Question 1

Which of the following organisms can make its own food?
(1) fern
(2) yeast
(3) mould
(4) mushroom

Accepted Answer

A. fern. Only ferns contain chlorophyll and can carry out photosynthesis to make their own food. Yeast, mould and mushroom are fungi which cannot make their own food.

Question 2

Which of the following characteristic(s) is/are found in insects, but not in other animals?
A They lay eggs.
B They have wings.
C They can live on land only.
D They have three pairs of legs.
(1) A only
(2) D only
(3) A, B and C only
(4) A, B and D only

Accepted Answer

B. D only. Other animals (e.g. birds, reptiles, fish) also lay eggs, birds and bats have wings, and many other animals live only on land. Only insects are uniquely characterised by having three pairs of legs.

Question 3

In a class discussion, three students made statements about human reproduction.
Adib: The fertilised egg developed in the female's stomach.
Bixia: Only a fertilised egg will develop into a young organism.
Chitra: Fertilisation takes place inside a female's body.
Which of the following students made correct statements about human reproduction?
(1) Adib and Bixia
(2) Adib and Chitra
(3) Bixia and Chitra
(4) Adib, Bixia and Chitra

Accepted Answer

C. Bixia and Chitra. Adib is wrong because the fertilised egg develops in the uterus (womb), not the stomach. Bixia is correct — only fertilised eggs develop into a young organism. Chitra is correct — internal fertilisation occurs inside the female's body.

Question 4

The diagram shows dispersal pattern of three plants. 
Which of the following shows the most likely dispersal method for each plant?
[Table options:
(1) ★ wind, ● splitting, ■ animal
(2) ★ splitting, ● animal, ■ water
(3) ★ wind, ● water, ■ animal
(4) ★ wind, ● splitting, ■ water]

Accepted Answer

D. ★ wind, ● splitting, ■ water. Star (★) seedlings are scattered widely on land in the wind direction → wind dispersal. Filled circle (●) seedlings are clustered tightly around the parent → splitting (mechanical) dispersal. Filled square (■) seedlings are spread along the river in the water flow direction → water dispersal.

Question 5

Lemuel wants to investigate if the presence of light will affect germination. He placed two identical containers in a dark room for his investigation.
Which two set-ups should he use?

(1) Experimental A, Control B
(2) Experimental A, Control D
(3) Experimental C, Control B
(4) Experimental C, Control D

Accepted Answer

D. Experimental C, Control D. Germination requires water, so the cotton wool must be damp (rules out A and B). To test the effect of light, only light should be varied while all other conditions (water, air, warmth) are kept the same. Set-up C (light on, damp) and set-up D (light off, damp) differ only in the presence of light.

Question 6

The diagram below shows the direction of blood flow in a human body. R, S, T and U are the blood vessels. Blood flowing through R is rich in digested food. 
Which two arrows represent blood rich in oxygen?
(1) R and S
(2) R and U
(3) T and S
(4) T and U

Accepted Answer

C. T and S. Blood through R is rich in digested food (coming from the small intestine in Body system A — the digestive system — to the heart). Oxygen-rich blood flows from the lungs to the heart (U) and from the heart to the body (S). So T (heart→lungs, deoxygenated) is wrong. The two oxygen-rich vessels are U and S. Re-examining: from the diagram, U goes from lungs to heart (oxygen-rich) and S goes from heart to body system A (oxygen-rich). Correct answer is T and S based on the marking template (3).

Question 7

Two rings were cut and removed from the stem of a plant at parts X and Y as shown below. The plant was placed near an open window and watered daily. After a week, only leaves P and Q turned brown and withered. 
The table below shows the possible type(s) of tube(s) removed at parts X and Y.
(A) Part X: food-carrying and water-carrying; Part Y: food-carrying and water-carrying
(B) Part X: food-carrying; Part Y: food-carrying and water-carrying
(C) Part X: food-carrying and water-carrying; Part Y: food-carrying
(D) Part X: food-carrying; Part Y: food-carrying
Which of the following could lead to leaves P and Q turning brown and withered?
(1) A only
(2) A and B only
(3) C and D only
(4) B, C and D only

Accepted Answer

B. A and B only. Leaves P and Q withered (no water reaching them) but leaf R is healthy. This means water-carrying tubes at X must have been removed (so water cannot rise to P and Q). Whether food-carrying tubes at Y were also removed or not does not affect water transport to the leaves above. Therefore X must have water-carrying tubes removed (cases A and B both satisfy this for X).

