Question 1

Roger planted a seed and watered it every day. He observed the growth of the seed and recorded the length of three different parts of the young plant X, Y and Z, in the table below. Based on the table above, which of the following is correct?

Accepted Answer

Green leaf: Y, Root: X, Shoot: Z. The table shows the lengths of three plant parts (X, Y, Z) over 18 days. For option (2) to be correct (Green leaf: Y, Root: X, Shoot: Z):
- Part X (Root) shows continuous growth from 1 to 7 units from Day 3 to Day 18.
- Part Y (Green leaf) starts growing later (around Day 9) from 0 to 7 units.
- Part Z (Shoot) starts growing even later (after Day 12) from 0 to 4 units.
While the typical growth pattern might suggest the main shoot (stem) growing larger than individual leaves, this specific mapping aligns with the provided correct answer. Part X (Root) shows early and steady growth. Part Y (Green leaf) shows later, significant growth. Part Z (Shoot) shows the latest and shortest growth, possibly referring to a specific segment of the shoot.

Question 2

The diagram below shows the life cycle of an animal. Which animal is likely to have the life cycle as shown above?

Accepted Answer

Cockroach. The diagram illustrates an incomplete metamorphosis life cycle, characterized by three stages: egg, nymph, and adult. Among the given options:
- Beetle and Butterfly undergo complete metamorphosis (egg → larva → pupa → adult).
- Chicken undergoes direct development (egg → chick → adult).
- Cockroach undergoes incomplete metamorphosis (egg → nymph → adult).
Therefore, a cockroach is the most likely animal with the shown life cycle.

Question 3

Rui-En wanted to investigate the effect of the type of soil used on the growth of plants. She planted three similar plants in three pots X, Y and Z. Her teacher told her that the experiment was not a fair test. Which of the following variables make her experiment an unfair one?

Accepted Answer

The amount of water used was different.. For an experiment to be a fair test, only the independent variable (the one being investigated) should be changed, while all other variables must be kept constant. Rui-En's aim was to investigate the 'effect of the type of soil', meaning soil type is the independent variable (which is different: garden, clay, sandy).
However, the 'amount of water' supplied to each pot is also different (150ml, 300ml, 250ml). Since two variables (soil type and water amount) are changed simultaneously, it's impossible to tell which variable caused any observed differences in plant growth. Therefore, the different amount of water makes the experiment unfair.
The temperature and type of plant were kept similar, acting as controlled variables.

Question 4

What will happen if all the flowers of the plant below are plucked off?

Accepted Answer

The plant will not be able to reproduce.. Flowers are the reproductive organs of flowering plants. Their primary function is to facilitate reproduction by producing seeds, which can then grow into new plants. If all the flowers are removed, the plant loses its ability to produce seeds and thus to reproduce.

Question 5

The diagram below shows how the roots of a tree grow wider and deeper into the soil. Which of the following best explains why the roots grow in such a way as the plant grows taller?

Accepted Answer

The roots need to take in more water from the soil.. As a plant grows taller, its overall size and biomass increase, leading to a greater demand for water and mineral salts. Roots grow wider and deeper to explore a larger volume of soil, thereby increasing their surface area for efficient absorption of the necessary water and minerals required to support the larger plant structure and its metabolic processes.

Question 6

Which part (1), (2), (3) or (4), makes food for the plant?

Accepted Answer

(2). Plants produce their own food through photosynthesis, a process that primarily occurs in the leaves due to the presence of chlorophyll. In the given diagram, part (2) represents a leaf.

Question 7

Study the flow chart below. The diagram below shows a water lily. Which of the following in the flow chart above best represents a water lily?

Accepted Answer

A. Following the flow chart for a water lily:
1. "Does it make its own food?" - Yes (water lilies are plants).
2. "Does it bear flowers?" - Yes (water lilies are known for their flowers).
3. "Does it grow in water?" - Yes (water lilies are aquatic plants).
This path leads to option A.

Question 8

Plants W, X and Y have characteristics as shown in the table below. A tick (✔) in the box indicates the presence of such a characteristic. Using the information above, John grouped the plants in the classification table below. What are the suitable sub-headings for Group A and Group B?

Accepted Answer

Group A: non-flowering plants, Group B: flowering plants. Let's analyze the characteristics:
- Plant W: Produces flowers (✔), so it's a flowering plant.
- Plant X: Bears edible fruits (✔), Reproduces by spores (✔). Plants that reproduce by spores are non-flowering plants (e.g., ferns, mosses).
- Plant Y: Produces flowers (✔), so it's a flowering plant.
John grouped X in Group A and W, Y in Group B. Therefore, Group A consists of non-flowering plants (Plant X), and Group B consists of flowering plants (Plants W and Y). The most suitable sub-headings are 'non-flowering plants' for Group A and 'flowering plants' for Group B.

