Question 1

Which of the following describe(s) both the field habitat and the garden habitat correctly?
A  Both habitats can have some common animal populations living in them.
B  The plants in both habitats provide food and shelter for some of the animals living there.
C  Flowering plants can only be found in the garden habitat while non-flowering plants can only be found in the field habitat.

Accepted Answer

A. A and B only. Both field and garden habitats share many common animal populations (A) and the plants in both provide food and shelter (B). Statement C is false because both habitats can contain flowering and non-flowering plants.

Question 2

Nora saw bird X in a garden. Thirty minutes later, she concluded that bird X forms a population in the garden community. Which of the following observations allowed her to make the conclusion?
A  Bird X eating earthworms
B  Bird X feeding two of its young
C  Bird X preyed on by its predator
D  Bird X building its nest with its mate

Accepted Answer

C. B and D only. A population is a group of the same species (kind) of organism living together in the same place. Observations B (feeding young) and D (building nest with a mate) both indicate the presence of more than one of the same kind of bird X — i.e. a population.

Question 3

Which of the following statements about the food web is false?

Accepted Answer

A. Energy in organism E is transferred to organism D.. Energy flows in the direction of the arrows in a food web (prey → predator). D points to E, so energy flows from D to E, not from E to D. Statement (1) is therefore false.

Question 4

Which of the following changes in population size could be observed after an increase in organism E's population size?

Accepted Answer

B. Increase in organism B's population size. E eats D, so when E increases, D decreases. With fewer D, B and C (D's prey) are eaten less and their populations rise. With B and C rising, A (their food source) is eaten more so A would decrease. The only valid increase listed is organism B's population size.

Question 5

Which of the food webs below shows three populations of predators?
(1) [Food web: P→T, T→U, P→Q, Q→R, P→S]
(2) [Food web: P→Q, Q→T, T→U, R→S, S→T]
(3) [Food web: P→Q, Q→R, R→S, T→U, U→S]
(4) [Food web: P→Q, Q→R, R→U, P→S, S→T, T→U]

Accepted Answer

D. (4). A predator is any organism that eats another animal (has at least one arrow pointing into it from another animal, not from a producer). In food web (4), Q (eats R-source? actually Q eats P producer), checking arrows pointing-from-animal-to-animal: R eats Q (predator), S eats P→ but P is producer so S is plant-eater; T eats S (predator); U eats R and T (predator). Three populations (R, T, U) act as predators.

Question 6

Which of the following examples of adaptations had been grouped correctly?

Accepted Answer

C. (3). Structural adaptations are physical features of the body, while behavioural adaptations are actions/behaviours. Body patterns are a physical/structural feature, and producing distinct sounds is a behaviour, so option (3) is correctly grouped.

Question 7

Which of the following adaptations of plants is correctly matched with its purpose?

Accepted Answer

C. (3). Spongy leaf stalks filled with air make the plant less dense than water, helping it to float on water (typical of aquatic plants like water hyacinth). Needle-like leaves reduce water loss (not store water); hanging stamens release pollen (not trap it); brightly-coloured fruits attract animals for seed dispersal, not pollinators.

Question 8

Which of the following describes adaptations of animals that prevent their predators from spotting them?
A  Changing body colour to green when on a green leaf
B  Changing fur colour from brown to white during snowy winter
C  A non-poisonous animal having the appearance of a poisonous animal
D  Having body shapes and colour that look like branches on the plant that they live on

Accepted Answer

C. A, B and D only. Camouflage (blending with surroundings) prevents predators from spotting prey. A, B and D are all camouflage adaptations (matching colour of leaf, matching snow, matching branches). C is mimicry — the predator can still spot it, it is just deterred from attacking because it looks poisonous.

Question 9

Which of the following is/are way(s) that help to conserve natural resources?
A  Use more paper bags instead of plastic bags
B  Using public transport instead of private vehicles
C  Clear forests by burning trees to make the soil fertile
D  Recycle used materials and make them into new products

Accepted Answer

C. B and D only. Using public transport (B) conserves fossil fuels, and recycling (D) reduces use of raw materials. A wastes trees (paper bag production uses many trees); C destroys forests and releases carbon dioxide.