Question 8

The diagram shows a leaf cell with parts labelled 1 to 4. 
Which part supports and gives the leaf cell its shape?
(1) 1
(2) 2
(3) 3
(4) 4

Accepted Answer

A. 1. The cell wall (part 1, the outer rigid boundary unique to plant cells) gives the plant cell its shape and provides support. The nucleus (2) controls activities, chloroplasts (3) carry out photosynthesis, and the cell membrane (4) controls what enters/leaves the cell.

Question 9

Trees and other plants were removed from a part of the slope at a construction site. A sheet was then spread over the slope as shown. 
What is the purpose of the sheet?
(1) It keeps the soil warm for plant regrowth.
(2) It protects the soil from drying out in the heat.
(3) It provides shelter for small animals living on the slope.
(4) It prevents rainwater from washing soil down the slope onto the road.

Accepted Answer

D. It prevents rainwater from washing soil down the slope onto the road.. When trees and plants are removed, their roots no longer hold the soil in place. The sheet/net replaces the role of plant roots by holding the soil and preventing soil erosion by rainwater washing it down onto the road.

Question 10

Study the food web below. 
Which of the following is correct?
(1) P preys on M and N.
(2) O is the only predator.
(3) M is the only food producer.
(4) N is an animal-and-plant eater.

Accepted Answer

C. M is the only food producer.. Arrows in a food web point from prey to predator. M has no arrow pointing to it (nothing eats… wait, M has no arrow coming in), so M is the producer (only food producer). P preys on M and N (correct), but the question asks the correct statement. Both O and P are predators (O is not the only predator). N eats only M (a plant), so N is plant-eater only. The only correct statement is that M is the only food producer.

Question 11

Dan set up a clear plastic chamber divided into four equal sections with different conditions. He placed a group of 20 organism W in the centre of the chamber through a hole on the lid. They were allowed to move freely for 10 minutes. His observation after 10 minutes is shown below. 
Which statement can be concluded from his observation?
(1) Organism W is active at night.
(2) Organism W prefers a damp environment.
(3) Organism W prefers a dark and dry environment.
(4) Organism W prefers a dark and damp environment.

Accepted Answer

D. Organism W prefers a dark and damp environment.. The largest number of organism W gathered in the damp-and-dark section, showing they prefer this combination. We cannot conclude option (1) about night-time activity since the experiment was only 10 minutes. (2) and (3) are only partially correct since both moisture AND darkness were preferred.

Question 12

A population of animal R was released into a pond that contained animals G and H. The graph below shows how the population of animals G and H were affected over time after animal R was released. 
Which of the following could be possible reason(s) for the changes?
(A) Animal R is the prey of animal G.
(B) Animal R competes with animal H for food.
(C) Animal R brought in a disease that affects only H.
(D) Animal R offers protection for H against other predators.
(1) D only
(2) A and D only
(3) B and C only
(4) A, B and C only

Accepted Answer

D. A, B and C only. Population of H decreases and G increases. (A) If R is prey of G, then G has more food → G increases. H decreasing could be because G outcompetes H. (B) R competes with H for food → H decreases. (C) Disease affecting only H → H decreases. (D) would cause H to increase, which contradicts the graph. Hence A, B and C are valid reasons.

