Question 1

The diagram shows the water cycle. What does P, Q and R in the boxes stand for?

Accepted Answer

A. P: water vapour, Q: clouds, R: rain. Water from rivers, lakes and sea evaporates to form water vapour (P). The water vapour rises and condenses to form clouds (Q). The clouds then release water that falls as rain (R), which returns to rivers, lakes and sea.

Question 2

The diagram shows a cup that contained green-coloured water at 90°C. The cup was then covered completely with a metal lid with ice cubes placed on it. One hour later, water droplets were observed. Which of the following correctly states the colour of the water droplets and where the water droplets were?

Accepted Answer

C. Colour: Colourless; Place: Under the metal lid. The green-coloured hot water evaporates to form water vapour, which is colourless. The water vapour rises and comes into contact with the cold metal lid (cooled by ice cubes), losing heat and condensing into colourless water droplets under the metal lid. Only pure water evaporates; the green colouring stays in the cup.

Question 3

Emma had three sheets, A, B and C, made of different materials. She observed that when she placed all three sheets in a straight line as shown below, she could not see the cardboard star. However, if she placed only sheets A and C in a straight line as shown below, she could see the cardboard star clearly. Based on her observations, which of the following statements is correct?

Accepted Answer

D. Sheets A and C allow most light to pass through.. When sheets A, B and C were all in a line, the star could not be seen, which means at least one sheet (B) blocks light. When only A and C were in a line, the star could be seen clearly, meaning both A and C allow most light to pass through (they are transparent), while B is the opaque sheet that blocked the light in the first set-up.

Question 4

John conducted an experiment using two identical beakers containing different amounts of hot water at 85°C, as shown below. He placed both beakers in a room with a temperature of 30°C. Four students made the following statements. Ann: The temperature of water in both beakers will eventually reach 30°C. Bess: The water in beaker A has more heat than the water in beaker B. Calvin: Both beakers of water have the same amount of heat. Dave: The water in beaker B has more heat than the water in beaker A. Which of the comment(s) made is/are correct?

Accepted Answer

B. Ann and Bess only. Ann is correct: heat flows from the hotter water to the cooler surroundings until thermal equilibrium is reached at 30°C. Bess is correct: although both beakers contain water at the same temperature (85°C), beaker A contains more water (greater mass), so it has more heat (thermal energy). Calvin is wrong because the amount of heat depends on mass at equal temperatures. Dave is wrong for the same reason — beaker A has more water than beaker B.

Question 5

Jason wants to classify some animals as either mammals or birds. Which of the following question(s) will help him to classify the animals into groups of either mammals or birds?

Accepted Answer

C. B and D only. To distinguish mammals from birds, the most reliable characteristics are body covering (mammals have fur/hair, birds have feathers — question B) and whether the young are fed with milk (only mammals do — question D). 'Does it fly?' (A) is unreliable because some birds (e.g. penguins) cannot fly and some mammals (e.g. bats) can. 'How many legs does it have?' (C) is unhelpful because both mammals and birds can have similar leg counts.

Question 6

David observed the life cycle of a beetle. He recorded the amount of food taken by the beetle at each stage of growth in its life cycle. He drew a bar graph to represent the amount of food the beetle ate. Which one of the following bar graphs correctly shows the amount of food taken by the beetle at each stage of growth in its life cycle?

Accepted Answer

C. Graph 3: egg = 0, larva = medium, pupa = 0, adult = tall. A beetle undergoes complete metamorphosis (egg → larva → pupa → adult). At the egg stage no food is eaten. The larva eats a lot to grow. During the pupal stage the beetle does not eat. The adult eats again, usually more than the larva. Therefore the correct bar graph has no bar for egg, a medium bar for larva, no bar for pupa, and a tall bar for adult — Graph 3.

Question 7

One night, Andy walked from point A to point C, passing a lamp post at point B as shown in the diagram below. The only light source nearby was the lamp post. Which one of the graphs below shows how the length of Andy's shadow changes from point A to point C?

Accepted Answer

C. Graph 3: shadow length falls from A to a minimum at B then rises to C. The lamp post is at B with the light directly overhead. The further Andy is from a light source directly above him, the longer his shadow. At A (far from B) his shadow is long; as he approaches B (directly under the lamp) his shadow becomes shortest; as he continues past B towards C the shadow lengthens again. Graph 3, a V-shape with the minimum at B, shows this correctly.

P5 Science SA1 2021 — Henry Park

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