Question 10

The graph below shows the number of fish over time at part Y of the river. [Figure: Line graph — Number of fish (y-axis) decreasing over Time (x-axis).] Which of the following could have happened at part X of the river bank to cause the change in the number of fish?
A Picking up litter
B Planting more trees
C Discharge of factory waste into the river
D Spraying of pesticides regularly on plants growing by the river

Accepted Answer

D. C and D only. The number of fish at Y decreased, meaning the river water flowing from X to Y was polluted. Factory-waste discharge (C) and pesticides washing into the river (D) both pollute the water and kill fish. A and B are positive actions that would not harm the fish.

Question 11

Which statement(s) is/are correct?
A Pollination had taken place.
B Part X developed from an ovule.
C The flower has many ovules in the ovary.

Accepted Answer

B. A and B only. For a flower to develop into a fruit with a seed, pollination (A) and fertilisation must have occurred. Part X (the seed) develops from an ovule (B). The diagram shows only one seed, so the flower had only one ovule, so C is false.

Question 12

Which one of the following correctly identifies cell P, cell Q and process H?
[Table: (1) P=egg, Q=sperm, H=fertilisation; (2) P=egg, Q=sperm, H=pollination; (3) P=sperm, Q=egg, H=fertilisation; (4) P=sperm, Q=egg, H=pollination]

Accepted Answer

A. (1). The large round cell is the egg (P) and the small tail-bearing cells are sperm (Q). When sperm fuses with egg in an animal, the process is fertilisation (H). Pollination is for plants only.

Question 13

Amy wanted to find out how the temperature of water affects the rate of movement of water in stems. She used three similar pieces of stem and three identical beakers with the same volume of water. She recorded the volume of water left in the beakers after 3 hours. Which one of the following variables should be kept constant in her experiment?

Accepted Answer

A. length of stem. The independent variable (changed) is temperature of water. The dependent variable (measured) is the volume of water transported. To make the experiment fair, length of stem must be kept constant — otherwise differing surface area/length would affect the rate of water uptake.

Question 14

Which one of the following correctly shows the main energy changes in the toy before it is released at point P and when it flew to point P to Q?
[Table: (1) Before: kinetic → P–Q: kinetic + sound; (2) Before: kinetic → P–Q: kinetic + potential + sound; (3) Before: potential → P–Q: kinetic + sound; (4) Before: potential → P–Q: kinetic + potential + sound]

Accepted Answer

D. (4). Before release at P, energy is stored in the twisted rubber band as (elastic) potential energy. From P to Q the toy gains height (potential energy increases), moves (kinetic energy) and the wings flap making loud sound (sound energy). So Before = potential energy → From P to Q = kinetic + potential + sound.

Question 15

Which of the following explains why the toy flew lower from R to S?
A  Gravitational force acts on the toy only from R to S.
B  There is less kinetic energy in the toy than before.
C  There is less potential energy in the rubber band than before.

Accepted Answer

C. B and C only. As the toy flies, the stored (elastic) potential energy in the rubber band continuously converts to kinetic and sound energy, so by R to S there is less potential energy in the rubber band (C) and consequently less kinetic energy in the toy to keep it aloft (B). A is wrong because gravitational force acts on the toy throughout its flight, not only from R to S.

Question 16

Which of the following organ systems are involved when we walk and run?
A  Skeletal system
B  Respiratory system
C  Circulatory system
D  Muscular system

Accepted Answer

D. A, B, C and D. All four systems are involved: skeletal supports the body and bones provide attachment for muscles; muscular contracts to move the bones; respiratory supplies oxygen and removes carbon dioxide; circulatory transports oxygen, nutrients and removes wastes from the working muscles.

