Question 1

John ate a sandwich for lunch. Which one of the graphs below correctly represents the amount of digested food found in the different body parts as it passes through John's digestive system?

Accepted Answer

C. Graph 3. Some digestion of carbohydrates begins in the mouth, so a small amount of digested food is present there. No digestion occurs in the gullet, so the amount stays roughly flat. Most digestion is completed in the small intestine, so the amount of digested food rises sharply there. Graph 3 shows a small initial rise (mouth), a flat region (gullet/stomach), then a steep rise at the small intestine.

Question 2

Which of the following statement(s) is/are true about the various systems in our body?
A  The skeletal system gives the body its shape.
B  The digestive system transports food to all parts of our body.
C  The muscular system is directly involved in the digestion of food.
D  The muscular, digestive and skeletal systems are directly involved when we breathe.

Accepted Answer

A. A only. Only statement A is correct — the skeletal system gives the body its shape. The digestive system does not transport food to all parts of the body (the circulatory system does). The breathing process directly involves the respiratory and muscular systems, not the digestive and skeletal systems. Hence A only.

Question 3

Sam set up the experiment as shown in the diagram below and placed it under a light source. What would most likely be collected in the basin after 30 minutes?

Accepted Answer

C. Colourless pure water will be collected in the basin.. The hot red-coloured seawater evaporates; only the water evaporates while the salt and colouring are left behind. The water vapour rises, condenses on the cool sloping plastic sheet (cooled by the ice cubes), and drips into the basin as colourless pure water.

Question 4

James conducted an experiment using 4 set-ups, P, Q, R and S, containing water in containers made of the same material. The table shows the starting conditions. James wanted to investigate how the rate of evaporation of water was affected by the temperature of water. Which of the following 2 set-ups are the best for him to use to ensure a fair test?

Accepted Answer

B. P and S. To test the effect of water temperature on evaporation, only the temperature of the water should differ while all other variables stay the same. P and S both have room temperature 28°C, exposed surface area 100 cm², volume 200 ml, and differ only in water temperature (40°C vs 50°C). Hence P and S form a fair test.

Question 5

Tim placed a beaker of crushed ice in a classroom which was at room temperature. The temperature of the melting ice was recorded and plotted in the graph shown. Based on the graph above, which of the following statements are true?
A  At point K, water in the beaker is evaporating.
B  At point J, all the ice in the beaker has melted.
C  At point L, there is no water present in the beaker.
D  At point H, the beaker contains a mixture of ice and water.

Accepted Answer

C. A, B and D only. At H the temperature is still at 0°C on the flat melting plateau, so ice and water coexist (D true). At J the temperature is rising above 0°C, meaning all ice has melted and the water is warming up (B true). At K the water has reached room temperature (28°C) and is evaporating (A true). At L water is still present in the beaker, so C is false. Hence A, B and D only.

Question 6

The diagram below represents a cell. Which of the following statements about the cell above are true?
A  Part R can only be found in animal cells.
B  Part T is the basic unit of any living organism.
C  Part S can be found in both plant and animal cells.
D  Part T contains information that is passed down from one generation to another.

Accepted Answer

B. C and D only. The diagram is a plant cell (rectangular with a cell wall). Part T is the nucleus, which contains genetic information passed from one generation to the next (D true), but the nucleus is not the basic unit of life — the cell is (B false). Part S is a structure (e.g. cytoplasm) found in both plant and animal cells (C true). Part R is a chloroplast, found only in plant cells, so A is false. Hence C and D only.

Question 7

The table below shows the parts present in cells W, X, Y and Z. Based on the information in the table above, which of the following statements are true?
A  Cell Z could be a cheek cell.
B  Cell X could be a sperm cell.
C  Cell Y could be a root hair cell.
D  Cell W could be an onion skin cell.

Accepted Answer

A. A only. Cell Z has a nucleus, cytoplasm and cell membrane but no cell wall or chloroplast — an animal cell, e.g. a cheek cell (A true). Cell X has a cell wall, so it cannot be a sperm cell (B false). Cell Y has no nucleus and no cell wall, so it cannot be a root hair cell (C false). Cell W has chloroplasts, but onion skin cells have no chloroplasts (D false). Hence A only.