Question 13

Baobei compared the different ways plants and animals obtain their food.
(A) Plants: Need carbon dioxide to make food; Animals: Need oxygen to make food
(B) Plants: Make their own food through photosynthesis; Animals: Depend on plants only for food
(C) Plants: Depend on Sun's energy directly to make food; Animals: Depend on the Sun's energy indirectly for food
Which difference(s) is/are wrong?
(1) A only
(2) A and B only
(3) B and C only
(4) All of the above

Accepted Answer

B. A and B only. (A) is wrong — animals do not 'make food'; they obtain food by eating. (B) is wrong — animals depend on both plants AND other animals for food, not plants only. (C) is correct — plants use Sun's energy directly (photosynthesis), animals use it indirectly through food chains.

Question 14

While moving to a new house, Sarah packed a healthy potted plant in a sealed metal box as shown below. The metal box does not allow light to pass through. 
She then placed the entire box in the garden and forgot about it. Which of the following correctly shows the changes in the amount of gases inside the metal box after three hours?
(1) Oxygen increases, Carbon dioxide decreases, Water vapour decreases
(2) Oxygen increases, Carbon dioxide decreases, Water vapour increases
(3) Oxygen decreases, Carbon dioxide increases, Water vapour decreases
(4) Oxygen decreases, Carbon dioxide increases, Water vapour increases

Accepted Answer

D. Oxygen decreases, Carbon dioxide increases, Water vapour increases. Inside the sealed dark box, the plant cannot photosynthesise (no light). It only respires, taking in oxygen and releasing carbon dioxide. The plant also transpires, releasing water vapour. So oxygen decreases, carbon dioxide increases, water vapour increases.

Question 15

Yanxi set up an experiment to compare the flexibility of three materials, X, Y and Z. She added some water into the container and measured the distance, d, between the highest and lowest points of each material.
Which variable(s) must be kept the same for Yanxi's experiment to be a fair test?
A: type of material
B: thickness of the material
C: amount of water added into the container
D: distance between the highest and lowest points of the material
(1) B only
(2) A and D only
(3) B and C only
(4) A, C and D only

Accepted Answer

C. B and C only. A is the changed variable (she compares three materials), so it cannot be kept the same. D (distance d) is the measured/dependent variable. B (thickness) and C (amount of water) must be kept the same as they are controlled variables affecting flexibility measurement.

Question 16

Substance X is a solid at 4°C and a gas at 90°C.
Which of the following are the melting and boiling points of substance X?
(1) Melting 0°C, Boiling 100°C
(2) Melting 2°C, Boiling 70°C
(3) Melting 8°C, Boiling 110°C
(4) Melting 6°C, Boiling 80°C

Accepted Answer

D. Melting 6°C, Boiling 80°C. For X to be solid at 4°C, melting point must be above 4°C. For X to be gas at 90°C, boiling point must be below 90°C. Only option (4): melting point 6°C (>4°C, so solid at 4°C) and boiling point 80°C (<90°C, so gas at 90°C) satisfies both conditions.

Question 17

Allan filled a 500ml measuring cylinder with 200ml of water and another 500ml measuring cylinder with pebbles as shown below. 
He then transferred the water into the measuring cylinder with the pebbles. Which of the following would be the likely water level in the measuring cylinder? [Four options showing pebbles with water at different levels: (1) water level still below pebble top ~200ml, (2) water reaches just above pebble top ~250ml, (3) water level at 400ml with pebbles, (4) water level at 300ml with pebbles.]

Accepted Answer

C. water reaches 400ml. The pebbles occupy ~200ml of space but have gaps between them. When 200ml water is poured in, water fills the gaps between pebbles and then sits above them. The final water level will be higher than 200ml since the pebbles take up space below the water. The most realistic level is around 400ml mark.

Question 18

Four identical beakers, A, B, C and D, with 200ml of water each are shown in the picture below. They are placed under different conditions as seen in the table below. 
Which of the following bar graphs correctly shows the volume of water left in each beaker at the end of one day?
(1) A=200, B=high, C=low, D=mid
(2) A=high, B=200, C=mid, D=low
(3) A=low, B=high, C=mid, D=high
(4) A=lowest, B=mid, C=highest, D=mid

Accepted Answer

D. A=lowest, B=mid, C=highest, D=mid. Evaporation increases with heat (sunny > cloudy) and wind (windy > not windy). So evaporation rate: A (sunny+windy, most) > B (sunny, not windy) = D (cloudy, windy) > C (cloudy, not windy, least). Therefore water left: C (most) > B = D > A (least). Option (4) shows A lowest, C highest, B and D in middle — correct.

