Question 1

Animal P was found in a garden. Which characteristics confirm that animal P is an insect?
A  It has wings.
B  It has feelers.
C  It has six legs.
D  It has three body parts.

Accepted Answer

2. C and D only. The defining characteristics of an insect are 6 legs and 3 body parts (head, thorax, abdomen). Wings and feelers are not present in all insects, so only C and D are required to confirm an insect.

Question 2

Noah wants to classify the three animals, X, Y and Z, according to their body covering. Which of the following shows the correct classification of the animals according to their body covering?

Accepted Answer

4. Have scales: Y and Z | Do not have scales: X. Animal X is a frog (amphibian, moist skin, no scales). Animal Y is a lizard (reptile, has scales). Animal Z is a fish (has scales). So Y and Z have scales, while X does not.

Question 3

Study the table below. The table shows parts A, B, C and D of the digestive system with ticks indicating: 'Digestion is completed' = C; 'Removal of water from food' = D; 'Digestion takes place' = A, B and C. Which of the following correctly represents A, B, C and D?

Accepted Answer

4. A=mouth, B=stomach, C=small intestine, D=large intestine. Digestion takes place in the mouth, stomach and small intestine (A, B, C). Digestion is completed in the small intestine (C). Water is removed from food in the large intestine (D). Option (4) labels: A=mouth, B=stomach, C=small intestine, D=large intestine — matches all conditions.

Question 4

Study the diagram below. Based on the diagram, which statements are correct?
A  The plant can bear fruits.
B  The plant has a weak stem.
C  The plant reproduces from spores.

Accepted Answer

1. A and B only. The plant has flowers, so it is a flowering plant — it bears fruits (A correct) and does not reproduce by spores (C wrong). It is climbing on a support, indicating a weak stem (B correct). Only A and B are correct.

Question 5

The diagram shows how energy is passed on to the living things. The main source of energy that is passed on from one living thing to another comes from the ____.

Accepted Answer

1. Sun. Energy flows in a food chain from the Sun → producer (grass) → consumer (grasshopper) → consumer (frog). The Sun is the ultimate source of energy for all living things.

Question 6

Which cycle shows the correct sequence of the reproduction of a flowering plant?

Accepted Answer

4. pollination → fertilisation → seed dispersal → germination → pollination. The correct sequence of flowering plant reproduction is pollination → fertilisation → seed dispersal → germination, then the cycle repeats. Only option (4) shows this order.

Question 7

The diagram below shows the life cycles of two animals. Which statements about the life cycles of the animals are correct?
A  Both give birth to young alive.
B  Both their young do not resemble the adult.
C  The young will only become insects at the adult stage.
D  The pupa does not eat before reaching the adult stage.

Accepted Answer

2. B and D only. Both beetle and butterfly hatch from eggs (not born alive), so A is wrong. Their larvae do not resemble adults (B correct). They are insects at all life stages, not only as adults (C wrong). The pupa stage does not eat (D correct). So only B and D are correct.

Question 8

A pupil made three statements about sexual reproduction in humans:
A  The fertilised egg is found in the ovary.
B  Fertilisation starts when the egg enters the sperm.
C  The fertilised egg develops into a baby in the womb.
Which statement(s) is/are correct?

Accepted Answer

2. C only. A is wrong — fertilisation occurs in the fallopian tube, not the ovary. B is wrong — fertilisation starts when the sperm enters the egg, not the other way around. C is correct — the fertilised egg implants and develops into a baby in the womb (uterus). Only C is correct.

Question 9

The diagram below shows how water and food are transported in a plant. Which of the following correctly represents A, B, C and D?

Accepted Answer

3. A=stem, B=flowers, C=roots, D=leaves. Water is absorbed by the roots (D) and travels up the stem (A) to the leaves (C, where food is made via photosynthesis) and flowers (B). Food made in the leaves travels back through the stem to all other parts. So D=roots, A=stem, C=leaves, B=flowers. This matches option (3).

Question 10

The graph below shows the changes in Wei Ming's heart rate. He ran and then stopped after some time. At which point, A, B, C or D, did Wei Ming stop exercising?

Accepted Answer

3. C. Heart rate rises during exercise and only starts to fall after the person stops. Heart rate is rising from A to B, stays high from B to C (still elevated immediately after stopping), then decreases from C to D as the body recovers. Wei Ming stopped exercising at point C, when the heart rate begins to decrease.

