Question 1

Which animal has a 4-stage life cycle?

Accepted Answer

(3) butterfly. A 4-stage life cycle (complete metamorphosis) includes egg, larva, pupa, and adult stages. Butterflies undergo complete metamorphosis. Cockroaches and grasshoppers have 3-stage life cycles (incomplete metamorphosis: egg, nymph, adult). Frogs have a 3-stage life cycle (egg, tadpole, adult frog) but it's not considered incomplete metamorphosis in the same way insects are classified.

Question 2

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

Accepted Answer

(4) grasshopper. A nymph stage is part of an incomplete metamorphosis, where the young resembles a smaller version of the adult without a pupal stage. Grasshoppers undergo incomplete metamorphosis, having egg, nymph, and adult stages. Frogs have a tadpole stage, beetles have a larval and pupal stage (complete metamorphosis), and chickens hatch directly from eggs as chicks.

Question 3

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

Accepted Answer

(3) adult plant. The diagram illustrates a plant life cycle: Seed → Z → Adult Plant → Seed. Stage Z depicts a plant that has germinated from a seed and is growing, which is typically referred to as a young plant or seedling. However, based on the provided answer key, option (3) 'adult plant' is indicated as the correct stage, likely classifying the plant's developed form after germination as 'adult plant' in a simplified representation of the cycle.

Question 4

Which one of the following shows the correct order when food moves through some parts of the digestive system?

Accepted Answer

(2) stomach -> small intestine -> large intestine. In the human digestive system, food first enters the stomach for initial digestion. From there, it moves to the small intestine, where most chemical digestion and nutrient absorption occur. Finally, undigested material passes into the large intestine for water absorption before excretion. Therefore, the correct order is stomach → small intestine → large intestine.

Question 5

Which one of the following objects is not made of a waterproof material?

Accepted Answer

(1) paper bag. Waterproof materials prevent water from passing through them. A plastic umbrella, metal fork (unless corroded), and rubber gloves are all made from waterproof materials. A paper bag, however, is made of paper, which readily absorbs water and is not waterproof.

Question 6

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

Accepted Answer

(4) thunder. Matter is defined as anything that has mass and occupies space. Air (a gas), juice (a liquid), and water (a liquid) all have mass and occupy space, thus they are matter. Thunder is the sound produced by lightning, which is a form of energy (sound waves) and does not have mass or occupy space, therefore it is not matter.

Question 7

Which one of the following is a source of light?

Accepted Answer

(4) fire. A source of light produces its own light. Fire generates light through combustion. Eyes detect light, trees reflect sunlight, and mirrors reflect light; none of these produce their own light.

Question 8

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

Accepted Answer

(4) a woollen blanket. A source of heat generates heat energy. The sun, a boiling kettle, and a lighted flame all produce heat. A woollen blanket is an insulator; it traps existing heat (e.g., body heat) to keep an object warm but does not generate heat itself.

Question 9

Lily places a metal spoon in a cup of hot tea.
The tea becomes colder after a while.
Which of the following explains this?

Accepted Answer

(4) The surrounding air gains heat from the tea.. Heat always flows from a region of higher temperature to a region of lower temperature. The hot tea is at a higher temperature than the surrounding air and the metal spoon. Therefore, heat will transfer from the hot tea to the cooler spoon and the surrounding air. As the tea loses heat to its surroundings, it becomes colder. The surrounding air gains this heat from the tea.

Question 10

Which of the following can be attracted by a magnet?

Accepted Answer

(1) iron rod. Magnets attract magnetic materials such as iron, nickel, and cobalt. Among the given options, only an iron rod is made of a magnetic material and will be attracted by a magnet. Glass, plastic, and copper are non-magnetic materials.

Question 11

The picture below shows a seedling.
What is the function of the part marked Z?

Accepted Answer

(4) provides food for the seedling. Part Z in the diagram points to the cotyledons (seed leaves) of the seedling. The primary function of cotyledons is to store and provide nutrients (food) to the developing seedling until its true leaves emerge and can begin photosynthesis.

Question 12

The diagram below shows the life cycle of animals X and Y.
Based on the information in the diagrams above, which of the following statement(s) is/are true?
A The adults of animals X and Y live in water.
B Animals X and Y give birth to their young alive.
C The young of animal Y looks like its parent.
D Animals X and Y have different number of stages in their life cycles.

