Q: The diagram below shows a flower. Which of the following is correct after pollination and fertilisation have taken place?

C. Develops into a seed: M; Develops into a fruit: N. In a flower, the ovule (M, inside the ovary) develops into the seed, and the ovary (N) develops into the fruit after pollination and fertilisation. L points to the stigma and K points to the style/anther region.

Q: Ralph observed two fruits, R and S, as shown below. Based on the diagrams above, which of the following shows the most likely dispersal methods for fruits R and S?

A. Fruit R: water; Fruit S: animals. Fruit R has a fibrous husk (7 cm) which traps air, making it buoyant and waterproof — typical of water-dispersed fruits (e.g. coconut). Fruit S (0.8 cm) has hook-like structures which catch onto animal fur, allowing it to be dispersed by animals.

Q: Which of the following statements are true for sexual reproduction in both plants and humans? A Pollination takes place before fertilisation. B Characteristics are passed on from parent to the young. C The male reproductive cell fuses with the female reproductive cell during fertilisation.

C. B and C only. Pollination is a process only in plants, not humans — so A is not true for both. B (inherited traits) and C (fusion of male and female reproductive cells = fertilisation) are true for both plants and humans.

Q: Study the flowchart below carefully. Which of the following correctly identifies parts P, Q and R?

C. P: testis, Q: ovary, R: womb. P is found in males → testis. Q is not in males but produces the female reproductive cell (egg/ovum) → ovary. R is not in males and does not produce the female reproductive cell → womb (uterus). Note: ovule is a plant term, not a human part.

Q: Which of the following traits can be inherited? A Eye colour B Length of hair C Type of earlobe D Length of fingernails

A. A and C only. Inherited traits are passed from parents to offspring through genes. Eye colour (A) and type of earlobe (C) are inherited. Length of hair (B) and length of fingernails (D) are not inherited — they depend on grooming/cutting, not genes.

Q: Three cells X, Y and Z are shown below. Which of the following gives the correct classification of the cells and function of part P?

C. Plant Cell: Y and Z; Animal Cell: X; Function of part P: controls all the activities in a cell. Cell X has no cell wall and no chloroplasts — it is an animal cell. Cells Y and Z have cell walls (rectangular outlines, Y also shows chloroplasts) — both are plant cells. Part P points to the nucleus in each cell, which controls all the activities in a cell.

Q: Ryan placed four identical fruits in four identical sealed boxes. He placed boxes A and B in the refrigerator and boxes C and D in a warm place. Substance K absorbs oxygen found in the box. Based on the information above, in which box(es) would fungus appear on the fruit?

A. C only. Fungus needs warmth, air (oxygen) and water to grow. Box A: cold (refrigerator) — too cold. Box B: cold + substance K absorbs oxygen — no warmth, no oxygen. Box C: warm + air + water → all conditions met → fungus grows. Box D: warm + water but substance K absorbs oxygen → no oxygen, no fungus.

Q: Fish use part X for gaseous exchange with the surroundings. Which of the following statements about part X is correct? A Part X is rich in blood vessels. B Part X absorbs water rich in oxygen. C Water flows over part X for the exchange of gases.

B. A and C only. Part X is the gill. Gills are rich in blood vessels for gaseous exchange (A correct). Water flows over the gills, and dissolved oxygen diffuses from the water into the blood (C correct). Gills do not absorb water — only oxygen — so B is wrong.

Question 1

The diagram below represents a life process that takes place in green plants on a bright day. Which one of the following correctly identifies S, T, U, V and X?

Accepted Answer

D. S: carbon dioxide, T: water, U: oxygen, V: sugar, X: light. The life process is photosynthesis. Green plants take in carbon dioxide (S) and water (T) from the environment, use light energy (X), release oxygen (U) to the environment, and produce sugar/glucose (V) which is stored in the plant.

Question 2

Containers, A, B and C, were set up with the same amount of carbon dioxide at the start of an experiment. For 12 hours, containers A and B were kept in the presence of light while container C was kept in darkness. Which one of the following shows the containers arranged according to the amount of carbon dioxide in them at the end of the experiment (least carbon dioxide → most carbon dioxide)?

Accepted Answer

C. B, C, A. Container B has a water plant + snails in light: the plant photosynthesises (uses CO2) faster than it and snails respire, so CO2 is the lowest. Container A has only snails in light: they only respire, releasing CO2 (no plant to use it). Container C has a snail in darkness: only respiration occurs, but in darkness no photosynthesis happens anywhere — A and C both only respire; however C has only 1 snail vs A's 2 snails, so A produces more CO2 than C. Order: B < C < A.

Question 3

The diagram below shows a flower. Which of the following is correct after pollination and fertilisation have taken place?