Question 8

Ali placed three identical potted plants in three glass containers, A, B and C. The glass containers had the same amount of carbon dioxide at the start and were placed at different locations: A in a dark cupboard, B under the sun, C in the shade. Arrange the glass containers accordingly, from the one containing the least amount of carbon dioxide to the one with the most carbon dioxide, after a few hours.

Accepted Answer

C. B, C, A. Plant B (under the sun) photosynthesises the most, using up the most carbon dioxide, so it has the least CO2. Plant C (in the shade) photosynthesises less, leaving more CO2. Plant A (in the dark cupboard) cannot photosynthesise and only respires, releasing CO2, so it has the most. Order from least to most CO2: B, C, A.

Question 9

Which of following statements about photosynthesis are correct?
A  Photosynthesis releases energy.
B  Water and carbon dioxide are taken in by the stomata.
C  Oxygen is given out during the process of photosynthesis.
D  Food made in the leaves is transported to all parts of the plants.

Accepted Answer

D. C and D only. Photosynthesis stores energy rather than releasing it (A false). Water is taken in by the roots, not the stomata (B false). Oxygen is released during photosynthesis (C true) and the food made in the leaves is transported to all parts of the plant (D true). Hence C and D only.

Question 10

Study the diagram below. Which one of the following correctly represents process X and substances A, B and C in the diagram?

Accepted Answer

D. X: photosynthesis, A: carbon dioxide, B: sugar, C: starch. The process takes in light, water and a gas (A) and releases oxygen — this is photosynthesis, so A is carbon dioxide. It produces food (B = sugar/glucose), and the excess is stored as C = starch. Hence X = photosynthesis, A = carbon dioxide, B = sugar, C = starch.

Question 11

Jane placed a pot of plant in a dark room for 3 days. She then set up the experiment under the sun to find out the effect of carbon dioxide on photosynthesis. Liquids S and T were placed in each of the plastic bags wrapping leaf Y and leaf Z. Jane conducted a starch test on both leaves, Y and Z. The iodine solution turned dark blue on leaf Y but it remained brown on leaf Z. Which of the following statements best explain the results from the above experiment?
A  Starch was absent in leaf Z.
B  Starch was present in leaf Y.
C  Liquid T removed carbon dioxide from the plastic bag.
D  Liquid S removed carbon dioxide from the plastic bag.

Accepted Answer

C. A, B and C only. Iodine turning dark blue on leaf Y means starch is present (B true), so photosynthesis occurred — liquid S did not remove carbon dioxide (D false). Iodine remaining brown on leaf Z means starch is absent (A true), so photosynthesis did not occur because liquid T removed the carbon dioxide (C true). Hence A, B and C only.

Question 12

Study the experimental set-up below. It was observed that the water plant produced oxygen bubbles during the experiment. Which one of the following factors would most likely cause a decrease in the number of oxygen bubbles produced?

Accepted Answer

D. Moving the set-up away from the light source.. The oxygen bubbles are produced by photosynthesis, which depends on light. Moving the set-up away from the light source reduces the amount of light reaching the plant, slowing photosynthesis and decreasing the number of oxygen bubbles produced.

Question 13

A plastic toy truck carrying some iron ball bearings was given a push and was moving in the direction of the magnet as shown. Which of the following change(s) would enable the plastic toy truck to take a shorter time to reach the magnet?
A  Replace the magnet with a stronger magnet.
B  Add additional copper ball bearings to the truck.
C  Flip the magnet such that the South Pole is facing the truck.
D  Replace the iron ball bearings with plastic ball bearings of the same mass.

Accepted Answer

A. A only. A stronger magnet exerts a greater magnetic force of attraction on the iron ball bearings, pulling the truck faster (A true). Copper is not attracted by magnets and only adds mass, slowing the truck (B false). Flipping the magnet does not change the attraction since both poles attract iron (C false). Plastic is not magnetic, so the truck would not be pulled at all (D false). Hence A only.

Question 14

Five rectangular blocks of the same thickness and width were placed in a straight line in a well-lit box. Shaun peered through the three small holes at positions A, B and C to look at the blocks from different positions. Which rectangular blocks would he be able to see from the various positions?

