Question 1

Sam spotted a staghorn fern and mushrooms, as shown in the diagram below. Which of the following is correct about both the staghorn fern and the mushrooms?
A Both reproduce from spores.
B Both are non-flowering plants.
C Both can make their own food.

Accepted Answer

A. A only. Both the staghorn fern (a non-flowering plant) and mushrooms (fungi, not plants) reproduce by spores. Only the staghorn fern is a plant — mushrooms are fungi, so statement B is wrong. Mushrooms cannot make their own food (no chlorophyll), so statement C is wrong. Only A is correct.

Question 2

Sarah bought a toy doll that came with a feeding bottle as shown below. She fed the toy doll daily and recorded the height of the doll weekly. Which of the following graphs correctly shows the results over four weeks?

Accepted Answer

D. Graph showing height of toy doll remaining constant at a non-zero value over weeks. A toy doll is non-living and therefore cannot grow even if 'fed'. Its height stays constant over the four weeks, shown by a horizontal line at a non-zero height (graph 4).

Question 3

The diagram below shows the development of a plant at different stages namely A, B and C. At which stage(s) do/does the seedling only depend on its seed leaves for food?

Accepted Answer

A. A only. At stage A the seed has just germinated and the seedling has no true leaves yet, so it depends entirely on the food stored in its seed leaves. By stage B true leaves have formed and the seedling can photosynthesise; by stage C it is a fully grown plant. So only stage A depends only on seed leaves.

Question 4

The graph below shows the changes in food intake by an insect throughout its life cycle. Based on the information above, which part of the graph represents the larval stage of the insect?

Accepted Answer

A. BC. The larval stage of an insect is when it feeds the most as it grows rapidly. On the graph, BC shows food intake rising steeply from zero up to a peak at C — the characteristic feeding spike of the larval (caterpillar) stage. DE is the pupal stage (no feeding), and EF is the adult stage (less feeding).

Question 5

Which of the following is not an inherited characteristic?

Accepted Answer

B. long hair. Hair length depends on whether and how often a person cuts their hair — it is an acquired characteristic, not inherited. Skin colour, nose shape and eye colour are all passed down from parents.

Question 6

The diagram shows a human reproductive system. Which of the following statement(s) is/are true when only part X was removed?
A No egg cells will be produced.
B A baby can still develop in her reproductive system.
C Fertilisation can still occur in her reproductive system.

Accepted Answer

D. B and C only. Part X is one of the two ovaries (with Y being the other). With one ovary removed, the other ovary still produces egg cells, so A is false. Eggs from ovary Y can still travel down the fallopian tube and be fertilised (C true), and a fertilised egg can still implant and develop in the uterus (B true). Both B and C are correct.

Question 7

Which of the following is correct?

Accepted Answer

B. Cycle: seed dispersal → germination → pollination → fertilisation → seed dispersal. The correct order of the flowering-plant life cycle is: seed dispersal → germination (seed grows into a seedling and then a mature plant) → pollination (pollen transferred to stigma of flowers) → fertilisation (fusion of male and female gametes producing seeds) → seed dispersal again.

Question 8

The diagram (not drawn to scale) below shows two pods, X and Y, dispersing their seeds when the pods split. The diagrams below show the distribution of young plants observed over a period of time. Based on the information provided above, which of the following is/are definitely true?
A Seeds of fruit X are lighter than seeds of fruit Y.
B Seeds of fruit Y are inedible but seed of fruit X is edible.
C Seeds of fruit X can stay afloat in the air longer and be dispersed further.
D Seeds of fruit X are dispersed by wind only while seeds of fruit Y are dispersed by splitting action only.

Accepted Answer

A. C only. Diagram 1 shows young plant X spread far in the direction of the wind from the parent — so seed X is light enough to be carried by wind and stays afloat longer to travel further (C correct). We cannot conclude X is lighter than Y from the diagrams alone (A unsupported). Edibility (B) is not shown. Pod Y also splits open (splitting action is shown for both pods), so D is wrong. Only C is definitely true.

Question 9

The diagram shows the functions of some parts of the human digestive system. Which of the following statements about parts A, B, C and D is correct?

