Question 1

The diagrams show 2 trees, R and S, at the same location in a garden. Jack noticed that the grass under one of the trees grew more healthily than that of the other. Which of the following correctly shows the tree under which the grass was healthier and the reason?

Accepted Answer

A. R — The grass gets more sunlight to make food.. Tree R is tall and thin with a small canopy, so more sunlight passes through to the grass below. Grass needs sunlight to photosynthesise and make food, so the grass under tree R grows more healthily than under the dense canopy of tree S.

Question 2

Joel saw animal X in a muddy area. Animal X has the following characteristics: A. It has fins. B. It lays eggs. C. It breathes through gills. D. Its body is covered with scales. Joel was told to classify animal X in either Group P or Group Q as shown below. Which of the characteristics of animal X would help Joel in his classification?

Accepted Answer

C. A, C and D only. Group P contains fish (shark, fish, seahorse) — all have fins, breathe through gills, and are covered with scales. Group Q contains amphibians/reptiles (lizard, frog, toad) — which do not have fins, scales, or breathe through gills. Both groups lay eggs, so characteristic B does not help distinguish them. Characteristics A, C and D distinguish fish (P) from non-fish (Q).

Question 3

The graph below shows the number of days of each stage in the life cycle of an insect. Based on the graph, Johari wrote the following statements. A. The larva takes 5 days to hatch from the egg. B. The insect takes 40 days to become an adult. C. The male insect dies soon after it fertilises the eggs. D. The insect takes 25 days to change from larva to pupa. Which of the above statement(s) is/are correct?

Accepted Answer

A. A only. From the bar chart, egg stage = 5 days, so the larva takes 5 days to hatch (A correct). Egg + larva + pupa = 5 + 15 + 10 = 30 days before becoming adult, not 40 (B wrong). The graph gives no info about whether males die after fertilisation (C unsupported). Larva to pupa change = 15 days (the larva stage length), not 25 (D wrong).

Question 4

The diagram below shows what the inside of a seed looks like. Which of the following graphs correctly shows the change in mass of parts X and Y if the seed is germinating and growing?

Accepted Answer

D. mass of Y increases while mass of X decreases. X is the young plant/embryo (shoot) and Y is the seed leaf / cotyledon (food store). During germination, the food store (Y) is used up to nourish the developing embryo, so mass of Y decreases. The embryo (X) grows into a young plant, gaining mass through photosynthesis, so mass of X increases.

Question 5

Dina placed five identical small plants into separate pots of the same size containing the same amount of soil. She wanted to investigate how different conditions affect the growth of plants. The different conditions are shown in the table below. A tick (✓) represents the presence of the factors. The diagrams show Dina's plants after one week. According to Dina's results, which factor has the least effect on plant growth?

Accepted Answer

B. sand. Compare Pot A (water, sand, light, no minerals) and Pot B (water, light, minerals, no sand) — both show healthy growth. Comparing Pot A (with sand) and Pot E (with sand and minerals) — Pot E is healthier but the difference is due to minerals. The plant in Pot C (no light) and Pot D (no water) were very small, showing water and light have big effects. Pot A grew well without minerals but pot without minerals also grew, so the presence/absence of sand made the least difference to growth.

Question 6

The diagram shows blood flowing through the large intestine of the human body. Which of the following is correct about the amount of oxygen, carbon dioxide and water in the blood flowing in A as compared to B?

Accepted Answer

A. more oxygen, less carbon dioxide, less water. Blood entering the large intestine (A) brings oxygen for cells and has not yet picked up carbon dioxide produced there, so A has more oxygen and less carbon dioxide than B. Water is absorbed from the large intestine into the blood, so blood leaving (B) has more water than blood entering (A); therefore A has less water than B.

Question 7

The diagram below shows the male reproductive system in human. If parts Z are removed, what will most likely happen as a result?

