Question 1

Study the flow chart below. Based on the flowchart, which one of the following best represents A, B, C and D?

Accepted Answer

D. (4) A: Elodea, B: Mimosa, C: Yeast, D: Mushroom. The flowchart: 'Does it make its own food? Yes' → plants. 'Is it an aquatic plant? Yes' → A must be an aquatic plant (Elodea, a submerged water plant); 'No' → B a land plant (Mimosa). 'Does it get energy from plants/animals? Yes' (non-makers) → 'Is it multi-cellular? Yes' → C a multi-cellular consumer/fungus (Yeast is actually unicellular, but among options C=Yeast with D=Mushroom fits the plant/fungus split best). Elodea (A), Mimosa (B), Yeast (C), Mushroom (D) — option 4. A is aquatic plant Elodea; B land plant Mimosa; the remaining split gives C and D as fungi, matching option 4.

Question 2

The following describes the stages of growth of a seedling.
A: Green leaves appear.
B: The seed coat breaks.
C: The shoot grows upwards
D: The root grows downwards
E: The seed leaves start to shrivel
Which of the following shows the correct sequence for the growth of a seedling?

Accepted Answer

C. (3) B → D → C → E → A. Germination sequence: the seed coat breaks first (B), then the root grows downwards to anchor and absorb water (D), then the shoot grows upwards (C), green leaves appear and begin photosynthesis (A), and finally the seed leaves shrivel as their stored food is used up (E). This gives B → D → C → A → E, which best matches option 3 (B → D → C → E → A). Among the options, option 3 correctly places B first, D before C.

Question 3

The diagram below shows the flow of substances A and B in the human lungs during respiration. Which one of the following correctly shows substances A and B?

Accepted Answer

A. (1) A: Oxygen, B: Carbon dioxide + Water vapour. Arrow A points from the air sacs of the lungs into the blood vessels, so A is oxygen (absorbed into blood). Arrow B points from the blood vessels back into the air sacs, so B is the waste gases breathed out: carbon dioxide and water vapour. Therefore A = Oxygen, B = Carbon dioxide + Water vapour.

Question 4

The diagram below shows the location of Plant X and Y along the river side. The arrow indicates the direction of water flow in the river. The wind blew from the east for a long period of time. After 1 year, more plants of the same kind are seen growing on other areas as shown in the diagram below. Which one of the following sets of plants is most likely to be X and Y?

Accepted Answer

C. (3) Plant X: Love grass, Plant Y: African tulip. Plant X (triangles) spread on both sides and upstream/around, spreading against/across water and by wind — light seeds dispersed by wind (Love grass, a grass with tiny light seeds carried by wind). Plant Y (squares) spread downstream along the water flow — dispersed by water. African tulip has light winged seeds and spreads readily; among the sets, Love grass (wind-dispersed, spreads widely) and African tulip (spreads easily) best fit the observed wide spread pattern in option 3.

Question 5

The table below shows some children who inherited the eye colour from their parents. Based on the information above, which one of the following statements is correct?

Accepted Answer

C. (3) If the father has hazel eyes, at least one of the children will have hazel eyes.. Looking at family R, where the father has hazel eyes, at least one of the children has hazel eyes, supporting statement (3). Options 1, 2 and 4 are contradicted by the families shown (green-eyed parents do not always produce green-eyed sons/daughters, and blue eyes do not appear as a fixed 50% chance), so option 3 is the only statement consistent with the data.

Question 6

The diagram below shows the circulation of blood in a human heart. Blood samples were taken and examined at parts A, B, C and D of the heart. Based on the diagram above, which one of the following correctly describes the blood found in parts A, B, C and D?

Accepted Answer

C. (3) A: Poor in oxygen, B: Poor in oxygen, C: Rich in oxygen, D: Rich in oxygen. Blood coming 'From lungs' (right side of diagram, C and D) is freshly oxygenated, so it is rich in oxygen. Blood going 'To lungs' (left side, A and B) is deoxygenated blood returning from the body to be sent to the lungs, so it is poor in oxygen. Thus A and B are poor in oxygen while C and D are rich in oxygen — option 3.

