Question 1

Study the classification table below. Which of the following are A, B and C most likely to be?

Accepted Answer

C. Ladder fern / Caterpillar / Bread mould. A can make food → must be a plant (Ladder fern). B cannot make food but can move on its own → an animal (Caterpillar). C cannot make food and cannot move on its own → a fungus (Bread mould).

Question 2

Study the diagrams of the three different types of cells shown below. Which of the following parts are present in all the three types of cells shown above?

Accepted Answer

C. nucleus, cell membrane and cytoplasm. All cells (animal and plant) have a nucleus, cytoplasm and cell membrane. Cell walls and chloroplasts are found only in plant cells, so they are not present in all three cells.

Question 3

The diagrams show different types of fruits and seeds with their characteristics. Based on the information given, which of the following shows the correct number of fruits and seeds dispersed according to the methods of dispersal given?

Accepted Answer

D. By animal: 2 / By water: 1 / By wind: 2. Fleshy and bright red fruit → by animal (1). Seed with fibrous husk → by water (1). Flat and light seed → by wind (1). Parachute-like seed → by wind (1). Fruit with stiff hairs → by animal (1). Totals: animal 2, water 1, wind 2.

Question 4

Jasper conducted an experiment to find out if plants take in water through their roots as shown in the diagrams below. He covered the roots of the plant in set-up B with a plastic bag. He measured the amount of water in each set-up every day for six days and recorded his results in a graph. Which of the following graphs shows the amount of water after six days?

Accepted Answer

D. Set-up A water decreases each day; Set-up B water stays constant. In set-up A the roots take in water so the water level falls each day. In set-up B the plastic bag prevents the roots from absorbing water, so the water level remains constant.

Question 5

Xiaohui observed two animals, X and Y, and recorded her observations in the table below. Which of the following correctly identifies animals X and Y?

Accepted Answer

A. Animal X: frog / Animal Y: butterfly. Animal X has a 3-stage life cycle, spends some stages in water, and the adult has no wings → frog. Animal Y has a 4-stage life cycle, does not live in water at any stage, and the adult has wings → butterfly.

Question 6

The following processes A, B, C and D take place in the various parts of the digestive system during digestion. A: Undigested food is stored here to be passed out. B: Food is digested and absorbed into the blood stream. C: Saliva is produced to break down food. D: Partially digested food is pushed down the muscular tube. Which of the following shows the correct order of the processes occurring during digestion?

Accepted Answer

D. C → D → B → A. Digestion begins in the mouth where saliva is produced (C). The food is pushed down the gullet/oesophagus (D). Food is then digested and absorbed in the small intestine (B). Finally undigested food is stored in the rectum and passed out (A).

Question 7

The diagram shows the movement of carbon dioxide in our environment. Which one of the following represents photosynthesis?

Accepted Answer

B. Q. Photosynthesis is the process by which plants take in carbon dioxide from the air to make food. Arrow Q points from 'carbon dioxide in the air' to 'ferns' (a plant), representing this absorption of CO2 by plants during photosynthesis.

Question 8

Gary removed the outer ring of the stem of a plant as shown in Figure A. He left the plant under the sun and watered it regularly. After a few days, he observed that the plant was alive and part of the stem above the ring was swollen as shown in Figure B. Which of the following statements best explains his observation?

Accepted Answer

C. Food travelling down the stem is trapped above the ring.. The outer ring of a stem contains the phloem, which transports food from the leaves down to other parts of the plant. When the outer ring is removed, food travelling down from the leaves becomes trapped above the cut, causing that part of the stem to swell.

Question 9

The diagram shows the upper and lower surfaces of a leaf from plant M after Bella had placed it into hot water. Bella investigated the amount of water loss from the upper surface and the lower surface of a leaf. She applied a thin layer of oil on some surfaces of the leaves taken from plant M. The leaves were hung for 48 hours as shown below. The graph shows the amount of water loss by the four leaves. Based on the results, which of the following shows the correct experimental set-up?

