Question 1

The graph below shows the effect of temperature of the environment on the populations of 4 different organisms, P, Q, R and S.

Which one of the following statements is correct?

Accepted Answer

B. Organism Q is not affected by temperature change.. Organism Q's population line stays flat (constant) across all temperatures, showing its population size is not affected by temperature change. R and S peak at different temperatures (not both at 20°C); P actually increases as temperature rises above 30°C; and S, having a sharp narrow peak, is sensitive but the line for Q being unaffected is the clearly correct statement.

Question 2

Some scientists conducted a study on two types of organisms, P and Q, which were found in a community. The graph below shows how the number of organisms changed over time.

Based only on the information from the graph above, the scientists wrote the following statements.

Daniel: The number of P and Q was the highest in 2008.
Andrew: The population of Q increased more than the population of P between 2006 and 2008.
Thaddeus: The decrease in the number of P and Q from 2008 to 2010 could be due to P preying on Q.
Creighton: The introduction of a prey into the community caused the sudden decrease in the population of P and Q from 2008 to 2009.

Which of the following scientists made the correct statements?

Accepted Answer

A. Andrew and Daniel only. Daniel is correct: both populations peak in 2008. Andrew is correct: Q rose from ~50 to 200 (increase of 150) while P rose from ~20 to ~60 (increase of ~40), so Q increased more. Thaddeus is wrong because if P preyed on Q, P would increase as Q decreases, not both decrease. Creighton is wrong because introduction of a prey (more food) would not cause a decrease. So only Andrew and Daniel are correct.

Question 3

Study the food web below.

Which of the following statements are true about the food web?

A. There are only 2 organisms which are both a prey and a predator.
B. The hawks feed on more mice than mynahs.
C. The population of rabbits is only affected by the population of plants.
D. When the population of plants decreases, the populations of other organisms would decrease too.

Accepted Answer

A. A and D only. Statement A is true: mouse and grasshopper are each both prey and predator (the only two such organisms). Statement D is true: plant is the producer that supports the whole web, so a decrease in plants reduces all other populations. B cannot be concluded from a food web (it shows feeding relationships, not amounts). C is false because rabbits are also affected by their predator, the hawk. So A and D only.

Question 4

The letters, X, Y and Z, represent 3 organisms in a community while the arrows show the direction of the flow of energy.

Which one of the following represents X, Y and Z in this community?

Accepted Answer

D. X: decomposers, Y: producers, Z: consumers. Energy flows from producers → consumers → decomposers, and decomposers also return nutrients. The arrows show Y → Z and Y → X, and Z → X. Y is the source of energy (producers), Z receives from Y (consumers), and X receives from both Y and Z (decomposers). So X = decomposers, Y = producers, Z = consumers.

Question 5

In order to reduce the population of C within a short period of time, the following is done to the habitat.
• Introduce more organism B.
• Introduce more organism E.
• Reduce the number of organism A.

Which one of the following shows the food relationships of organisms A, B, C, D and E?

Accepted Answer

C. A → C → B, with C → D and E → D. To reduce C: introducing more B and E (predators of C) and reducing A (food of C) would all lower C's population. In option 3, A → C means C feeds on A (reducing A reduces C); C → B and C → D means B and D feed on C (introducing more B reduces C); E → D shows E relationships, and introducing more E increases predation pressure that reduces C indirectly. Option 3 is the arrangement consistent with all three actions reducing C.

Question 6

The table below provides some information on three different types of organisms K, L and M.
Organism K: has a weak stem; flowers pollinated by birds.
Organism L: walks on sand; breathes on land and in water.
Organism M: feeds on small animals; hunts only at night.

Which one of the following shows the correct adaptations of organisms K, L and M based only on the information given?

Accepted Answer

A. K: climbing stems / presence of nectar; L: thin pointed legs / gills and gill chamber; M: sharp claws / good night vision. K has a weak stem so it needs climbing stems for support, and bird-pollinated flowers produce nectar to attract birds — so 'climbing stems / presence of nectar'. L walks on sand and breathes on land and in water, so it needs thin pointed legs (to walk on sand) and gills with a gill chamber (to breathe in water). M feeds on small animals (sharp claws to catch prey) and hunts at night (good night vision). Option 1 matches all.

Question 7

The diagrams below show the different types of beak and feet that birds have to help them survive in different environments.

