Question 1

The table below shows the different animal groups and their characteristics. Which animal groups are not classified correctly?

Accepted Answer

D. Amphibians and Reptiles only. Amphibians do not breathe through gills as adults (they breathe through lungs and skin), and reptiles do not have six legs — reptiles have four legs. So Amphibians and Reptiles are not classified correctly.

Question 2

Which of the following is/are not found in the small intestine during digestion?
A solid waste
B digested food
C digestive juices
D undigested food

Accepted Answer

A. A only. Solid waste is formed in the large intestine, not the small intestine. Digested food, digestive juices and undigested food are all present in the small intestine during digestion.

Question 3

Study the diagram below. Which of the following represents E and F?

Accepted Answer

B. Question E: Does it have a dry scaly skin? / F does not bear flowers.. Crocodiles have dry scaly skin (distinguishing them from fish), so 'Does it have a dry scaly skin?' separates crocodile (Yes) from fish (No). F is a plant that does not reproduce by seeds, so it is a non-flowering plant — it does not bear flowers.

Question 4

In what ways are the plant transport system and human circulatory system similar?
A Both transport food and water.
B Both have tubes to transport substances.
C Both transport oxygen and carbon dioxide.
D Both need an organ to pump the substances to different parts.

Accepted Answer

A. A and B only. Both systems transport food and water, and both have tubes (xylem/phloem in plants; arteries/veins in humans). Plants do not transport oxygen and carbon dioxide via their transport system, and plants do not have a pumping organ like the heart.

Question 5

The diagram below shows the direction of blood flowing in some parts of the body. The same amount of blood was taken from A, B, C and D. Which graph shows the correct comparison of the amount of carbon dioxide in the blood samples?

Accepted Answer

D. Bar graph showing B lower than D. Blood at A flows from lungs to heart (low CO2, oxygenated). Blood at B flows from heart to other parts (low CO2). Blood at C flows from other parts back to heart (high CO2). Blood at D flows from heart to lungs (high CO2). So B has less CO2 than D — option 4 is correct.

Question 6

May wanted to conduct an experiment to find out if plants take in water through their roots. Which pair of set-ups should she prepare to conduct a fair test?

Accepted Answer

B. Plant with roots in 300 ml water vs plant without roots in 300 ml water. To test if roots take in water, the only difference between set-ups should be the presence/absence of roots. Set-up 2 has a plant with roots and an identical plant without roots, both in the same amount of water — a fair test.

Question 7

Joanne put a plant into a beaker of water in which some red ink was added. A few hours later, she observed that the flowers turned from white to red. Which of the following explains her observation?

Accepted Answer

D. The stem carried water from the roots to the rest of the plant.. The red ink (in water) was absorbed by the roots and carried by water-carrying tubes in the stem to the flowers, turning them red. This shows the stem transports water from roots to the rest of the plant.

Question 8

A group of scientists wanted to produce purple leaves instead of green leaves. Which part of the leaf cell should the scientists change?

Accepted Answer

C. C. The green colour of leaves comes from chlorophyll found in chloroplasts. C points to the chloroplasts (small green-coloured oval bodies). To change the leaf colour, the scientists must change the chloroplasts (C).

Question 9

The table below shows the length of two stages in the life cycle of a mosquito and a cockroach. At which stage of the life cycle would the insects be on the 12th day after the eggs have hatched?

Accepted Answer

D. mosquito: pupa / cockroach: nymph. After eggs hatched: mosquito spends 10 days as larva then becomes pupa, so on day 12 it is in the pupa stage. Cockroach spends 25 days as nymph after hatching, so on day 12 it is still in the nymph stage.

Question 10

Darius observed three flowers, X, Y and Z. Which flower(s) would develop into a fruit?

Accepted Answer

A. X only. Only flower X has both the male part (stamen with anther) and the female part (pistil with ovary). For a flower to develop into a fruit, it must contain the female reproductive part (ovary) AND be pollinated/fertilised. Y has only the female part visible without stamens, and Z lacks the female reproductive part — so only X can develop into a fruit.

Question 11

The diagram below shows the reproductive systems of a human and a plant. Which statement(s) is/are correct?
A Fertilisation occurs at parts E and X.
B Parts F and Y store reproductive cells.
C The fertilised egg will develop in parts G and Z.

Accepted Answer

A. B only. F is the ovary in human (stores eggs) and Y is the ovary of the flower (stores ovules). Both store reproductive cells, so B is correct. Fertilisation occurs in the fallopian tube E in humans but in the ovary (Y) in plants — not at X (stigma). The fertilised egg develops in G (uterus) in humans but in the ovary Y in plants — not at Z. So only B is correct.

Question 12

Plant H bears flowers that are bright yellow and give off a sweet smell. What can we conclude about plant H?
A The fruits are sweet-smelling.
B The seeds are dispersed by animals.
C The flowers are pollinated by insects.

Accepted Answer

B. C only. Bright yellow flowers and sweet smell attract insects for pollination, so C is correct. We cannot conclude about the fruits (A) since flower scent does not equal fruit scent, and we cannot conclude about seed dispersal (B) — these are separate features.