Question 11

The diagram below shows fruits P and Q. Which graph correctly shows the relationship between the distance the seeds are dispersed from their parent plant and the amount of wind?

Accepted Answer

2. Both curves rising; fruit Q above fruit P. Fruit P has a pod-like structure — it is dispersed by splitting/explosive mechanism, not wind, so wind has little effect on distance. Fruit Q has hair-like structures — it is wind-dispersed, so the more wind, the further it travels. Therefore fruit Q's distance increases more steeply with wind than fruit P. Option (2) shows fruit Q above fruit P, both increasing.

Question 12

John prepared four set-ups, A, B, C and D. Using identical plants in each set-up, the conditions in each of the four set-ups are shown below. Which two set-ups should John use to find out how the presence of carbon dioxide affects the rate of photosynthesis?

Accepted Answer

3. B and D. To test the effect of carbon dioxide, only carbon dioxide should differ; all other factors needed for photosynthesis (water, sunlight, and ideally oxygen) must be the same. Comparing B (water, oxygen, sunlight; no CO₂) with D (water, oxygen, sunlight, CO₂) — only carbon dioxide differs. So B and D is the correct fair test.

Question 13

Enoch wants to investigate whether leaves can make food if the tiny openings on the leaves are coated with oil. The table below shows how Enoch prepares leaves A, B and C from the same plant placed in the garden. Excess food made in the leaves is stored as substance X. There are more tiny openings found on the underside of the leaves. Leaf A: not coated with oil. Leaf B: only the upperside coated with oil. Leaf C: only the underside coated with oil. After two days, he conducts a test using liquid Y. He puts two drops of liquid Y on each leaf. Liquid Y will turn from brown to blue-black if substance X is present. Which of the following shows the results of the test?

Accepted Answer

2. Leaf A: blue-black; Leaf B: blue-black; Leaf C: brown. Tiny openings (stomata) allow CO₂ in for photosynthesis. Leaf A is not coated, so photosynthesis occurs — turns blue-black. Leaf B has only the upperside coated; most stomata are on the underside, which is uncoated, so photosynthesis still occurs — turns blue-black. Leaf C has the underside (where most stomata are) coated, so very little CO₂ enters — little/no photosynthesis — stays brown. Option (2) matches.

Question 14

Shu Hui carried out an experiment using three set-ups as shown below. At the start, the colour of liquid L in each set-up was red. The glass tanks were sealed and left in a well-lit room. The colour of liquid L would change according to the amount of carbon dioxide present in the tank: less than normal → purple; normal → red; higher than normal → yellow. What would the colour of liquid L in each set-up be after three hours?

Accepted Answer

1. P=purple, Q=yellow, R=red. Set-up P contains only a plant in a well-lit room — the plant photosynthesises and takes in more CO₂ than it releases by respiration, so CO₂ is less than normal → liquid L turns purple. Set-up Q contains only a mouse — it respires and releases CO₂, so CO₂ is higher than normal → yellow. Set-up R contains both a plant and a mouse — the CO₂ released by the mouse balances the CO₂ used by the plant for photosynthesis, so CO₂ stays normal → red. Matches option (1).

Question 15

Jing Ting wants to find out if the time taken for seed K to reach the ground is affected by the wingspan of the seed. Which variables should she keep constant?
A  mass of seed
B  presence of wind
C  height at which seed is dropped
D  time taken for the seed to reach the ground

Accepted Answer

3. A, B and C only. The variable being changed is the wingspan; the variable being measured is the time taken. All other factors must be kept the same: mass of seed (A), presence of wind (B) and height at which seed is dropped (C). Time taken (D) is the measured/dependent variable, not constant.

Question 16

The diagrams below show the reproductive organs of a male human and a flowering plant. Which part of the flower, A, B, C or D, has the same function as part W in the male reproductive organ?

Accepted Answer

2. B. Part W in the male reproductive organ is the testes, which produce sperm cells (male reproductive cells). The equivalent in a flower is the anther, which produces pollen grains (male reproductive cells). Part B labels the anther. So B has the same function as W.

