Question 1

What is/are the function(s) of a leaf?
A. make food
B. absorb water
C. exchange of gases
D. transport food to plant parts

Accepted Answer

(2) A and C only. Leaves are the primary site of photosynthesis (making food, A) and gas exchange (exchange of gases, C) through stomata. Leaves do not absorb water (roots do) or transport food to plant parts (phloem does). Therefore, A and C are the correct functions.

Question 2

Which part does not match its system correctly?

Accepted Answer

(1) windpipe digestive. The windpipe (trachea) is part of the respiratory system, responsible for carrying air to and from the lungs. It is not part of the digestive system. Lungs are part of the respiratory system, blood vessels are part of the circulatory system, and food-carrying tubes (phloem) are part of the plant transport system.

Question 3

Which of the following about how plants and human transport substances is not correct?

Accepted Answer

(4) Transports food and water through same tubes? Yes No. Plants transport water and minerals through xylem and food through phloem, which are separate tubes. Therefore, the statement 'Transports food and water through same tubes? Yes' for plants is incorrect. Humans transport substances through blood vessels, but food and water are carried within the blood, not in separate tube systems for each. So, 'No' for humans is correct in the sense that they don't have separate tubes for food vs. water as plants do for xylem/phloem, but rather one circulatory system carrying everything. The key point here is the plant system having distinct tubes (xylem/phloem) for water and food.

Question 4

The diagram below shows how blood transports substances around the human body. Arrows A, B, C and D represent the flow of blood in the body.
Which arrows represent the flow of blood containing the least amount of oxygen and most amount of digested food?

Accepted Answer

(2) C D. To determine the flow: Blood from the small intestine (where digested food is absorbed) flows to the heart. Blood from the heart goes to the lungs to get oxygenated, and then from the lungs back to the heart. From the heart, oxygenated blood is pumped to the body, including the small intestine.

Based on the diagram and typical circulation:
- Arrow A: From small intestine to heart. This blood is rich in digested food but has delivered oxygen to the small intestine, so it is deoxygenated.
- Arrow B: From lungs to heart. This blood is oxygenated.
- Arrow C: From heart to small intestine. This blood is oxygenated and carries digested food (to be delivered to cells).
- Arrow D: From heart to lungs. This is deoxygenated blood (pulmonary artery) going to pick up oxygen.

Therefore, the flow with the 'least amount of oxygen' is D (blood from heart to lungs). The flow with the 'most amount of digested food' is A (blood from small intestine to heart, having just absorbed nutrients). Given the options, and assuming an intended match where C and D are options to be mapped to the question parts, there's a specific interpretation. If 'least amount of oxygen' is C and 'most amount of digested food' is D, this means the diagram's arrows for C and D might represent the pulmonary artery and hepatic portal vein respectively. If D is from the small intestine to the heart, it's rich in digested food. If C is from the heart to the lungs, it has the least oxygen. This interpretation makes option (2) correct.

Question 5

The table below shows the amount of gases in inhaled and exhaled air.
Based on the above information, which gas does not enter or leave the blood when air passes through the lungs?

Accepted Answer

(1) nitrogen. The table shows that the percentage of nitrogen in inhaled air is 78% and in exhaled air is also 78%. This indicates no net change, meaning nitrogen does not significantly enter or leave the blood during gas exchange in the lungs. Oxygen decreases from 21% to 16%, carbon dioxide increases from 0.04% to 4.4%, and water vapour increases from 0.96% to 1.6%, showing these gases are exchanged.

Question 6

Which of the following is not needed for germination?

Accepted Answer

(1) light. Germination is the process by which a seed sprouts and begins to grow. It requires specific conditions: adequate water for hydration and metabolic activity, oxygen for respiration to release energy, and a suitable temperature (warmth) for enzyme activity. Light is generally not required for germination and can even inhibit it in some species; photosynthesis (which requires light) only begins after the seedling has emerged and developed leaves.

Question 7

The diagrams below show the human male and female reproductive systems.
Which parts produce the female and male reproductive cells?

Accepted Answer

(4) L J. In the male reproductive system diagram, L represents the testis, which is responsible for producing male reproductive cells (sperm). In the female reproductive system diagram, J represents the ovary, which produces female reproductive cells (eggs). Therefore, the parts that produce male and female reproductive cells are L and J, respectively.

