Question 1

Which animal has a 3-stage life cycle?

Accepted Answer

D. grasshopper. Grasshopper undergoes incomplete metamorphosis with a 3-stage life cycle: egg → nymph → adult. Beetle, butterfly and mosquito all have 4-stage life cycles (egg → larva → pupa → adult).

Question 2

Which animal has a pupa as a stage in its life cycle?

Accepted Answer

C. mosquito. Only insects with complete metamorphosis have a pupa stage. Among the options, only the mosquito (egg → larva → pupa → adult) passes through a pupa stage. Frogs go through tadpoles, chickens hatch from eggs to young to adult, and cockroaches have incomplete metamorphosis (no pupa).

Question 3

The diagram shows the life cycle of a plant. What is the stage marked X?

Accepted Answer

D. young plant. The life cycle of a flowering plant is: seed → young plant (seedling) → adult plant → seed (again via flowering). The stage X comes after the seed germinates but before the adult plant, so X is a young plant (seedling).

Question 4

In which part of the digestive system is water absorbed?

Accepted Answer

D. large intestine. The large intestine absorbs water from the undigested food, leaving behind solid waste (faeces). The small intestine mainly absorbs digested nutrients, the stomach digests food, and the mouth chews and mixes food with saliva.

Question 5

The diagram below shows a pair of spectacles. The frame of the spectacles is made of metal because metal ____.

Accepted Answer

C. does not break easily. Spectacle frames need to be strong and durable so they do not break easily during everyday handling. Reflecting light, sinking in water and being opaque are not the relevant properties for a spectacle frame.

Question 6

Matter is anything that has mass and occupies space. Which one of the following is NOT matter?

Accepted Answer

C. shadow. Air (gas), flour (solid) and orange juice (liquid) all have mass and occupy space, so they are matter. A shadow is only an absence of light; it has no mass and does not occupy space, so it is not matter.

Question 7

Which one of the following is a source of light?

Accepted Answer

C. sun. A source of light produces its own light. The sun produces its own light from nuclear reactions. The moon only reflects sunlight, while grapes and clouds do not give off their own light.

Question 8

Which one of the following is NOT a source of heat?

Accepted Answer

D. A woolen jacket. A source of heat produces its own heat. The sun, a lighted bulb and a lighted candle all give off heat. A woolen jacket only traps and reduces heat loss from the body; it does not produce its own heat.

Question 9

Lucy places a metal spoon in a bowl of hot soup as shown below. After a while, the spoon becomes hot. Which one of the following explains this?

Accepted Answer

C. The spoon gains heat from the soup.. Heat always flows from a hotter object to a cooler object. The hot soup is at a higher temperature than the spoon, so heat is transferred from the soup to the spoon. The spoon gains heat and becomes hot.

Question 10

In which one of the following would the two magnets push each other away?

Accepted Answer

C. A horizontal bar magnet labelled N (left) S (right) next to a vertical bar magnet labelled S (top) N (bottom).. Like poles repel; unlike poles attract. In option C, the right end of the horizontal magnet is S and the top of the vertical magnet (facing it) is also S, so the two like (S–S) poles push each other away.

Question 11

The diagram below shows how a plant grows from a seed over a period of time. At which stage(s) of its growth, A, B, C or D, is/are the plant NOT able to make its own food?

Accepted Answer

B. A and B only. Plants make food (photosynthesis) in their green leaves. At stage A (seed) and stage B (just-germinated shoot), the plant has no green leaves yet, so it cannot make its own food. At stages C and D the plant has leaves and can photosynthesise.

Question 12

The graph below shows the number of days in each stage of the life cycle of insect Y. Based on the graph above, which of these statements about insect Y is NOT correct?

Accepted Answer

C. Insect Y takes thirty days to become an adult.. From the graph: egg = 4 days, larva = 12 days, pupa = 8 days, adult = 6 days. Insect Y becomes an adult after egg + larva + pupa = 4 + 12 + 8 = 24 days, not 30 days. Statement C is therefore NOT correct.

Question 13

The diagram below shows part of the large intestine in the digestive system. Substances P and Q are found in the large intestine. Which one of the following identifies substances P and Q correctly?

Accepted Answer

C. P: undigested food; Q: water. The large intestine absorbs water from undigested food into the bloodstream; the undigested food (P) remains in the intestine while water (Q) is absorbed across the wall into surrounding blood vessels.

Question 14

The diagram below shows a plant. Which one of the following identifies the function of the parts W, X and Y correctly?

Accepted Answer

A. W: makes food for the plant; X: transports water and food to all parts of the plant; Y: holds the plant firmly to the ground. W are the leaves (make food by photosynthesis), X is the stem (transports water and food), and Y are the roots (hold the plant firmly in the ground and absorb water).

Question 15

James wanted to find out if the amount of roots affect the volume of water absorbed by a plant. He placed the two set-ups near a window as shown below. He recorded the volume of water left in the beaker for five days. Which one of the following graphs shows his results correctly?

Accepted Answer

A. Volume of water decreases over time for both P and Q, with P decreasing faster (lower final volume) than Q.. Plant P has more roots than plant Q, so it absorbs water from the beaker faster. The volume of water remaining in beaker P decreases more quickly than in beaker Q. A layer of oil prevents evaporation, so any water loss is due to absorption by the roots.