Question 17

Six people were trapped in a lift. There was no fresh air entering the lift. Some adults started banging the door and a child started crying. Which graph shows the correct change in the amount of gases at different intervals?

Accepted Answer

1. Oxygen decreases each interval; carbon dioxide increases each interval. The trapped people are respiring (and the more they exert themselves by banging/crying, the faster they respire). Respiration takes in oxygen and releases carbon dioxide. With no fresh air entering, oxygen in the lift will decrease over time and carbon dioxide will increase over time. Graph (1) shows oxygen decreasing and carbon dioxide increasing across 10, 20 and 30 min — correct.

Question 18

Study the diagram below. Matter is shown classified into 'cannot be compressed' (ice, scissors) and 'can be compressed' (milk, steam). Which matter is not classified correctly?

Accepted Answer

2. milk. Solids (ice, scissors) and liquids (milk) cannot be compressed because their particles are tightly packed. Only gases (steam) can be compressed. Milk is a liquid and is wrongly placed under 'can be compressed'. So milk is the incorrectly classified item.

Question 19

The diagram below shows two similar containers of capacity 900 cm³ on a balance. The balance was horizontal. Each container contains 400 cm³ of water and has a stopper. Halim pumped in 100 cm³ of air into container W but did not pump in any air into container X. Which statement(s) is/are correct after air was pumped into container W?
A  The volume of air in container W was 600 cm³.
B  Container W was heavier as more air was added.
C  The balance did not tilt as air can be compressed.

Accepted Answer

2. B only. Container W's capacity is 900 cm³; it already contains 400 cm³ of water, leaving 500 cm³ of air space. Pumping in 100 cm³ more air does NOT make the volume of air 600 cm³ — air is compressed into the 500 cm³ space (so A is wrong). Air has mass, so adding air makes container W heavier (B correct). Because W is heavier, the balance WILL tilt down on W's side (C wrong). Only B is correct.

Question 20

Khai placed bar magnet W at a distance from some iron pins as shown in diagram 1. He then moved magnet W towards the pins until it attracted the pins from a distance, d, in diagram 2. He repeated the procedure and calculated the average distance. He then repeated the experiment with three other bar magnets, X, Y and Z, of the same length. Average distances: W=2.1 cm, X=1.6 cm, Y=1.9 cm, Z=2.3 cm. Based on the above results, which of the following shows the correct order of the magnetic strength of each magnet, starting from the weakest to the strongest?

Accepted Answer

1. X, Y, W, Z. The greater the distance at which a magnet attracts iron pins, the stronger the magnet. Distances in increasing order: X (1.6) < Y (1.9) < W (2.1) < Z (2.3). So from weakest to strongest: X, Y, W, Z — matches option (1).

Question 21

Sarah placed some blocks of ice in a sealed glass box. After ten minutes, she noticed that some of the ice melted as shown below. Which of the following describes what happened to the temperature of the ice, water and air in the glass box at the 10th minute?

Accepted Answer

3. ice: remains the same; water: remains the same; air: decreases. At the moment some ice has just melted (still a mixture of ice and water), the ice and water are at 0°C — temperature of ice and water remains the same while melting takes in heat. The warmer air in the sealed box gives up heat to melt the ice, so the air temperature decreases. This matches option (3).

Question 22

The table below shows the properties of substance G at different temperatures.
0°C: has definite shape — yes; has definite volume — yes.
100°C: has definite shape — yes; has definite volume — yes.
180°C: has definite shape — no; has definite volume — yes.
260°C: has definite shape — no; has definite volume — no.
Which statement(s) about substance G is/are correct?
A  It is a gas at 260°C.
B  It has a boiling point higher than 180°C.
C  It has a melting point lower than 100°C.

Accepted Answer

2. A and B only. At 0°C and 100°C substance G has definite shape AND volume → solid. At 180°C it has no definite shape but definite volume → liquid. At 260°C it has neither → gas. So A is correct (gas at 260°C). It is still liquid at 180°C, so boiling point is higher than 180°C → B correct. At 100°C it is still solid, so melting point is higher than 100°C, not lower → C wrong. Only A and B are correct.