Accepted Answer

C. oil on both: leaf H / upper only: leaf E / lower only: leaf G / no oil: leaf F. Bubbles forming on the lower surface in hot water show that the leaf has more stomata on the lower surface, so it loses more water from the lower surface. F (no oil) loses the most water. G (oil on upper surface only — water still escapes through the lower stomata) loses the next most. E (oil on lower surface only — most stomata blocked) loses little. H (oil on both surfaces) loses the least. This matches option (3).

Question 10

Which one of the following diagrams of a flower is correctly labelled?

Accepted Answer

B. Diagram with 'ovary' and 'ovule' labelled correctly inside the flower. Only option (2) correctly identifies the ovary (the swollen base of the pistil) and the ovule (the small egg-like structures inside the ovary). The other options mislabel either the petal, the ovary or the ovule.

Question 11

The diagrams below show the reproductive systems of a human and a plant. Which of the following represents the parts involved in producing the male reproductive cells?

Accepted Answer

B. B and Y. Male reproductive cells are sperm (in humans) and pollen (in plants). B labels the testes (where sperm is produced). Y labels the anther (where pollen is produced). A is the sperm duct and X is the stigma — both are not where the male reproductive cells are produced.

Question 12

Margaret set up three glass jars as shown in the diagram. She measured and recorded the amount of carbon dioxide in each glass jar. J was left in sunlight for 6 hours. K was left open to the surrounding air for 6 hours. L had air breathed out by Margaret for 10 times. At the end of the experiment, which glass jar has the most amount of carbon dioxide and which has the least amount?

Accepted Answer

C. most: L / least: J. Jar L contains breathed-out air, which has the most carbon dioxide. Jar J contains a plant in sunlight, which carries out photosynthesis and uses up carbon dioxide, so it has the least. Jar K only contains surrounding air with normal CO2 levels.

Question 13

In flowering plants, process P occurs when pollen grains are transferred from the anther to the stigma as shown by the arrow in the diagram below. The following statements describe the various stages that happen next. W The pollen grain grows a pollen tube. X The pollen tube enters the ovule. Y The pollen tube grows down the style. Z Male reproductive cell fuses with an egg cell. In which order do these stages occur?

Accepted Answer

B. W → Y → X → Z. After pollination: first the pollen grain on the stigma grows a pollen tube (W), the pollen tube grows down the style (Y), it enters the ovule (X), and finally the male reproductive cell fuses with the egg cell (Z).

Question 14

The diagram shows a mobile phone connected to a solar-powered charger. The charger transfers light energy from the Sun to the battery of the mobile phone. Which of the following shows a part of the energy conversion correctly?

Accepted Answer

D. electrical energy (in the charger and the cable) → potential energy (in the battery of the mobile phone). The solar charger converts light energy from the Sun into electrical energy, which flows through the cable and is stored as potential (chemical) energy in the battery of the mobile phone.

Question 15

The table shows the state of four different substances, W, X, Y and Z, at different temperatures. Which substance has the lowest boiling point?

Accepted Answer

C. Y. Y is already gaseous at 40°C, while the other substances are still liquid or solid at that temperature. Therefore Y has the lowest boiling point (below 40°C).

Question 16

Mr Li set up the experiment shown below to find out which substance, air or water, will push the stopper to a greater height when heated. He heated a flask over a strong flame and recorded the height the stopper reached. Next, he repeated the experiment with an identical flask completely filled with water. The table below shows the results of his experiment. Which of the following statements explain(s) his observations? A Air conducted heat faster than water. B Water expands less than air when heated. C The flask with water expanded more than the one with air when heated.

Accepted Answer

B. B only. The stopper above air rose much higher (avg 16 cm) than the stopper above water (avg 4 cm) because air expands more than water when heated. Statement A is irrelevant to the height; C is wrong because the flask itself does not expand more with water. Only B is correct.

Question 17

Opaque objects P, Q and R were placed in a straight line at positions X, Y or Z, between the screen and the light source as shown in the diagram below. The dimensions and shapes of objects P, Q and R when viewed from the front are as shown below. The shadow formed on the screen is shown below. Which of the positions X, Y or Z should objects P, Q and R be placed in order to form the shadow as shown above?

