Question 1

The table below shows some observations about four cells W, X, Y and Z. A tick (✓) represents that the characteristic is present in the cell.

Which of the following statements about cells W, X, Y and Z is false?

Accepted Answer

D. Cell W and X do not have regular shapes.. Cell W has a cell wall (present) — cells with cell walls have regular/fixed shapes. Therefore the statement that W and X do not have regular shapes is false. Z (no chloroplast, no cell wall) is an animal cell — true. Only X has chloroplast, so only X can make food — true. Y has no nucleus, so only W, X and Z (which have nuclei) can reproduce — true.

Question 2

Which of the following correctly matches the cell part to its function?

Accepted Answer

A. Chloroplast — Traps light to enable the plant to make food.. Chloroplast traps light energy used for photosynthesis — correct. The cell membrane (not cell wall) controls which substances enter/leave; the nucleus (not cytoplasm) controls cell activities; the cell wall (not cell membrane) gives the cell shape.

Question 3

Three people were trapped in a lift that had broken down. The air ventilation system in the lift had shut down.

Which of the following best shows the changes in the levels of the different gases present in the lift after one hour?

Accepted Answer

D. Oxygen decrease, Carbon dioxide increase, Water vapour increase, Nitrogen no change. Trapped people breathe in oxygen and breathe out carbon dioxide and water vapour, so oxygen decreases while CO₂ and water vapour increase. Nitrogen is not used in respiration, so it stays unchanged.

Question 4

Study the model of a human respiratory system shown below.

Which of the following observations is correct?

Accepted Answer

D. When part C is pulled downwards, part B inflates as air rushes in through part A.. In the bell-jar lung model, pulling the rubber sheet (C, diaphragm) downwards increases the space inside the jar, so air is drawn in through the tube (A, trachea) and the balloons (B, lungs) inflate — modelling inhalation.

Question 5

Kaelyn set up an experiment involving four set-ups C, D, E and F. Each set-up has a different amount of food and digestive juice.

Which two set-ups should she use if she wanted to find out if the size of the food would affect the rate of digestion?

Accepted Answer

C. D and F only. To test if food size affects digestion rate, only the size of food may differ while all other variables stay the same. D and F both have 50 ml of digestive juice and 10 g of food — D uses one whole piece while F uses food cut into pieces. Only the size of food differs, making it a fair test.

Question 6

Mandy made the following observations about three organisms X, Y and Z. A tick (✓) represents that the characteristic is present in the organism.

Which of the following is true?

Accepted Answer

C. Organism X could be a butterfly.. Organism X has six legs, four stages in its life cycle, and lays eggs — these are characteristics of insects with complete metamorphosis such as butterflies. Y has young resembling adult and lays eggs (so not a frog — frogs have young that don't resemble adults). Z has young resembling adult but does not lay eggs, so Z cannot be a bird.

Question 7

The stalk of a white flower was split into two and dipped into two beakers containing different coloured water as shown below.

After one day, the flower was cut along PQ as shown in the diagram above. Which of the following shows the cut surface of the flower stalk?

Accepted Answer

D. Cross-section with red water-conducting tubes on the P side and blue water-conducting tubes on the Q side. Water and dissolved dyes only travel up the xylem (water-conducting tubes) in a one-way manner from root/stalk to flower. The half of the stalk in the red dye will only have red dye in its xylem, and the half in the blue dye will only have blue dye in its xylem. There is no mixing of colours since the dye stays within the tubes on its own side.

Question 8

Natalie conducted an experiment as shown below. She placed an equal number of identical spores in four dishes A, B, C and D. She then placed them in four different locations as shown in the diagram below.

Which one of the following is not a possible aim of her experiment?

Accepted Answer

A. To find out if spores need air to germinate.. All four dishes are open to the air, so air is not a variable being tested — it cannot be the aim. The setup varies light (dark vs bright), temperature (8 °C vs 30 °C), and the type of solution (water vs nutrient solution), so these three can be aims.

Question 9

The diagram below shows the life cycle of organism A.

Based on the diagram above, which of the following statements is false?

Accepted Answer

D. The only stage that organism A does not feed is the pupal stage.. Organism A is a mosquito. It also does not feed in the egg stage — it doesn't feed in TWO stages (egg and pupa), not just the pupal stage, so statement D is false. There are 4 stages (egg → larva → pupa → adult), young does not look like adult, and from larva to adult takes about 7 + 3 = 10 days.

Question 10

Nora placed a pole in an open field and made some observations about the length of its shadow.

Which one of the following graphs shows what Nora could have observed over a period of time?

Accepted Answer

B. Length of shadow is high at 8 am, drops to almost zero at 12 pm, then rises again by 6 pm.. The sun is low in the sky in the morning so shadows are long; the sun is overhead at midday so shadows are shortest; the sun is low again in the afternoon so shadows lengthen again. The V-shaped graph with minimum at 12 pm is correct.

Question 11

Ming accidentally dropped a small ball into a hole of a drain and was unable to see it. His friend suggested that he lowers a mirror into the drain so that he can see where the ball is.

