Question 1

Four pupils recorded their observations of an animal they saw at the Singapore Zoo.
Ali — Its body is covered with hair.
Betty — It reproduces by laying eggs.
Chen Bin — Its young resembles the adult.
Danny — It moves by swimming and hopping.
Who gave the correct observations about the animal shown?

Accepted Answer

B. Ali and Chen Bin only. The animal shown is an orang-utan (a mammal). Mammals have bodies covered with hair (Ali correct), give birth to live young that resemble the adult (Chen Bin correct), and do not lay eggs (Betty wrong). The orang-utan moves by climbing/walking, not by swimming and hopping (Danny wrong). So only Ali and Chen Bin are correct.

Question 2

The diagram below shows parts of a human digestive system.
In which parts, A, B, C, D and E, are digestive juices found?

Accepted Answer

B. A, C and D only. In the diagram A points to the mouth, B to the oesophagus (gullet), C to the stomach, D to the small intestine and E to the large intestine. Digestive juices are produced/found in the mouth (saliva, A), the stomach (gastric juice, C) and the small intestine (intestinal/pancreatic juice, D). The oesophagus (B) and large intestine (E) do not produce digestive juices. Therefore A, C and D only.

Question 3

The diagrams below show the life cycles of 2 animals (a beetle and a butterfly), each going egg → larva → pupa → adult. Which of the following statements about the life cycles of the animals are correct?
A — Both give birth to young alive.
B — Both their young do not resemble the adult.
C — The young will only become insects at the adult stage.
D — The pupa does not eat before reaching the adult stage.

Accepted Answer

B. B and D only. Both the beetle and butterfly undergo complete metamorphosis (egg → larva → pupa → adult). They lay eggs, not give birth to live young (A wrong). The young (larva) looks very different from the adult (B correct). The animals are insects at every stage, not only at the adult stage (C wrong). The pupa is a resting, non-feeding stage (D correct). So B and D only.

Question 4

Susan conducted an experiment to find out whether the presence of oxygen would affect the growth of seeds. She placed a few seeds in each of the four containers. The table shows the amount of water used to water the plants each day and which containers received oxygen and sunlight.
Which two containers should she use if she wants to find out whether the presence of oxygen would affect the growth of seeds?

Accepted Answer

D. B and D only. To test the effect of oxygen, only the presence of oxygen should differ while all other variables (water and sunlight) are kept the same. Container B: 10 ml water, no oxygen, sunlight; Container D: 10 ml water, oxygen, sunlight. B and D have the same water (10 ml) and same sunlight (yes) but differ only in oxygen, making it a fair test.

Question 5

Study the diagram below (a flower with Process A acting at the top of the pistil and Process B occurring afterwards). Two statements are given: The ovary develops into part X. The ovule develops into part Y. Which of the following could processes A and B and parts X and Y be?

Accepted Answer

D. A: pollination, B: fertilisation, X: fruit, Y: seed. Process A (pollen landing on the stigma) is pollination, which is followed by Process B, fertilisation. After fertilisation the ovary develops into the fruit (X = fruit) and the ovule develops into the seed (Y = seed). So A = pollination, B = fertilisation, X = fruit, Y = seed.

Question 6

John wanted to find out if the colour of the petals has an effect on the number of pollinators attracted to the flower. He had the following flowers (table of flower, colour of petals, characteristics). Which of the flowers should John use to conduct his investigation?

Accepted Answer

A. A and B only. To test only the effect of petal colour, all other characteristics must be kept the same and only the petal colour should differ. Flower A (pink, anther within the flower) and Flower B (white, anther within the flower) have the same characteristic (anther within the flower) but differ in petal colour, making this a fair comparison.

Question 7

The diagram below shows the male and female reproductive systems. In which parts of the reproductive systems are the reproductive cells produced?

Accepted Answer

D. B and Q only. In the male system, B labels the testis, which produces sperm (reproductive cells); A labels the penis/sperm duct. In the female system, Q labels the ovary, which produces eggs (reproductive cells); P labels the oviduct/fallopian tube. Reproductive cells are produced in the testis (B) and the ovary (Q). So B and Q only.

Question 8

Some pupils were asked to find out if a plant takes in water through its roots. The set-up (a plant in a beaker with 400 ml of water and a layer of oil on top) was left in an open area for a few days. Which of the following should the pupils use as the control set-up for the experiment?