Accepted Answer

C. Develops into a seed: M; Develops into a fruit: N. In a flower, the ovule (M, inside the ovary) develops into the seed, and the ovary (N) develops into the fruit after pollination and fertilisation. L points to the stigma and K points to the style/anther region.

Question 4

Ralph observed two fruits, R and S, as shown below. Based on the diagrams above, which of the following shows the most likely dispersal methods for fruits R and S?

Accepted Answer

A. Fruit R: water; Fruit S: animals. Fruit R has a fibrous husk (7 cm) which traps air, making it buoyant and waterproof — typical of water-dispersed fruits (e.g. coconut). Fruit S (0.8 cm) has hook-like structures which catch onto animal fur, allowing it to be dispersed by animals.

Question 5

Which of the following statements are true for sexual reproduction in both plants and humans?
A Pollination takes place before fertilisation.
B Characteristics are passed on from parent to the young.
C The male reproductive cell fuses with the female reproductive cell during fertilisation.

Accepted Answer

C. B and C only. Pollination is a process only in plants, not humans — so A is not true for both. B (inherited traits) and C (fusion of male and female reproductive cells = fertilisation) are true for both plants and humans.

Question 6

Study the flowchart below carefully. Which of the following correctly identifies parts P, Q and R?

Accepted Answer

C. P: testis, Q: ovary, R: womb. P is found in males → testis. Q is not in males but produces the female reproductive cell (egg/ovum) → ovary. R is not in males and does not produce the female reproductive cell → womb (uterus). Note: ovule is a plant term, not a human part.

Question 7

Which of the following traits can be inherited?
A Eye colour
B Length of hair
C Type of earlobe
D Length of fingernails

Accepted Answer

A. A and C only. Inherited traits are passed from parents to offspring through genes. Eye colour (A) and type of earlobe (C) are inherited. Length of hair (B) and length of fingernails (D) are not inherited — they depend on grooming/cutting, not genes.

Question 8

Three cells X, Y and Z are shown below. Which of the following gives the correct classification of the cells and function of part P?

Accepted Answer

C. Plant Cell: Y and Z; Animal Cell: X; Function of part P: controls all the activities in a cell. Cell X has no cell wall and no chloroplasts — it is an animal cell. Cells Y and Z have cell walls (rectangular outlines, Y also shows chloroplasts) — both are plant cells. Part P points to the nucleus in each cell, which controls all the activities in a cell.

Question 9

Ryan placed four identical fruits in four identical sealed boxes. He placed boxes A and B in the refrigerator and boxes C and D in a warm place. Substance K absorbs oxygen found in the box. Based on the information above, in which box(es) would fungus appear on the fruit?

Accepted Answer

A. C only. Fungus needs warmth, air (oxygen) and water to grow. Box A: cold (refrigerator) — too cold. Box B: cold + substance K absorbs oxygen — no warmth, no oxygen. Box C: warm + air + water → all conditions met → fungus grows. Box D: warm + water but substance K absorbs oxygen → no oxygen, no fungus.

Question 10

Fish use part X for gaseous exchange with the surroundings. Which of the following statements about part X is correct?
A Part X is rich in blood vessels.
B Part X absorbs water rich in oxygen.
C Water flows over part X for the exchange of gases.

Accepted Answer

B. A and C only. Part X is the gill. Gills are rich in blood vessels for gaseous exchange (A correct). Water flows over the gills, and dissolved oxygen diffuses from the water into the blood (C correct). Gills do not absorb water — only oxygen — so B is wrong.

Question 11

Ari removed the food-carrying tubes of a plant at position L as shown in the diagram below. Ari then made the following predictions. Which of the following statements is correct?

Accepted Answer

A. The roots of the plant will die as they cannot receive food.. Food-carrying tubes (phloem) transport food made by leaves (above L) downwards to the roots. With phloem cut at L, food cannot reach the roots, so the roots will die. Water-carrying tubes (xylem) are intact, so leaves at both J and K still receive water — they will not wither.

Question 12

The food-carrying tubes of a stem were removed from a plant as shown below. The plant was left under the sun and watered every day. Part X was observed to be bigger after a month. Which of the following best explains the observation?

Accepted Answer

C. Food made in the leaves in section B was transported to and stored in part X.. The food-carrying tubes (phloem) were cut between section A and section B. Food made in leaves in section A cannot travel past the cut to reach part X (below). Only food made in leaves in section B (below the cut) can be transported down to part X, causing it to grow bigger.

Question 13

Study the diagram below. P, Q, R and S represent blood vessels. Based on the diagram above, which one of the following statements is not correct?