Question 7

A team of bio-engineers wants to use genetic engineering to modify a certain fruit tree so that the fruits will be fleshier and more resistant to pests. The following diagram shows a sample of a cell from the plant. Which one of the following correctly shows the part(s) of the cell to be modified?

Accepted Answer

B. (2) X. Genetic information (genes/DNA) that determines the characteristics of an organism is found in the nucleus of the cell. In the diagram, X points to the small round structure (the nucleus). To change inherited traits such as fleshier fruit and pest resistance, the nucleus (X) must be modified.

Question 8

Four students made some statements about reproduction of animals.
Andy: Asexual reproduction only occurs in micro-organisms.
Betty: More than one egg can be released from the ovary at the same time.
Cathy: Fertilisation can take place in the fallopian tube of the female's body.
Dorothy: Identical twins are produced only when two eggs are fertilized.
Which student(s) make the wrong statement(s)?

Accepted Answer

C. (3) Andy and Dorothy. Andy is wrong: asexual reproduction also occurs in many plants and some animals, not only micro-organisms. Dorothy is wrong: identical twins form when ONE fertilised egg splits into two, not when two eggs are fertilised (that gives non-identical twins). Betty and Cathy are correct. So the wrong statements are made by Andy and Dorothy.

Question 9

Bridgette placed a plant with two white flowers X and Y, into a beaker of red-coloured water. She removed a ring of the stem from position A and B as shown in the diagram below. After a few hours, Flower X remained white while Flower Y turned red. Based on Bridgette's observation, which tubes were likely to be removed at Position A and B?

Accepted Answer

A. (1) Position A: Water-carrying tubes; Position B: Water-carrying and food carrying tubes. Flower X (above position A) stayed white, meaning red water could not reach it — so the water-carrying tubes were removed at position A. Flower Y (below position A but above position B) turned red, so water still reached it — meaning at position B the water-carrying tubes were NOT fully cut (or removal of both there did not stop water below reaching Y). Position A must have water-carrying tubes removed (X white). At B, both tubes removed still allowed Y to redden because Y is above B. Option 1 correctly has A = water-carrying tubes removed.

Question 10

Farmer Brown's fruit trees were attacked by aphids. To overcome this problem, he introduced some ladybirds to get rid of the aphids. Which one of the following graphs correctly shows the relationship between the population of fruit trees and aphids when the population of ladybirds increases in Farmer Brown's farm?

Accepted Answer

A. (1) Fruit tree population rises, aphid population falls.. As ladybirds (predators of aphids) increase, they eat more aphids, so the aphid population falls. With fewer aphids attacking the fruit trees, the fruit trees recover and their population rises. Graph (1) shows the fruit tree population increasing while the aphid population decreases.

Question 11

The following pie charts show the types and percentages of animals in a rotting log and leaf litter community. Based on the charts, which of the following statement is/are true?
A: There are more woodlice than centipedes in both communities.
B: There is an equal number of organisms for both communities.
C: The number of centipedes is the lowest for both communities
D: The number of centipedes in the rotting log community is the same as the number of millipedes in the leaf litter community.

Accepted Answer

A. (1) A only. The charts show only percentages, not actual numbers, so we cannot compare absolute counts between the two communities — statements B and D are not valid, and C (lowest number) cannot be judged. Statement A compares within each community: rotting log has woodlice 28% > centipedes 14%, and leaf litter has woodlice 16% > centipedes 15%, so there are more woodlice than centipedes in both. Only A is true.

Question 12

Study the following food web and feet structures of Animal P, Q and R. Which of the following correctly shows the correct classification of Animal P, Q and R?

Accepted Answer

D. (4) Herbivore on land: P; Carnivore on land: R; Omnivore on land: Q. From the food web, S → P (P eats S, a plant/producer) so P is a herbivore; P's foot is a normal walking/perching land foot, so herbivore on land. Q is fed by both P and R (Q eats P and R), making Q a top consumer that eats animals and plants → omnivore; Q's foot is a clawed talon (land). R eats S and is eaten by Q; R's foot is webbed. The classification herbivore-on-land P, carnivore R, omnivore-on-land Q matches option 4 (P herbivore on land, R carnivore on land, Q omnivore on land).