Accepted Answer

(4) C and D only. Statement A is false; both animals appear to be land insects. Statement B is false; both animals show an 'egg' stage, indicating they lay eggs. Statement C is true; animal Y (grasshopper) undergoes incomplete metamorphosis, so its young (nymph) resembles the adult. Statement D is true; animal X (beetle) has 4 stages (egg, larva, pupa, adult), while animal Y (grasshopper) has 3 stages (egg, nymph, adult). Therefore, C and D are the true statements.

Question 13

Which one of the following graphs shows the amount of undigested food over time as it travels from the mouth to the large intestine?

Accepted Answer

(2). Digestion begins in the mouth and continues in the stomach, but most digestion and nutrient absorption occur in the small intestine. Therefore, the amount of undigested food remains relatively high in the mouth and gullet (oesophagus), decreases significantly in the stomach due to protein digestion, and then drops sharply in the small intestine as carbohydrates, fats, and most proteins are digested and absorbed. A small amount of indigestible material then passes to the large intestine. Graph (2) correctly represents this pattern of decrease.

Question 14

The following are statements about the plant transport system.
A: The leaves make food for the plant.
B: The plant transport system is made of food-carrying tubes only.
C: The roots transport water and mineral salts to all parts of the plant.
D: The stem transports food from the leaves to the flowers through the food-carrying tube.
Which statements about the plant transport system are correct?

Accepted Answer

(1) A and D only. Statement A is true, as leaves are the primary site of photosynthesis. Statement B is false because the plant transport system (vascular bundles) includes both food-carrying tubes (phloem) and water-carrying tubes (xylem). Statement C is inaccurate; while roots absorb water and minerals, the transport to all parts of the plant is carried out by the continuous xylem network throughout the roots, stem, and leaves, not solely by the roots themselves. Statement D is true, as the phloem in the stem transports food (sugars) from the leaves (source) to other parts like flowers (sinks). Therefore, only A and D are correct.

Question 15

Jia Ling wanted to find out if the number of leaves on a plant affects the volume of water absorbed by a plant. She placed the two set-ups near a window as shown below...
Which one of the following shows the correct change in the volume of water in both set-ups and its corresponding reason?

Accepted Answer

(4) decrease, decrease, The leaves in set-up X receive less water than the leaves in set-up Y.. Plants absorb water through their roots and release it as water vapour through their leaves (transpiration). Therefore, the volume of water in both containers will decrease. Set-up X, with more leaves, will transpire more water than Set-up Y, causing a greater decrease in its water volume. Option (4) correctly states that the volume of water in both set-ups decreases. The reason given is that 'The leaves in set-up X receive less water than the leaves in set-up Y', implying a higher rate of water movement and loss through transpiration in Set-up X.

Question 16

The diagram below shows a picture of a frying pan.
The table below shows the physical properties of materials A, B, C and D.
A tick (✔) indicates the physical property of the material.
Based on the information given in the table, which one of the following materials is best used for making part X?

Accepted Answer

(1) A. Part X is the handle of a frying pan. A frying pan handle must be strong to safely hold the pan's weight, and it should be waterproof for hygiene and durability during washing. Flexibility is not a desired property for a handle. Material A is listed as strong and waterproof, making it the most suitable choice. Materials B and D are flexible, and Material C is only strong but not indicated as waterproof.

Question 17

A syringe is half filled with oil and air as shown in the diagram below. The end of the syringe is sealed. The plunger is pushed as shown in the diagram below.
Which one of the following graphs shows the change in the volume of oil and air as the plunger is pushed in?

Accepted Answer

(2). Air is a gas and is highly compressible, so its volume will decrease significantly as the plunger is pushed in. Oil is a liquid and is practically incompressible, meaning its volume will remain almost constant even under pressure. Therefore, as the plunger is pushed in, the volume of air will drop substantially, while the volume of oil will remain stable. Graph (2) correctly illustrates this behavior.

Question 18

A container filled with water has two openings, A and B, as shown in the diagram below.
A stone tied to a thread is carefully lowered into opening A as shown.
What will happen to the water level at B?

Accepted Answer

(1) increases. When the stone is lowered into the water, it displaces a volume of water equal to its own volume. Since the container is already filled with water, this displaced water will cause the overall water level in the container to rise, leading to an increase in the water level at opening B.

Question 19

Jean is walking under a street lamp at night as shown below.
At which position, A, B, C or D, will her shadow be the shortest?

Accepted Answer

(2) B. The length of a shadow is shortest when the light source is directly overhead. As Jean walks directly under the street lamp (position B), the light rays from the lamp fall almost vertically on her, causing her shadow to be minimal or directly beneath her feet. At other positions further from the lamp, the angle of the light will create longer shadows.

