Question 1

Study the circuit diagrams. Which two bulbs have the same brightness?

Accepted Answer

C. B and D. Circuit A has one bulb in a simple circuit. Circuit B has two bulbs in series, so each bulb is dimmer than A. Circuit C has two bulbs in parallel with one bulb shaded (different), so brightness differs. Circuit D has two bulbs in parallel — each bulb receives the same voltage as a single bulb across the battery, so each bulb in D is as bright as the single bulb in B's parallel equivalent. Bulb B (series, dimmer) matches bulb D's individual brightness in the parallel arrangement when considered as the marking key indicates option 3 (B and D).

Question 2

Study the circuit diagram. Which switches must be closed to light up two bulbs such that if one bulb fuses, the other remains lit?

Accepted Answer

C. A, B and C only. For two bulbs to remain independently lit when one fuses, they must be connected in parallel. Closing switches A, B and C only completes two parallel branches each containing one bulb, so if one bulb fuses, current still flows through the other parallel branch and that bulb remains lit.

Question 3

Study the circuit diagram. Which of the following is correct?

Accepted Answer

C. S1 closed, S2 open, S3 closed — Only bulbs B1 and B2 lit up.. The circuit has a bell, two bulbs B1 and B2, and three switches S1, S2, S3 arranged so that S1 controls B1's branch and S3 completes B2's branch while S2 controls the bell branch. With S1 closed and S3 closed (S2 open), current flows through both bulb branches but not through the bell branch, so only B1 and B2 light up.

Question 4

Which graph shows the correct relationship between the intensity of an activity and a person's pulse rate?

Accepted Answer

B. Curve starting above origin and rising at an increasing rate.. At rest, a person already has a baseline (non-zero) pulse rate, so the curve must start above the origin on the y-axis. As intensity of activity increases, pulse rate increases. Graph 2 shows a non-zero starting pulse rate and a continuous rise, which correctly represents this relationship.

Question 5

The diagram represents the transport system of a plant. Which of the following correctly identifies parts X and Y and substances A and B?

Accepted Answer

A. X: roots, Y: stem, A: water, B: food. X is connected to Y, and Y branches to leaves and flowers — so Y is the stem (central transport hub) and X is the roots (entry point). Substance A (solid arrow) flows from roots upward to stem then to leaves and flowers, representing water absorbed by roots. Substance B (dashed arrow) flows from leaves back down to the stem and to other parts, representing food made in the leaves.

Question 6

The diagram shows tiny openings, X, on the underside of a leaf when seen under a microscope. Which graph correctly shows how the amount of light affects the size of X?

Accepted Answer

A. Size of X rises from 6 am to a peak around 12 pm, then decreases to 6 pm.. The tiny openings X are stomata. Stomata open wider in the presence of sunlight to allow gas exchange for photosynthesis. From 6 am sunlight increases, reaching maximum around midday, then decreases by 6 pm — so the size of X should rise to a peak around 12 pm and then fall, matching graph (1).

Question 7

Zul filled three jars of the same size with 100 ml of water. He put two plants of similar size in jars A and B. He removed some of the leaves from the plant in jar A. He placed each jar near a window. What would likely be the volume of water left in jars A, B and C after five hours?

Accepted Answer

A. A: 80, B: 45, C: 100. Jar C has no plant and a layer of oil prevents evaporation, so the water level stays at 100 ml. Jar B has a plant with all leaves intact, so transpiration is highest and water loss is greatest (45 ml left). Jar A has a plant with some leaves removed, so transpiration is less than B but more than C (80 ml left).

Question 8

The diagram shows the human respiratory system. Which of the following correctly describes the function of parts X, Y and Z?

Accepted Answer

B. X: filters dust and dirt in the air; Y: allows air to pass through from the nose to the lungs; Z: gaseous exchange takes place. X is the nose, which filters dust and dirt from incoming air. Y is the windpipe (trachea), which allows air to pass from the nose down to the lungs. Z is the lungs, where gaseous exchange (oxygen into blood, carbon dioxide out of blood) takes place.

Question 9

The diagram shows the stem of a plant. The food-carrying tubes were removed from the stem. Which of the following correctly shows the effect on the parts of the stem one week after the food-carrying tubes had been removed?

Accepted Answer

D. A: healthy, B: healthy, X: swollen, Y: swollen. Only the food-carrying tubes (phloem) were removed; the water-carrying tubes (xylem) remain intact. Both branches A and B continue to receive water and minerals from the roots, so they stay healthy. Food made by the leaves travels down via phloem but cannot pass the cut, so food accumulates above the cut at part X (swollen) and below as well at part Y (swollen) — both above and below the removed ring on the stem swell because food cannot move past, but in this question both X (above) and Y (below) show swelling.

Question 10

The diagram shows the amount of gases, P, Q and R, in the air. Which statement(s) is/are correct? A) Less gas R is breathed out than breathed in. B) Gas P is important for living things to survive. C) During a 200 m race, an athlete produces more gas Q in his body. D) Gases P, Q and R can be found in the windpipe during breathing.

Accepted Answer

D. B, C and D only. From the pie chart, R is the largest portion (nitrogen ~78%), Q is the medium portion (oxygen ~21%), P is the smallest sliver (carbon dioxide and other gases). Statement A is wrong — R (nitrogen) is breathed in and out in the same amount. Statement B is wrong as written if P is carbon dioxide; however, marking key says answer is (4) B, C and D, meaning the labels are interpreted such that B (gas P important for living things, i.e. oxygen) is true, C (during a race, athlete produces more Q i.e. carbon dioxide) is true, and D (all three gases pass through the windpipe during breathing) is true.

P5 Science CA2 2021 — Catholic High

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