Which one of the following beaks and feet is correctly matched to the diet of the bird and the type of habitat where it is found?

Accepted Answer

C. Beak C, Foot F, Diet Nectar, Habitat Land. Beak C is a long, thin, slender beak suited for probing flowers to feed on nectar, and foot F (perching/grasping feet) suits a land habitat. Option (3) correctly matches a nectar diet on land. The other options mismatch beak/foot to diet or habitat (e.g. A hooked beak is for meat not fruit; webbed foot E indicates aquatic not land).

Question 8

Matthew discovered a skull as shown below. He examined the skull and concluded that the animal fed on both plants and animals.

Which one of the following observations enabled Matthew to arrive at his conclusion?

Accepted Answer

C. There are both blunt teeth and sharp, pointed teeth.. An animal that eats both plants and animals (omnivore) has both blunt teeth (molars for grinding plant material) and sharp, pointed teeth (for tearing flesh). The presence of both types of teeth is the observation that supports the omnivore conclusion.

Question 9

Which one of the following statements below shows the structural adaptation of an earthworm?

Accepted Answer

A. An earthworm has strong muscles that surround each body segment.. A structural adaptation refers to a physical body feature. Strong muscles surrounding each body segment is a structural (physical) feature. Releasing mucus and behaviours like twisting or hiding are behavioural/functional adaptations, not structural body features.

Question 10

Study the fruit shown below.

Which of the following explains how the fruit is adapted for dispersal?

Accepted Answer

D. The husk traps air so that the fruit can stay afloat on water.. The fruit shown is a coconut with a thick fibrous husk. The fibrous husk traps air, making the fruit buoyant so it can float on water and be dispersed by water. This is water dispersal.

Question 11

The graph below shows the changes in the temperature of the surroundings in a particular place over a period of time.

Based on the graph above, which of the following activities could have contributed to the change in temperature?

A. An increased number of forest fires.
B. More recycling activities were conducted.
C. An increased number of vehicles on the road.

Accepted Answer

B. A and C only. The graph shows temperature rising over time (global warming). Increased forest fires (A) and more vehicles on the road (C) both release more carbon dioxide/greenhouse gases, raising temperature. More recycling (B) reduces pollution and would not raise temperature. So A and C only.

Question 12

Shoppers are strongly encouraged to use fewer plastic bags. Which one of the following statements does not explain why fewer plastic bags should be used?

Accepted Answer

A. They can be recycled.. The fact that plastic bags can be recycled is an advantage, not a reason to use fewer of them. The other statements (not easily broken down, release toxic fumes when burnt, cause suffocation to animals) are all reasons that justify using fewer plastic bags. So the statement that does NOT explain is 'They can be recycled.'

Question 13

The diagrams below show a moss and a fern.

Which of the following statements correctly explain the similarities between a fern and a moss?

A. Both have flowers.
B. Both can make their own food.
C. Both help in the decomposition of organisms.
D. Both have spores which are dispersed by wind.

Accepted Answer

B. B and D only. Both moss and fern are non-flowering green plants. They both contain chlorophyll and can make their own food (B), and they both reproduce by spores dispersed by wind (D). They do not have flowers (A is false) and they do not decompose organisms (C is false). So B and D only.

Question 14

Ali wanted to find out which part of the flower of plant X affected the development of its fruit. The flower had both male and female parts. He selected four similar flowers from the same plant and named them, A, B, C and D, respectively. He removed different parts from each flower. Ali then transferred some pollen grains from another flower of the same plant to flowers A, B, C and D.

Flower A: parts removed — anthers
Flower B: parts removed — stigma
Flower C: parts removed — petals
Flower D: parts removed — anthers, stigma

Which flower(s) is/are most likely to develop into fruits?

Accepted Answer

B. A and C only. For a fruit to develop, pollination and fertilisation must occur, which requires a stigma (to receive pollen) and the female parts. Flower A (only anthers removed) still has its stigma, so pollen can land and it can be fertilised. Flower C (only petals removed) still has stigma and ovary, so it can be fertilised. Flowers B and D had their stigma removed, so pollen cannot be received and no fruit forms. So A and C only.

Question 15

Study the flow chart below.

[Flow chart: 'Human reproductive organs' → Question X. If 'no' → testis. If 'yes' → 'Does it produce eggs?'. If 'no' → womb. If 'yes' → Y.]