Question 23

Claire conducted an experiment using the four set-ups as shown below. She used similar beakers, cups and glass dishes for all the set-ups. They were placed in the Science Room. Set-up A: 50 ml of water at 10°C, no ice. Set-up B: 50 ml of water at 10°C, ice on the glass dish. Set-up C: 50 ml of water at 90°C, ice on the glass dish. Set-up D: 50 ml of water at 90°C, no ice. In which set-up would Claire observe the most water collected in the cup after 15 minutes?

Accepted Answer

3. set-up C. Hot water (90°C) evaporates faster than cold water (10°C), producing more water vapour. The cold ice on the glass dish provides a cold surface that increases the rate of condensation. Set-up C combines fastest evaporation (90°C water) and fastest condensation (cold ice above) → most water collected in the cup. Set-up D has hot water but no cold surface, so less condensation. Set-ups A and B have cold water → little evaporation.

Question 24

Matthew set up four different circuits using identical bulbs and batteries as shown below. In which circuit would bulb A be the brightest?

Accepted Answer

3. Circuit 3: bulb A in parallel with two other bulbs (different layout). In a series circuit (1, 4), the voltage from the battery is shared among the bulbs, so each bulb (including A) is dimmer. In a parallel circuit, each branch gets the full battery voltage. Circuit 3 has bulb A in its own branch in parallel with the other bulbs — it gets the full voltage of the battery, so bulb A would be the brightest. (Circuit 2 also has parallel bulbs but its arrangement still places bulb A on a shared branch in this diagram.)

Question 25

Dingwei used different materials, W, X, Y and Z, to set up four circuits as shown below. The batteries and bulbs in the circuits were in good working condition. Circuit 1 uses W and X (bulb did not light), Circuit 2 uses Y and X (bulb lit), Circuit 3 uses Y and W (bulb did not light), Circuit 4 uses Z and X (bulb lit). Based on the table above, what could Dingwei conclude?

Accepted Answer

3. Materials X, Y and Z are electrical conductors.. If a bulb lights, both materials in that circuit must be conductors. Circuit 2 lit: Y and X are conductors. Circuit 4 lit: Z and X are conductors. Combined: X, Y and Z are conductors. Circuits 1 and 3 did not light because they contain W (Y is already proven a conductor in Circuit 2, so W must be the non-conductor). So Dingwei can conclude X, Y and Z are conductors — option (3).

Question 26

Natasha constructed a circuit by connecting two identical batteries, three bulbs and two switches. All the components are in good working condition. She closed only one switch and found that all three bulbs lit up. Which is not a possible circuit constructed by Natasha?

Accepted Answer

3. Circuit with two batteries, three bulbs and two switches, but with a switch in series with one bulb only. For all three bulbs to light with only one switch closed, that one switch must complete the only required closed loop, and the open switch must not break any branch containing a bulb. Option (3) has a configuration where one of the switches must be closed for one of the bulbs to be in a complete circuit — closing only the other switch would leave at least one bulb without a complete path. So circuit (3) is not possible.

Question 27

Nur set up a tunnel made from a drink carton. She placed a light source at one end of the tunnel and a slanted mirror as shown in the diagram below. She looked in from the other end of the tunnel but could not see the light. What changes should she make so that she could see the light?

Accepted Answer

4. Add another mirror slanted parallel to the existing one further down the tunnel.. Light travels in straight lines but can be reflected by mirrors. The first slanted mirror reflects the light downward into the lower section of the carton. To redirect the light back upward to Nur's eye at the other end, a second slanted mirror (parallel-but-opposite slope) is needed further along the tunnel. Option (4) shows two slanted mirrors that together bounce the light from source to Nur's eye via a periscope-style path.

Question 28

Amy conducted an experiment as shown below. Amy poured different volumes of water into three identical beakers. She placed each beaker on top of materials P, Q and R before heating it. The table below shows how well each material conducted heat (best → poorest: Q, R, P). It was observed that the time taken for the water to boil was the same. Which of the following most likely show the volume of water Amy poured into the beakers?

Accepted Answer

1. material Q: 300, material R: 200, material P: 100. The better the heat conductor, the faster heat reaches the water. For all three beakers to boil in the same time, the best conductor (Q) must have the most water (slowest to heat if equal volumes), and the poorest conductor (P) must have the least water. So volumes from largest to smallest: Q > R > P → Q=300, R=200, P=100 cm³. This matches option (1).

P5 Science SA2 2021 — Catholic High

Related papers