Question 16

Joy set up an experiment as shown below to test the absorbency of four different materials, R, S, T and U. The materials are of identical length, size and thickness. After half an hour, Joy removed the materials from the basin and string and measured the distance 'd' of each material that was stained blue. She recorded the results in the table below. The umbrella as shown below is used to keep Joy dry on a rainy day. Based on the results in the above table, which material is most suitable to make part Y of the umbrella?

Accepted Answer

A. R. Part Y is the canopy of the umbrella which must keep rainwater out, so the most suitable material is the least absorbent (most waterproof) one. Material R had distance d = 0 cm stained blue, meaning it absorbed no water — it is the most waterproof.

Question 17

Sam used some clay to make a cylinder. Then he reshaped the same piece of clay that was used to make the cylinder into a cube as shown in diagrams below. In what ways are the cylinder and cube similar to each other? Both the cylinder and the cube have the same ____. A: mass; B: shape; C: volume

Accepted Answer

C. A and C only. Reshaping the same piece of clay does not change the amount of matter or the space it occupies, so the mass (A) and volume (C) stay the same. Only the shape changes (cylinder → cube), so B is not a similarity.

Question 18

Alex wanted to find out the mass of the lemons using the set-up shown in the diagram below. He placed five lemons and a wooden block on a balance. He repeated the experiment by replacing the wooden block with other wooden blocks of different masses. Then he recorded his observations in the table below. Based on the results above, which one of the following is most likely to be the mass of five lemons?

Accepted Answer

B. 650 g. At 500 g and 600 g the lemons side (X) goes down — lemons are heavier than 600 g. At 700 g and 800 g the wooden side (W) goes down — lemons are lighter than 700 g. So the mass of the lemons is between 600 g and 700 g, and 650 g is the only value in that range.

Question 19

Which one of the following statements about light is NOT correct?

Accepted Answer

A. Light occupies space.. Light is a form of energy. It travels in straight lines and can be reflected. However, light is not matter — it does not have mass and does not occupy space. Therefore statement A is NOT correct.

Question 20

The diagram below shows the layout of the stage for a puppet performance. Three puppets, A, B and C, were placed between the light source and the screen. The three puppets were of the same height but different shapes. The audience saw the shadows of the puppets cast on the screen as shown below. Which one of the following shows the correct position of the three puppets, A, B and C?

Accepted Answer

D. Light source at top; A nearest to light, C in middle, B on the screen.. A puppet placed closer to the light source casts a larger shadow; a puppet placed closer to the screen casts a smaller shadow. The shadows show A (tree) as the largest, C (house) as medium, and B (cat) as the smallest. So A must be nearest the light, C in the middle, and B nearest the screen — matching option D.

Question 21

The diagram below shows a picture of an opened umbrella. The opened umbrella was placed between a light source and a screen in different positions. Which one of the following is NOT likely to be the shadow of the opened umbrella?

Accepted Answer

C. A solid circular shadow with a short rectangular stick attached at the side.. Depending on the orientation of the umbrella, possible shadows include a side-on dome with a curved or straight handle, or, when viewed end-on along the handle's axis, a full circular disc with no handle visible. A circular dome with the handle sticking out sideways (option C) does not match any orientation of the umbrella, so it is NOT a possible shadow.

Question 22

Kate filled three pails, X, Y and Z, with the same amount of water with different temperatures. Kate dipped her left hand into pail X and right hand into pail Y for three minutes. She then put both her hands into pail Z. Which one of the following correctly describes how Kate's hands felt in pail Z?

Accepted Answer

C. Left Hand: warmer; Right Hand: cooler. The left hand was in cold water at 10 °C and then moved into water at 30 °C — heat now flows from the warmer water to the hand, so it feels warmer. The right hand was in hot water at 55 °C and then moved into water at 30 °C — heat now flows from the hand to the cooler water, so it feels cooler.

Question 23

Peter poured the same volume of water at 25°C into two identical containers, A and B, as shown below. Both containers A and B were placed on a heater. After 15 minutes, which one of the following comparisons of the amount of heat in the water in both containers and explanation is correct?

Accepted Answer

C. Water in container A had more heat than the water in container B. Container A had a larger surface area in contact with the heater and gained more heat.. Container A is wider and has a larger base in contact with the heater than container B, so heat is transferred to A at a faster rate. After 15 minutes the water in A has gained more heat than the water in B.

Question 24

A tray of iron pins is placed below the magnets of identical size. The diagram below shows the different number of iron pins that are attracted to the different magnets A, B, C and D. Based on the observations above, which one of the following is the strongest magnet?

Accepted Answer

A. A. The strength of a magnet can be compared by the number of iron pins it can attract over the same distance. Magnet A attracted iron pins from the greatest distance (the pins were lifted highest from the tray), so A is the strongest magnet.

Question 25

Jane hung object X on a spring as shown in diagram 1. Then she placed object Y directly below object X. She observed that the length of the spring became shorter as shown in diagram 2. Based on her observations, which of the following statement(s) is/are correct? A: Objects X and Y were magnets. B: Unlike poles of objects X and Y were facing each other. C: Object X was non-magnetic and object Y was a magnet.

Accepted Answer

A. A only. The spring became shorter, meaning object X was pushed upwards by object Y — a repulsion force. Repulsion only occurs between two magnets with like poles facing each other. So both X and Y must be magnets (A is correct). Unlike poles would attract, not repel, so B is wrong. A non-magnetic X cannot be repelled, so C is wrong.

P4 Science SA2 2020 — Raffles Girls

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