Question 17

Study the flowchart below carefully. Which of the following correctly represents X, Y and Z?
[Table: (1) X=frictional, Y=elastic spring, Z=gravitational; (2) X=magnetic, Y=frictional, Z=elastic spring; (3) X=elastic spring, Y=magnetic, Z=frictional; (4) X=frictional, Y=magnetic, Z=gravitational]

Accepted Answer

D. (4). X = does NOT act from a distance → frictional force (requires contact). Y = acts from a distance but does NOT only pull (magnets can push and pull) → magnetic force. Z = acts from a distance and only pulls → gravitational force (always a pull).

Question 18

Emma set up an experiment as shown in the diagram below. She hung different number of weights on the spring and measured the length of the spring. Then, she plotted a graph below to show the results. [Figure: Graph — Length of spring (cm) on y-axis vs Number of weights on x-axis. Data points: 0 weights → 2 cm; 1 → 4 cm; 2 → 6 cm; 3 → 8 cm; 4 → 10 cm; 5 → 12 cm; 6 → 14 cm.] Using her results, she calculated the extension of the spring. Extension = New length of spring − original length of spring. If the extension of the spring is 4 cm, how many weights did she use?

Accepted Answer

B. 2. Original length of spring (0 weights) = 2 cm. Extension of 4 cm means new length = 2 + 4 = 6 cm. From the graph, length 6 cm corresponds to 2 weights.

Question 19

Jeremy set up a circuit as shown in the diagram below. He placed different objects, J, K, L and M at positions A and B to connect the circuit and recorded if the bulb lights up in the table below. [Table: J at A & K at B → bulb did NOT light up; J at A & L at B → lit up; L at A & M at B → lit up.] Which of the following are likely the materials that objects J, K, L and M are made of?
[Table: (1) J=steel, K=rubber, L=iron, M=aluminium; (2) J=wood, K=iron, L=rubber, M=steel; (3) J=iron, K=aluminium, L=steel, M=rubber; (4) J=rubber, K=wood, L=aluminium, M=steel]

Accepted Answer

A. (1). J+L lights → both conductors. L+M lights → both conductors. J+K does NOT light → at least one of J or K must be an insulator. Since J is already a conductor (lights with L), K must be the insulator. Option (1): J=steel (conductor), K=rubber (insulator), L=iron (conductor), M=aluminium (conductor) satisfies all rows.

Question 20

Kai set up the following circuits using similar bulbs and batteries as shown in the diagram below. All the bulbs and batteries are in good working condition. He arranged the bulbs from dimmest to brightest. Which of the following has been arranged correctly?
[Table: Brightness Dimmest→Brightest — (1) H, G, E, F; (2) F, E, G, H; (3) E, G, F, H; (4) G, H, F, E]

Accepted Answer

C. (3). More batteries and parallel bulbs → brighter. With 1 battery, series bulbs (E) are dimmest. With 2 batteries in series, series bulbs (G) are brighter than E. With 1 battery, parallel bulbs (F) are brighter than G because each bulb gets full battery voltage. With 2 batteries and parallel bulbs (H), each bulb is brightest. Order dimmest→brightest = E, G, F, H.

Question 21

Which actions below help to conserve electricity?
A  Use the fan instead of air-conditioner.
B  Switch off the lights when leaving the room.
C  Shower without the water heater on a hot day.
D  Use the half flush instead of full flush for liquid waste.

Accepted Answer

C. A, B and C only. A, B and C all reduce use of electrical appliances (air-con, lights, water heater) so they conserve electricity. D conserves water, not electricity.

Question 22

Manfred conducted an experiment using the set-up consisting of a torch, an object, a screen and a light sensor, as shown in the diagram below. He attached the light sensor on top of the object to measure the amount of light received. Then, he repeatedly moved the position of only one item in the set-up before recording the light sensor readings in the table below. [Table: Height of shadow (cm) — 100, 125, 140, 165; Light sensor reading (units) — 40, 40, 40, 40 for all four readings.] What change did Manfred make?

Accepted Answer

D. He moved the screen further away from the object.. The light sensor on the object reads the same (40 units) every time, so the distance between torch and object did not change (rules out A). The shadow height increased, so the screen must have been moved further from the object — moving the screen away enlarges the shadow without changing the light hitting the object.

