Question 1

Which of the following graphs correctly shows the amount of digested and undigested food as it leaves the mouth, stomach and small intestine?

Accepted Answer

A. Graph showing mouth has small digested portion on top of undigested, stomach has larger digested portion, small intestine has only a tiny undigested portion. Digestion begins in the mouth (small amount digested) and continues in the stomach (more digested), so by the time food leaves the small intestine almost all food has been digested and absorbed, leaving only a tiny amount of undigested food. Option (1) correctly shows progressive digestion with very little remaining at the small intestine.

Question 2

Oliver wanted to conduct an experiment to find out if the presence of light affects the growth of a plant. He put four similar plants into four identical pots and gave each plant the same amount of water each day. Which two set-ups should Oliver choose in order to carry out a fair test?

Accepted Answer

B. P and R only. To test the effect of light on plant growth, the variable changed must be light (one in dark, one in light) while all other conditions are kept the same. Plant P is in the cupboard (no light) and Plant R is in the garden (light), so choosing P and R only changes the presence of light, making it a fair test.

Question 3

The diagram below shows systems A and B in a human body. The arrows represent blood transporting substances X and Y. Which of the following options correctly represents systems A and B as well as substances X and Y?

Accepted Answer

C. System A: circulatory, System B: respiratory, X: carbon dioxide, Y: oxygen. The diagram shows blood circulating between two systems and the body parts. System B exchanges gases with the air (respiratory), and System A pumps blood (circulatory). Substance X (solid arrow) is carried from the respiratory system to the body — oxygen, but in the diagram solid line goes from body to System B = carbon dioxide; dashed arrow Y goes from System B to body = oxygen. Hence System A = circulatory, System B = respiratory, X = carbon dioxide, Y = oxygen.

Question 4

The table below shows the composition of gases in air that are inhaled and exhaled by a child. Based on the information provided, which of the following statements is correct?

Accepted Answer

D. Carbon dioxide is produced by the body.. From the table, carbon dioxide rises from less than 1% in inhaled air to 4% in exhaled air, showing the body produces carbon dioxide. Oxygen drops from 21% to 16% (only some, not all, is taken in). Nitrogen remains at 78% (not absorbed).

Question 5

The food-carrying tubes between positions X and Y of a plant's stem were removed, leaving behind the water-carrying tubes. After some time, which of the following diagrams would best represent how the stem would look?

Accepted Answer

A. Stem bulges (swells) above position X. When the food-carrying tubes (phloem) between X and Y are removed, food made in the leaves cannot travel down past X. The food accumulates above the cut (above X), causing the stem to swell/bulge above position X. Water can still travel up through the xylem.

Question 6

Ariff conducted two experiments with two balls, P and Q, of similar shape and size. The set-ups are as shown below. Based on the results of the experiment above, what can he conclude about P and Q?

Accepted Answer

B. Q has a larger mass than P.. Set-up 1 (balance) shows the side with Q is lower, so Q has a larger mass than P. Set-up 2 shows both balls displace the same volume of water (same rise in water level), so they occupy the same space. Hence Q has a larger mass than P.

Question 7

The diagram below shows a container with a capacity of 500 cm³ and a plunger fitted to it. Each time the plunger is pulled completely, 20 cm³ of air is drawn out of the container. Which of the following correctly shows the change in the volume and mass of both air and water in the container after the plunger is pulled completely once?

Accepted Answer

D. Volume of air: Remains the same, Mass of air: Decreased, Volume of water: Remains the same, Mass of water: Remains the same. Air fills the entire container, so even after some air is drawn out, the remaining air still expands to occupy the whole container (volume of air remains the same = 500 cm³ minus water). However, the mass of air decreases because some air has been removed. Water is a liquid with fixed volume and mass — both remain the same.

Question 8

Derrick walked in a straight line at the same pace from point A to point C. Which of the following graphs correctly shows how the length of Derrick's shadow will change as he walks from point A to point C?

Accepted Answer

A. V-shape: shadow length decreases from A to B, then increases from B to C. The light source (lamp) is directly above point B. As Derrick walks from A toward B, he moves closer to the point directly below the light, so his shadow gets shorter. At B (directly under the lamp) the shadow is shortest. As he continues from B to C, he moves away from the point below the lamp and his shadow gets longer again. This produces a V-shape graph.

Question 9

Vera placed four different materials, P, Q, R, S, in a straight line as shown below. When Vera switched on the torch and placed it in front of material P, she observed a patch of light shining on material R, but not on materials P or S. Which of the following statements can be concluded from her experiment? A: Material P allows most light to pass through it. B: Material R allows no light to pass through it. C: Material S allows some light to pass through it.

Accepted Answer

C. A and B only. Light passed through P to reach Q (so P allows light to pass — statement A correct). Light passed through Q's hole and hit R as a patch (light did not pass through R to reach S), so R blocks light (statement B correct). We cannot conclude anything about S since no light reached it (statement C unsupported). Hence A and B only.

P5 Science SA1 2025 — Red Swastika

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