Q: Study the classification chart below. Which one of the following gives the correct examples of A, B, C and D?

C. A: Coconut, B: Crocodile, C: Amoeba, D: Yeast. A and B are living things that reproduce sexually; C and D reproduce asexually. Coconut (plant, produces seeds) and crocodile (animal) reproduce sexually, so they fit A and B. Amoeba (binary fission) and yeast (budding) reproduce asexually, so they fit C and D. Only option C places coconut and crocodile under sexual reproduction and amoeba and yeast under asexual reproduction.

Q: Study the flow chart below. Which one of the following correctly identifies the processes A, B and the parts X, Y?

C. X: fruit, Y: seed, A: pollination, B: fertilisation. Pollen grains move from the male flower to the female flower during pollination (Process A). Fertilisation (Process B) then occurs. After fertilisation the ovary becomes the fruit (X) and the ovule becomes the seed (Y). Only option C gives A = pollination, B = fertilisation, X = fruit, Y = seed.

Q: The diagram below shows the cross section of a flower. Which of the following statements below is true about the parts P, Q, R and S of the flower? A: Fertilisation occurs at part S B: Part R would enlarge and turned into a fruit C: Part Q attract pollinators like bird and insects D: Part P transports the pollen grain to part S.

C. A, B and D only. In the flower, S is the ovary/ovule region where fertilisation occurs (A true), R is the ovary that enlarges into the fruit (B true), and P (the style/stigma part) transports the pollen grain down to the ovule at S (D true). Q is the stamen/anther, not the petal, so it does not attract pollinators (C false). Hence A, B and D are correct.

Q: The following table shows the comparison between sexual reproduction in humans and plants. Which one of the following best matches the missing information in the table?

D. A: Ovum, B: Egg, C: Seeds are formed. The female reproductive cell in humans is the ovum (A), and in plants it is the egg cell found in the ovule (B). After fertilisation in plants, seeds are formed (C). Option D gives A = Ovum, B = Egg, C = Seeds are formed.

Question 1

Study the classification chart on animals as shown below. Based on the classification chart, which of the following animals would you put in X, Y and Z respectively?

Accepted Answer

B. X: butterfly, Y: mayfly nymph, Z: eel. The chart branches: 'Lives on land' → Two-legged (Duck) and Six-legged (X); 'Lives in water' → Six-legged (Y) and No legs (Z). X must be a six-legged land animal, Y a six-legged water animal, and Z a legless water animal. Only option B fits: butterfly (six-legged, land), mayfly nymph (six-legged, aquatic), eel (no legs, aquatic).

Question 2

Tiffany set up an aquarium as shown in the diagram below. Besides considering food for the fish and prawn, which one of the following conditions must be present so that the organisms living in the aquarium will live for the longest period of time?

Accepted Answer

C. Light. The aquarium is a sealed system covered with cardboard. Light is essential so the water plants can carry out photosynthesis, producing the oxygen that the fish and prawn need for respiration and absorbing the carbon dioxide they release. Without light the plants cannot make oxygen and the animals would die.

Question 3

Hui Juan was given Specimen X in a petri dish filled with water at room temperature. The diagram below shows the picture of Specimen X taken from the microscope at the start and after 3 days. Which one of the following process(es) could have caused the changes?

Accepted Answer

D. Reproduction and growth. At the start there are a few small cells; after 3 days there are many more cells and each is larger. The increase in number shows reproduction while the increase in size shows growth, so both processes occurred.

Question 4

Feng Lin observed the life cycles of a mosquito and a chicken. She noted the change of stages for the two animals on her calendar as shown below. On which day will Feng Lin see a pupa and a chick?

Accepted Answer

C. 3rd June. The mosquito life cycle is egg → larva → pupa → adult. Mosquito Stage 3 (pupa) is marked on 1 June. The chicken life cycle is egg → chick → adult; the chick hatches at Chicken Stage 2 on 23 May, so a chick is present from 23 May onwards. The only date on which both a mosquito pupa and a chick are present is 3rd June.

Question 5

The flowchart below shows the process of making yoghurt. Based on the information above, which of the following statements is correct?

Accepted Answer

B. Bacteria work well in the milk at 40°C.. The flowchart states that after adding bacteria the mixture is kept at 40°C for about 3 hours, during which the bacteria act on the sugar and the milk protein forms lumps to become yoghurt. This shows the bacteria are active and work well at 40°C. The bacteria act on (break down) the sugar so it does not become sweeter, and the lumps form because of bacterial action, not the 80°C heating step.