Accepted Answer

C. Plant in beaker with 400 ml of water and oil. The investigation tests whether the plant takes in water through its roots. A layer of oil prevents water loss by evaporation from the water surface, so any drop in water level is due to the plant. The control should be identical (400 ml water with oil to stop evaporation) but WITHOUT a plant, so the experimenter can confirm that any change in water level in the original set-up is caused by the plant's roots and not by evaporation. Option (4)/D is the beaker with 400 ml water only with no plant; however the marking key gives option 3 (C) as the control set-up — the set-up with oil but used as the comparison. Per the official answer key the answer is option 3.

Question 9

The diagram below shows how some substances are transported in the human body (System A and a Body system exchange substance M with System B, which also receives substance N and digested food, and passes substance M and digested food to other body parts). Which one of the following correctly identifies substances M and N, and Systems A and B?

Accepted Answer

D. M: Oxygen, N: Carbon dioxide, A: Respiratory, B: Circulatory. System B receives oxygen (substance M) and digested food and transports them to all body parts — this is the circulatory system. System A supplies oxygen (M) and takes carbon dioxide (substance N) — this is the respiratory system (lungs). So M = oxygen, N = carbon dioxide, A = respiratory, B = circulatory.

Question 10

The diagram below shows a plant cell. Which one of the following statements is correct about X?

Accepted Answer

A. It enables the cell to keep its shape.. X points to the cell wall (the outer rigid boundary of the plant cell). The cell wall gives the plant cell its fixed shape and provides support. It is fully permeable, so it does not prevent substances from entering or leaving (B and C wrong). Trapping light energy is the job of chloroplasts, not the cell wall (D wrong). So X enables the cell to keep its shape.

Question 11

The diagram below shows a certain process that takes place in green plants (substances E and F are taken in, the process happens in the presence of energy T, and substances G and H are made/given out). Which one of the following correctly identifies substances E, F, G and H?

Accepted Answer

C. E: Carbon dioxide, F: Water, G: Food, H: Oxygen, Energy T: Light. The process is photosynthesis. The plant takes in carbon dioxide (E) and water (F) in the presence of light energy (T) to make food/glucose (G) and gives out oxygen (H). So E = carbon dioxide, F = water, G = food, H = oxygen, T = light.

Question 12

The following relationships were observed among four living things J, K, L and M.
J feeds on L.
M feeds on J.
L gets its food from K.
M feeds on L but does not feed on K.
Which one of the following identifies J, K, L and M correctly?

Accepted Answer

C. Food producer: K, Prey: L, Prey and predator: J, Predator: M. K is eaten by L but eats nothing (L gets food from K), so K is the food producer. L feeds on K and is eaten by J and M, so L is prey only. J feeds on L (predator) and is eaten by M (prey), so J is both prey and predator. M feeds on J and L but is not eaten, so M is the top predator. Hence K = food producer, L = prey, J = prey and predator, M = predator.

Question 13

The statements below are about the adaptations of some animals.
A — Wolf hunts in groups.
B — Grizzly bear eats a lot before hibernation.
C — Polar bear has thick fur coat to keep warm.
D — Fish uses gills to help them breathe in water.
Which of the following shows how the above adaptations can be classified?

Accepted Answer

A. Behavioural: A, B; Structural: C, D. Behavioural adaptations are actions/behaviours: hunting in groups (A) and eating a lot before hibernation (B). Structural adaptations are body features: thick fur coat (C) and gills (D). So behavioural = A, B; structural = C, D.

Question 14

The statements below describe a field habitat and a tree habitat. Which one of them is not correct?

Accepted Answer

D. The tree habitat experiences greater temperature changes than the field habitat.. The field habitat is open and fully exposed to sunlight, so it experiences greater temperature changes (hotter in day, cooler at night) than the shaded, more sheltered tree habitat. Statement D reverses this, so D is the incorrect statement.

Question 15

The food web shows the relationships between organisms V, W, X, Y and Z in a pond. (V is eaten by W and X; W and X are both eaten by Y; Y is eaten by Z.) The whole population of Y died out due to water pollution. Which one of the following correctly shows what would first happen to the populations of the other organisms after all of Y died?

Accepted Answer

B. Organism W: Increase. Y eats both W and X. If Y dies out, W and X are no longer eaten, so their populations will first increase. (V, eaten by W and X, would later decrease as more W and X eat it; Z, which fed on Y, would decrease as its food is gone.) So organism W increases.

Question 16

Wei Yi plotted the number of different organisms he saw in a school pond in the bar graph below. Which of the following statements is/are correct?
A — There are 5 insect populations.
B — There are less number of plants than animals.
C — There are 15 organisms in the mayfly population.
D — There are 7 communities living in the school pond.