Accepted Answer

A. The production of sperms will not take place.. Parts Z are the testes, the organs responsible for producing sperms. If the testes are removed, sperm production will not take place at all.

Question 8

Ahmad opened up fruit D shown below and found many seeds inside. Which of the following statements about fruit D are correct? A. There were many ovules in the ovary of the flower. B. Pollination and fertilisation had taken place to form the fruit above. C. The strong smelling seeds attracted animals to eat and help dispersed them.

Accepted Answer

A. A and B only. Each seed inside the fruit develops from a fertilised ovule, so many seeds means many ovules were in the ovary (A correct). For seeds and fruit to form, pollination and fertilisation must have occurred (B correct). For durian-like fruits, it is the smell of the FRUIT (not the seeds) that attracts animals, so C is incorrect.

Question 9

The diagram shows process P carried out by plants. Process P: water + U + V → sugar + W. Which of the following correctly describes U, V and W?

Accepted Answer

D. U = carbon dioxide, V = light, W = oxygen. Process P is photosynthesis. The equation is: water + carbon dioxide + light → sugar (glucose) + oxygen. So U = carbon dioxide, V = light, W = oxygen.

Question 10

The diagram shows the stages and processes X and Y in the life cycle of a flowering plant. Which of the following correctly shows the possible process for X and Y?

Accepted Answer

C. Process X = fertilisation, Process Y = germination. The cycle goes: seed → adult plant with flowers → young plant → seed. Process X is from seed to adult plant — but here X actually is labelled from 'adult plant with flowers' part of the cycle relating to seed formation, while Y is from adult plant with flowers to young plant. Reading the diagram: X (seed → adult plant with flowers) is the growth and is actually labelled wrong. Re-reading: X arrow goes from 'adult plant with flowers' direction to seed (fertilisation forms seed), and Y arrow goes from seed to 'young plant' (germination). So X = fertilisation, Y = germination.

Question 11

Mary set up an experiment as shown below. After a few hours, a dark blue coloration was observed in the starch solution outside the bag in the beaker. The diagram below shows a plant cell. Which part of the cell, A, B, C or D, does the bag in Mary's experiment represent?

Accepted Answer

B. B. The bag allowed iodine to pass through but not starch (since the blue colour only formed outside the bag where iodine met starch), meaning the bag acts as a partially permeable membrane. In a plant cell, part B is the cell membrane (just inside the cell wall) which controls movement of substances into and out of the cell.

Question 12

Hashim wanted to find out the effect of substance W on an aquatic plant. He placed some water moss fern in a beaker of water containing substance W as shown below. Which of the following should Hashim do to enable him to compare the effect of substance W on the water moss fern after two weeks? A. Pour a layer of oil on the water at the start. B. Set up a control beaker containing water and water moss fern only at the start. C. Measure the mass of water moss fern after two weeks. D. Count the number of water moss fern that are alive after two weeks.

Accepted Answer

D. B, C and D only. To compare effect: needs a control beaker without substance W (B). To measure the effect, he can measure mass change (C) or count number alive (D). A (pouring oil) is not necessary and would alter the experiment. Therefore B, C and D are needed.

Question 13

The diagram below shows several air sacs, surrounded by blood vessels, which are found in our lungs. The blood vessel X carries blood from the heart while the blood vessel Y carries blood to the heart. Which of the following statements are correct about X, Y and the air sac? A. The blood in X is richer in oxygen than the blood in Y. B. The blood in Y is poorer in carbon dioxide than the blood in X. C. The air leaving the air sac and out of the lungs contains nitrogen. D. The blood vessels around the air sac help to exchange gases efficiently.

Accepted Answer

C. B, C and D only. X carries blood from the heart to the lungs — this is deoxygenated blood with more carbon dioxide. Y carries oxygenated blood (after gas exchange at air sacs) back to the heart with less carbon dioxide. So A is wrong (X is poorer in oxygen). B is correct (Y has less CO2 than X). C is correct (exhaled air still contains nitrogen — about 78%). D is correct (capillaries surrounding alveoli enable efficient gas exchange).