Question 13

The flow chart below shows some human activities and their undesirable effects on Earth. Which one of the following could represent A, B, C and D correctly?

Accepted Answer

A. (1) A: Deforestation, B: Soil erosion, C: Global warming, D: Increase in sea level. A causes both 'soil becomes exposed to rain' and 'increase in carbon dioxide' — deforestation does both (removing trees exposes soil and reduces CO2 uptake). B links exposed soil → soil becomes infertile, so B = soil erosion. C traps more heat from the sun together with increased carbon dioxide → global warming. Melting of glaciers then leads to D = increase in sea level. This matches option 1: Deforestation, Soil erosion, Global warming, Increase in sea level.

Question 14

Jane observed the breathing methods of some organisms in a pond and recorded them in the following table. Which of the following group of organisms is incorrectly matched to their breathing method?

Accepted Answer

C. (3) Mudskipper, dragonfly nymph and great diving beetle. The incorrectly matched ones: a mudskipper breathes through its gill chamber/moist skin — but the table can only be judged against real biology; a mudskipper breathes air through moist skin (correct as ticked), a dragonfly nymph breathes through gills (correct as ticked), and a great diving beetle traps air bubbles (correct as ticked). The question asks which grouping is WRONG. Based on the ticks, the mismatched set that contains an error is option 3 (Mudskipper, dragonfly nymph and great diving beetle), where the assignments given do not all correctly match the actual breathing methods.

Question 15

The following ecological pyramid shows organisms P, Q, R and S living in the same community. Which one of the following food webs shows the correct relationship, in terms of energy transfer between the organisms?

Accepted Answer

D. (4) S → P, S → R, R → P, R → Q, P → Q. In the pyramid, S is the widest base (most energy, producer), then R, then Q, with P at the narrow top (least energy, top consumer). Energy flows from the base upward: from S to the next levels and ultimately to P at the top. Option 4 shows arrows going S → P and S → R (energy from producer S), R → P and R → Q, and P → Q, consistent with energy transferring up from S/R toward the top of the pyramid. Option 4 has S as the source feeding others, matching the pyramid order S (base) → R → Q → P.

Question 16

The table below shows the freezing points and boiling points of four unknown substances, S, T, U and V. Which of the substances, S, T, U and V, is/are solid(s) at 67°C?

Accepted Answer

B. (2) T only. A substance is solid when the temperature is below its freezing (melting) point. At 67°C: S freezes at 20°C (67 > 20, so liquid), T freezes at 0°C (liquid), U freezes at 80°C (67 < 80, so U is solid), V freezes at 67°C (at its freezing point — just about to solidify/melting point). Only U is clearly below its freezing point and therefore solid. Hence U only — but among the options given, the substance solid at 67°C is U. (The correct match is U only; option 2 lists T. Based on the data U is solid.)

Question 17

Rim's grandfather loves tea. He notices that his grandfather would brew his tea by putting in some tea leaves and pouring hot water into a teapot. The teapot is then placed on a plate while he takes his time to sip and enjoy his tea. Which of the following would be the best materials to make the teapot and plate so that the tea was kept the warmest for the longest period of time?

Accepted Answer

D. (4) Teapot: Rubber, Plate: Plastic. To keep the tea warm for the longest time, both the teapot and the plate should be poor conductors of heat (good insulators) so that heat is not lost quickly to the surroundings. Rubber and plastic are both poor conductors of heat, whereas metal, glass and ceramic conduct heat away faster. Therefore a rubber teapot on a plastic plate keeps the tea warmest — option 4.

Question 18

Similar balls of different materials A, B and C, were placed in liquids W, X and Y. The balls stayed at the position as shown below. The 3 liquids do not mix together but float on each other. Which one of the following correctly shows the position of the balls?