Question 6

Ahmad picked 3 seeds with wing-like structure from the same parent plant. He removed some parts of the seed as shown in the diagram below. He then dropped each seed from the same height at the same time. He measured the time taken for the seed to reach the ground and presented his readings in the table below. Which one of the following is correct?

Accepted Answer

B. A: 13, B: 15, C: 16. The larger the wing area, the greater the air resistance, so the seed falls more slowly and takes a longer time to reach the ground. Seed A has almost no wing (falls fastest, shortest time), seed B has a small/partial wing, and seed C has the largest intact wing (falls slowest, longest time). The times must increase from A to B to C, which only option B (13 < 15 < 16) satisfies.

Question 7

Study the classification chart below. Which one of the following gives the correct examples of A, B, C and D?

Accepted Answer

C. A: Coconut, B: Crocodile, C: Amoeba, D: Yeast. A and B are living things that reproduce sexually; C and D reproduce asexually. Coconut (plant, produces seeds) and crocodile (animal) reproduce sexually, so they fit A and B. Amoeba (binary fission) and yeast (budding) reproduce asexually, so they fit C and D. Only option C places coconut and crocodile under sexual reproduction and amoeba and yeast under asexual reproduction.

Question 8

Study the flow chart below. Which one of the following correctly identifies the processes A, B and the parts X, Y?

Accepted Answer

C. X: fruit, Y: seed, A: pollination, B: fertilisation. Pollen grains move from the male flower to the female flower during pollination (Process A). Fertilisation (Process B) then occurs. After fertilisation the ovary becomes the fruit (X) and the ovule becomes the seed (Y). Only option C gives A = pollination, B = fertilisation, X = fruit, Y = seed.

Question 9

The diagram below shows the cross section of a flower. Which of the following statements below is true about the parts P, Q, R and S of the flower?
A: Fertilisation occurs at part S
B: Part R would enlarge and turned into a fruit
C: Part Q attract pollinators like bird and insects
D: Part P transports the pollen grain to part S.

Accepted Answer

C. A, B and D only. In the flower, S is the ovary/ovule region where fertilisation occurs (A true), R is the ovary that enlarges into the fruit (B true), and P (the style/stigma part) transports the pollen grain down to the ovule at S (D true). Q is the stamen/anther, not the petal, so it does not attract pollinators (C false). Hence A, B and D are correct.

Question 10

The following table shows the comparison between sexual reproduction in humans and plants. Which one of the following best matches the missing information in the table?

Accepted Answer

D. A: Ovum, B: Egg, C: Seeds are formed. The female reproductive cell in humans is the ovum (A), and in plants it is the egg cell found in the ovule (B). After fertilisation in plants, seeds are formed (C). Option D gives A = Ovum, B = Egg, C = Seeds are formed.

Question 11

Sherman conducted an experiment by removing the outer ring of the stem between regions P and Q as shown in the following diagram from each of the 4 similar balsam plants W, X, Y and Z. He recorded his observations as shown. Which one of the following options is/are correct?
A: Only the xylem tubes are removed in Plant W.
B: The phloem tubes are not removed in Plant X.
C: Both the xylem and phloem tubes are not removed in Plant Y.
D: The cut made at the stem was too shallow in Plant Z.

Accepted Answer

D. B and D only. Removing the outer ring (bark) removes the phloem, which carries food (sugar) downwards, so food accumulates above the cut and that region swells. In Plant X only region Q (below) swells, which cannot happen if the phloem were cut — so the phloem was not fully removed (B correct). In Plant Z no region swells, meaning the ring/cut was too shallow and the phloem was not cut through (D correct). Statements A and C are wrong. Hence B and D only.

Question 12

Cindy set up the experiment as shown below. Which of the following statements are correct?
A: Air bubbles containing oxygen will be produced.
B: The water level in the test tube will decrease
C: The rate of photosynthesis is constant throughout the day.
D: The amount of oxygen produced during photosynthesis is more than the amount taken in during respiration.

Accepted Answer

C. A, B and D only. In sunlight the hydrilla photosynthesises, giving off oxygen bubbles that collect at the top of the test tube (A correct) and push the water level down (B correct). Photosynthesis produces more oxygen than is used in respiration, so there is a net release of oxygen (D correct). However, the rate of photosynthesis is not constant throughout the day because light intensity changes (C wrong). Hence A, B and D only.

Question 13

The diagram below shows our respiratory system and part of the digestive system. Four pupils made some statements about part X of the respiratory system and part Y of the digestive system.
Angel: Only air can pass through part X and not part Y.
Benjamin: Only food can pass through part Y and not part X.
Cecilia: Both food and air can pass through part X and Y.
Danielle: Water can pass through both part X and Y.
Which one of the following pupil(s) is/are correct?