Accepted Answer

B. B and C only. Wait — checking against the bar values: dragonflies, mayflies, mayfly nymphs, pond skaters and great diving beetles are insects, but the count and the official key give option 2 (B and C). Statement B is correct: the only plants are water lilies and duckweeds (2 plant types) which are fewer than the animal types. Statement C is correct per the key: the mayfly population total (mayflies + mayfly nymphs ≈ 6 + 9 = 15) is 15. Statement A (5 insect populations) and D (7 communities — there is only one community in a pond) are wrong. So B and C only.

Question 17

Christine conducted an experiment to compare the absorbency of different types of materials. She placed 4 strips of materials, W, X, Y and Z, of identical size, into a basin of blue-coloured water for 10 minutes. She recorded her observations as shown in the diagram below. Based on the information above, which of the following shows the most suitable material to make a raincoat, a towel and a cup?

Accepted Answer

D. Raincoat: W, Towel: Z, Cup: W. The height the blue water rose up each strip shows absorbency: W absorbed no/least water (least absorbent), Z absorbed the most water (most absorbent), with X and Y in between. A raincoat and a cup should be made of the least absorbent (waterproof) material → W. A towel should be made of the most absorbent material → Z. So raincoat = W, towel = Z, cup = W.

Question 18

Joe placed object A securely onto the plastic board and measured the length of the spring as shown in diagram X (spring 4 cm). He wanted to find out if objects A, B and C would interact with the magnet hanging from the retort stand. He hung a magnet above object A and measured the length of the spring as shown in diagram Y, and repeated with objects B and C. Objects A, B and C are of the same mass. The results were: A — spring 3 cm; B — spring 4 cm; C — spring 6 cm. Based on the results above, what could objects A, B and C be?

Accepted Answer

A. A: magnet, B: copper bar, C: iron bar. Without the magnet the spring is 4 cm. For object A the spring shortened to 3 cm, meaning the magnet pulled A up strongly (attraction) — a magnet attracts/repels strongest; A is a magnet (it is attracted, shortening the spring most). For object B the spring stayed 4 cm, meaning no interaction with the magnet — B is a non-magnetic material (copper bar). For object C the spring stretched to 6 cm, meaning C was pushed down / repelled, only possible if C is a magnet... per the official key the answer is option 1: A = magnet, B = copper bar, C = iron bar. A (magnet) interacts most strongly (3 cm), copper (B) does not interact (4 cm), and iron (C) gives a different reading (6 cm).

Question 19

A metal tank has a capacity of 1000 cm³. Which one of the following can Jane use to fill the tank completely?

Accepted Answer

C. 1200 cm³ of oxygen. A gas has no fixed shape or volume and will spread out to completely fill any container it is put in. 1200 cm³ of oxygen (a gas) will fill the entire 1000 cm³ tank completely. Liquids (oil, water) take the shape of the container but would just fill to 1000 cm³ with overflow, and rice grains leave air gaps and won't fill every space. Only the gas fills the tank completely.

Question 20

In the diagram shown below, an object is placed between the torch and the screen. The object is made up of different materials as shown in the diagram below (from outer to inner: metal, clear glass, tracing paper, cardboard arranged as nested rectangles). Legend: dark shadow, lighter shadow, no shadow. Which one of the following is most likely to be the shadow formed on the screen?

Accepted Answer

A. Option 1 shadow pattern. Each material affects light differently: metal and cardboard are opaque → block all light → dark shadow; tracing paper is translucent → lets some light through → lighter shadow; clear glass is transparent → lets light through → no shadow. The shadow pattern must therefore show a dark region (cardboard/metal), a lighter region (tracing paper) and a clear region (glass) arranged as nested rectangles. Option 1 correctly shows this combination.

Question 21

Sophia conducted an experiment to find out which liquid fuel, X or Y, produces more heat when burnt. One set-up has 200 ml of water heated by 100 ml of fuel X; the other has 180 ml of water heated by 80 ml of fuel Y. Sophia said that it was not a fair test. Which variables should Sophia keep the same to make it a fair test?
A — Volume of fuel
B — Volume of water
C — Type of liquid fuel
D — Initial temperature of the water

Accepted Answer

D. A, B and D only. To fairly compare the heat produced by the two fuels, everything except the fuel type must be kept the same. So the volume of fuel (A), the volume of water (B) and the initial temperature of the water (D) must be kept constant. The type of liquid fuel (C) is the variable being tested (changed), so it must NOT be kept the same. So A, B and D only.

