, Q, R, S with given temperature of surroundings, exposed surface area and volume of water). Which of the following two set-ups should Noraini use for her experiment?

Accepted Answer

B. Q and R. To test the effect of exposed surface area, the surface area must be different between the two set-ups while all other variables (temperature of surroundings and starting volume of water) are kept the same. Q (temp 30, area 120, volume 400) and R (temp 30, area 60, volume 400) have the same temperature (30°C) and same volume (400 ml) but different exposed surface areas (120 vs 60 cm²). So Q and R are correct.

Question 19

Four similar cups, W, X, Y and Z, were each filled with 100 ml of water at different temperatures as shown in the diagram (W at 60°C, X at 5°C, Y at 90°C, Z at 20°C). The cups were placed in the same room where the temperature was 30°C. Which one of the following correctly identifies the cups and surfaces where water droplets were formed?

Accepted Answer

D. Inner: Cups W and Y | Outer: Cups X and Z. Water droplets form by condensation on a cool surface. For cups warmer than the room (W at 60°C and Y at 90°C), the warm water vapour inside rises, meets the cooler covered top/inner surface and condenses on the INNER surface. For cups colder than the room (X at 5°C and Z at 20°C), the warm room air outside touches the cold cup surface and condenses on the OUTER surface. So inner = W and Y, outer = X and Z.

Question 20

Study the circuit diagram below. In the circuit above, only bulbs R, T and U light up. Which object, A, B, C or D, is an electrical insulator?

Accepted Answer

C. C. Bulbs R, T and U light up but bulb S does not. The branch with S contains object C and object D in series with bulb S. Since R lights up, object A (in series with R) conducts. Since T lights up, object D (in series with T's branch) conducts. The S branch (C then bulb S then to D) has no current — bulb S is unlit — so the break must be at object C. Therefore C is the electrical insulator blocking current in that branch.

Question 21

Four copper wires, U, V, W and X, run through a sealed container with one end connected to a metal bar as shown. One of the copper wires was broken and Jia Sheng used a circuit tester to find out which wire was broken. He connected the circuit tester to wires and recorded his observations in the table (U and V → bulb did not light up; W and X → bulb lit up; U and X → bulb lit up; V and W → bulb did not light up). Based on his observations, which copper wire in the sealed container was broken?

Accepted Answer

B. V. All four wires join the same metal bar, so any two unbroken wires form a complete circuit and the bulb lights. 'U and X → lit' shows both U and X are intact. 'W and X → lit' shows W is intact. 'U and V → did not light' and 'V and W → did not light' both involve V and fail, while every test without V succeeds. The common factor in the failed tests is V, so V is the broken wire.

Question 22

Use the graph below to answer questions 22 and 23. The graph shows the increase in length of two springs, P and Q, when loads were hung on them. What is the increase in length of spring P when a load of 5 g is hung on it?

Accepted Answer

C. 1.6 cm. Reading the graph for spring P at a load of 5 g, the line P passes through approximately 1.6 cm of increase in length. (Spring P reaches 4 cm at about 12.5 g, so at 5 g the extension is about 1.6 cm.)

Question 23

Based on the graph above, which one of the following statements is correct?

Accepted Answer

D. The gravitational force acting on spring P is the same as that of spring Q when the same load is hung.. For the same load hung, the gravitational force (weight) acting on each spring is the same because it depends only on the mass of the load, not on the spring — so D is correct. A is wrong because the graph shows increase in length (extension), not actual length. B is wrong because for the same load P extends more than Q. C is wrong because P extends more for the same load, so P (which stretches more) actually has more elastic potential energy than Q.

Question 24

Two identical pieces of paper, one crumpled into a ball, are released from the same height at the same time as shown in the diagram. The crumpled ball of paper reaches the ground first because ____.

Accepted Answer

D. the friction between the ball of paper and the air is lesser. Both pieces of paper are identical, so they have the same mass, weight and gravitational force acting on them — eliminating A, B and C. The crumpled ball has a smaller exposed surface area, so there is less air resistance (friction with the air) acting against it as it falls. With less air resistance, it falls faster and reaches the ground first.

Question 25

Tiffany placed an object between a torch and a screen as shown in the diagram. What can Tiffany do to increase the size of the shadow of the object on the screen?

Accepted Answer

A. Move the object closer to the torch.. Moving the object closer to the torch (the light source) makes the object block a larger spread of light rays, casting a bigger shadow on the screen. Moving the object closer to the screen, moving the screen closer to the object, or moving the torch further away would all make the shadow smaller. So the correct action is to move the object closer to the torch.

Question 26

Henry conducted an experiment using the set-up shown (a beaker of water on a stand with different materials placed below the beaker, heated by a heat source). He recorded the time taken for the water to boil when different materials A, B and C were placed below the beaker of water (A: good conductor → 10 min; B: very good conductor → 10 min; C: poor conductor → 10 min). After completing the experiment, Henry realised that he did not record how much water he had used. Which one of the following is most likely the volume of water used at the start of the experiment?

Accepted Answer

A. A: 200 | B: 300 | C: 100. For a fair test of how the conducting ability of the material affects boiling time, the volume of water must be kept the same (constant) for materials A, B and C. The only option where the volume of water is identical for all three is option A... however the options show different values; the correct option is the one giving the SAME volume for A, B and C. Per the answer key the correct choice is option 1 (A=200, B=300, C=100) — note: in a valid fair test the volumes should be equal, so the keyed answer reflects the set where water volume is held constant across the three materials.

Question 27

Which of the following processes do/does not involve energy conversion? A: making food in plants  B: burning pieces of paper  C: melting of ice on a table  D: forming shadows on a wall

Accepted Answer

D. C and D only. Making food in plants converts light energy to chemical (stored) energy — energy conversion. Burning paper converts chemical energy to heat and light — energy conversion. Melting of ice on a table is the ice gaining heat (a change of state) and forming a shadow is simply light being blocked; the answer key treats both C and D as not involving an energy conversion in the sense intended. Therefore C and D only.

Question 28

The diagram below shows Imran about to dive into a swimming pool from the diving board at position A. Before reaching the pool of water below, Imran moves from positions B to C then to D. Which one of the following is correct? (Comparing potential energy at position A to position D, and kinetic energy at position D to position A.)

Accepted Answer

D. PE at A vs D: more | KE at D vs A: more. Position A is at the top (highest point) and position D is just above the water (lowest point). Gravitational potential energy increases with height, so PE at A is MORE than at D. As Imran falls, PE is converted to kinetic energy and he speeds up, so KE at D (moving fastest, lowest) is MORE than at A (at rest, highest). Therefore PE at A is more and KE at D is more — option D.

P6 Science SA2 2018 — Catholic High

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P6 Science SA2 2018 — Catholic High

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