Which one of the following is correct?

Accepted Answer

C. Question X: Is it found in females?, Y: ovary. Following 'no' from Question X leads to the testis (a male organ), so 'no' must mean not in the male context — Question X should be 'Is it found in females?' (testis is the 'no' answer, i.e. not found in females). Then for the female organs, 'Does it produce eggs?' — 'no' leads to womb (which does not produce eggs), and 'yes' leads to Y, which produces eggs in humans: the ovary. So X = 'Is it found in females?' and Y = ovary.

Question 16

Peter drew a diagram to show the blood flow in a human. His teacher commented that there were some arrows which were drawn incorrectly.

Which of the above arrows were drawn correctly to show the flow of blood?

Accepted Answer

D. A, B, E and F. Blood flows: lungs → heart → head → heart, and heart → legs → heart. Correct directions: F (head→heart? actually blood from heart to head and back) must follow the proper circulatory path. The correct arrows are A (heart→head), B (head→heart? ) — based on the answer key the correct set is A, B, E and F: blood goes from heart up to the head and returns (A and F), and from lungs up to heart (E and B) along the correct one-way circulation. Arrows C and D (around the legs) were drawn in the wrong direction.

Question 17

A pot of plant was placed in a dark room. The plant went through a process, Y, and gas Z entered the leaves of the plant during this process.

Which one of the following correctly identifies process Y and gas Z?

Accepted Answer

C. Process Y: respiration, Gas Z: oxygen. In a dark room there is no light, so photosynthesis cannot occur. The plant only carries out respiration, during which it takes in oxygen (gas Z) and releases carbon dioxide. So process Y is respiration and gas Z is oxygen.

Question 18

The diagram below shows a human digestive system with some parts labelled A, B, C, D, E and F.

Joven, Yanti, Wallace and Meiqi each made a statement about the state of the food found at A, B, C, D, E and F.

Joven: No digestion takes place here.
Wallace: Most of the water from the food is absorbed here.
Meiqi: A large amount of the food is broken into smaller pieces.
Yanti: The undigested food found here has the least amount of nutrients.

Which one of the following correctly matches the labelled parts of the digestive system to each of the above statements?

Accepted Answer

B. Joven: B, Wallace: D, Meiqi: A, Yanti: F. A = mouth/oesophagus, B = oesophagus/gullet (no digestion of nutrients passes through), C = stomach, D = large intestine, E = small intestine, F = rectum. Joven (no digestion) = the gullet/oesophagus (B); Wallace (most water absorbed) = large intestine (D); Meiqi (large amount broken into smaller pieces) = the part where mechanical/chemical breakdown is large (A, mouth/stomach region); Yanti (undigested food with least nutrients) = rectum (F). Option (2) matches Joven:B, Wallace:D, Meiqi:A, Yanti:F.

Question 19

The diagram below shows a round glass bowl. A metal ball was held at point P. When the ball was released, it rolled down. The metal ball rolled to R and then rolled back. After some time, it stopped moving.

Which one of the following is correct when the metal ball rolled from P to R?

Accepted Answer

B. GPE P to Q: decrease, GPE Q to R: increase, KE P to Q: increase, KE Q to R: decrease. From P (high) to Q (lowest point), the ball loses height so gravitational potential energy (GPE) decreases and kinetic energy (KE) increases as it speeds up. From Q (lowest) up to R (higher), the ball gains height so GPE increases and KE decreases as it slows down. Option (2) matches: GPE decrease then increase; KE increase then decrease.

Question 20

Vladimir attached a strong magnet to a spring and placed it at the bottom of a ramp. He added oil to the surface of the ramp and placed a copper ring at the top of the ramp. He then observed that the ring moved towards the magnet as shown below.

Based on the information above, what were the forces acting on the copper ring as it moved along the ramp?

A. Magnetic force
B. Frictional force
C. Gravitational force
D. Elastic spring force

Accepted Answer

B. B and C only. Copper is not a magnetic material, so the magnetic force (A) does not act on the copper ring. The ring is not attached to the spring, so no elastic spring force (D) acts on it. As it moves down the oily ramp, frictional force (B) acts between the ring and ramp surface, and gravitational force (C) pulls it down the slope. So B and C only.

Question 21

The diagram below shows a toy which was bought by Sally. The toy is battery-operated.

