Question 1

Study the water cycle below. Which of the following describes Process A and Process B?

Accepted Answer

(2) evaporation condensation. Process A shows water changing from liquid (lake) to water vapour in the air, which is evaporation. Process B shows water vapour in the air forming clouds and then rain, which is condensation.

Question 2

In the set-up below, the sea water is allowed to boil and pure water can be obtained at the end of the process. The steam from the boiling sea water enters the condenser. The tap water flows around the outer tube of the condenser and does not mix with the steam in the inner tube. Based on the set-up above, what is the function of the continuous flow of tap water in the outer tube of the condenser?

Accepted Answer

(3) It allows the steam to lose heat to the tap water.. The continuous flow of cold tap water in the outer tube of the condenser acts as a coolant. It absorbs heat from the hot steam in the inner tube, causing the steam to lose heat and condense into pure water.

Question 3

Hassan wanted to investigate if the amount of exposed surface area of water affects the rate of evaporation. Containers C, D, E and F, are made of the same material but filled with different amounts of water as shown below. Which containers could he use for his experiment?

Accepted Answer

(2) D and E. To investigate how the amount of exposed surface area affects the rate of evaporation, the experiment should keep the amount of water constant and vary only the exposed surface area. Containers D and E both contain the same amount of water (90 ml). Assuming they are designed to have different exposed surface areas despite appearing visually similar in width (or that subtle differences are intended), this pair allows for a controlled comparison where the volume of water is constant and surface area is the independent variable.

Question 4

Muthu prepared two set-ups with the same amount of water but of different temperatures. He placed them on digital balances at the room temperature of 25°C as shown below. Which of the following shows the possible changes in the mass shown on the digital balance after 15 minutes?

Accepted Answer

(4) set-up A: decreases; set-up B: increases. Set-up A has water at 25°C, exposed to the air. At room temperature (25°C), water will evaporate into the air, causing its mass to decrease. Set-up B has water at 2°C, which is colder than the room temperature of 25°C. Although an oil layer prevents evaporation, water vapour from the surrounding warmer air can condense onto the cold surface of the beaker or its contents, increasing the measured mass of the setup.

Question 5

Simone recorded her heart rate before, during and after exercising as shown below. Her heart rate was at 70 beats per minute when she was resting. At which point of the graph did Simone stop exercising?

Accepted Answer

(4) D. Point A represents the resting heart rate (70 bpm). From A to B, the heart rate increases, indicating the start of exercise. From B to C, the heart rate remains high, indicating continued exercise. At point D, the heart rate starts to decrease, moving back towards the resting rate, which signifies that exercising has stopped.

Question 6

Study the flowchart below. Based on the flowchart above, which systems do J, K and L represent?

Accepted Answer

(1) J: skeletal; K: circulatory; L: digestive. Following the flowchart:
1. 'Does it protect the organs in the body?' If 'Yes' to J: The skeletal system (bones) protects vital organs (e.g., rib cage protects heart/lungs). So, J is skeletal.
2. If 'No' to the first question, 'Does it transport substances?' If 'Yes' to K: The circulatory system transports substances (blood, oxygen, nutrients) throughout the body. So, K is circulatory.
3. If 'No' to the second question, 'Does it absorb digested food into the blood stream?' If 'Yes' to L: The digestive system (specifically the small intestine) absorbs digested food into the bloodstream. So, L is digestive.
This matches option (1).

Question 7

The diagram below shows the direction of blood flow in the blood vessels W, X, Y and Z, in Jatin's body. Which graph below shows the amount of carbon dioxide present in the blood flow of blood vessels at W and Y?

Accepted Answer

(1) [Bar chart with W high CO2, Y low CO2]. Blood vessel W carries deoxygenated blood from 'Other parts of the body' to the 'Heart'. Blood returning from body tissues is rich in carbon dioxide, so W has a high amount of carbon dioxide. Blood vessel Y carries oxygenated blood from the 'Lungs' back to the 'Heart'. In the lungs, carbon dioxide is released and oxygen is absorbed, so Y has a low amount of carbon dioxide. Therefore, W has high CO2 and Y has low CO2, which is represented by graph (1).

Question 8

A, B and C are different parts of a plant. The diagram below shows how water and food are transported in the plant. Which of the following correctly shows the parts of the plant?

Accepted Answer

(2) A: leaf; B: flower; C: root. The key indicates dashed arrows for water and solid arrows for food. 
- Part A: Dashed arrow (water) points towards A, and solid arrow (food) points away from A. This indicates A receives water and produces food, which is a leaf.
- Part B: Dashed arrow (water) points towards B, and solid arrow (food) points towards B. This indicates B receives both water and food, typical of a growing part like a flower or a fruit.
- Part C: Dashed arrow (water) originates from C and points upwards into the stem, indicating C absorbs water. Solid arrow (food) points downwards from the stem to C, indicating C receives food for storage. This is characteristic of a root.
Therefore, A is a leaf, B is a flower, and C is a root, which matches option (2).

Question 9

The diagram below shows a plant growing in a field. An outer ring of the stem was removed. It was observed that Z grew bigger after one week. Which of the following statements best explains the observation?

Accepted Answer

(3) Food is transported from Y to Z.. The outer ring of the stem contains the phloem, which is responsible for transporting food (sugars) made during photosynthesis in the leaves (Y) to other parts of the plant, including the roots (Z). When an outer ring of the stem (X) is removed, it disrupts the downward flow of food. Food produced in the leaves (Y) is transported downwards but gets blocked at the cut (X), causing it to accumulate in the region just above the cut and the part of the stem and roots below it (Z). This accumulation of food causes Z (the part of the stem/root below the cut) to swell or grow bigger.

P5 Science SA1 2025 — Tao Nan

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