Question 23

Kit filled four identical containers, W, X, Y and Z, with water as shown in the diagram below. Which containers of water have the least and most amount of heat?
[Table: (1) Least=Z, Most=Y; (2) Least=X, Most=Z; (3) Least=Z, Most=W; (4) Least=Y, Most=X]

Accepted Answer

C. (3). Amount of heat depends on both amount (volume) of water and its temperature. W has the largest volume of water at the highest temperature (95°C) → most heat. Z has the smaller volume of cold water (40°C) compared to X → least heat (Y has hotter water but smaller volume than X, while Z has cool water and a moderate volume; least heat is Z which has both low temperature and smaller water amount than X).

Question 24

Chloe set up an experiment using four similar-sized rods made of different materials, P, Q, R and S. She placed the same amount of wax on top of each rod and lowered each rod into a container. Then, she poured water into the container as shown in the diagram below. Chloe recorded the time taken for all the wax on rods P, Q, R and S, to melt in the table below. [Table: P → 5 min; Q → 3 min; R → 6 min; S → 7 min.] Which material, P, Q, R or S, should Chloe use to make a box to store ice cubes so that the ice cubes will melt the slowest?

Accepted Answer

D. S. The material whose wax took the longest to melt is the poorest conductor of heat (best insulator). S took 7 minutes, the longest. A box made of S would conduct heat from the surroundings to the ice cubes the slowest, so the ice would melt the slowest.

Question 25

Ray lowered an empty glass with a small wooden ball into a container of water until it touched the bottom of the container. The small wooden ball floated as shown in the diagram below. Which one of the following statements correctly explains the difference in the water level inside and outside the glass?

Accepted Answer

A. The air trapped in the glass occupied space.. The inverted glass traps air inside. Air is matter and occupies space, so it pushes the water level down inside the glass — hence the water level inside is lower than outside.

Question 26

Three identical metal containers were each filled with substances P, Q and R respectively. A rubber lid was placed at the opening of the three containers. A 1 kg weight was then placed on the rubber lid of each container. Only the rubber lid on the container filled with substance Q moved downwards, as shown in the diagram below. Which of the following statements correctly explained this observation?

Accepted Answer

B. Substance Q has no definite volume.. Only Q's rubber lid moved down, which means Q can be compressed (its volume changed). Only gases can be compressed; gases have no definite volume, so Q has no definite volume. P and R must be solids or liquids (definite volume, cannot be compressed).

Question 27

Ali wanted to find out which of the three metal bars, AB, CD and EF, are magnets. He hung each bar from a string and brought them near to each other before releasing them. His results are shown below. Which of the following is correct?
[Table: (1) AB=magnetic object, CD=magnetic object, EF=magnet; (2) AB=magnet, CD=magnetic object, EF=magnet; (3) AB=magnet, CD=magnet, EF=magnetic object; (4) AB=magnet, CD=magnet, EF=magnet]

Accepted Answer

C. (3). Only magnets repel each other. Test 2 shows AB and CD (in DC orientation) repel, so both AB and CD are magnets. Magnets always attract magnetic objects; in tests 3 and 4, EF is attracted to both AB and CD when brought near, but a magnet would repel one of them if rotated. Since EF only attracts (never repels), EF is a magnetic object, not a magnet.

Question 28

The diagram below shows a bar magnet repelled by an electromagnet when two batteries are used. A pointer attached to the spring moves when the spring stretches or compresses. Which one of the following is correct when only one battery is used?
[Table: (1) pointer upwards, electromagnet increased; (2) pointer upwards, electromagnet decreased; (3) pointer downwards, electromagnet increased; (4) pointer downwards, electromagnet decreased]

Accepted Answer

D. (4). Fewer batteries → less current → electromagnet is weaker (decreased strength). With a weaker repulsive force pushing the bar magnet up, the bar magnet sinks lower, stretching the spring, so the pointer moves downwards.

P6 Science CA1 2025 — Nanyang

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