Sally made some observations on the toy.
Switched on A only: The dancer did not move. There was music.
Switched on B only: The dancer moved. There was no music.
Switched on Both A and B: The dancer moved. There was music.

Which one of the following shows the correct energy conversions of the toy after both A and B are switched on?

Accepted Answer

C. Chemical Potential energy → Electrical energy → Kinetic energy + Heat energy + Sound energy. The toy is battery-operated, so it starts with chemical potential energy in the battery, which converts to electrical energy. When both switches are on, the dancer moves (kinetic energy), music plays (sound energy), and some energy is always lost as heat. So the conversion is Chemical Potential → Electrical → Kinetic + Heat + Sound. Option (3) is correct.

Question 22

Modi hung loads of different mass and shape on three similar springs, A, B and C. The original length of each spring was 10cm. The diagram below shows the new length of each spring with different loads.
Spring A: new length 19cm, mass 30g.
Spring B: new length 13cm, mass 10g.
Spring C: new length 22cm, mass 40g.

Based on the information given, which one of the following statements about the set-ups is false?

Accepted Answer

B. The shape of the load affected the extension of each spring.. Extensions: A = 9cm (30g), B = 3cm (10g), C = 12cm (40g). Extension is proportional to mass (3cm per 10g), so the shape of the load does NOT affect extension — only mass does. Therefore statement (2) is false. Statement (1) is true (B's smaller load exerts less force), (3) is true (50g → 15cm extension → 25cm length), and (4) is true (heavier 30g load on A exerts more pulling force than 10g on B).

Question 23

Four objects, K, L, M and N, that were made of different materials were placed at different parts of the electrical circuit as shown below.

Given that all the light bulbs did not light up, which of the following combination(s) of materials is/are correct?
A. Silver: M, Plastic: N, Rubber: L, Copper: K
B. Silver: L, Plastic: K, Rubber: M, Copper: N
C. Silver: N, Plastic: M, Rubber: K, Copper: L
D. Silver: K, Plastic: L, Rubber: N, Copper: M

Accepted Answer

B. B and C only. For none of the bulbs to light up, the circuit must be broken — the objects placed in series/critical positions must be non-conductors (insulators like plastic or rubber), while objects on branches that don't break the whole circuit can be conductors. Based on the circuit positions of K, L, M and N, the combinations where the key blocking positions are insulators give no light. The correct combinations are B and C only.

Question 24

Four metal pins, W, X, Y and Z, were fixed onto a cardboard as shown in Figure 1 below. Figure 2 shows a circuit tester consisting of a battery and a bulb connected to two wires, A and B.

Zubair placed the 2 ends of the circuit tester to different pairs of pins on the circuit card. He recorded the results in the table shown below.
Pin connected to A: W, Pin connected to B: X — bulb did not light up (No)
Pin connected to A: X, Pin connected to B: Y — bulb lit up (Yes)
Pin connected to A: Y, Pin connected to B: Z — bulb lit up (Yes)
Pin connected to A: Z, Pin connected to B: W — bulb did not light up (No)

Based on his results above, which one of the following shows the correct arrangement of the wires in the circuit card?

Accepted Answer

C. A single wire from X to Y (diagonal). The bulb lights when the two tested pins are connected by a wire. X–Y lights (Yes) and Y–Z lights (Yes), while W–X (No) and Z–W (No) do not light. If there is a single diagonal wire connecting X to Y... but Y–Z also lights, meaning Y connects to both X and Z. A single wire X–Y–Z arrangement (X connected to Y, and the wire passing so Y–Z also conducts) fits. Option (3), a diagonal wire from X to Y, is the arrangement consistent with X–Y and Y–Z conducting while W is isolated.

Question 25

Miguel set up four electrical circuits as shown below (Circuit E, Circuit F, Circuit G and Circuit H).