Accepted Answer

D. Position X: P / Position Y: R / Position Z: Q. The composite shadow shows a large circle with a vertical rectangular shape across the middle. To form it: P (solid circle) at position X (nearest the screen) gives the large round shadow; R (ring/donut) placed at Y blocks light corresponding only to the outer ring; Q (vertical rectangle) at Z (closest to light source) casts a vertical bar that appears across the circle. Hence X=P, Y=R, Z=Q.

Question 18

Similar balls of different materials, A, B and C, were placed in liquids X and Y. The balls stayed at the positions as shown below. Liquid X and Y do not mix. When they were poured into a container, liquid Y floated on top of liquid X. If similar balls of materials A, B and C were added to this container, which one of the following diagrams would show the correct positions?

Accepted Answer

A. C sinks to bottom of liquid X, B floats at X-Y interface, A floats on top of liquid Y. From the first set-up: in liquid X, ball A sinks and ball B floats → A is denser than X, B is less dense than X. In liquid Y, ball B sinks and ball C floats → B is denser than Y, C is less dense than Y. Since Y floats on X, X is denser than Y. Order of density: A > X > B > Y > C. When poured together: C floats on top of Y, B sits at the X–Y interface (floats on X, sinks in Y), and A sinks to the bottom of X.

Question 19

Lisa tested the strength of materials, A, B, C and D, by dropping a 2 kg weight from a height using the set-up as shown below. The materials were of the same size, thickness and shape. She noted the number of times the weight was dropped before the materials broke. Her results are shown in the table below. Based on the results in the table above, which of the following conclusions is correct?

Accepted Answer

C. Material C is stronger than material B.. More drops before breaking = stronger material. Results: A=10, B=15, C=21, D=8. C took the most drops, D the fewest. So C is the strongest (not D), D is the least strong (not A). Hence C is stronger than B (21 > 15).

Question 20

Four metal pins A, B, C and D were fixed onto a wooden board as shown below. Figure 2 shows two batteries and a bulb connected to two wires X and Y. Ravi connected some but not all the pins with wires. He then connected X and Y across different pairs of pins. He recorded his results in the table below. Which one of the following correctly shows the connections tested by Ravi?

Accepted Answer

A. Wires connecting A-B and D-C (i.e. AB and DC pairs joined inside the board). Bulb lit when X-Y was across A-B and across D-A → A is connected to both B and D internally. Bulb did not light when across B-C or C-D → C is not connected to any other pin. The internal wiring that matches all four results is A connected to B, A connected to D, with C left isolated, which corresponds to option (1).

Question 21

Mary conducted an experiment to investigate elastic spring force. She hung a spring from a beam and attached a heavy wooden block to the spring as shown below. She wanted to measure the extension of the spring and determine the direction of the force exerted on the wooden block by the spring. Based on the information given, which of the following is correct?

Accepted Answer

B. Parts to measure: from S to T; Direction of force on block: upward. Before the block is attached, the spring's bottom hook is at S. After the block is attached, the spring stretches and the bottom hook reaches T. The extension is therefore the distance from S to T. The spring pulls the wooden block upward (the elastic spring force opposes the weight of the block).

Question 22

Yasmin set up an experiment as shown in the diagram below. When released, the trolley moves down the ramp and hits the block causing it to move. Distance y refers to the distance moved by the block when the trolley hits it as shown in the diagram below. Yasmin wanted to investigate how different variables in the above set-up affect distance y. Based on the experimental set-up given, which of the following is not correct? A reduce the mass of the block — decrease. B increase the mass of the trolley — decrease. C increase the angle of the ramp — increase.

Accepted Answer

A. A and B only. Reducing the mass of the block would actually let it travel further (distance y increases), so A is wrong. Increasing the mass of the trolley gives more kinetic energy to push the block further, so distance y increases, so B is wrong. Increasing the angle of the ramp does give the trolley more speed and the block goes further (C is correct). The 'not correct' rows are A and B only.

