Question 1

John classified the following living things as shown. Group X contains butterfly and mosquito. Group Y contains chicken and cockroach. Which of the following correctly shows what X and Y could be?

Accepted Answer

A. X: beetle, Y: grasshopper. X groups animals that undergo complete metamorphosis (butterfly, mosquito, and beetle all have a larva/pupa stage). Y groups animals that do not undergo complete metamorphosis (chicken, cockroach, grasshopper — grasshoppers undergo incomplete metamorphosis). So beetle fits X and grasshopper fits Y.

Question 2

Which of the following characteristics can be used to separate insects from mammals?
A. Number of legs
B. Presence of wings
C. Number of body parts
D. Type of body covering

Accepted Answer

C. A, C and D only. Insects have 6 legs vs mammals' 4 (A), insects have 3 body parts vs mammals' body (C), and insects have an exoskeleton vs mammals' hair/fur (D). Presence of wings (B) is unreliable because not all insects have wings and some mammals (bats) have wing-like structures.

Question 3

Study the flow chart below. Which one of the following is correct (giving what P is and what Question Q should be)?

Accepted Answer

D. P is not a plant; Question Q: Are the seeds dispersed by wind?. P does not bear flowers and does not make its own food, so it is not a plant (e.g. a fungus). Question Q must separate mimosa from lalang, both flowering plants: lalang seeds are dispersed by wind (Yes → lalang) while mimosa seeds are not (No → mimosa), so Q is 'Are the seeds dispersed by wind?'

Question 4

Study the three set-ups X, Y and Z. Set-up X has insects on a wire mesh above substance P in a clear glass container under light. Set-up Y has a plant in soil under light. Set-up Z has only substance P under light. Substance P turns green when oxygen is less than normal, purple when normal, and yellow when higher than normal. What is the colour of substance P in each set-up after 6 hours?

Accepted Answer

B. set-up X: green, set-up Y: yellow, set-up Z: purple. In X the insects respire and use up oxygen, lowering it below normal → green. In Y the plant photosynthesises under light and releases oxygen, raising it above normal → yellow. In Z nothing changes the oxygen → normal → purple.

Question 5

Kevin set up an experiment using four similar leaves A, B, C and D. He coated some surfaces with non-dripping oil and hung them in an open area. Leaf A: oil on top surface. Leaf B: oil on bottom surface. Leaf C: oil on top and bottom surfaces. Leaf D: no oil. After 6 hours the loss in mass was: leaf A = 7 g, leaf B = 3 g, leaf C = 0 g, leaf D = 10 g. Which of the following can be concluded from the results?

Accepted Answer

C. There are more stomata on the bottom surface than the top surface of the leaves.. When the bottom is covered (B) only 3 g is lost, but when the top is covered (A) 7 g is lost — covering the bottom reduces water loss more, so there are more stomata on the bottom surface. C is correct: C lost the least (0 g), A had top covered yet still lost water (so stomata exist on top), and D's remaining water cannot be determined.

Question 6

Jane conducted an experiment to find out if carbon dioxide is needed for photosynthesis. She prepared four set-ups. Set-up A: green plant under a glass bell jar with a substance to remove oxygen. Set-up B: green plant under a glass bell jar with a substance to remove carbon dioxide. Set-up C: green plant under a glass bell jar (nothing added). Set-up D: green plant under a glass bell jar covered with a black cloth, with a substance to remove carbon dioxide. Which two set-ups should Jane use to carry out her experiment?

Accepted Answer

B. Set-ups B and C. To test only the effect of carbon dioxide, the two set-ups must differ only in carbon dioxide while keeping light constant. B (no carbon dioxide, in light) versus C (carbon dioxide present, in light) is the only fair test.

Question 7

Plants take in water from the soil through their roots. Where is the water transported to? (Parts A, B, C and D are labelled on a plant: A = flower, B = leaf, C = fruit, D = stem.)

Accepted Answer

D. A, B, C and D. Water absorbed by the roots is transported through the plant to all its parts — the flower, leaves, fruit and stem — for various life processes, so the answer is all of A, B, C and D.

Question 8

Samuel recorded information about the organism shown (a germinating seed/seedling with part X labelled, X being the seed/food store).
A. This plant reproduces by seeds.
B. The seed depends on part X to grow.
C. The seed can only germinate when there is water and sunlight.
D. Part X will continue to grow bigger as the seedling grows to an adult plant.
Which statement(s) is/are correct about the organism?