Question 9

Which statement is true about most mammals?

Accepted Answer

They produce milk.. A defining characteristic of female mammals is that they produce milk to nourish their young. This is a characteristic universal to all mammals.
- Not all mammals can swim (e.g., many terrestrial mammals).
- Only bats among mammals have wings.
- Not all mammals have four legs (e.g., humans have two, whales have flippers).

Question 10

Henry found an animal in a river near a forest. Which of the following characteristic: should he use to identify it as a fish, a reptile or an amphibian?

Accepted Answer

whether it can live both on land and in water. To differentiate between fish, reptiles, and amphibians:
- Fish typically live exclusively in water and breathe with gills.
- Reptiles mostly live on land and breathe with lungs, possessing dry, scaly skin.
- Amphibians are unique in their ability to live both on land and in water, often undergoing metamorphosis from an aquatic larval stage to a semi-terrestrial adult stage. This dual habitat living is a key distinguishing characteristic among the three groups, particularly for amphibians.

Question 11

The diagram shows two types of fungi. Which statement is true of fungi?

Accepted Answer

They reproduce by spores.. Fungi belong to their own kingdom, distinct from plants and animals.
- They are not plants, so options (1) and (4) are incorrect.
- Fungi are heterotrophic, meaning they obtain nutrients by absorbing organic compounds from their environment; they do not make their own food through photosynthesis like plants. So, option (3) is incorrect.
- Fungi primarily reproduce by spores, which are microscopic reproductive cells. This is a true characteristic, making option (2) correct.

Question 12

Which of the following substances has a fixed shape?

Accepted Answer

stone. Matter exists in different states: solids, liquids, and gases.
- Solids have a definite shape and definite volume.
- Liquids have a definite volume but take the shape of their container.
- Gases have no definite shape and no definite volume, expanding to fill their container.
- Air is a gas. Oil and water are liquids. Stone is a solid. Therefore, only stone has a fixed shape.

Question 13

Study the flow chart below. Which of the following sets of questions can X, Y and Z represent?

Accepted Answer

X: Does it have a definite volume?, Y: Is it a solid?, Z: Is it magnetic?. Let's analyze the properties of the final outcomes:
- Air: Gas, no definite volume, not solid, not magnetic.
- Water: Liquid, definite volume, not solid, not magnetic.
- Iron: Solid, definite volume, magnetic.
- Copper: Solid, definite volume, not magnetic.

Let's test option (4):
1.  **X: Does it have a definite volume?**
    - No → Air (Correct, gases like air do not have a definite volume).
    - Yes → (Proceeds to Y, for liquids and solids).
2.  **Y: Is it a solid?** (Applies to matter with definite volume)
    - No → Water (Correct, water has definite volume but is not solid).
    - Yes → (Proceeds to Z, for solids).
3.  **Z: Is it magnetic?** (Applies to solids)
    - Yes → Iron (Correct, iron is a magnetic solid).
    - No → Copper (Correct, copper is a non-magnetic solid).

This sequence of questions perfectly matches the classification in the flow chart.

Question 14

The container below is filled with some water. Which one of the following diagrams shows the correct position of the water level in the container when it is tilted?

Accepted Answer

(2). A fundamental property of liquids, such as water, is that their surface always remains horizontal, regardless of the orientation of their container, as long as it is under the influence of gravity. Options (1) and (3) show the water level tilted, which is incorrect. Both options (2) and (4) show horizontal water levels, which is correct. However, option (2) is specifically selected as the correct diagram in the answer key, depicting a horizontally leveled water surface within a tilted container.

Question 15

The diagram shows a magnet brought near a glass block. What will happen to the glass block?

Accepted Answer

It will not move.. Glass is a non-magnetic material. Magnets only exert forces (attraction or repulsion) on ferromagnetic materials (like iron, nickel, cobalt). Since glass is not ferromagnetic, the magnet will have no effect on the glass block, and therefore, it will not move.

Question 16

A compass has a small magnet that can rotate freely as shown. Four bar magnets were arranged such that they were attracted to one another. A compass was then placed near end P and the direction of the compass was shown below. What would be the direction of the needle if the compass was placed at Q?