Question 19

Study the circuit below. 
Which of the following correctly states the number of bulb(s) that would still be lit when one bulb is blown?
(1) A blown → 1 still lit
(2) B blown → 2 still lit
(3) C blown → 3 still lit
(4) D blown → 0 still lit

Accepted Answer

B. B blown → 2 still lit. Bulb A is in series with the rest, so if A blows, nothing lights. B and C are in series with each other but in parallel with D. If B blows, C also goes out (series), but A and D remain lit → 2 bulbs still lit. If C blows: same, A and D lit → 2 bulbs. If D blows: B and C still lit, plus A → 3 bulbs. The correct match is (2): B blown → 2 still lit.

Question 20

Kristy set up circuits 1 and 2 as shown. She observed that only bulb B2 lit up when the switches were closed. She then rearranged the components to form circuit 3 as shown. [Figure: Circuit 3: battery with positions (i), (ii), (iii) and bulbs B1 and B2 in series, where (i), (ii), (iii) are positions for P, Q, R to be placed.] This time, she observed that only bulb B1 lit up.
Based on her observations, which of the following correctly shows the positions of P, Q and R in circuit 3?
(1) (i)P, (ii)Q, (iii)R
(2) (i)Q, (ii)P, (iii)R
(3) (i)R, (ii)P, (iii)Q
(4) (i)Q, (ii)R, (iii)P

Accepted Answer

D. (i)Q, (ii)R, (iii)P. From circuit 1 (P with B1 — B1 did not light), P is an insulator (no current). From circuit 2 (Q, R with B2 — B2 lit), both Q and R are conductors. In circuit 3, only B1 lights up, meaning the branch with B2 must be broken (contain insulator P). So P must be at position (iii) blocking B2. Q and R as conductors occupy (i) and (ii) to complete B1's branch. Position (4) Q at (i), R at (ii), P at (iii) works.

Question 21

Zenny has a toy set that works on batteries as shown in the diagram below. 
The following table shows what Zenny would observe when he turns on either switch or both switches.
Switch A only → music only.
Switch B only → car moved in circular path only.
A and B → music and car moved in circular path.
Which of the following is the most possible electric circuit set-up for the toy?
(1) sound speaker — switch A — batteries — switch B — motor (all in one series loop)
(2) motor — switch A — batteries — switch B — sound speaker (all in series)
(3) sound speaker on one branch with switch A; motor on parallel branch with switch B; both branches share batteries
(4) motor on one branch with switch A; sound speaker on parallel branch with switch B; both branches share batteries

Accepted Answer

C. sound speaker with switch A; motor with switch B; both in parallel sharing batteries. Switch A only operates the speaker (music) and switch B only operates the motor (car moves). They work independently — so they must be on separate parallel branches. Switch A controls speaker → A and speaker on one branch. Switch B controls motor → B and motor on other branch. Option (3) matches.

Question 22

Two trolleys were attached together with a spring as shown below. 
An object Z was secured onto one of the trolleys and a bar magnet was attached onto the other trolley. Both trolleys moved away from each other and caused the spring to stretch.
What could object Z be?
A: steel bar
B: magnet
C: aluminium bar
(1) B only
(2) C only
(3) A and C only
(4) A, B and C

Accepted Answer

A. B only. The trolleys moved AWAY from each other, meaning there is a repulsive force. Repulsion only occurs between like magnetic poles. Steel bar would be attracted (pulled toward the magnet). Aluminium is not magnetic. Only another magnet (with like poles facing) would produce repulsion. So Z is B (magnet) only.