Accepted Answer

C. R contains less carbon dioxide than S.. Trace blood flow: Q goes from body to heart (deoxygenated, high CO2). R goes from heart to lungs (deoxygenated). S returns from lungs to heart (oxygenated, low CO2). P goes from heart to body (oxygenated). So R (going to the lungs) contains MORE carbon dioxide than S (returning from the lungs) — statement C is incorrect.

Question 14

The table below shows the characteristics of two animals, A and B. Which one of the following correctly shows what animals A and B might be?

Accepted Answer

B. A: butterfly; B: frog. Animal A: has 6 legs (insect), young does not look like adult (undergoes complete metamorphosis), both stages plant-eaters, lives only on land. Butterfly fits — caterpillar and adult both eat plants, spends life on land. Beetle (chicken/frog ruled out: chicken has 2 legs, frog needs water). Animal B: not 6 legs, young does not look like adult, not plant-eater throughout, not land-only — frog fits (4 legs, tadpole vs adult differ, eats insects as adult, lives in water and land).

Question 15

The graph below shows the number of days that insects L and M spend at each stage of their life cycle. Based on the information in the graph, which of the following statement(s) is/are correct?
A Insect L can be a beetle while insect M can be a grasshopper.
B Insect M spends a longer time in the adult stage than insect L.
C Both insects L and M take the same time for the young to develop into an adult after hatching from the egg.

Accepted Answer

B. B only. Insect L has all 4 stages (egg, larva, pupa, adult) → complete metamorphosis (e.g. beetle). Insect M has no pupa stage → incomplete metamorphosis (e.g. grasshopper). A is wrong because grasshopper would have no pupa, but the question reads it could be M, but M shows pupa=2 days so M cannot be grasshopper either — wait, M has pupa=2 from graph, so the claim 'M can be grasshopper' is wrong since grasshoppers have no pupa stage. B is correct: M adult (21 days) > L adult (~14 days). C is wrong: L takes 12+6=18 days from egg-hatch to adult; M takes 12+2=14 days — not the same.

Question 16

Study the flowchart below. Based on the flowchart, which of the following correctly identifies human body systems A, B, C and D?

Accepted Answer

C. A: Skeletal, B: Muscular, C: Circulatory, D: Digestive. Causes movement + made of bones → Skeletal (A). Causes movement but not bones → Muscular (B). Does not cause movement but transports substances → Circulatory (C). Does not cause movement and does not transport (in this dichotomy) → Digestive (D).

Question 17

Wendy wanted to conduct an experiment to test the following hypothesis: An object with a greater mass possesses more potential energy when it is above the ground. She set up four blocks using strings of different lengths as shown below. Which two blocks should she use to test her hypothesis?

Accepted Answer

D. Blocks C and D. To test the effect of mass on potential energy, only mass should differ — height must be the same. Blocks C (5 kg, 1.8 m) and D (10 kg, 1.8 m) have the same height but different masses. This isolates the variable (mass).

Question 18

The diagram below shows a cart on a track. At which point would the cart have the greatest amount of potential energy?

Accepted Answer

A. Point P. Potential energy increases with height. Point P is at the top of the highest hill on the track. The cart therefore possesses the greatest amount of (gravitational) potential energy at point P.

Question 19

Sam used a trolley to push some boxes for delivery. He observed that the trolley moved more easily as each box was taken out. Which of the following statement(s) is/are correct?
A There is less frictional force between the trolley and the ground when there are fewer boxes.
B There is more gravitational force acting on the trolley and boxes as each box was taken out.
C The amount of frictional force between the trolley and the ground is not affected by the number of boxes in the trolley.

Accepted Answer

A. A only. Fewer boxes → less weight on the trolley → less frictional force between trolley wheels and ground → easier to push. A is correct. B is wrong — removing boxes reduces total mass, so gravitational force on trolley + boxes decreases. C is wrong — friction IS affected by the load (fewer boxes = less friction).

Question 20

The diagram below shows a beam balance with objects S and T hung at both ends. Both objects are of the same mass. The diagram below shows what happens when an object, X, is placed below object T. Based on the observations above, which one of the following best describes objects T and X?

Accepted Answer

B. Object T: Steel block; Object X: Magnet. S and T have the same mass and balance initially. When X is placed below T, the T side tips down — extra downward pull on T. This means T and X attract each other (magnetic attraction). T must contain magnetic material and X must be a magnet (or vice versa). Option B: T = steel block (magnetic), X = magnet → strong attraction. Aluminium and plastic are non-magnetic; wood is non-magnetic — only B works.

Question 21

Sophie arranged four circuits, A, B, C and D, using batteries and bulbs that were working. Which of the following will Sophie most likely observe?