Question 23

Michael hits a moving rubber ball as shown below. Which of the following changes could happen to the ball when it is hit? A A change in mass. B A change in speed. C A change in direction.

Accepted Answer

B. B and C only. A force can change the speed, direction or shape of an object, but not its mass. Hitting the rubber ball can change its speed (B) and its direction (C), but not its mass (A).

Question 24

Jovan carried out an experiment using a set-up as shown below to find out if the presence of wind affects the rate of evaporation of water. Which of the following should he use as a control set-up?

Accepted Answer

C. Glass of water inside a similar container with no fan. The only difference between the experimental set-up and the control should be the variable being tested (presence of wind). Everything else (container, glass, water amount) must be identical. The control should therefore be the same container and glass of water but WITHOUT the fan, which is option (3).

Question 25

An ice cube is taken from a freezer and is placed on a wooden table at room temperature to melt as shown in the diagram below. Which of the following shows the correct energy transfer taking place during the melting of ice and immediately after the ice has completely melted?

Accepted Answer

D. when melting: from the surrounding to the ice cube; after melted: from the surrounding to the water. The ice cube is colder than the surrounding, so heat is transferred from the surrounding to the ice cube to make it melt. After melting, the resulting water (still colder than room temperature) continues to gain heat from the surrounding until it warms up.

Question 26

Jenny arranged three similar iron bars, X, Y and Z, on a wooden table as shown below. Jenny brought ends of different iron bars together and observed what happened. Based on the information given, which of the following is likely to be observed?

Accepted Answer

D. Ends that repel: C and F / Ends that attract: B and D. Iron Bar X is attracted to magnet Y (lying flat), so X is a non-magnetic iron bar that has been attracted by induced magnetism (or vice-versa). Looking at the arrangement, the only consistent observation that uses both like-pole repulsion and unlike-pole attraction is: C and F repel (like poles), B and D attract (unlike poles).

Question 27

Diagram 1 shows Tom skydiving in a wingsuit. After some time, to avoid serious injuries from the fall, Tom opened up a parachute, as shown in diagram 2. The following statements show the information about Tom's skydiving experience. A In diagram 1, Tom falls faster. B In diagram 1, Tom experiences more air resistance. C In diagram 2, more weight is exerted on Tom. D In diagram 2, Tom experiences more air resistance. Which of the above statements are correct?

Accepted Answer

B. A and D only. The parachute has a much larger surface area than the wingsuit, so in diagram 2 there is more air resistance and Tom falls more slowly. Hence in diagram 1 Tom falls faster (A is correct) and in diagram 2 he experiences more air resistance (D is correct). His weight does not change (C is wrong), and B contradicts D.

Question 28

A magnet is placed on an electronic balance as shown in diagram 1. The reading on the electronic balance changes when another magnet or an iron bar is held close to the first magnet as shown in the diagrams below. Which of the following shows the likely readings in diagrams 1 and 3?

Accepted Answer

A. Diagram 1: 90 g / Diagram 3: less than 137. In diagram 2 the magnet's N pole is above the lower magnet's S pole — they attract — pulling the bottom magnet up so the balance reads less than the true mass (it reads 137 g). Therefore the true mass (diagram 1, with nothing held above) is more than 137 g — only 150 g matches… Re-evaluating: the suspended magnet faces N-down to S-up of bottom magnet → poles attract → bottom magnet is pulled up → reading is less than true mass, so 137 g is less than true mass → true mass is 150 g. Wait — but the question expects D? Reconsider: The lower magnet's top is N (per drawing) and suspended magnet shows N facing down → like poles → repel → push bottom magnet down → reading higher than true mass. If 137 g shown in diagram 2 is the result of repulsion (higher than true), the true (diagram 1) must be less: 90 g. In diagram 3 an iron bar is held above; the magnet attracts the iron bar (and vice versa), pulling the magnet up → reading less than 90 → less than 137. So diagram 1 = 90 g and diagram 3 = less than 137 g. Option (1) is correct.

P6 Science SA2 2021 — Henry Park

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