Accepted Answer

B. A and B only. A is correct — it grew from a seed, so it reproduces by seeds. B is correct — part X (the cotyledon/seed food store) provides food for the seedling before its leaves can make food. C is wrong — germination needs water, air and warmth but NOT sunlight. D is wrong — part X shrivels and falls off as the seedling grows.

Question 9

The diagram shows the human digestive system with parts labelled A, B, C and D (A = mouth/oesophagus region, B = stomach, C = large intestine, D = small intestine). In which parts are digested food and water absorbed into the blood vessels?

Accepted Answer

A. digested food: D, water: C. Digested food is absorbed into the blood mainly in the small intestine (D), while water is absorbed mainly in the large intestine (C).

Question 10

The following relationships were observed among four living things E, F, G and H: E feeds on H. G feeds on E and H. H gets its food from F. Which one of the following classifications is correct?

Accepted Answer

C. producer F, prey H, predator G, prey and predator E. F is the producer (H gets its food from F). H is prey (eaten by E and G). G is the top predator (eats E and H, is not eaten). E is both prey and predator — it eats H but is itself eaten by G.

Question 11

The graph shows the populations of five organisms S, T, U, V and W living in a community, with bar heights (number of organisms) in the order U (lowest) < V < S < T < W (highest). Based on the information, which of the following food chains is possible?

Accepted Answer

B. W → S → U. In a food chain the population decreases from producer to top consumer. W (highest) → S (middle) → U (low) shows a decreasing population along the chain, so it is the only possible one.

Question 12

The diagram shows a population of Animal M (meerkat-like animals). Several Animal M often stand on their rear legs and gaze alertly over the open area where they live. They watch the skies and give a sharp, shrill call when they see hawks and eagles. The other animals would then run and hide in underground burrows. Which of the following statements shows how the population of Animal M works together in numbers?

Accepted Answer

B. Animal M stands guard to look out for birds that can snatch them from the ground.. Working together in numbers means some stand guard to watch for predatory birds (hawks/eagles) and warn the group, allowing the rest to escape into burrows. The call is for danger, not food (so A is wrong); C and D misstate the purpose.

Question 13

The diagram shows a desert plant with long roots and curved-shaped leaves. The leaves have small surfaces and are toothed-edge. Which of the following does not explain how the plant is adapted to survive in the desert?

Accepted Answer

B. The toothed-edge leaves prevent animals from feeding on them.. Desert survival is about obtaining and conserving water: long roots reach water (A), curved leaves channel water to the base (C), and small leaf surfaces reduce water loss (D). Toothed edges preventing animals from feeding (B) is protection from herbivores, not an adaptation to the dry desert conditions.

Question 14

Bird P lives in a very cold environment. Bird P usually stands with its back facing the sun and stays close to another Bird P.
A. Bird P stays close to one another to keep warm.
B. Bird P stays close to one another for protection from predators.
C. The black surface on Bird P's back absorbs the heat from the sun.
D. The black surface on Bird P's back helps it blend in with the surrounding.
Which of the following are the reasons for such behaviour?

Accepted Answer

C. A, B and C only. In a cold environment the birds huddle close to keep warm (A) and also for protection in numbers (B), and the black back faces the sun because dark surfaces absorb heat well (C). Blending with the surroundings (D) is not the reason for facing the sun.

Question 15

The diagram shows a plant and some fishes in a pond. Leaf P is growing above water and leaf Q is growing in the water. Small fishes swim among the submerged leaves. Which one of the following statements about Leaf P and Leaf Q is not correct?

Accepted Answer

B. Leaf P is a source of food for the fishes.. Leaf P grows above the water, so the fishes (in the water) cannot use it as a food source, making B incorrect. Submerged leaf Q does shelter the fishes (A) and absorbs dissolved carbon dioxide (C), and the broad emergent leaf P captures more sunlight (D).

Question 16

The diagram shows an eagle searching for food. Which one of the following structural adaptations of the eagle is not correctly matched to its function?

Accepted Answer

B. sharp pointed beak — to catch and hold on to prey. An eagle catches and holds prey with its sharp talons/claws, not its beak; the beak is used to tear flesh. So 'sharp pointed beak — to catch and hold on to prey' is the mismatched pair. The others are correctly matched.

Question 17

Fruit trees, vegetables and butterflies make up a community in a farm. The farmer sprayed insecticide on the vegetables when he found that they were eaten by caterpillars. How would the spraying of insecticide affect the amount of fruits and vegetables produced and the population of butterflies?