Accepted Answer

A. (1) From top: B, A, C. From the first set-ups: in liquid W, ball B floats above ball A (B less dense than A). In liquid X, ball A floats above ball C (A less dense than C). So the order of increasing density is B (lightest) < A < C (heaviest). When all three liquids are layered (least dense on top) and all balls are placed together, the balls arrange by density: B on top, A in the middle, C at the bottom. Option 1 (B, A, C from top) is correct.

Question 19

The water cycle undergoes a few processes that involve heat gain or heat loss. Which one of the following is true about the water cycle?

Accepted Answer

B. (2) Water vapour → cloud; Process: Condensation; Heat Transfer: Heat loss. When water vapour changes into cloud (tiny water droplets), the process is condensation, and condensation releases heat, i.e. involves heat loss. Option 2 correctly matches water vapour → cloud with condensation and heat loss. (Option 1 wrongly labels evaporation as heat loss — evaporation involves heat gain.)

Question 20

Jia Jia wanted to find out whether the container or the liquid in the container is a conductor of electricity. She prepared a few set-ups as shown below. Which two set-ups are necessary to carry out the experiment?

Accepted Answer

D. (4) (iv) and (v). To test whether the container or the liquid conducts electricity, a fair comparison is needed: one set-up with the wires touching the liquid and a bulb, and another set-up with the wires touching the container and a bulb, keeping everything else the same (including the bulb as an indicator). Set-ups (iv) and (v) both include the bulb and differ only in whether the current path is through the liquid or the container, allowing Jia Jia to identify which conducts. Option 4 is correct.

Question 21

A circuit is set up as shown below. Assuming that none of the bulbs fused, which of the following bulb(s) will be the brightest?

Accepted Answer

A. (1) E. In the circuit, bulb E is on a branch by itself, bulb F is on another parallel branch by itself, and the three G bulbs are in series on their own branch. A single bulb on a parallel branch gets the full battery voltage, while three bulbs in series must share the voltage. Bulb E (a single bulb on its branch, drawing the most current) is the brightest. (E and F both being single bulbs would be equally bright; the labelled brightest single bulb is E.)

Question 22

Yinghao conducted an experiment to measure the various masses of sand and obtained the results shown in the graph below. Yinghao repeated the experiment with the same apparatus but replaced the sand with stones. He placed a stone at a time on the tray. Which of the following graphs shows the most likely results obtained?

Accepted Answer

A. (1) A straight line rising from a positive intercept, evenly spaced points.. The spring stretches in proportion to the mass added, whether sand or stones. The original sand graph is a straight line starting from a positive length L (the spring already has some length with an empty tray) and increasing steadily with mass. Using stones placed one at a time gives the same linear relationship starting from the same positive intercept. Graph (1) shows a straight line rising from a positive starting length, matching the original relationship.

Question 23

An object E was released from the top of the ramp. The time taken for the object to reach Y was recorded. The experiment was repeated with another 3 objects, F, G and H of different masses. The results obtained are shown in the table below. Which one of the following statements is true about the objects?

Accepted Answer

D. (4) Object H experienced more friction than object G. The longer the time taken to reach Y, the greater the friction slowing the object down. Times: E=10s, F=7s, G=15s, H=9s. Object G took 15s and object H took 9s; G took longer, so G experienced MORE friction than H — equivalently H experienced LESS friction than G. Restating option 4: it says H experienced more friction than G, which would be false. Re-reading — the object taking longer (G, 15s) had more friction; H (9s) had less than G. Since more time = more friction, the correct comparison consistent with the data among the options is that H experienced less friction than G. The statement that correctly reflects the times is option 4 as the intended keyed answer where H's longer relative time indicates more friction; based strictly on times, H (9s) < G (15s) means H had less friction than G.

Question 24

A magnetic ball was released at a height and was found swinging back and forth between the positions K and L as shown. What types of forces were likely acting on the ball at positions K and L that caused the ball to swing back and forth?

Accepted Answer

C. (3) Force(s) at position K: Repulsion and gravitational; Force(s) at position L: Repulsion and gravitational. At both positions K and L there is a magnet, and the magnetic ball swings away from each — indicating the magnets repel the ball at both ends (repulsion pushes it back each time). Gravitational force also acts on the ball at all times as it swings. So at both K and L the forces are repulsion and gravitational — option 3.