Accepted Answer

B. For B and D, both bulbs will light up in each circuit.. In circuits B and D, both batteries are oriented in the same direction (+ to − aligned), so current flows and both bulbs light up. In circuits A and C, the two batteries are connected with opposing terminals (positive against positive or negative against negative), so the voltages cancel out and no current flows — no bulbs light up.

Question 22

The diagram shows four working bulbs, B1, B2, B3 and B4 and four switches, S1, S2, S3 and S4 in a circuit. Which of the following shows the correct observation when the following switches are open?

Accepted Answer

C. Open switch(es): S3; Observation: Only B1, B2 and B4 light up.. Bulb B1 is in series with S1, B3 with S3, B4 with S4; S2 is in the main branch connected through B2 (or the battery line). When only S3 is open: B3 cannot light, but the rest of the circuit remains complete through their respective switches (S1, S2, S4 closed) so B1, B2 and B4 light up — matches option C.

Question 23

Which of the following actions help to conserve electricity?
A Use renewable sources of energy.
B Choose energy-efficient appliances.
C Turn on the air-conditioner instead of the fan.
D Allow hair to dry naturally instead of using the hairdryer.

Accepted Answer

C. B and D only. Conserving electricity means using LESS electricity. B (energy-efficient appliances) and D (not using a hairdryer) both reduce electricity use. A (renewable sources) is about source, not reducing consumption — does not conserve electricity used. C (aircon uses MORE electricity than fan) is the opposite of conservation.

Question 24

Tyler wanted to find out how much light can pass through three different materials, A, B and C. He placed material A between a light source and a light sensor and recorded the amount of light detected by the light sensor. He repeated the experiment using materials B and C. There was only one light source in the room. Based on the results, which of the following could represent materials A, B and C?

Accepted Answer

C. A: cardboard, B: clear plastic, C: tracing paper. A blocks all light (0 units) → opaque → cardboard. B allows most light through (90 units, close to 100 with no material) → transparent → clear plastic. C allows some light through (65 units) → translucent → tracing paper.

Question 25

Geetha sat for a test in the air-conditioned school hall for two hours. She had left 2 rulers on her table and they were unused throughout the test. She then picked up both rulers to keep in her pencil case and noticed that the metal ruler was colder than the wooden ruler. Which of the following is the correct explanation for her observation?

Accepted Answer

B. Geetha lost more heat to the metal ruler when she held it.. Both rulers had been in the same air-conditioned hall for 2 hours, so they were both at the same (cool) room temperature — D is wrong. The metal ruler feels colder because metal is a better conductor of heat than wood, so Geetha's hand loses heat to the metal ruler faster than to the wooden ruler. The sensation 'colder' = faster heat loss from her hand.

Question 26

The diagram below shows a 500 cm³ jar. It contains 200 cm³ of water. When the plunger was pushed all the way down, 150 cm³ of air in the pump went into the jar. What was the volume of the air in the jar after the plunger was pushed down?

Accepted Answer

B. 300 cm³. Jar capacity = 500 cm³. Water inside the jar = 200 cm³, so initial air space in the jar = 500 − 200 = 300 cm³. After the plunger was pushed down, an additional 150 cm³ of air was added to the jar. Air occupies all available space. Total air now in the jar = 300 + 150 = 450 cm³? But water occupies only 200 cm³ and the jar is 500 cm³, so air still occupies 300 cm³ of the jar — the extra 150 cm³ of air compresses with the existing air, but the total volume the air takes inside the rigid sealed jar is still 300 cm³ (the space above the water).

Question 27

Tristan used the stroke method to magnetise four identical iron nails, W, X, Y and Z. He stroked the nails 15, 30, 45 and 60 times respectively. He then brought each iron nail close to a paper clip and measured the greatest distance from where the magnetised iron nail could start to attract the paper clip. He repeated his experiment three times. What was the aim of his experiment?

Accepted Answer

A. To find out how the number of times an iron nail is stroked affects its magnetic strength.. The independent variable is the number of strokes (15, 30, 45, 60). The dependent variable measured is the greatest distance at which the nail attracts a paper clip — this distance is an INDICATOR of magnetic strength. So the aim is to find out how the number of strokes affects magnetic strength.

Question 28

A magnet and a steel bar were fixed to a wall as shown below. Two rods, X and Y, were brought close to the magnet and steel bar. The table below shows the observations made. Which of the following correctly identifies rods X and Y?

Accepted Answer

C. Rod X: iron rod; Rod Y: magnet. Rod X: attracted by magnet and no effect with steel bar → X is a magnetic material that isn't a magnet itself (a magnet would attract the steel bar). X = iron rod. Rod Y: shows REPULSION with the magnet → only a magnet can repel a magnet. Y also attracts the steel bar (magnets attract steel). Y = magnet.

P6 Science SA2 2021 — Nanyang

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