Accepted Answer

B. Position A: R, S and T; Position B: P, Q, R, S and T; Position C: P, Q, R and S. The blocks from left to right are P (opaque), Q (translucent), R (opaque), S (transparent), T (opaque). From Position B (top view) all five blocks can be seen. From Position A (right side) one can see T, see through S, and see R, but the opaque R blocks the view of Q and P — so R, S and T. From Position C (left side) one can see P, Q, R and see through S — so P, Q, R and S. Hence option (2).

Question 15

Peter walked in a straight line from P to R as shown in the figure below. At Q, he was directly under the lamp. The distance between P and Q is half the distance between Q and R. Which one of the following graphs correctly represents the length of Peter's shadow from point P to point R?

Accepted Answer

D. Graph 4. As Peter approaches Q (directly under the lamp) his shadow shortens to almost nothing at Q, then lengthens again as he moves away towards R. Because PQ is only half of QR, the shadow lengthens over a longer distance on the Q-to-R side, giving a non-symmetrical V-shape with a longer, gentler rise after Q — matching graph 4.

Question 16

The table below shows the states of 4 substances, E, F, G and H, at different temperatures. Which of the following statements correctly describe substances E, F, G and H?
A  The freezing point of substance E is 1°C.
B  The boiling point of substance F is 98°C.
C  Substance H has the highest boiling point.
D  Substance G has the highest melting point.

Accepted Answer

A. C only. E is solid at 2°C, so its freezing point is above 2°C, not 1°C (A false). F is gas at 95°C, so its boiling point is below 95°C, not 98°C (B false). H is still solid at 52°C and only becomes liquid by 95°C, with its boiling point above 95°C — the highest of the four (C true). G is already liquid at 2°C, so its melting point is the lowest, not the highest (D false). Hence C only.

Question 17

An experiment was set up using a sealed iron container that contains 300cm³ of air as shown in the diagram below. Air was pumped into the container at a rate of 20cm³ per second for 10 seconds. Which one of the following graphs represents the volume of air in the sealed container during the experiment?

Accepted Answer

C. Graph 3. The container is made of iron, which is rigid, and is sealed, so its internal volume cannot change. Although more air is pumped in, the volume of air remains fixed at 300 cm³ (the air is merely compressed). The volume-time graph is therefore a constant horizontal line — graph 3.

Question 18

Which of the following action(s) demonstrate(s) a person exerting a push force?
A  A person lifting a box off the ground.
B  A person walking up a flight of steps.
C  A person hitting the ping pong ball with a bat.
D  A person pressing the emergency button in a lift.

Accepted Answer

D. B, C and D only. Lifting a box off the ground is a pull force (upward against gravity), so A is not a push. Walking up steps (pushing against the steps), hitting a ball with a bat, and pressing a button are all push forces. Hence B, C and D only.

Question 19

The diagram below shows a ball that was released from a certain height. Which one of the following graphs correctly shows how the gravitational force acting on the ball is affected by the distance of the ball from the ground?

Accepted Answer

B. Graph 2. Over the small distances involved near the Earth's surface, the gravitational force (weight) acting on the ball stays essentially the same regardless of its distance from the ground. The graph is therefore a constant horizontal line — graph 2.

Question 20

The graph below shows how 4 springs, J, K, L, and M, were stretched when different weights were hung on them. Which spring was the least elastic when a mass of 500g was hung on it?

Accepted Answer

D. M. The least elastic spring stretches the least for the same load. At a mass of 500 g, spring M shows the smallest increase in length (reaching only about 12 cm from 10 cm), so it is the least elastic.

Question 21

Two circuits using identical bulbs were set up as shown in the diagram below. A black cardboard was placed between the 2 bulbs in each set-up such that the light sensor was only able to detect light coming from one light bulb. Which one of the following graphs correctly shows how the readings of the light sensor would vary with the two set-ups?

Accepted Answer

B. Graph 2 (B higher than A). In Set-up A the two bulbs are connected in series, so each bulb is dimmer. In Set-up B the two bulbs are connected in parallel, so each bulb receives the full voltage and shines brighter. The sensor in Set-up B therefore reads a higher (brighter) constant value than in Set-up A — graph 2.

Question 22

A circuit was constructed as shown. When some switches were closed, only bulbs B1, B3 and B5 lit up. Which of the following switches were closed?