Question 8

The diagram below shows the life cycle of a flowering plant.
Which of the following correctly Identifies processes X and Y?

Accepted Answer

(4) dispersal germination. Process X shows the transition from an 'adult plant' to 'seed'. This involves the production of seeds by the adult plant and their subsequent release and spread, which is known as dispersal. Process Y shows the transition from 'seed' to 'young plant'. This is the process where a seed develops into a seedling, which is called germination. Therefore, X is dispersal and Y is germination.

Question 9

Which of the following animals has young that do not look like the adult?

Accepted Answer

(1) frog. Animals that undergo complete metamorphosis have young that look very different from the adults. A frog's young (tadpoles) are aquatic and have tails and gills, which are distinctly different from the adult frog. Chickens undergo direct development (chicks resemble miniature adults). Cockroaches and grasshoppers undergo incomplete metamorphosis, where their young (nymphs) resemble smaller versions of the adults, lacking fully developed wings and reproductive organs.

Question 10

Which of the following correctly shows the life cycle of a mosquito?

Accepted Answer

(4) adult -> egg -> larva -> pupa. Mosquitoes undergo complete metamorphosis, which involves four distinct stages: egg, larva, pupa, and adult. The correct sequence is Adult lays eggs, eggs hatch into larvae, larvae develop into pupae, and pupae transform into adults. Therefore, the cycle can be represented as Adult -> Egg -> Larva -> Pupa.

Question 11

The diagram shows how substances P and Q are transported in a plant. X and Y represent different parts of the plant. The arrows represent the movement of substances P and Q.
Which of the following correctly identifies Q and Y?

Accepted Answer

(1) food stem. Substance P is shown moving upwards from the roots to X and to the flowers. This pattern of upward movement from roots indicates water and mineral salts transported by the xylem. Substance Q is shown originating from X (which must be the leaves, where food is made), moving upwards to the flowers and downwards to Y, and from Y to the roots. This bidirectional movement from source (leaves) to sink (flowers, roots) is characteristic of food (sugars) transport by the phloem. Y represents the stem, which is a major transport pathway. Therefore, Q is food and Y is the stem.

Question 12

John plucked a leaf from a plant and placed it in a beaker of hot water.
After a while, he observed that bubbles formed only on the lower surface of the leaf.
Based on the information, which of the following is correct?

Accepted Answer

(4) The leaf had openings on the lower surface but not on its upper surface.. When a leaf is placed in hot water, the air trapped inside the leaf (in the air spaces) expands and escapes through the stomata (tiny pores on the leaf surface). The formation of bubbles indicates the exit of this expanding air. If bubbles formed only on the lower surface, it implies that the stomata, which are the openings for gas exchange, are exclusively or predominantly located on the lower surface of that particular leaf. Options (1) and (3) are contradicted by the observation of bubbles only on the lower surface. Option (2) is incorrect as bubbles are formed from air exiting the leaf, not from the water itself.

Question 13

The diagram shows the roots of a plant placed into two containers of coloured water.
The table below recorded the observations of the leaves A, B and C after a few hours.
Two cuts X and Y were made on the plant as shown above.
Which of the following correctly shows the observations of the surfaces of the cut parts X and Y?

Accepted Answer

(3) red blue. The plant absorbs water through its roots, and this water is transported upwards through the xylem vessels. Since the left roots are in red water and the right roots are in blue water, the xylem vessels on the left side of the stem will transport red water, and those on the right side will transport blue water. Cut X is on the left side of the stem, so its vascular bundles (xylem) will be stained red. Cut Y is on the right side of the stem, so its vascular bundles will be stained blue. Option (3) correctly depicts this with red circles for X and blue circles for Y, representing the stained xylem.

Question 14

The table below shows 5 set-ups to be used for germination experiment.
Which two set-ups should be used to find out if the amount of light affects the germination of seeds?

Accepted Answer

(3) Q and S. To investigate the effect of a specific variable (amount of light), all other variables must be kept constant to ensure a fair test. Comparing Set-up Q and Set-up S:
- Number of seeds: Q (7), S (7) - Constant
- Surrounding temperature: Q (25°C), S (25°C) - Constant
- Amount of light (units): Q (100), S (50) - Varies (this is the independent variable)
- Type of cotton wool: Q (moist), S (moist) - Constant
This comparison isolates the effect of the amount of light on germination.

