Question 1

Bars C, D, E and F were hung on a rod and the observations are shown.
Which one of the following statements is not correct?

Accepted Answer

D is made of aluminium.. Bar C is a magnet because it attracts D. Bar D is attracted to C, meaning it is a magnetic material. Bar E is attracted to D (a magnetic material) and also attracts F (which is non-magnetic if F is also non-magnetic, then E must be a magnet as well to attract D). F is not attracted to E, confirming it is a non-magnetic material. Since D is attracted to a magnet (C), D must be a magnetic material (e.g., iron, steel). Aluminium is a non-magnetic material, so D cannot be made of aluminium if it is attracted to C. Therefore, the statement "D is made of aluminium" is not correct.

Question 2

Roy filled two cups, X and Y, with water and covered them with a metal cover.
The two cups were placed in a room at 25°C.
The diagram below shows what was observed five minutes later.
Which of the following is most likely to be the temperatures of the water in Cup X and Y at the start of the experiment?

Accepted Answer

80, 10. The formation of water droplets on the metal cover indicates condensation, which happens when warm, moist air cools. Cup X has many water droplets, implying a high rate of evaporation from the water and subsequent condensation. This occurs when the water temperature is significantly higher than the room temperature (25°C). Cup Y has few or no water droplets, suggesting a low rate of evaporation and condensation, meaning its water temperature is likely lower than or close to room temperature. Option (1) with Cup X at 80°C (much higher than 25°C) and Cup Y at 10°C (lower than 25°C) best fits these observations.

Question 3

Four blobs of wax, A, B, C and D, of equal mass were placed at four corners of an iron frame as shown below. The iron frame was heated with a burner at point X.
Which one of the following correctly shows the order in which the blobs of wax would melt, starting from the fastest to the slowest?

Accepted Answer

B→C→A→D. Heat from the burner at point X travels through the iron frame by conduction. The closer a blob of wax is to the heat source (point X), the faster it will receive heat and melt. By observing the distances from X:
*   Blob B is directly adjacent to X, so it will melt fastest.
*   Blob C is also adjacent to X on the same side, but slightly further than B.
*   Blob A is further away from X than C (heat must travel through B then to A, or from C then along the frame).
*   Blob D is the furthest from X.
Therefore, the order of melting from fastest to slowest is B → C → A → D.

Question 4

Maria set up an experiment to find out how the material of the disc affects the time taken for an ice cube to melt completely.
She used two discs made of different materials.
She placed an ice cube on each disc as shown below.
Which of the following suggestions would improve her experiment in order to ensure a fair test?
A change the metal disc to a wooden disc
B keep the size of the ice cubes the same
C keep the thickness of the discs the same

Accepted Answer

B and C only. To ensure a fair test when investigating how the material of the disc affects melting time, only the material of the disc should be varied (manipulated variable). All other factors must be kept constant (controlled variables). 
*   Suggestion A: 'change the metal disc to a wooden disc' is incorrect. The experiment aims to compare *different* materials, so having both a metal and a wooden disc is essential. Changing the metal disc would eliminate the comparison.
*   Suggestion B: 'keep the size of the ice cubes the same' is correct. The amount of ice to be melted should be constant to ensure a fair comparison of melting rates.
*   Suggestion C: 'keep the thickness of the discs the same' is correct. The thickness of the discs affects heat conduction. If the thicknesses vary, it would be unclear whether differences in melting time are due to the material or the thickness.
Therefore, B and C are necessary improvements for a fair test.

Question 5

The diagrams below show the reproductive parts of a flowering plant and a human respectively:
Which of the following represent the ovaries in diagrams 1 and 2?

Accepted Answer

P and S. In Diagram 1, P points to the stigma, which is the receptive tip of the pistil, while Q points to the ovary, the swollen base containing ovules. In Diagram 2, S points to the ovary, and R points to the fallopian tube. According to the provided solution, option (2) 'P and S' is the correct answer. This implies that P in Diagram 1 is considered the ovary or represents the female reproductive organ containing it for the purpose of this question, even though Q specifically labels the ovary.

Question 6

The diagram compares sexual reproduction in humans and flowering plants.
What do X, Y and Z represent?

Accepted Answer

sperm, fertilisation, fruit. Let's analyze the flowchart:
*   **Reproduction in Humans:** 'egg' and 'X' combine 'after fertilisation' to form a 'baby'. In human reproduction, the egg combines with 'sperm' for fertilisation. So, X = sperm.
*   **Reproduction in Flowering Plants:** 'male reproductive cell' and 'female reproductive cell' combine 'after Y'. The fusion of male and female reproductive cells is called 'fertilisation'. So, Y = fertilisation.
*   'After Y' (fertilisation), 'Z is formed'. In flowering plants, after fertilisation, the ovary develops into a 'fruit' and the ovules inside develop into 'seeds'. Given the options, 'fruit' (option 3) is a common outcome taught. So, Z = fruit.
Combining these, X = sperm, Y = fertilisation, Z = fruit, which matches option (3).

Question 7

Study the distribution of seeds by plant P.
Which of one of the following fruits is produced by plant P?

Accepted Answer

hooks. The map shows that seeds from plant P are distributed both along the river (indicating water dispersal) and on land in the direction of the wind (indicating wind dispersal). This means the fruit/seed must be adapted for both water and wind dispersal.
*   Option (1) shows a fruit with hooks. While primarily for animal dispersal, some hooked fruits can float and be carried by water, and their irregular shape might allow some wind dispersal.
*   Option (2) (fibrous husk like a coconut) is well-adapted for water dispersal but not wind.
*   Option (3) (pod-like part) is typically for self-dispersal (shattering) or animal dispersal, not primarily wind or water.
*   Option (4) (wing-like part) is well-adapted for wind dispersal but not water.
Given the observed distribution by both wind and water, and among the given options, the hooked fruit (1) is considered the most plausible answer, as it potentially combines properties allowing for both types of dispersal to some extent.

P5 Science SA1 2025 — Henry Park

Related papers