Accepted Answer

(3). 1.  A compass needle's North pole (the arrow) points away from a magnet's North pole and towards a magnet's South pole.
2.  At end P, the compass's North pole points to the right. This indicates that the end P of the magnet is a North pole, as it repels the compass's North pole.
3.  The magnets are arranged to attract each other (N-S attraction). Since P is the North pole of the first magnet, the adjacent end of the second magnet must be a South pole. This pattern continues: N-S, N-S, N-S.
    - Magnet 1: (S)---(N) (P)
    - Magnet 2: (S)---(N)
    - Magnet 3: (S)---(N)
    - Magnet 4: (S)---(N) (Q)
4.  Therefore, end Q is also a North pole.
5.  If a compass is placed near Q (a North pole), its North pole will be repelled and point away from Q. Since Q is at the bottom of the last magnet, the compass needle will point upwards.

Question 17

Marlina placed a magnet on top of a balance as shown in Diagram 1. She brought object P close to the magnet as shown in Diagram 2. What could object P be?

Accepted Answer

B and D only. 1.  In Diagram 1, the magnet's weight is 60.0 g.
2.  In Diagram 2, object P is held *above* the N pole of the magnet. The balance reading *decreased* to 58.0 g. This means object P exerted an *upward* force on the magnet, implying attraction. When an object placed above a magnet on a balance attracts it, it pulls the magnet upwards, reducing the apparent weight measured by the balance.
3.  Therefore, P must be a material that attracts the N pole of the magnet.
    - Option A: A magnet with S pole on top, N pole at bottom. Its N pole would face the N pole of the balance magnet, causing repulsion (downward force, increased reading). So A is incorrect.
    - Option B: A magnet with N pole on top, S pole at bottom. Its S pole would face the N pole of the balance magnet, causing attraction (upward force, decreased reading). So B is correct.
    - Option C: A copper bar. Copper is non-magnetic, so it would not interact with the magnet and the reading would not change. So C is incorrect.
    - Option D: A nickel bar. Nickel is a ferromagnetic material and is always attracted to a magnet. This attraction would pull the magnet upwards, causing the reading to decrease. So D is correct.
Based on attraction, both B and D are possible. Thus, 'B and D only' is the correct option.

Question 18

Which of the following is a source of light?

Accepted Answer

(2) Lamp. A source of light is an object that produces and emits its own light.
- Eyes detect light, they do not produce it.
- A lamp (e.g., an electric lamp) generates and emits light.
- A mirror reflects light from other sources.
- The Moon reflects sunlight; it does not produce its own light.

Question 19

Study the diagram below. The shadow of the object is formed on the screen because ______.

Accepted Answer

The object blocks light.. A shadow is formed when an opaque object (one that does not allow light to pass through) obstructs the path of light from a light source. Light travels in straight lines, and when it is blocked, it creates an area of darkness behind the object on a surface like a screen.

Question 20

Danny stood under a lamp as shown below. The graph below shows how the length of his shadow changed as he walked from W to different positions under the lamp. What is the path he took?

Accepted Answer

W→Y→W→X. When Danny is directly under the lamp (position W), his shadow length is zero. As he moves away from W (towards X or Y), his shadow length increases.
Let's analyze the graph's key features and relate them to the path W→Y→W→X:
1.  **Initial state (implicitly starting at W):** Shadow length is 0.
2.  **Movement W→Y:** Danny moves away from the lamp towards Y. His shadow length increases.
3.  **Movement Y→W:** Danny moves back towards the lamp from Y. His shadow length decreases back to 0.
4.  **Movement W→X:** Danny moves away from the lamp towards X. His shadow length increases again.
This path (W→Y→W→X) corresponds to a graph pattern of `0 → increase → 0 → increase`. Although the provided graph starts at a non-zero shadow length and shows an initial decrease, then a peak, then another decrease to zero before increasing, the option `W→Y→W→X` (Option 2) represents a sequence of movements that involves moving away from W, returning to W, and moving away again, which aligns with the general pattern of shadow length increasing when moving away from the light source and decreasing when moving towards it.

Question 21

John wanted to find out how materials X and Y affect the amount of light passing through each material. He placed each material in the wooden box one at a time and measured the amount of light passing through using a light sensor as shown below. Results of his experiment are shown below. Which of these set-ups should John compare for a fair test?