Accepted Answer

C. C — Digests food completely and absorbs it into the bloodstream. Part A is the gullet/oesophagus — actually no digestion occurs there but this option's tabled wording in the question matches it; however, looking at the diagram, A is the mouth area where digestion begins. B is the stomach — digestion is not completed here. C is the small intestine where digestion is completed and absorption into the bloodstream takes place. D is the large intestine which absorbs water only (not digested food). Therefore the correct statement is C — the small intestine completes digestion and absorbs digested food into the bloodstream.

Question 10

The diagram shows two plants, P and Q. Plant P grows in the water and plant Q grows on land. Which is/are the main function(s) of the roots of both plants P and Q?
A To store food
B To take in water and nutrients
C To hold a plant down in the soil

Accepted Answer

A. B only. Both plants use their roots to take in water and (dissolved) nutrients (B is correct for both). Plant P grows in water and is not anchored in soil, so its roots do not need to hold it in soil — C is not common to both. Neither plant is shown to have food-storage roots — A is not common to both. Only B is true for both.

Question 11

The diagram below shows two cells, A and B, examined under the microscope. Which of the following correctly identify cells A and B and the function of part X?

Accepted Answer

B. Cell A: plant; Cell B: animal; Function of part X: control all activities within the cell. Cell A has a definite rectangular shape with a thick cell wall — a plant cell. Cell B is round/oval without a cell wall — an animal cell. Part X in both is the nucleus, which controls all the activities within the cell. Chloroplasts (which capture sunlight) are usually green/oval bodies, not labelled here.

Question 12

Clara prepared an experimental set-up by placing a plant under strong light as shown below. After eight hours, she removed leaf X from the plant and tested for the presence of starch. She placed leaf X in a beaker of boiling water for twenty minutes and then placed the leaf on a white tile as shown below. She added a few drops of yellowish-brown iodine solution on the whole leaf. She recorded her observations in the table below. Based on the information above, which of the following is correct?

Accepted Answer

A. Inside bottle: Yellowish-brown; Outside bottle: Dark blue. Photosynthesis (and starch production) needs carbon dioxide, water and light. The part of leaf X inside the bottle had no carbon dioxide (it was absorbed by the substance), so no starch was made → iodine stays yellowish-brown. The part outside the bottle had carbon dioxide, light and water, so it photosynthesised and produced starch → iodine turns dark blue.

Question 13

Volcano scientists wear lava suits to work close to hot molten lava as shown below. Based on the properties shown below, which material is most suitable for making a lava suit?

Accepted Answer

B. Material Q — flexible, strong, waterproof, poor heat conductivity. A lava suit must be flexible (so the scientist can move), strong (durable), waterproof (lava contains hot liquid) and a poor conductor of heat (so heat does not pass through to the body). Only Material Q meets all four criteria.

Question 14

Ali received three parcels, D, H and L, that contained styrofoam balls, dish sponges and feathers respectively. He was also given a lever balance to compare the mass of parcels. Which of the following diagrams best shows how the lever balance would look like?

Accepted Answer

C. Lever balance with parcel H on the left arm tilted down and parcel L (larger) on the right arm tilted up. D = 150 g, H = 300 g, L = 150 g. Option (3) compares H (300 g) on one side and L (150 g) on the other — the side with H must go down because it is heavier, which matches option C's description.

Question 15

Roy prepared four set-ups, A, B, C and D, using identical measuring cylinders each containing 20 cm³ of water. He placed identical corks and metal cubes in the four set-ups as shown below. Based on the observation above, what is the volume of the cork and the metal cube respectively?

Accepted Answer

A. Cork 5 cm³; Metal cube 15 cm³. Set-up A has just water (20 cm³). Set-up B (water + cork floating) reads 35 cm³ — but cork floats so only part of it displaces water. Use set-up with cork fully submerged (e.g. metal cube on top pushing cork down) to find true cork volume. The cork displaces 5 cm³ of water (20 → 25 cm³ when submerged) and the metal cube displaces 15 cm³ (20 → 35 cm³). Cork = 5 cm³, metal cube = 15 cm³.

Question 16

A beaker of boiling substance X was taken off the heat source at K and left to cool in the freezer. The changes in temperature of the substance X over time were recorded and shown in the graph below. Based on the graph, which of the statement(s) about substance X below is/are true? It is ____.
A gaining heat at JK
B in liquid state at KL
C gaining heat at LM
D in solid state at MN

Accepted Answer

D. A, B and D only. JK is at 356 °C and the substance is still being heated (boiling) — A is true. KL is the cooling region from 356 °C down to −38 °C — substance is in liquid state — B is true. LM is at −38 °C constant (freezing point) — substance is losing heat (not gaining) as it solidifies — C is false. MN is below −38 °C and going lower — substance is fully solid and still losing heat — D is true. A, B and D are true.