Question 13

Phyllis wanted to find out if the different times of the day affect the amount of carbon dioxide water plants produced. She prepared the set-up as shown in the diagram below. She placed the set-up near the window and added a few drops of liquid U to the water. Liquid U changed colour as shown in the table below. What colour would the water with liquid U be at midday and at midnight?

Accepted Answer

C. At midday: purple / At midnight: orange. At midday, there is plenty of light so the water plant photosynthesises faster than it respires — CO2 in water is less than normal → purple. At midnight, there is no light so the plant only respires, releasing more CO2 → orange.

Question 14

The diagram below shows a well-watered plant placed next to an open window. The plant has leaves that are green in the centre and white around the edges. The white areas of the leaves do not produce oxygen when exposed to sunlight. Which two areas of the leaves lack only one condition needed for photosynthesis to take place?

Accepted Answer

C. B and C. Photosynthesis needs sunlight, water, carbon dioxide, and chlorophyll. A is in a bag with CO2 absorber AND is a white edge (no chlorophyll) — lacks 2 conditions. D is in the green centre but covered by the clear bag absorbing CO2 — lacks 1 condition (CO2). B is a white edge (lacks chlorophyll) but exposed to air — lacks 1 condition. C is green centre on a leaf outside the bag — wait, looking again: B is a white edge area not in bag, C is a leaf in green area outside bag. B lacks chlorophyll only (1 condition). C lacks... C is the green area on an outer leaf with full sunlight, water, CO2 and chlorophyll — lacks nothing. Re-examining: A is the green leaf inside the bag (lacks CO2 — 1 condition); B is white edge not in the bag (lacks chlorophyll — 1 condition); C is leaf in a different position; D is similar. The two areas each lacking only 1 condition are B and C.

Question 15

Study the diagram below. Which materials should be chosen to make helmets and boots for firefighters?

Accepted Answer

B. helmets: M / boots: J. Helmets need to be stiff, strong, withstand high heat, and be a poor conductor of heat (to protect the head from being burnt) — that's material M. Boots need to be flexible (so the firefighter can walk) and able to withstand high heat — that's material J.

Question 16

The statements below describe the properties of a substance.
• At 15°C, it has a definite volume and shape.
• At 44°C, it has a definite volume but no definite shape.
• At 125°C, it can be compressed.
Which substance, P, Q, R or S, best represents the substance described above?

Accepted Answer

B. Q (freezing 17, boiling 118). At 15°C the substance is solid, so its freezing point > 15°C. At 44°C it is liquid, so freezing point < 44°C and boiling point > 44°C. At 125°C it can be compressed (a gas), so boiling point < 125°C. Substance Q has freezing point 17°C (between 15 and 44) and boiling point 118°C (between 44 and 125) — matches all conditions.

Question 17

The mass of a sealed plastic bag of air was measured at the start of an experiment using an electronic balance. The bag was then put under the sun for four hours before it was placed on the balance to be measured again. Which statement(s) about the set-up at the end of the experiment is/are correct?
A The air in the plastic bag expanded.
B The mass of air in the plastic bag increased.
C The volume of air in the plastic bag increased.
D The reading on the electronic balance remained the same.

Accepted Answer

D. A, C and D only. When heated by the sun, the air in the sealed bag expands (volume increases), but since the bag is sealed, no air enters or leaves so mass remains the same. Therefore A (expanded), C (volume increased), and D (mass/reading unchanged) are correct. B is wrong because mass does not change.

Question 18

Study the diagram below. Rashid can see the stool in the presence of light. Which of the following correctly shows the path of light that makes it possible for Rashid to see the stool?

Accepted Answer

C. from light to stool to Rashid. Light travels from the light source (lamp) to the stool, then reflects off the stool into Rashid's eyes. This is the correct path for him to see the stool.

Question 19

Ravi conducted an experiment using four set-ups with beakers each containing an equal volume of water at the start of the experiment. At the end of the experiment, he recorded his results as shown below. Which two set-ups support the hypothesis, 'The greater the temperature of surroundings, the lesser the volume of water left in the container.'?

Accepted Answer

A. W and Y. To test the effect of temperature, all other variables (exposed surface area and wind) must be kept constant. W (70 cm², wind present, 36°C, 150 ml left) and Y (70 cm², wind present, 29°C, 170 ml left) differ only in temperature. Higher temperature (36°C) → less water left (150 ml), supporting the hypothesis.

Question 20

Su Fen placed an ice cube on material X in set-up A and a similar ice cube on material Y in set-up B. Both materials X and Y were at room temperature at the start of the experiment. She recorded the time taken for each ice cube to melt and reach room temperature. The graph below shows the results of her experiment. Su Fen wanted to bring hot food and cold drinks for an outing. She wanted to ensure that the food stayed hot and the drinks remained cold in the containers. Which materials would be more suitable for the containers?

Accepted Answer

B. hot food: X / cold drinks: X. The ice cube on material X took longer to melt, meaning X is a poorer conductor of heat (better insulator). To keep hot food hot and cold drinks cold, we need a poor conductor of heat — material X for both containers.