Question 14

Ravi placed a bell jar over a plant which had been watered. He then covered the bell jar with a thick black cloth. Next, he placed his set-up under the sun from 9 a.m. to 12 noon. Which one of the following graphs shows correctly the changes in the amount of carbon dioxide and oxygen in the bell jar during the period of time?

Accepted Answer

D. oxygen falling, carbon dioxide rising (lines cross). The bell jar is covered with a thick black cloth, so no light reaches the plant — photosynthesis cannot take place. Only respiration occurs: the plant uses oxygen and releases carbon dioxide. So oxygen amount decreases and carbon dioxide amount increases. Graph 4 (option D) shows oxygen (solid line) decreasing and carbon dioxide (dashed line) increasing, with lines crossing — correct.

Question 15

The flow chart below shows some properties of materials A, B, C, D, E and F. Based on the information above, which of the following shows the most suitable material for making gloves and helmets for firemen?

Accepted Answer

C. Gloves = B, Helmets = E. Firemen's gloves need to be waterproof, flexible (to grip) and NOT conduct heat easily (to protect from heat). Following the chart: waterproof (yes) → flexible (yes) → conduct heat easily (no) → material B. Firemen's helmets need to be waterproof, NOT flexible (rigid), strong and NOT melt easily at high temperature. Following the chart: waterproof (yes) → flexible (no) → strong (yes) → melt easily (no) → material E. So gloves = B, helmets = E.

Question 16

The diagrams show three objects of different shapes and made of different materials. (A disc made of steel and clear glass, a star made of clear glass, and a square made of wood and clear glass.) The three objects were glued together. They were placed between a torch and a screen as shown below. Which one of the following shows the shadow cast on the screen?

Accepted Answer

C. Arc-shaped shadow (only outer ring of disc). Only opaque parts of objects cast shadows. The disc has a steel ring (opaque) with clear glass inside (transparent) — casts a ring-shaped shadow. The star is entirely clear glass — transparent, casts no shadow. The square has wood on top half (opaque) and clear glass on bottom half (transparent) — casts a rectangle shadow on top. But the only shape giving an arc (the steel ring of disc partially) is option 3. The arc shadow shown is the outer steel ring of the disc only — the wood part of square overlaps but the answer key indicates option 3 — an arc/curved shadow.

Question 17

Two substances, S and T, were in a beaker placed on a table as shown below. The same beaker was then placed on a wooden wedge as shown below. Based on the diagrams above, which of the following statements about substances S and T are correct? A. Substances S and T occupy space. B. Substances S and T have definite volumes. C. Substance S cannot be compressed but substance T can. D. Substance S has a definite shape but substance T does not.

Accepted Answer

A. A and B only. When the beaker is tilted, S (top layer) takes the shape of its container (tilted level) — this is the behaviour of a liquid. T (bottom layer) also takes the shape of its container — also a liquid (or possibly liquid both). Both occupy space (A correct) and have definite volumes (B correct). Liquids cannot easily be compressed and do not have definite shapes — so C and D are wrong.

Question 18

Study the diagram below carefully. The capacity of the enclosed glass container is 800 cm³ and it contains some water at the start. When syringes A and B are pushed in completely twice, the final volume of air in the glass container becomes 480 cm³. What is the volume of water in the glass container before the syringes are pushed in?

Accepted Answer

B. 320 cm³. Container capacity = 800 cm³. Final air volume = 480 cm³, so final water volume = 800 − 480 = 320 cm³. The water amount in the glass container doesn't change when only air is pushed in (water is the unchanged portion). So initial water volume = 320 cm³.

Question 19

Roy placed a torch at position K. The torch shone at an object that was placed at position M as shown below. A shadow was cast on the screen. At which positions of the ruler should the torch and the object be placed so as to obtain a bigger shadow on the screen than before? Options: A. torch at K, object at N; B. torch at J, object at K; C. torch at L, object at M; D. torch at J, object at N.