Accepted Answer

A. fruits decrease, vegetables increase, butterflies decrease. The insecticide kills the caterpillars, so vegetables are no longer eaten and increase. Caterpillars are the larvae of butterflies, so fewer caterpillars means fewer butterflies (decrease). With fewer butterflies to pollinate the fruit trees, fewer fruits are produced (decrease).

Question 18

The conditions in habitats S, T, U and V are: S — sunny, grassland, moderate amount of water available; T — sunny, sandy soil, little rainfall throughout the year; U — dark, damp, a lot of dead plant matter; V — shady, muddy soil, fresh water. Organism A has a swollen stem and needle-like leaves. Organism B feeds on wood and hides under dead logs. In which habitat can we find organisms A and B?

Accepted Answer

D. Organism A: T, Organism B: U. Organism A's swollen stem (water storage) and needle-like leaves (reduce water loss) suit the hot, dry, sandy habitat T. Organism B feeds on wood and hides under dead logs, so it needs the dark, damp habitat U with a lot of dead plant matter.

Question 19

Food relationships between some organisms are shown in the food web: Plants → A, Plants → B, A → C, B → C, C → D. If the population of Animal C decreases, which of the following graphs shows the changes in the population of Animal A and D?

Accepted Answer

D. Graph 4: A increases and D decreases (lines cross). C eats A, so if C decreases, less A is eaten and A's population increases. C is the food of D, so if C decreases, D has less food and its population decreases. The graph showing A rising and D falling (crossing) is correct.

Question 20

The diagram represents the changes of state of water between solid, liquid and gas, with processes labelled A (solid → liquid), B (liquid → gas), C (gas → liquid), and 'freezing' (liquid → solid). Which one of the following correctly describes the processes at A, B and C?

Accepted Answer

A. A: melting, B: evaporation, C: condensation. A changes solid to liquid = melting; B changes liquid to gas = evaporation (boiling); C changes gas to liquid = condensation.

Question 21

The diagram shows the shadows of a stick as the Sun moves from position A to C (A low on one side, B high in the middle, C low on the other side). As the Sun moves from position A to C, what can be said about the shadow of the stick?

Accepted Answer

D. The shadow of the stick formed when the Sun is at A is longer than the shadow formed when the Sun is at B.. The lower the Sun, the longer the shadow. At A the Sun is lower than at B (highest), so the shadow at A is longer than at B. The shortest shadow is at B (Sun highest), not C, and there is no basis for A being the single longest or B's shadow equalling the stick.

Question 22

Samuel pushed a toy car towards a wooden plank AB. The toy car went up the plank, stopped at X and rolled down. Samuel pushed the same toy car from the same starting point again, but this time the toy car stopped at a lower point Y and rolled down. Which of the following could explain why the toy car did not reach X when Samuel pushed it the second time?

Accepted Answer

C. The kinetic energy of the toy car was smaller.. The car stopped lower (Y) the second time, so it gained less height and therefore less gravitational potential energy. This means it started with less kinetic energy. Greater speed (B) or more energy converted (D) would make it go higher, and it is the same car (A is irrelevant).

Question 23

Many of our activities involve pulling and pushing. E, F, G and H are the forces exerted by the men (E and F shown in a tug-of-war/lifting scene on the left; G and H shown for a man climbing a pole on the right). Which one of the following shows the correct force (classified as Push or Pull)?

Accepted Answer

A. Push: F, H; Pull: E, G. In the tug-of-war the rope force E is a pull. For the man climbing the pole, the hands (G) pull the body up while the feet (H) push against the pole. The lifting/upward force F is a push. So the pulls are E and G, and the pushes are F and H.

Question 24

A man did a bungee jump from a bridge. He stood at A before jumping off the bridge. When he jumped off, he fell towards the water, passing point B during the fall. After bouncing up and down a few times, he came to a stop at C (hanging above the water). Which one of the following statements about the man is correct?

Accepted Answer

A. The amount of kinetic energy of the man at C is zero.. At C the man has come to a stop, so he is not moving and his kinetic energy is zero. Gravitational force (his weight) is the same everywhere (B wrong); he moves faster at B than at A, so KE is higher at B (C wrong); and B is higher than C, so GPE is not lowest at B (D wrong).

Question 25

The diagram shows some energy conversions: Potential Energy → (B) → Kinetic Energy → (D) → Sound Energy; Potential Energy → (A) → Light Energy; Kinetic Energy → (C) → Heat Energy. A, B, C and D are 4 different actions: A. Burning a candle; B. Roller coaster going up the track; C. Rubbing your hands together; D. Blowing a whistle. Which actions A, B, C and D are correctly represented in the diagram?

