Question 1

The pie chart below shows the proportion of gases in air exhaled by a person. Which pie chart shows the proportion of gases in inhaled air?

Accepted Answer

B. Pie chart with a large oxygen slice, a very small carbon dioxide and other gases slice, and a large nitrogen slice. Inhaled air contains about 21% oxygen, 78% nitrogen and only about 0.04% carbon dioxide and other gases. Compared to exhaled air, inhaled air has more oxygen and much less carbon dioxide. The pie chart in option (2) shows a larger oxygen slice and a very small carbon dioxide slice, matching inhaled air composition.

Question 2

The diagram below shows the movement of blood in the human circulatory system to parts of the body. The arrows A, B, C and D represent blood vessels. Which statement describes the content of the blood in blood vessels A, B, C and D?

Accepted Answer

B. The blood in D has more oxygen than in A.. Vessel C carries deoxygenated blood from the heart to the lungs; vessel D carries oxygenated blood from the lungs back to the heart. Vessel B carries oxygenated blood from the heart to the legs; vessel A carries deoxygenated blood from the legs back to the heart. Therefore the blood in D (from lungs to heart, oxygenated) has more oxygen than in A (from legs to heart, deoxygenated).

Question 3

The diagram below shows Fiona's heart rate as she carried out certain activities. Her resting heart rate is 75 beats per minute (bpm). Based on the information above, which row best describes the activities Fiona was engaged in at E, F, G and H?

Accepted Answer

C. E: slow walk, F: stretching, G: sitting, H: sprinting. At E, the heart rate rises slightly above the resting rate of 75 bpm, consistent with a slow walk. At F, the heart rate decreases slightly (stretching, minimal exertion). At G, the heart rate drops to or below resting rate (sitting). At H, the heart rate rises sharply and stays at the highest level, indicating vigorous activity such as sprinting. Row (3) matches this pattern.

Question 4

Heidi took part in a 400-meter race. The volume of air in her lungs was measured before and immediately after the race. Which graph shows how the volume of air in Heidi's lungs changes before and after the race?

Accepted Answer

B. Solid line shows small oscillations; dashed line shows large, rapid oscillations at higher amplitude. After running a race, breathing becomes both deeper and faster. The volume of air per breath (amplitude) increases AND the breathing rate (frequency) increases. Option (2) shows the dashed 'after' line with both greater amplitude AND higher frequency than the solid 'before' line, which matches the expected change.

Question 5

Jacob carried out an experiment using the set-up below with four leaves W, X, Y and Z of the same size and from the same plant. He coated some of the leaf surfaces with oil that did not drip. Each leaf was then weighed and hung up in an open space as shown below. After six hours, each of the leaves were weighed again. Which of the following results shows that leaves have more tiny openings on the bottom surface?

Accepted Answer

B. W: 15→6, X: 15→12, Y: 15→15, Z: 15→9. Leaves lose water through tiny openings (stomata). W has no oil (loses most water), Y has both surfaces coated (loses least, almost none), X has only the bottom coated (loses through top only), Z has only the top coated (loses through bottom only). If there are more openings on the bottom surface, Z (bottom uncovered) should lose more water than X (top uncovered). In option (2): W loses 9g, X loses 3g, Y loses 0g, Z loses 6g. Z's loss (6g) > X's loss (3g), confirming more openings on the bottom surface.

Question 6

The diagram below shows the life cycle of animal K. What is animal K?

Accepted Answer

D. Mealworm beetle. The life cycle shown has four stages: Adult → Egg → Larva → Pupa → Adult. This is complete metamorphosis with a pupal stage. Among the options: Frog has egg → tadpole → adult; Chicken has egg → chick → adult; Grasshopper has egg → nymph → adult (incomplete metamorphosis, no pupa). Only the Mealworm beetle goes through all four stages including pupa.

P5 Science CA2 2025 — Anglo Chinese

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