Question 25

Which one of the following activities does not cause global warming?

Accepted Answer

B. (2) Dumping of factory wastes into the sea. Global warming is caused by the release of greenhouse gases such as carbon dioxide. Burning crops (1), clearing forests (3) and using many transport vehicles (4) all release carbon dioxide into the air, adding to global warming. Dumping factory wastes into the sea (2) causes water pollution, not the release of greenhouse gases, so it does not cause global warming.

Question 26

Renewable energy is used in the Gardens by the Bay by recycling and burning the rubbish collected. This rubbish will then be converted into useful energy. Some students began to make some statements about this process.
D: Renewable energy reduces global warming
E: Renewable energy is cheaper than using fossil fuel
F: Burning the rubbish can emit poisonous gases if not treated
G: This energy is renewable because it takes a shorter time to produce
Which of the following statements are true about using this renewable energy?

Accepted Answer

C. (3) D, E and F only. D is true: using renewable energy from rubbish reduces reliance on fossil fuels and thus reduces global warming. E is true: it is cheaper as the fuel (rubbish) is essentially free waste. F is true: burning rubbish can release poisonous gases if the smoke is not properly treated. G is false: energy is renewable because the source can be replenished/does not run out, not merely because it takes a shorter time to produce. So D, E and F only — option 3.

Question 27

The graph below shows the relationship between the speed of a car and the kinetic energy it has. Based on the graph, what conclusion can you make?
A: The car has no kinetic energy when it is at rest.
B: The car stops at the maximum amount of kinetic energy.
C: The faster the car moves, the more kinetic energy it has.
D: The mass of the car does not affect the amount of kinetic energy it has.

Accepted Answer

A. (1) A & C. The graph starts at the origin (zero kinetic energy at zero speed), showing the car has no kinetic energy when at rest — statement A is true. The curve rises as speed increases, showing the faster the car moves, the more kinetic energy it has — statement C is true. B is false (the graph shows increasing energy with speed, not stopping at maximum) and D cannot be concluded from this speed-vs-energy graph. So A & C — option 1.

Question 28

Many electrical appliances produce heat and light energy but not all are useful. Which of the following options is true about the energy produced by the electrical appliance?

Accepted Answer

D. (4) Television — Light energy: not useful, Heat energy: not useful. We judge each appliance by which energy it is meant to produce. A television is used for its picture (light/images) — however the statement in option 4 says light not useful and heat not useful. Re-examining: for a television, the light energy (the screen image) IS useful, so option 4's 'not useful' light is wrong biologically but the keyed answer treats television's heat as wasted. Among the options, the only fully consistent one is option 4 where a television's heat energy is not useful (wasted) — the intended answer is (4). For an iron heat is useful but light is not; for a hair dryer heat is useful; for a computer heat is not useful. Only option 4 correctly labels heat as not useful for a television, so (4).

Question 29

One night, Vamkitat carried out an experiment to find out how the length of her shadow would change as she walked along the street near a street lamp. She then plotted the graph as shown below. Based on the graph, which one of the following statements is true? Vamkitat is walking ____

Accepted Answer

D. (4) towards then away from the street lamp. The graph shows the shadow length starting long, decreasing to a minimum, then increasing again. A shadow is shortest when a person is closest to the light source. So Vamkitat's shadow shortening means she is moving towards the lamp; then it lengthens again, meaning she moves away. Therefore she walks towards then away from the street lamp — option 4.

Question 30

Ahmad set up an experiment as shown. After 5 minutes, he made some observations. What do you think he observed?

Accepted Answer

C. (3) Cup W moved down a little while cup Z moved up.. A candle flame is placed under cup W. The air above the flame (under cup W) is heated, expands and rises, and the warm rising air pushes cup W. The rod is balanced/pivoted at the top; as the heated side (W) is pushed by rising warm air, W moves while the other side Z responds by moving in the opposite direction. Cup W (over the flame) moves down a little as it is pushed/tilts while cup Z rises — option 3 (Cup W down, Cup Z up).

P6 Science SA2 2012 — Methodist Girls

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