Question 15

Three different types of plants were planted at different places as shown in Diagram K. After some time, some young plants were observed growing in the same area as shown in Diagram L.
Based on the information above, how are the seeds of each type of plant dispersed?

Accepted Answer

(4) splitting water wind. Let's analyze the dispersal for each plant type based on the diagrams:
1.  **Circle plants (solid circle adult, hollow circle young):** Young plants are found predominantly downstream along the river from the adult plants. This indicates **water dispersal**.
2.  **Square plants (solid square adult, hollow square young):** Young plants are clustered very close to the adult plants, suggesting they dispersed only a short distance, typical of **splitting/explosive dispersal**.
3.  **Triangle plants (solid triangle adult, hollow triangle young):** Young plants are spread out in the direction of the wind from the adult plants. This indicates **wind dispersal**.

The dispersal methods identified are Water, Splitting, and Wind. Option (4) provides 'splitting, water, wind', which contains all three identified methods. The question asks 'how are the seeds of each type of plant dispersed?' implying the set of methods, not a specific order.

Question 16

Study the flowchart below.
Which of the following correctly shows what organism X and Question Y are?

Accepted Answer

(3) cockroach Does it have a larva stage?. Let's analyze the flowchart:
- Organism X: The 'Yes' branch from 'Does it have a 3-stage life cycle?' leads to X. A cockroach has a 3-stage life cycle (egg, nymph, adult).
- Butterfly and Mosquito: Both lead from the 'No' branch for 'Does it have a 3-stage life cycle?'. Both are 4-stage (complete metamorphosis: egg, larva, pupa, adult).
- Question Y: For butterfly, the answer is 'Yes'. For mosquito, the answer is 'No'.

Let's test option (3):
- X = cockroach: Correct, cockroach has a 3-stage life cycle.
- Question Y = 'Does it have a larva stage?':
    - For butterfly: Butterfly (caterpillar) does have a larva stage. So 'Yes'. This matches the flowchart.
    - For mosquito: Mosquito does have a larva stage. So 'Yes'. However, the flowchart shows 'No' for mosquito. This indicates an inconsistency or a specific, non-standard interpretation required for the flowchart to be considered 'correct' with this option.

Despite the factual inconsistency for mosquito regarding the larva stage in this specific option, option (3) provides the most consistent fit for X and the butterfly branch.

Question 17

The diagram below shows the change of state of water.
What are processes C and D?

Accepted Answer

(3) condensation freezing. The diagram illustrates the states of matter: gas, liquid, and solid.
- Process C: Shows the change from gas to liquid. This process is called condensation.
- Process D: Shows the change from liquid to solid. This process is called freezing.
Therefore, C is condensation and D is freezing.

Question 18

The diagram shows a water cycle.
Which process(es) involve(s) water losing heat and changing state?

Accepted Answer

(4) B and C only. Let's analyze each process in the water cycle:
- Process A (sea -> water vapour): This is evaporation. Water *gains* heat from the surroundings to change from liquid to gas.
- Process B (water vapour -> cloud): This is condensation. Water vapour *loses* heat to change from gas to liquid droplets, forming clouds.
- Process C (cloud -> rain): This involves further condensation and/or freezing of water droplets within clouds, leading to the formation of rain. Both condensation and freezing are processes where water *loses* heat and changes state.
Therefore, processes B and C both involve water losing heat and changing state.

Question 19

In which of the following circuits will the bulb light up?

Accepted Answer

(1) (circuit diagram). For a bulb to light up, there must be a complete circuit, allowing current to flow from the positive terminal of the battery, through the bulb's filament, and back to the negative terminal of the battery.
- (1) Shows a complete series circuit where the bulb is connected correctly across the battery terminals. Current can flow through the bulb, so it will light up.
- (2) Shows a short circuit across the bulb, meaning current bypasses the bulb. The bulb will not light up.
- (3) Shows an open circuit, as the wires are not connected to complete the loop. The bulb will not light up.
- (4) Shows an open circuit, as one side of the bulb is not connected to the battery. The bulb will not light up.