Accepted Answer

D. A, C and D only. A (burning a candle) converts chemical potential energy to light — matches arrow A (PE→Light). C (rubbing hands) converts kinetic to heat — matches arrow C (KE→Heat). D (blowing a whistle) converts kinetic energy of moving air to sound — matches arrow D (KE→Sound). B is wrong: a roller coaster going UP converts kinetic to potential energy, the opposite of arrow B (PE→KE).

Question 26

Deforestation is harmful to our environment. What is the impact of deforestation?
A. Less variety of animals
B. More rainfall in the forest
C. Less carbon dioxide in the air
D. More soil being washed away by rain

Accepted Answer

A. A and D only. Deforestation destroys habitats, reducing the variety of animals (A), and removes tree roots that hold soil, so more soil is washed away by rain (D). It causes LESS rainfall (not more) and MORE carbon dioxide in the air (fewer trees to absorb it), so B and C are wrong.

Question 27

The Earth has experienced an increase in the temperature of the air over the last ten years due to global warming. Which of the following activities can contribute to global warming?
A. Driving a petrol car to work
B. Building more incinerators to burn rubbish
C. Turning on the air-conditioner in the bedroom
D. Growing different types of plants in the garden

Accepted Answer

C. A, B and C only. Driving a petrol car (A) and burning rubbish in incinerators (B) release carbon dioxide. Running an air-conditioner (C) uses more electricity, which usually comes from burning fossil fuels, releasing carbon dioxide. Growing plants (D) absorbs carbon dioxide and does not contribute to global warming.

Question 28

Ahmad arranged four metal bars, EF, GH, WX and YZ, so that the bars attracted each other without any repulsion. Two bars are magnets and the other two are iron bars. He was then told that EF is a magnet and E is the N-pole, and F will repel X when placed facing each other. Based on the information given, which two of the following statements would be true of the metal bars?
A. YZ is an iron bar.
B. H will be attracted to Z.
C. GH is a magnet and G is the S-pole.
D. WX is a magnet and W is the N-pole.

Accepted Answer

B. A and D. F repels X, and repulsion happens only between like poles of two magnets. Since E is N-pole, F is S-pole, so X is also S-pole, meaning WX is a magnet with W as N-pole (D true). Thus the two magnets are EF and WX, so GH and YZ are the iron bars (A true; C false). H and Z are both iron bars and would not attract each other (B false).

Question 29

The Pollutant Standards Index (PSI) is a type of air quality index that indicates how polluted the air is. The map shows the PSI of different locations in Country P, which is experiencing hazy conditions due to a forest fire in Country Q. Town A has PSI 250 and Town B has PSI 50; the wind blows from Country Q towards Country P, and there are rain clouds near Town B. Which two of the following explain why the PSI at Town A is higher than the PSI at Town B?
A. Country P is larger than Country Q.
B. The rain has washed away some of the dust in the air.
C. Town A is located further from the forest fire than Town B.
D. The wind has blown the ash from the forest fire in Country Q to Town A.

Accepted Answer

C. B and D. Town B has rain clouds, so rain washes dust out of its air, lowering its PSI (B). The wind blows ash from the Country Q fire towards Town A, raising its PSI (D). Together these explain why A's PSI is higher than B's. Country size (A) is irrelevant, and Town A is actually nearer/downwind of the fire (C is false).

Question 30

Matthew had three bars, X, Y and Z, made of unknown materials. He placed them in positions A, B and C of the circuit shown (containing lamps L1, L2, L3 and L4). When X was at A, Y at B and Z at C, lamps L1, L2 and L3 lit up but L4 did not. Which of the following would show the correct results if the bars X, Y and Z were placed at different positions?

Accepted Answer

D. A: X, B: Z, C: Y → only L4 lights. From the first result, X (at A) and Y (at B) are conductors (L1, L2, L3 light) and Z (at C) is an insulator (L4 stays off). In the circuit L2 and L3 need position B closed, L1 needs both A and B closed, and L4 needs C closed. Placing X at A (closed), Z at B (open) and Y at C (closed): position B is open so L1, L2 and L3 cannot light, while C is closed so only L4 lights — matching option D.

P6 Science SA2 2015 — Pei Hwa

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P6 Science SA2 2015 — Pei Hwa

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