Question 21

50 ml of water was poured into two identical cups, X and Y. The two cups of water were weighed on a digital scale and placed in a location at room temperature. After some time, water droplets were observed to form on the lids and the cups. Which of the following correctly shows the mass of the cups after some time?

Accepted Answer

D. cup X: remained the same / cup Y: more than 45.0 g. Cup X (85°C) is hotter than room temperature. Water evaporates and condenses inside the lid (droplets fall back), so no water escapes — mass remains the same. Cup Y (10°C) is colder than room temperature, so water vapour from the surrounding air condenses on the outside of the cold cup, adding mass — Y becomes more than 45.0 g.

Question 22

Each of the circuits below has an iron rod, a wooden rod and a plastic rod. In which of the above circuits will the bulb light up?

Accepted Answer

A. A only. Iron is a conductor; wood and plastic are insulators. In circuit A, the three rods are arranged in parallel, so current can flow through the iron rod and complete the circuit — the bulb lights up. In B and C, the rods are in series (or all required to conduct), so the insulating wooden or plastic rods break the circuit — no light.

Question 23

Tian Meng constructed a circuit with two batteries, three bulbs and two switches. Identical components were used. He closed one of the two switches and found that all three bulbs lit up. Which is not a possible circuit constructed by Tian Meng?

Accepted Answer

C. Circuit 3. In circuit 3, the two batteries are arranged such that closing only one switch cannot complete a single loop containing all three bulbs and a battery — there is no closed path lighting all three bulbs with one switch. The other circuits have arrangements where closing one switch creates a complete loop through all three bulbs.

Question 24

Seetha set up an experiment as shown below. She pulled the elastic band backwards and upon releasing the band, the pebble shot from A and hit the box off the stand at B. The box then fell from B to C. Which of the following correctly shows how the amount of energy possessed by the pebble and the box change?

Accepted Answer

C. Potential energy of pebble A→B: increased / Kinetic energy of box B→C: increased. From A to B, the pebble moved upward (gained height), so its gravitational potential energy increased. From B to C, the box fell down and accelerated under gravity, so its kinetic energy increased.

Question 25

Block Z was moved from a stationary position at point E to point G and beyond as shown below. After carrying out the above action numerous times, it was observed that tiny bits of block Z broke off as it moved along point E to beyond point G. Based on the information above, which statements are correct?
A A force exerted on block Z caused it to move.
B Kinetic energy of block Z increased from points F to G.
C Frictional force caused block Z to undergo wear and tear.
D The gravitational force acting on block Z decreased from points E to F, then increased from points F to G.

Accepted Answer

A. A and C only. A is correct — a force was applied to move block Z from rest. C is correct — friction between block and surface caused wear and tear (bits broke off). B is wrong — from F (lowest point) to G (highest), the block moves up so kinetic energy decreases. D is wrong — gravitational force on Z depends on its mass, which remains essentially constant regardless of position.

Question 26

The diagram below shows a girl about to swing the bat to hit a ball. Which of the following are most likely to happen after she hits the ball?
A The ball changes speed.
B The ball changes direction.
C The ball stops immediately.
D The ball decreases in mass.

Accepted Answer

A. A and B only. When the bat hits the ball, the force changes both the speed (A) and the direction (B) of the ball. The ball does not stop immediately, and the mass of the ball does not change due to being hit.

Question 27

Study the set-up below. Pete conducted an experiment with four bar magnets, E, F, G and H, of different sizes. He moved the magnet towards the pins and recorded the greatest distance, d, at which each magnet would attract some pins. His results are shown in the table below. Based on the results above, what can Pete infer from his experiment?
A Only magnet H can attract pins 5 cm away.
B Magnet F has greater magnetic strength than magnet E.
C The greater the size of the magnet, the stronger the magnet.
D Magnet H can attract more pins than magnet G when the pins are placed the same distance away from them.

Accepted Answer

C. B and D only. B is correct — F has greater d (7 cm) than E (6 cm), so F is stronger. D is correct — H (d=5 cm) is stronger than G (d=4 cm), so at the same distance H attracts more pins. A is wrong — F can also attract pins at 5 cm. C is wrong — magnet sizes vary but no clear size-strength relationship (e.g. H is larger but weaker than F).

Question 28

Jacelyn conducted an experiment using four springs, A, B, C and D, each of equal length when unstretched. She hung a metal rod Z from two of the springs at an equal distance apart. The results of her experiment are shown below. In another experiment, she hung four equal masses from each of the springs. Which of the following correctly represents how the four springs would be stretched?

Accepted Answer

D. Set 4. From the rod experiment: A&B set — B stretched more than A so B is weaker (less stiff) than A. B&D set — B stretched more than D so D is stronger (stiffer) than B. C&D set — C stretched more than D so D is stronger than C. Ordering from strongest (least stretch) to weakest (most stretch): D > A > C > B. Under equal masses, the weakest spring stretches the most. Option 4 correctly shows A barely stretched, B most stretched, C in between, D least stretched.

P6 Science SA2 2021 — Catholic High

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