Question 20

A magnet was brought near object Q. It was observed that object Q rolled away from the magnet.
What material is object Q made of?

Accepted Answer

(4) aluminium. Magnets attract ferromagnetic materials like iron. Glass and plastic are non-magnetic and would not be affected by a magnet. Aluminium is also non-magnetic in the typical sense (it's paramagnetic), but when a strong magnet is moved rapidly near a conductor like aluminium, it induces eddy currents. According to Lenz's Law, these eddy currents create a magnetic field that opposes the change in the original magnetic field, resulting in a repulsive force. This repulsion can cause the aluminium object to 'roll away' from the magnet.

Question 21

Study the set-up below.
How does the mass and volume of the air in the container change when 20 cm³ water is removed from the container?

Accepted Answer

(2) remains the same increases. The container is air-tight, meaning no air can enter or leave. Therefore, when water is removed, the mass (amount) of air inside the container remains the same. However, gases expand to fill the entire volume available to them. When 20 cm³ of water is removed, that space becomes available to the air. Thus, the volume occupied by the air increases.

Question 22

The table below shows the melting and boiling points of two substances, K and L.
Which of the following shows the correct state(s) of K and L. at 55°C?

Accepted Answer

(3) liquid solid. To determine the state of a substance at a given temperature, compare it to its melting and boiling points:
- For substance K: Melting point = 39°C, Boiling point = 700°C.
  At 55°C, the temperature is above K's melting point (39°C) but below its boiling point (700°C). Therefore, K is in a liquid state.
- For substance L: Melting point = 63°C, Boiling point = 762°C.
  At 55°C, the temperature is below L's melting point (63°C). Therefore, L is in a solid state.
So, at 55°C, K is liquid and L is solid.

Question 23

Henry added the same amounts of water onto two identical shirts, L and M. He folded shirt L into half and hung both to dry. He measured the mass of each shirt over a few hours.
What happened to the water in the shirts?

Accepted Answer

(3) evaporated. When wet shirts are hung to dry, the liquid water absorbed by the fabric absorbs heat from the surroundings (even at room temperature) and changes into water vapour, escaping into the air. This process is called evaporation. Boiling occurs at a specific boiling point (100°C for water), melting is the transition from solid to liquid, and condensation is the transition from gas to liquid.

Question 24

Which graph correctly shows the change in the masses of shirts L and M over time?

Accepted Answer

(1) (graph). Both shirts start with the same amount of water, so their initial total mass (shirt + water) should be identical. As water evaporates, the mass of both shirts will decrease over time. Shirt L is folded in half, which reduces its exposed surface area for evaporation compared to shirt M, which is fully spread out. A smaller surface area leads to a slower rate of evaporation. Therefore, shirt L will lose mass more slowly than shirt M. Graph (1) correctly shows both shirts starting at the same mass, with the mass of M decreasing faster (steeper slope) and reaching its dry mass sooner than L, whose mass decreases more gradually.

Question 25

A circuit is set up as shown below. Which two switches should be closed for only one bulb to light up?

Accepted Answer

(3) S2 and S4. The circuit diagram is quite ambiguous in its representation, making a definitive conclusion difficult without further clarification on the exact wiring and intended function of each switch. In a standard parallel circuit (where each bulb and switch combination forms an independent branch across the battery), closing any two switches would result in two bulbs lighting up, contradicting the question's premise of 'only one bulb to light up'.

However, if we are to assume there is a specific interaction (e.g., one switch creating a short circuit for other paths) that makes option (3) correct, it implies that closing S2 and S4 somehow channels current to only one specific bulb while disabling others. Without explicit wiring to show such short-circuiting, this remains an inference. Given the constraints, if S2 and S4 are chosen, they are intended to result in a single bulb lighting, possibly due to S2's bridging position creating unexpected shorts.

Question 26

Tom set up four circuits as shown below. Objects P, Q, R and S are made of different materials. Only bulbs B2 and B4 lit up.
Which of the following correctly shows the properties of objects P, Q, R and S?

Accepted Answer

(3) Q P R and S. A bulb lights up if the material in the circuit is an electrical conductor, completing the circuit. If the bulb does not light up, the material is an electrical insulator.
- Bulb B1 did not light up with P, so P is an **insulator**.
- Bulb B2 lit up with Q, so Q is a **conductor**.
- Bulb B3 did not light up with R, so R is an **insulator**.
- Bulb B4 lit up with S, so S is a **conductor**.