Accepted Answer

C. B and C. A shadow becomes bigger when the object is closer to the light source (or the screen is moved further from the object). Original: torch at K, object at M. Option B: torch at J (further) but object at K (much closer to torch) — object closer to light, bigger shadow. Option C: torch at L (closer to object) and object at M — moving torch closer to object also enlarges shadow. So B and C are correct.

Question 20

Anne set up an experiment as shown below using two iron bars, P and Q, which have a mass of 40 g each. The table below shows the readings on the weighing scale and spring balance when the iron bars were arranged as shown above. Reading on spring balance: less than 40 g. Reading on weighing scale: more than 40 g. Based on the results in the table above, which one of the following statements is most likely to be correct?

Accepted Answer

C. There is force of attraction between iron bar P and iron bar Q.. Spring balance reads less than 40 g — meaning bar P feels lighter than its weight (something pulling it down would normally make it more; pulling it from below upwards isn't here — actually if Q attracts P downward, spring reads MORE, not less). The spring reading is less than 40 g and the scale shows more than 40 g — this means Q is pulling P down... wait, less than 40 means upward force on P from Q, but weighing scale shows more than 40 means downward force on Q. Both readings indicate force of attraction between P and Q (Q is above the scale; P hangs above Q — Q being attracted up to P would reduce scale reading, not increase; but here scale shows MORE than 40g and spring shows LESS than 40g, meaning P is pulled DOWN toward Q and Q is pushed DOWN onto scale via P's pull — this indicates attraction between P and Q).

Question 21

Sharon had four mugs of the same size and thickness. They were made of different materials W, X, Y and Z. She filled each mug with 250 ml of hot water at 60°C. The temperature of the water in the mugs was then measured every two minutes. The results of the experiment were plotted on the graph below. Which of the following statements about the four materials are correct? A. Material X is a poorer conductor of heat than material Z. B. Material Z is the best conductor of heat among the four materials. C. Water will heat up the fastest if it is placed in the mug made of material W. D. Water remained hot for a longer period of time in the mug made of material Y than material X.

Accepted Answer

A. A and B only. From the graph: W loses least heat (best insulator), Z loses most heat (best conductor of heat). A: X loses less heat than Z, so X is a poorer conductor of heat than Z — correct. B: Z drops fastest temperature, so Z is best conductor among the four — correct. C: W keeps water warm longest (slowest heat transfer), so water would heat up the SLOWEST in W, not fastest — wrong. D: Y loses heat faster than X (Y line drops below X), so water remained hot LONGER in X than Y — wrong. Only A and B are correct.

Question 22

The diagram shows the movement of water in the environment. Based on the diagram given, which of the following correctly shows the change in state of water?

Accepted Answer

B. From liquid to gas: C; From gas to liquid: A. From the water-cycle diagram: A = water vapour → clouds (gas to liquid, condensation); B = clouds → water bodies / plants (precipitation, liquid); C = water bodies → water vapour (evaporation, liquid to gas); D = plants ↔ water bodies (liquid). So liquid → gas is C (evaporation), gas → liquid is A (condensation in clouds).

Question 23

John set up a circuit as shown below which consists of three bulbs, A, B and C, as well as three different materials, X, Y and Z. When the switch is closed, only bulbs B and C lit up. What are some possible reasons for this observation? A. Bulb A has fused. B. Material X cannot conduct electricity. C. The batteries are not connected properly. D. Materials Y and Z are conductors of electricity.

Accepted Answer

C. A, B and D only. Only bulbs B and C lit, meaning the circuit through bulb A is broken. Possible reasons: A is fused (statement A correct), or material X (in bulb A's branch) is a non-conductor (statement B correct). For B and C to light up, materials Y and Z (in their branches) must conduct electricity (statement D correct). If batteries were not connected properly (C), no bulb would light, but B and C did light — so C is wrong. Therefore A, B and D are correct.