Question 17

Sue set up an electrical circuit to find out the electrical conductivity of materials Q, R and S. All the components used in the circuit shown below were in working condition. Sue observed that when the switch was closed, only bulbs B2 and B4 lit up. Which of the following materials is/are insulator(s) of electricity?

Accepted Answer

B. P and R only. Bulb only lights if the material in series with it allows current to flow (conductor). B2 lit → Q is conductor; B4 lit → S is conductor. B1 did not light → P is an insulator (it is in series with B1). B3 did not light → R is an insulator. Therefore the insulators are P and R.

Question 18

Siti conducted an experiment with one of the four circuits, prepared using identical components, as shown below. She then recorded her results in a table as shown below. Which of the following circuits did Siti use?

Accepted Answer

A. Circuit with two bulbs and two switches Y and Z arranged so that the table results are produced. From the table: when Y open and Z closed, 2 bulbs light; when Y closed and Z open, 1 bulb lights; when both closed, 2 bulbs light. Circuit (1) has one bulb in the main loop (always lit when current can flow) and a second bulb in series with switch Z in a parallel branch, while switch Y short-circuits part of the loop. This combination gives the observed pattern, matching option (1).

Question 19

The diagrams, A and B, below show how a high speed train can move forward faster than a normal train. Diagram A shows the electromagnet under the train and on the train track. Diagram B shows the rows of magnets lined along the side of the train and inner side of the beam. The arrows show the directions of interactive magnetic force amongst the magnets as the train travels. Which of the following explanations about the interaction amongst the magnets shown in diagrams A or B is correct?

Accepted Answer

D. Diagram B; Like poles repelled to push the train forward faster; Unlike poles attracted to pull the train forward faster.. In Diagram B, alternating N and S poles along the side of the train interact with the N and S poles on the beam. Behind the train, like poles face each other and repel — pushing the train forward. Ahead of the train, unlike poles face each other and attract — pulling the train forward. This combination of repulsion behind and attraction ahead drives the high-speed train.

Question 20

Raj dropped two identical pieces of paper, A and B, from the same height. He crushed paper A before he dropped them. Which of the following is likely to be the correct observation and the corresponding reason?

Accepted Answer

D. Paper B landed on the ground slower — It had more frictional force acting on it.. Paper B is flat, so it has a much larger exposed surface area in contact with the air. This causes more air resistance (frictional force) acting against its downward motion, so paper B falls slower and lands later than the crushed paper A.

Question 21

The diagram below shows a hammock holding a baby that moves up and down from position A to B, and then from B to A repeatedly. Which of the following statement(s) about the above hammock is/are true?
A More gravitational force is acting on the baby at B than A.
B Frictional force is acting on the baby as she moves from A to B.
C Elastic spring force is pulling the baby in the opposite direction of her weight.
D Elastic spring force acting on the hammock is increasing as it moves from A to B.

Accepted Answer

C. B and C only. Gravitational force depends on mass — the baby's mass is constant so gravitational force is the same at A and B (A false). The baby moves through air, so air resistance (a frictional force) acts on her as she moves (B true). The stretched spring pulls the baby upward, opposite to her weight which acts downward (C true). As the hammock moves from A (lowest, most stretched) to B (highest, least stretched), the elastic spring force decreases, not increases (D false). Only B and C are true.

Question 22

Anne made a paper butterfly. She attached the paper butterfly and an inflated balloon on the top and bottom of a straw respectively, as shown below. She then put a string through the straw before attaching it onto two poles. Which one of the following explains how the paper butterfly moved when the air was released from the untied inflated balloon? The force exerted by the moving air was ____.

Accepted Answer

C. greater than the friction between the string and straw. When air escapes from the balloon, it pushes against the surrounding air, which in turn pushes the balloon (and the straw with the butterfly) in the opposite direction. For the butterfly to move along the string, the force from the moving air must overcome the friction between the straw and the string. So the air force was greater than that friction.

Question 23

An experiment was set up to find out the degree of transparency of four sheets of material A, B, C and D. Sheets A and B had cut-outs of different shapes, as shown below. Which one of the following correctly describes the properties of sheets A, B, C and D?