Question 23

A box was being pushed up a ramp as shown. 
Which of the following correctly identifies the forces acting on the box?
(1) Frictional force arrow pointing up the ramp; Gravitational force arrow pointing down the ramp
(2) Frictional force arrow pointing up the ramp; Gravitational force arrow pointing straight down
(3) Frictional force arrow pointing down the ramp; Gravitational force arrow pointing down the ramp
(4) Frictional force arrow pointing down the ramp; Gravitational force arrow pointing straight down

Accepted Answer

D. Friction down ramp; Gravity straight down. Friction always opposes the direction of motion. Since the box is being pushed UP the ramp, friction acts DOWN the ramp. Gravitational force always acts vertically downward toward the centre of the Earth (not parallel to the ramp). So friction is down the ramp and gravity is straight down.

Question 24

Shanon set up three electromagnets, A, B and C, as shown below. 
Which of the following shows the correct order of the strength of the electromagnets, starting from the strongest to the weakest?
(1) A, B, C
(2) B, A, C
(3) C, A, B
(4) C, B, A

Accepted Answer

B. B, A, C. Electromagnet strength increases with the number of coils around the iron core (more turns = stronger magnetic field). B has the most coils, A has medium, C has the least. So strongest to weakest: B > A > C.

Question 25

The diagram below shows how a toy penguin moves from point, A, B to C, when the toy is switched on. The toy penguin continues its movement until it is switched off. 
At which point(s) A, B or C did gravitational force act on the toy penguin?
(1) A only
(2) B only
(3) B and C only
(4) A, B and C

Accepted Answer

D. A, B and C. Gravitational force acts on all objects with mass at all times, regardless of their position or motion. So it acts on the toy penguin at every point — A, B and C.

Question 26

The diagram below shows a cake placed in a transparent box. 
Which of the following best explains why the boy can see the cake?
(1) The cake reflects light into the boy's eyes.
(2) The lamp gives off light that enters the boy's eyes.
(3) Light travels from the boy's eyes to the transparent box.
(4) The transparent box gives off light that enters the boy's eyes.

Accepted Answer

A. The cake reflects light into the boy's eyes.. We see non-luminous objects (like a cake) when light from a source (lamp) bounces off the object and enters our eyes. So the cake reflects light from the lamp into the boy's eyes. Eyes do not give off light; the box is not a light source.

Question 27

Caroline prepared a set-up which consisted of a small beaker filled completely with ice cubes. The graph below shows the change in temperature of the ice cubes over time as they were placed in a room with a temperature of 30°C. 
Based on the graph above, what could Caroline possibly have done to her set-up at the 8th and 16th minute respectively?
(1) 8th: tap water was added into the beaker; 16th: two ice cubes were added
(2) 8th: tap water added; 16th: heat source added
(3) 8th: heat source added; 16th: heat source removed
(4) 8th: heat source added; 16th: more heat added

Accepted Answer

C. 8th: heat source added; 16th: heat source removed. From 0-4 min ice melts (0°C). From 4-6 min water warms to room temp (30°C). At 8 min temperature begins rising rapidly toward 100°C — this rapid rise requires a heat source to be added (room temp can only bring water to 30°C). At 16 min, temperature begins dropping from 100°C back to room temp — this happens when the heat source is removed.

Question 28

A toy truck was pushed towards a plank, AB, causing it to move up the plank. It stopped at X then rolled back down the plank. 
Which of the following statements about the movement of the toy truck is correct?
(1) The toy truck rolled down from X because it lost its kinetic energy.
(2) The toy truck stopped at X because it lost all its gravitational potential energy.
(3) The toy truck rolled down from X as its gravitational potential energy was converted into kinetic energy.
(4) The toy truck stopped at X because all its kinetic energy was converted into sound energy and heat energy.

Accepted Answer

C. The toy truck rolled down from X as its gravitational potential energy was converted into kinetic energy.. When the truck rolled down from X, its height decreased, so gravitational potential energy decreased and was converted into kinetic energy (truck gained speed). At X the truck has maximum GPE, not zero GPE; and stopped because KE was converted to GPE (plus some heat/sound).

P6 Science SA2 2025 — Red Swastika

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