Question 24

Joyce made a toy with a block and a balloon. She pumped air into the balloon and then released it. The toy moved on the surface of the table in the direction shown by the arrow in the diagram below. It came to a stop at position X. Which of the following correctly shows the energy conversion in the toy beginning with the balloon filled with air?

Accepted Answer

D. elastic potential → kinetic → kinetic + heat + sound. An inflated balloon stores elastic potential energy. When released, the air escapes and pushes the toy forward, converting elastic potential to kinetic energy (the toy moves). As the toy moves and rubs against the table, kinetic energy is converted to heat and sound energy due to friction, until the toy stops at X.

Question 25

Peter hung three wooden blocks, A, B and C, one at a time, from a string and released each one from either position X or Y as shown in the diagram below. The mass of each block and the position from which it was released are shown in the table below. A: 100 g released from X; B: 200 g released from X; C: 100 g released from Y. Each time the block hit the wall, a sound was produced. Peter measured the sound level using a data logger and recorded his findings. Which of the following correctly shows the sound level recorded for each wooden block?

Accepted Answer

C. A=300, B=350, C=225. Sound loudness depends on the kinetic energy when the block hits the wall, which depends on both mass and release height. B (200g from X) is heavier than A (100g from X), so B produces louder sound. C (100g from Y, which is lower than X) has less potential energy than A (100g from X), so C produces softer sound. Ordering: B > A > C. Only option C (300, 350, 225) shows this ordering.

Question 26

Arif dropped a ball from a table. The dotted lines shown in the diagram below represent the path that the ball took. Based on the diagram, Arif wrote the following statements in his notebook. A. The kinetic energy increases from A to B. B. The kinetic energy decreases from D to E. C. The potential energy remains unchanged from A to C. D. The potential energy increases from F to G. Which of the statements written by Arif are correct?

Accepted Answer

C. A, B and D only. A: From A (top) to B (ground), ball falls and speeds up, so kinetic energy increases — correct. B: From D (ground after second bounce) to E (top of next bounce), ball rises and slows down, so kinetic energy decreases — correct. C: From A to C (the height of first bounce), potential energy changes (decreases from A to B, increases from B to C). Also energy is lost to heat/sound on bounce, so PE at C is LESS than at A — not unchanged. Wait — actually statement C says 'remains unchanged from A to C', which is FALSE because PE at C < PE at A. So C is wrong. D: From F to G (rising), PE increases — correct. Therefore A, B and D are correct.

Question 27

Kai and Don were playing a game of Frisbee (a light plastic disc). Kai threw the Frisbee as shown in diagram 1. Don tried to catch the Frisbee as shown in diagram 2 but failed. He only managed to touch the Frisbee. Which of the following statements about forces correctly explain the result of Kai's and Don's actions?

Accepted Answer

C. Kai: A force causes a stationary object to move. Don: A force changes the speed of a moving object.. Kai threw the stationary Frisbee — his force caused a stationary object to move. Don touched the moving Frisbee but did not stop it — his force changed the speed (and possibly direction) of the moving Frisbee, but it kept moving. So the best match: Kai = force causes stationary object to move; Don = force changes the speed of a moving object.

Question 28

The diagram below shows a car driving up a slope. Which of the following correctly shows the change in gravitational force as the car moves from P to Q and from Q to R?

Accepted Answer

D. P to Q: remains unchanged; Q to R: remains unchanged. Gravitational force on an object near Earth's surface depends on its mass and the Earth's gravitational pull, which essentially remains constant whether the object is on flat ground or on a slope at small heights. The car's mass does not change, so gravitational force remains unchanged from P to Q (going up slope) and from Q to R (continuing on the higher flat ground).

P6 Science SA2 2020 — Henry Park

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