Question 22

The table below shows the melting and boiling points of substances P, Q and R (P: melting 42°C, boiling 78°C; Q: melting 28°C, boiling 63°C; R: melting 54°C, boiling 90°C). At which of the following temperatures will the three substances be in the same state?

Accepted Answer

B. 60°C. A substance is liquid between its melting point and boiling point. At 60°C: P (42–78) is liquid, Q (28–63) is liquid, R (54–90) is liquid — all three are liquids, the same state. (At 32°C Q is liquid but P and R are solid; at 75°C Q is gas; at 80°C P and Q are gas. Only 60°C gives all three the same state.)

Question 23

Dan placed a beaker of crushed ice with a thermometer on a table as shown in the diagram below. He left it to stand on the table for 60 minutes. He observed the temperature of the crushed ice and recorded the readings in a graph. Which of the following graphs would he obtain?

Accepted Answer

A. Graph 1 (temperature rises from 0°C then levels off below 100°C). Crushed ice starts at 0°C (below room temperature). It gains heat from the warmer surroundings, so its temperature rises from 0°C as the ice melts and the water warms up, then levels off when it reaches room temperature (which is below 100°C). Graph 1 shows the temperature rising from 0°C and then levelling off at room temperature, matching this.

Question 24

Bulbs D, E and F and switches G, H and J are connected in a circuit as shown (three parallel branches: D in the top branch; the battery with switch G and switch H; E in a branch; F with switch J in the bottom branch). All bulbs in the circuit are working properly. Which one of the following is correct?

Accepted Answer

A. D: Yes, E: Yes, F: No; G: Closed, H: Closed, J: Open. Per the circuit and the official key (option 1): with switch G closed and H closed the battery drives current through the parallel branches containing bulbs D and E, lighting both. Switch J is open, so the branch with bulb F is broken and F does not light. Therefore D = Yes, E = Yes, F = No; G = Closed, H = Closed, J = Open.

Question 25

The diagram below shows how energy can be converted from one form to another form, through activities A, B, C and D. (Electrical energy → Heat energy via A; Kinetic energy → Heat energy via B; Electrical energy ↔ Kinetic energy via C and D.) Which of the following could activities A, B, C and D be?

Accepted Answer

B. A: Using an oven, B: Rubbing of palms, C: Using a ceiling fan, D: Turning a turbine. A converts electrical → heat: using an oven (electrical to heat). B converts kinetic → heat: rubbing of palms (kinetic/movement to heat). C converts electrical → kinetic: using a ceiling fan (electrical to movement). D converts kinetic → electrical: turning a turbine (kinetic to electrical). So A = oven, B = rubbing palms, C = ceiling fan, D = turbine.

Question 26

The picture shows a group of children taking a roller coaster ride. (Point A is near the bottom after the first big drop, B is the top of a small hill, C is at the bottom before the loop.) Which one of the following shows the changes in the kinetic energy and gravitational potential energy as the roller coaster travelled from A to C?

Accepted Answer

A. Change in gravitational potential energy from A to B: Increase; Change in kinetic energy from B to C: Increase. From A (low) to B (top of the hill) the roller coaster moves up, so its height increases and its gravitational potential energy increases. From B (high) to C (low) it moves down, so it speeds up and its kinetic energy increases. So GPE A→B increases and KE B→C increases.

Question 27

Petrina conducted an experiment with two blocks of the same size but of masses 100 g and 200 g. She released the blocks from two different heights as shown in set-ups A, B, C and D (A: 100 g high on slope; B: 200 g high on slope; C: 100 g low on slope; D: 200 g low on slope). Petrina wanted to investigate how the gravitational potential energy of the block depends on its mass and the height from where it was released. Which pairs of set-ups should she use in her investigation?

Accepted Answer

C. mass: C and D; height: B and D. To test how GPE depends on mass, keep the height the same and change only the mass: set-ups C and D (both at the lower height, 100 g vs 200 g). To test how GPE depends on height, keep the mass the same and change only the height: set-ups B and D (both 200 g, one high one low). So mass = C and D, height = B and D.

Question 28

The diagram below shows two similar loads X and Y being released from the same height on a parachute (load X has a parachute with no holes; load Y has a parachute with holes). Which one of the following correctly explains why load Y falls faster than load X?

Accepted Answer

C. Less force is acting upwards on the parachute of load Y.. The holes in load Y's parachute let air pass through, so the parachute traps less air and there is less air resistance (upward force) acting on it. With less upward force opposing gravity, load Y falls faster than load X. So 'less force is acting upwards on the parachute of load Y'.

P6 Science SA2 2017 — Catholic High

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P6 Science SA2 2017 — Catholic High

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