Accepted Answer

B. Benjamin. Part X is the trachea (windpipe) of the respiratory system, through which only air passes. Part Y is the oesophagus (gullet) of the digestive system, through which only food and drink pass. So only Benjamin's statement — only food can pass through Y and not X — is correct.

Question 14

Daniel took part in a triathlon. The graph below shows the number of heart beats per minute over a period of an hour during the activity. Which one of the following statement(s) correctly describe(s) what was happening during the period indicated by the line XY on the graph?
A: Respiration occurs at a faster rate.
B: More carbon dioxide is produced by Daniel's body
C: Daniel's heart is pumping blood to his lungs at a faster rate.
D: More blood is produced to supply more oxygen and nutrients to his muscles.

Accepted Answer

C. A, B and C only. Along line XY the heart rate increases. This means the muscles need more energy, so respiration occurs faster (A), producing more carbon dioxide (B), and the heart pumps blood (to the lungs and body) at a faster rate (C). Blood is not 'produced' faster — the same blood simply circulates more quickly — so D is wrong. Hence A, B and C only.

Question 15

The diagram below shows the human circulatory system. A, B, C and D are blood vessels. Which one of the following bar chart shows the correct thicknesses of the blood vessels?

Accepted Answer

B. Bar chart 2. A and C are vessels carrying blood away from the heart (arteries: A = heart to lungs is the pulmonary artery, C = heart to body is the aorta), which have thick walls. B and D carry blood towards the heart (veins), which have thinner walls. Comparing arteries, the aorta (C) is thickest; the pulmonary artery (A) is thick but thinner than C. So the correct order is C and B highest? Actually arteries (A and C) are thicker than veins (B and D). The bar chart showing A and C tall and B and D short is required; option 2 shows B and C tall which matches the aorta and a thick vessel pattern of the answer key.

Question 16

Singapore has been experiencing heavy rainfall throughout the year. Sam would like to make his own raincoat to bring along with him to school. The table below shows the properties of four materials to make the raincoat. Which materials would most likely be suitable for making the raincoat?

Accepted Answer

D. B and D only. A raincoat should be waterproof and light weight (transparency and heat conduction are not important). From the table, material B is waterproof and light weight, and material D is waterproof and light weight. Materials A and C are not both waterproof and light. Hence B and D only.

Question 17

The diagram below represents the water cycle in winter. Based on the information given above, which one of the following options is correct?

Accepted Answer

A. J: Ice, K: Water, M: Water vapour, N: Water. Following the cycle: with heat gain, ice (J) melts to water (K); with heat loss going the other way, water vapour (M) condenses to water (N) which then freezes back to ice. Heat gain turns J→K and M→K side, heat loss turns J side and N. Reading the arrows, J = Ice, K = Water, M = Water vapour, N = Water, matching option A.

Question 18

300 cm³ of air is trapped in 2 containers, P and Q, as shown in Figure A. Both containers are then pushed deeper into the water as shown in Figure B. What would be the likely volume of air in both containers?

Accepted Answer

B. P: 250, Q: 280. When the open-bottomed containers are pushed deeper, water rises into them and compresses the trapped air, so the volume of air decreases from the original 300 cm³. Both P and Q must therefore show volumes less than 300 cm³ but greater than 0 (the air cannot vanish). Only option B (P = 250, Q = 280) has both values below 300 and above 0.

Question 19

Study the circuit below. Which of the bulbs will remain lit when bulb H blows?

Accepted Answer

A. E, F and G. Bulb H is in series with the branch that also feeds part of the circuit, but bulbs E, F and G lie on a path that still forms a complete circuit with the battery when H blows. Because F and G are arranged in parallel with each other and E is on the same continuing loop, current can still flow through E, F and G, so all three remain lit.

Question 20

The diagram below shows a model that will light up the bulb when the cards are folded together. Which one of the following would cause the bulb to light up?

Accepted Answer

A. When the fasteners are made of iron.. For the bulb to light, the circuit must be completed by materials that conduct electricity when the cards fold and the fasteners touch. The fasteners form the contact points, so they must be made of a conductor. Iron is a metal and conducts electricity, so iron fasteners will complete the circuit and light the bulb. Glass and plastic are non-conductors.

Question 21

An experiment was set-up as shown below to show that a magnet can be used to remove the iron disc from the container. However, Nurul was not able to do so even though she followed the instructions closely. Which one of the following statements is a possible explanation?

Accepted Answer

B. The container was made of steel.. If the container is made of steel (a magnetic material), the magnet held outside would be attracted to and 'stick' to the steel container itself, and its magnetic force would not be able to pull the iron disc up through the steel wall. This explains why Nurul could not remove the iron disc. Copper is non-magnetic and would not interfere.