Accepted Answer

B. Allows light through: B; Does not allow: A and C; Not possible to tell: D. Sheet A has a cut-out but no light is seen on Sheet C behind it → light from the torch could not pass through Sheet A (opaque). Sheet B has a cut-out and a bright patch is visible on Sheet C → light passed through Sheet B (translucent/transparent). Sheet C shows a bright patch from light passing through B's cut-out and is hit by light → since the light stopped at sheet C (forming the bright patch), Sheet C is opaque. Sheet D is behind C with no light reaching it — we cannot tell its properties. So B allows light through, A and C don't, D unknown.

Question 24

Peter made an object by attaching a wooden disc on a frosted rectangular block. He wanted to find out how the different positions, A and B, of the torch would affect the shadow of the object cast on the screen. The experimental set-up is shown below. Which of the following shows the changes in the shadow of the object cast on the screen?

Accepted Answer

C. Position A: smaller dark oval on dark rectangle; Position B: larger dark oval on dark rectangle. The wooden disc is opaque (forms a solid dark shadow), while the frosted block is translucent (forms a lighter shadow). When the torch moves from position A (further from the object) to position B (closer to the object), the shadows become larger because the light rays diverge more sharply. So the dark disc shadow grows from A to B.

Question 25

The diagram below shows an ice cube placed on a metal sheet. After a while, Martha touched the ends of the metal sheet and her fingers felt cold. Which one of the following is a possible reason for Martha's observation?

Accepted Answer

A. Her fingers lost heat to the metal sheet.. Cold is the absence of heat. The ice cube absorbed heat from the metal sheet, cooling it. When Martha touched the cooled metal, her warmer fingers lost heat to the colder metal, so her fingers felt cold.

Question 26

An experiment was conducted by placing two identical beakers each containing 100 ml of the same liquid in a room with a constant temperature of 25°C. The temperature of the liquid in each beaker was different. After four hours, the temperature of the liquids in both beakers became the same and the volume of liquid left in each beaker was recorded in the table below. Then a fan was placed above one of the beakers for six hours. The volume of liquid left in each beaker was recorded in the table below. Which of the following correctly identifies the beaker exposed to a fan and the initial temperature, T, of the liquid in beaker A?

Accepted Answer

A. Beaker A; T = 40 °C. Beaker B started at 70 °C and after 4 hours both reached 25 °C, having evaporated 30 ml. Beaker A reached 25 °C having evaporated only 15 ml, so its initial temperature must have been lower than B's — 40 °C (not 80 °C). After the fan was placed for 6 hours, the beaker exposed to the fan lost more water. Beaker A went from 85 → 65 (lost 20 ml); Beaker B went from 70 → 65 (lost 5 ml). Beaker A lost more, so the fan was placed above Beaker A. Therefore T = 40 °C and the fan was over Beaker A.

Question 27

The diagram below shows two toys, C and D, which are used to shoot a ping pong ball. The ping pong ball in Toy C will shoot forward when the elastic band is released. The ping pong ball in Toy D will shoot forward when the handle is released. Based on the information provided, which of the following graphs shows the relationship between the length of the pull and the elastic potential energy in both toys?

Accepted Answer

A. Toy C: linear increase; Toy D: linear increase. In Toy C (slingshot), pulling the elastic band further stretches it more, increasing elastic potential energy proportionally. In Toy D, pulling the handle compresses the spring more — and a more compressed spring also has more elastic potential energy. So in both toys elastic potential energy increases linearly with the length of pull. Option (1) shows both rising.

Question 28

The diagram below shows a man walking on a pavement lined with special tiles. During the day, when a person steps on the tiles, electricity is generated. The battery stores energy which is used to light up the street lamps at night. Based on the information above, which of the following statement(s) is/are correct?
A The amount of electricity stored in the battery increases, as the number of people walking on the pavement increases.
B The amount of electrical energy generated increases, as the number of people walking on the pavement increases.
C As the number of people walking on the pavement increases, the amount of chemical potential energy in the battery decreases.

Accepted Answer

A. B only. More people walking → more pressure on the tiles → more electrical energy generated (B true). The 'amount of electricity stored in the battery' is the chemical potential energy stored — as more electricity is produced, the chemical potential energy in the battery increases (so both A is debatable and C is false). The most clearly correct statement is B only. (The accepted key is (1) B only.)

P6 Science SA2 2021 — Raffles Girls

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