Which of the following diagrams show the correct position of the mirror so that Ming can see the ball in the drain?

Accepted Answer

C. Mirror at the bottom of the drain tilted at 45° so its reflective face slopes from upper-right down to lower-left, with the reflective side facing the ball.. Light from the ball travels horizontally into the drain, hits the mirror, and must be reflected vertically up into Ming's eye. This requires the mirror to be tilted at about 45° with its reflective surface facing the ball. Only option C shows this orientation correctly.

Question 12

Ashley set up an experiment as shown below. Four identical beakers K, L, M and N were filled with different amounts of water at different temperatures. She then heated up four identical metal blocks to a temperature of 80 °C and placed each block into each beaker of water as shown below.

In which beaker would the water show the greatest increase in temperature?

Accepted Answer

B. L. Heat flows from the hotter metal block (80 °C) to the cooler water. The biggest rise in water temperature occurs when (i) the water starts coldest (largest temperature gap from 80 °C) and (ii) the water has the smallest mass (less water heats up faster). Beaker L has 50 ml of water at 10 °C — coldest and smallest amount — so it shows the greatest temperature increase. M and N start at 90 °C (hotter than the block) so their water actually loses heat, not gains.

Question 13

Wen Ling picked up a metal spoon and it felt cold. Which one of the following statements explains why the metal spoon felt cold to touch?

Accepted Answer

A. Wen Ling's hand lost heat to the metal spoon.. Heat always flows from a hotter object to a cooler one. Wen Ling's hand is warmer than the metal spoon, so heat flows from her hand to the spoon. The loss of heat from her hand is felt as 'cold'. 'Coldness' is not transferred — only heat.

Question 14

The diagram below shows three identical beakers A, B and C. Three pebbles of different sizes were placed into the beakers. The beakers were then filled to the brim with water.

Which of the following shows the most likely amount of water added into each beaker?

Accepted Answer

A. A = 250 ml, B = 460 ml, C = 320 ml. All three beakers are identical and filled to the brim. The bigger the pebble, the more space it takes up, so the less water can be added. From the diagram, B has the smallest pebble (most water needed), C has a medium pebble, and A has the biggest pebble (least water needed). So A = 250 ml (least), C = 320 ml (middle), B = 460 ml (most).

Question 15

Study the diagram below.

Which of the following observation(s) can be made when the plunger was pushed downwards as far as possible without any air or water escaping?

A  The plunger will stop at the 20 cm³ marking.
B  The volume of air would be less than 10 cm³.
C  The total volume of air and water will be 30 cm³.
D  The volume of water would remain the same at 20 cm³.

Accepted Answer

C. B and D only. Water cannot be compressed, so its volume stays at 20 cm³ (D true). Air can be compressed, so pushing the plunger reduces the air's volume to less than 10 cm³ (B true). The plunger cannot stop at 20 cm³ because air is compressible (A false), and the total volume becomes less than 30 cm³ since air is squeezed (C false).

Question 16

Karyn placed five identical ring magnets A, B, C, D and E, 3 cm apart from each other, on a wooden rod as shown below.

Which one of the following diagrams shows the final positions of the magnets when she releases her grip on magnets B, C and D?

Accepted Answer

D. A alone; gap; B and C together; gap; D and E together.. From the initial diagram the poles facing one another are: A(S) ↔ (S)B → repel; B(N) ↔ (S)C → attract; C(N) ↔ (N)D → repel; D(S) ↔ (N)E → attract. Since A and E are fixed, B is repelled from A but attracted to C, so B and C move together; D is attracted to E, so D and E move together; the C↔D pair repel one another, leaving a gap between (B,C) and (D,E). This matches option (4).

Question 17

Jenny wanted to find out whether the number of turns of the coil of wire around an iron nail would affect the magnetic strength of an electromagnet.

Which of the following variables should she keep the same to ensure a fair test?

A  The type of battery
B  The size of the iron nail
C  The number of batteries used
D  The number of turns of the coil of wire
E  The number of iron nails the electromagnet can attract

Accepted Answer

C. A, B and C only. The changed variable is the number of turns of coil (D), and the measured/observed variable is the number of iron nails attracted (E). All other variables — type of battery (A), size of iron nail (B) and number of batteries (C) — must be kept the same to ensure a fair test.

Question 18

Murai conducted an experiment as shown below using materials P, Q, R and S.

When he moved the magnet under materials P and Q in set-up X, he observed that the iron ball moved in the same direction as the magnet.

He then repeated his experiment with materials R and S in set-up Y but this time the ball did not move.

Which of the following is definitely true?

Accepted Answer

C. Materials P and Q are non-magnetic materials.. The magnetic force is able to pass through both P and Q to attract the iron ball, so P and Q must be non-magnetic (magnetic force passes through non-magnetic materials without being blocked). For set-up Y the ball did not move — this only tells us that at least one of R or S blocks the magnetic force (is magnetic), but we cannot say both are magnetic. So only 'P and Q are non-magnetic' is definitely true.

P5 Science SA1 2023 — CHIJ

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