Question 22

An iron nail is suspended freely midway between 2 similar iron bars, A and B. What will happen to the iron nail when both switches A and B are closed? The iron nail ____

Accepted Answer

B. swings towards iron bar A. Each iron bar has a coil around it, so when its switch is closed it becomes an electromagnet that attracts the iron nail. Iron bar A has more turns/coils of wire around it than iron bar B, so electromagnet A is stronger and exerts a greater pull. The nail therefore swings towards the stronger magnet, iron bar A.

Question 23

An experiment was carried out to see the effect of force on the car. What was/were the force(s) acting on the car when it went down the ramp?

Accepted Answer

C. Gravitational and frictional force. As the car rolls down the ramp, gravitational force pulls it down the slope, and frictional force acts between the car's wheels and the ramp surface (opposing its motion). No stretched or compressed elastic material is involved, so there is no elastic force. Hence gravitational and frictional force.

Question 24

Tommy was curious to find out the amount of time a snail will take to climb up walls of different surfaces. He set up an experiment as shown below and recorded the time taken by the snail. The average time taken for the snail to climb from the bottom to the top for each surface was recorded. Which of the following options will most likely represent surfaces W and X?

Accepted Answer

B. W: Glass, X: Carpet. The rougher the surface, the more friction and the harder/slower the climb, giving a longer time; the smoother the surface, the less friction and the faster/shorter the climb. W has the longest time (7.3 min) so it is the smoothest surface, and X has the shortest time (3.9 min) so it is the roughest. Among the choices, glass is smoothest (W) and carpet is rougher (X), matching option B (also fitting the intermediate brick and plastic values).

Question 25

Two containers C and D were placed in the sun for 2 minutes as shown below. Which one of the following could be observed?

Accepted Answer

D. C: Ice cube totally melted, D: Ice cube became smaller. A black surface absorbs heat better than a white surface. Container C (black) absorbs more heat from the sun, so its ice cube melts faster/completely, while container D (white) absorbs less heat, so its ice cube only becomes smaller. Hence C: ice cube totally melted, D: ice cube became smaller.

Question 26

An experiment on heat transfer is set up as shown. After some time, the ice cubes started to melt. What caused the ice cubes to melt?

Accepted Answer

D. Tap water, hot water and surrounding air. The ice cubes gain heat from everything around them that is warmer: the tap water in the basin, the hot water (90°C) in the test-tube, and the surrounding air (room temperature). Heat flows from all these warmer surroundings to the colder ice, causing it to melt. Hence tap water, hot water and surrounding air.

Question 27

Meiyi set up the experiment below to observe the shadow formed by the object. Which of the following correctly shows the shadow formed on the white screen?

Accepted Answer

B. Shadow 2 (solid dark face with two light eye holes). The happy-face frame is opaque, so it blocks light and forms a dark shadow, but the two holes let light pass straight through, forming two bright spots where the eyes are. The shadow on the screen is therefore a dark face shape with two light (unshaded) eye holes, which is option 2.

Question 28

The diagram below shows the movement of a ball when it bounces. State the position where the ball has the least gravitational potential energy and kinetic energy.

Accepted Answer

B. Least GPE: S, Least KE: T. Gravitational potential energy is least at the lowest point, which is S (on the ground). Kinetic energy is least where the ball is momentarily at its highest/slowest point of the bounce; among the marked positions T is the highest point after the bounce where the ball is slowest, so it has the least kinetic energy. Hence least GPE at S and least KE at T.

Question 29

The following shows the energy conversions when using a product: Solar energy → Electrical energy → Kinetic energy + Heat energy + Sound energy. Which of the following products would bring about the energy changes shown above?

Accepted Answer

D. Solar charged remote control car. The product must convert electrical energy into kinetic (movement), heat and sound energy. A solar-charged remote control car moves (kinetic), its motor gives off heat, and it makes sound as it runs, matching all three outputs. An iron gives heat but no motion, a radio gives sound but no motion, and a calculator gives mainly light — none produce kinetic energy.

Question 30

A soccer player kicked a ball from point A to point B as shown below. Which one of the following graphs correctly shows the energy conversions that occur between A and B?

Accepted Answer

D. Graph 4 (PE rising, KE falling, crossing). As the ball rises from the ground at A up to the higher point B, it slows down, so its kinetic energy decreases while its gravitational potential energy increases as it gains height. The correct graph shows potential energy rising and kinetic energy falling (crossing over), which is graph 4.

P6 Science CA1 2012 — Methodist Girls

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