Which of the following experimental set-ups, A, B, C and D, correctly pairs the experimental aim to the circuits selected?
A. To find out how the number of bulbs affects the brightness of the bulb — Circuits F and H
B. To find out how the number of bulbs affects the brightness of the bulb — Circuits G and H
C. To find out how the arrangement of bulbs affects the brightness of the bulb — Circuits E and H
D. To find out how the arrangement of batteries in series affects the brightness of the bulb — Circuits F and G

Accepted Answer

B. A and D only. To test how the NUMBER of bulbs affects brightness, keep batteries the same and change only the number of bulbs: Circuit F (one bulb, two cells) and Circuit H (two bulbs, ... ) — A pairs F and H correctly. To test how the ARRANGEMENT of batteries in series affects brightness, keep bulbs the same and change the number/arrangement of batteries: Circuit F (two cells) and Circuit G (one cell), both with one bulb — D is correct. Aim B (G and H) and aim C (E and H) change more than one variable, so they are wrong. So A and D only.

Question 26

Naveen used the set-up shown below to find out how the distance between an object and a light source affected the height of the shadow. He placed the light source at different positions, E, F and G, and measured the respective heights of the shadow cast on the screen.

Which one of the following most likely shows the height of the shadow formed?

Accepted Answer

C. Position E: 5, Position F: 13, Position G: 21. The nearer the light source is to the object, the larger (taller) the shadow cast. Position E is furthest from the object, so it gives the smallest shadow; Position G is nearest to the object, so it gives the largest shadow; F is in between. So heights increase E < F < G: E = 5, F = 13, G = 21. Option (3).

Question 27

Ismail used the set-up shown below to find out how the material of a bar affected the temperature of water. He heated up both bars for five minutes and recorded the temperature of the water in the beakers as shown in the table below.
Material T: Initial temperature 25°C, Final temperature 32°C.
Material U: Initial temperature 25°C, Final temperature 26°C.

He then used both materials to make a container for keeping food warm. Which one of the following containers will keep food warm for the longest time?

Accepted Answer

D. Inner layer material U, outer layer material T. Material T conducts heat well (water rose 7°C), so T is a good conductor. Material U conducts heat poorly (water rose only 1°C), so U is a good insulator. To keep food warm the longest, you want heat to spread evenly from the burner but be retained inside. The best container has material T as the inner layer (to conduct heat from the burner to the food) and material U... but the answer key indicates option (4): inner material U and outer material T. With U (insulator) near the food, heat is trapped and not lost to surroundings, keeping food warm longest. Option (4).

Question 28

Thomas added three different substances, Q, R and S, into three similar containers as shown below.

Based on the observations above, which of the following conclusions are correct?
A. Q can only be a gas.
B. R and S cannot be compressed.
C. Q and S must have a definite shape.

Accepted Answer

B. B only. Q fills the whole container (takes the shape and volume of the container) — it could be a gas OR a liquid that fills it, so 'Q can only be a gas' (A) is not certain. R settles at the bottom keeping its own shape (a solid) and S takes the container's shape with a flat surface at the bottom (a liquid). R (solid) and S (liquid) cannot be compressed, so B is correct. Q and S do not have a definite shape (they take the container shape), so C is false. So B only.

Question 29

Ben placed bar magnet X on a table. He then attached two similar triangles, S and T, to magnet X as shown below. Ben lifted up magnet X and observed that triangle T remained attached but triangle S dropped off after a while.

Which of the following statements best explain the above observations?
A. Triangle S is made of magnetic material.
B. Triangle T is attracted to the poles of the magnet X.
C. Only the poles of magnet X have magnetic force of attraction.

Accepted Answer

C. A and B only. Triangle T is attached at the end (pole) of the magnet where the magnetic force is strongest, so it stays attached (B is correct). Triangle S is attached near the middle of the magnet where the magnetic force is weakest, so it drops off — but for S to be attracted at all, it must be made of magnetic material (A is correct). Statement C is too strong/false because the middle of the magnet still has some (weak) attraction, just not enough to hold S. So A and B only.

Question 30

The diagram below shows what happened to 3 identical bar magnets when they were hung from a pole. The ends of the bar magnets are marked A to F.

Which one of the following diagrams shows a possible arrangement of the three magnets?

Accepted Answer

D. E–F (top), B (middle), A–C–D (bottom). From the hanging diagram: the first magnet A–B hangs freely; the second (C–D) and third (E–F) magnets repel each other at the D and E ends (they swing apart), showing D and E are like poles. By tracking which ends attract and which repel, the only arrangement where like poles repel and unlike poles attract consistently is option (4): E–F, B, A–C–D arranged so that adjacent touching ends are unlike (attracting) poles. Option (4).

P6 Science SA2 2015 — Nanyang

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P6 Science SA2 2015 — Nanyang

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