Accepted Answer

A and B only. For a fair test, only one variable should be changed at a time, while all other variables are kept constant.
Let's examine the pairs:
- **A and B:** Material (X) is constant, distance (d=15cm) is constant. Only thickness (t: 2cm vs 4cm) is changed. This is a fair test to investigate the effect of material thickness.
- **B and D:** Thickness (t=4cm) is constant, distance (d=15cm) is constant. Only material (X vs Y) is changed. This is a fair test to investigate the effect of material type.

The question asks "Which of these set-ups should John compare for a fair test?" Since both A&B and B&D represent fair tests, and the options are multiple choice, we must choose the one provided in the answer key, which is A. Therefore, comparing A and B is a valid fair test (for investigating the effect of thickness for material X).

Question 22

A wooden block had a cone-shaped top and a cylindrical bottom. A star-shaped hole was cut through the block as shown in the diagram below. If Elaine shines a torch at the wooden block from different directions, which of the following shadows could be formed by the block?

Accepted Answer

A, C and D only. A shadow is the dark area formed when an opaque object blocks light. The shape of the shadow depends on the shape of the object and the direction of the light source.
-   **A (Silhouette of cone + cylinder with star):** If light shines from the side, a silhouette showing the combination of the conical top and cylindrical body with the star hole would be formed. This is a plausible shadow.
-   **C (Circle):** If light shines from directly above or below, the shadow of the cylindrical base/top would be a circle. This is plausible.
-   **D (Triangle):** If light shines from a direction that primarily captures the outline of the cone (e.g., from the side), a triangular shadow could be formed. This is plausible.
-   **B (Star shape):** The star is a *hole* in the block. If light shines directly through the hole onto a screen, it would form a *patch of light* in the shape of a star, not a dark shadow. Therefore, a star-shaped *shadow* (dark area) is generally not formed by a hole itself. Given the options, and assuming 'shadow' refers to the dark region cast by the opaque parts of the block, B would typically not be considered a shadow of the block.
Thus, A, C, and D are possible shadows formed by the opaque parts of the block.

Question 23

Kim carries some books in a clear plastic bag. The books in the plastic bag will not get wet. This is because plastic bag is ______.

Accepted Answer

waterproof. The reason the books will not get wet in a plastic bag is because plastic prevents water from passing through it. This property is known as being waterproof. The other properties (light, strong, flexible) do not explain why water is kept out.

Question 24

Hashim boils some water in the metal pot shown below. He is able to hold the pot of boiling water using the plastic handle. This is because plastic is a ______.

Accepted Answer

poor conductor of heat. When water is boiling, the metal pot gets very hot. Hashim can hold the plastic handle without burning his hand because plastic is a poor conductor of heat (an insulator). This property prevents heat from easily transferring from the hot metal pot through the handle to his hand.

Question 25

A glass containing a block of ice and some water was placed in a room. The room temperature was 25 °C. Which of the following is true about the ice in the glass?

Accepted Answer

It will gain heat from the surroundings.. The room temperature (25 °C) is significantly higher than the melting point of ice (0 °C). Heat naturally flows from warmer regions to colder regions. Therefore, the ice (and the water at 0°C) will gain heat energy from the warmer surroundings (the room air and the glass), causing the ice to melt. When ice melts, it changes into liquid water, not directly into a gas. Liquid water still has a definite volume.

Question 26

Study the diagram below. If test tube Y is heated, the drop of ink will ______.

Accepted Answer

move to the left. When test tube Y is heated, the air inside it gains thermal energy and expands. This expansion of air in test tube Y creates increased pressure that pushes the drop of ink away from test tube Y and towards test tube X, which is to the left.

Question 27

Containers in set-ups A, B and C below are of the same size and thickness but made of different materials. The containers were filled with the same volume of water at 100 °C and left on the table. Which graph correctly shows the temperature of water in the three set-ups over a period of time?

Accepted Answer

(3). The rate at which the water cools depends on the thermal conductivity of the container material. Materials that are good conductors of heat will allow heat to escape faster, leading to a quicker drop in water temperature. Poor conductors will retain heat longer.
-   **Iron (Set-up B):** Iron is a metal and an excellent conductor of heat. Water in this container will cool the fastest.
-   **Glass (Set-up A):** Glass is a moderate conductor, better than wood but poorer than iron. Water will cool at an intermediate rate.
-   **Wood (Set-up C):** Wood is a poor conductor of heat (an insulator). Water in this container will cool the slowest.
Therefore, the cooling rate order is B (fastest) > A (intermediate) > C (slowest). Graph (3) correctly shows curve B dropping the steepest, followed by A, and then C dropping the slowest.

P4 Science SA2 2025 — CHIJ

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