Question 20

Mary prepared a set-up as shown below. She tried to change the position of the bottle and observe the shadow cast on the screen.
Which one of the following cannot be a shadow cast by the bottle on the screen?

Accepted Answer

(4). The bottle is cylindrical with a cap. Depending on the orientation and angle of the light source, a cylindrical object can cast shadows that are rectangular (side view), circular (top/bottom view), or variations of these shapes. Options (1), (2), and (3) show shadows that resemble a rectangle, a circle, or a rectangular shape with a cap, all of which are possible shadows of a bottle. Option (4) shows a very small, almost square shadow, which is unlikely to be cast by a standard bottle from any typical angle, as its dimensions would always produce a more elongated or distinctly circular/rectangular shape.

Question 21

Four sheets, K, L, M and N, made of different materials of identical size and thickness are shown below. The sheets are arranged in a straight line. They are placed in front of a torch as shown. When a torch is switched on, a shadow is cast on sheet M only.
Which of the following correctly describes the properties of sheets K, L, M and N?

Accepted Answer

(3) K, L, M N. A shadow is cast when an opaque object blocks light. The statement 'a shadow is cast on sheet M only' implies that sheets K and L are transparent or translucent, allowing light to pass through them without casting a shadow. Sheet M must be opaque ('allows no light to pass through') as it is the only sheet on which a shadow is explicitly stated to be cast. For the shadow to be 'on M only', it means that light reaches M through K and L, and M blocks the light. Sheet N's property might not be determinable from the given information regarding a shadow 'on M only', as light could pass through N or N could be in M's shadow without a specific shadow 'on N'. Option (3) is the most consistent with K, L being transparent/translucent, M being opaque, and N's property not being explicitly determined as allowing or not allowing light through based solely on the phrasing 'shadow on M only'.

Question 22

Which one of the following statements about heat and temperature is correct?

Accepted Answer

(2) Heat is the quantity of hotness of an object.. Temperature is a measure of the average kinetic energy of particles, not a form of energy itself; heat is a form of energy transfer. Thus, (1) is incorrect. Heat represents the total internal kinetic energy of particles within an object, which can be conceptually understood as the 'quantity of hotness'; thus (2) is the most suitable description at this level. (3) is incorrect because a 40g object at 90°C would have more total heat energy than a 20g object at the same temperature. (4) is incorrect because touching provides a subjective and inaccurate measure of temperature; thermometers are needed for accurate measurement.

Question 23

Sara placed an empty and dented plastic water bottle into a cup of warm water as shown in the diagram below. After fifteen minutes, she noticed that the water bottle was no longer dented.
Which of the following explains her observation?

Accepted Answer

(4) The air in the bottle gained heat from the warm water and expanded.. When the dented plastic bottle is placed in warm water, heat from the warm water is transferred to the cooler air trapped inside the bottle. As the air inside the bottle gains heat, its particles move faster and spread further apart, causing the air to expand. This expansion exerts pressure on the inner walls of the bottle, pushing out the dents and restoring its original shape.

Question 24

Sam attached a bar magnet with poles A and B onto a piece of styrofoam block and spun it in a basin of water.
The diagram below shows the top view of the set-up when the magnet stopped spinning.
The diagram below shows the north direction indicated by the compass.
The above bar magnet was then brought near another bar magnet.
Which of the following shows the correct interaction between the two bar magnets?

Accepted Answer

(3). A freely suspended magnet aligns itself with the Earth's magnetic field, with its North pole pointing towards the Earth's geographic North. From the first diagram and compass, end A of the floating magnet points North, so A is the North pole and B is the South pole. Thus, the first bar magnet has poles N-S (North at A, South at B). Magnetic like poles repel, and opposite poles attract. Option (3) shows the N-S magnet with its S pole facing another S pole, leading to repulsion. This matches the properties of magnets.

Question 25

Billy placed a sheet of material X in between a bar magnet and a ball made of material Y as shown in the diagram below. The bar magnet attracted the ball.
Which one of the following statements is correct?

Accepted Answer

(1) Material Y can be made into magnets.. Since the bar magnet attracted the ball made of material Y, material Y must be a magnetic material (like iron, nickel, or cobalt). Magnetic materials can be magnetized and thus made into magnets, making statement (1) correct. The fact that the magnetic force passes through material X to attract material Y indicates that X is a non-magnetic material, refuting (2) and (3). Statement (4) is incorrect as the ball is attracted, indicating it is magnetic.

P4 Science CA2 2023 — Raffles Girls

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