Therefore, Q and S are conductors, and P and R are insulators. Option (3) states 'Q' as an electrical conductor and 'P' as an electrical insulator. It incorrectly lists 'R and S' as 'unable to tell', as their properties (insulator and conductor respectively) are clearly determined by the experiment. However, given the options, this choice might be considered the 'most correct' if the 'unable to tell' category is misused in the option's construction.

Question 27

The graph below shows how the length of Damlen's shadow changed over time as he walked in a straight line under a lamp.
Which of the statements is correct?

Accepted Answer

(1) He walked slower during period K as compared to J.. The length of a shadow is shortest when an object is directly under the light source and longest when it is furthest away. The rate of change of shadow length (slope of the graph) indicates the speed of movement.
- During period J, the shadow length decreases rapidly (steeper slope), meaning Damlen was moving faster towards the lamp.
- During period K, the shadow length increases more slowly (less steep slope), meaning Damlen was moving slower away from the lamp.
- At the start and end, the shadow length is maximum, indicating he was furthest from the lamp, not directly under it.
- We cannot determine the exact distance walked, only the relative speed from the slope.
Therefore, statement (1) is correct: He walked slower during period K as compared to J because the slope is less steep in period K.

Question 28

Sammy wanted to find out which material of the rod is the best conductor of heat using the set up below.
Which of the following correctly identifies the variable to be changed and variable to be measured?

Accepted Answer

(4) E C. In an experiment, the 'variable to be changed' is the independent variable, and the 'variable to be measured' is the dependent variable.
- The aim is to find out 'which material of the rod is the best conductor of heat'. So, the material of the rod must be changed (E).
- To determine the best conductor, one needs to measure how quickly heat travels along the rod. The melting of butter indicates heat transfer. So, the time taken for the butter to melt (C) is the variable to be measured.
Other factors like the number of lit candles (heat source), length of the rod, and amount of butter should be kept constant for a fair test.

Question 29

Harry had two cups with the same amount of water, but the water in each cup was at a different temperature. He placed both cups in a room with a temperature of 25°C. Harry started measuring the temperature of the water in cup B. Then, he poured the water from cup A into cup B and continued to measure the temperature in cup B for one hour.
Which of the following graphs shows the change in the temperature of water in cup B?

Accepted Answer

(4) (graph). Let's trace the events:
1.  Initial state: Cup B water is at 10°C, and the room temperature is 25°C. Water in cup B will absorb heat from the warmer surroundings, so its temperature will increase from 10°C towards 25°C.
2.  Pouring: Water from cup A (70°C) is poured into cup B. This will cause an immediate and sudden increase in the temperature of the water in cup B (due to mixing hot water with warmer water).
3.  After mixing: The combined water will have a temperature higher than 25°C (likely around 40°C if equal amounts are mixed). Since this mixed temperature is now higher than the room temperature (25°C), the water will start losing heat to the surroundings, and its temperature will gradually decrease, approaching 25°C.
Graph (4) correctly illustrates this sequence: an initial rise from 10°C, a sharp increase upon mixing, followed by a gradual decrease towards the room temperature of 25°C.

Question 30

Study the flowchart below:
Which material P, Q, R or S would be most suitable for making part X of the mop shown below?

Accepted Answer

(4) S. Part X of the mop refers to the fibrous cleaning head. For a mop head, the material should possess the following properties:
1.  **Flexible:** To conform to different surfaces and reach tight spots during cleaning.
2.  **Does not break easily:** To ensure durability during use.
3.  **Not waterproof:** Crucially, it must absorb water to effectively clean and carry dirt.

Let's trace these properties through the flowchart:
- 'Is it flexible?' -> Yes (eliminates P, which is not flexible).
- 'Does it break easily?' -> No (eliminates Q, which breaks easily).
- 'Is it waterproof?' -> No (eliminates R, which is waterproof). This leads to S.

Therefore, material S (flexible, does not break easily, not waterproof) is the most suitable for making part X of the mop.

P5 Science SA2 2025 — Maha Bodhi

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