Accepted Answer

B. B and D only. For only bulbs B1, B3 and B5 to light up, the current must flow along the path passing through B1, B3 and B5 while leaving B2 and B4 unlit. Closing switches B and D completes exactly this path, so the switches closed are B and D only.

Question 23

Alice set up the circuit diagram as shown below. In which position should she add a switch such that she is able to control all the bulbs at the same time?

Accepted Answer

C. C. To control all the bulbs at once, the switch must be placed on the part of the circuit through which all the current flows (the main line). Position C lies on this common path, so a switch there will turn all the bulbs on or off together.

Question 24

The diagram below shows a light bulb. Which parts of the light bulb are conductors of electricity?

Accepted Answer

C. B, C and D only. Part B (the filament/connecting wires), part C (the metal screw thread) and part D (the metal base contact) are all metals and conduct electricity. Part A is the glass of the bulb, which is an insulator. Hence B, C and D only.

Question 25

Study the circuit diagram shown below. Which of the following statement(s) is/are true of the above set-up?
A  When only S1 is closed, only B1 will light up.
B  When only S3 is closed, only B3 will light up.
C  When only S2 is closed, only B2 and B4 will light up.
D  When only S2 and S3 is closed, only B2, B3 and B4 will light up.

Accepted Answer

B. C and D only. B4 is on the common (main) line, so it lights whenever current flows through the lower section. Closing only S2 allows current through B2 and B4 (C true). Closing S2 and S3 allows current through B2, B3 and B4 (D true). Closing only S1 (B1's branch) or only S3 (B3's branch) cannot complete a circuit through B4 alone as stated, so A and B are false. Hence C and D only.

Question 26

Which of the following statements about energy are true?
A  Energy can exist in different forms.
B  Energy is not needed during sleeping.
C  Energy is needed by green plants only.
D  Energy can be converted from one form to another.

Accepted Answer

B. A and D only. Energy can exist in different forms (A true) and can be converted from one form to another (D true). Energy is still needed during sleeping for body processes (B false), and energy is needed by all living things, not green plants only (C false). Hence A and D only.

Question 27

Three metal balls of the same size, R, S and T, were hung from the ceiling. The strings were cut at point X and the metal balls landed on a tray of fine sand, leaving dents made by them respectively. Based on the above diagram, which of the following statements is/are correct?
A  T has the greatest mass.
B  S has a greater mass than R.
C  T has the greatest gravitational potential energy.

Accepted Answer

C. B and C only. The balls are the same size and were all released from the same cutting line X. The depth of the dent shows the impact/energy. T was hung lowest (so released from the greatest height above the sand) and makes the deepest dent, giving it the greatest gravitational potential energy (C true). Comparing the dents, S made a deeper dent than R, so S has a greater mass than R (B true), but T does not necessarily have the greatest mass (A false). Hence B and C only.

Question 28

A ball was pushed at point A. The ball rolled along the floor, hit the wall and it stopped immediately as shown in the diagram below. Which one of the following statements best describes the forms of energy involved in the above activity?

Accepted Answer

B. Heat energy was produced when the ball rolled on the floor.. As the ball rolls along the floor, friction between the ball and the floor produces heat energy (B true). The ball is on the floor, so it has no gravitational potential energy to speak of (A false). Friction continually reduces the kinetic energy, so it is highest just after the push, not just before hitting the wall (C false). Kinetic energy is not converted to gravitational potential energy on the flat floor (D false).

Question 29

Bob took a roller coaster ride. The graph below shows the changes in the height of the roller coaster at different points in time. Based on the graph above, which one of the following statements is correct?

Accepted Answer

C. The kinetic energy of the roller coaster was greater at L than N.. The lower the roller coaster, the less gravitational potential energy and the more kinetic energy it has. L is lower than N on the graph, so the kinetic energy is greater at L than at N (C true). K (the highest point) has the maximum gravitational potential energy, not M (B false); L and N are at different heights so their kinetic energies differ (A false); and energy conversion happens throughout the ride, not only from K to L (D false).

Question 30

The diagram below shows a diagram of a circuit used in an alarm system. A bell is connected to the circuit. Which of the following shows the correct energy conversions when S1 is opened and S2 is closed?

Accepted Answer

B. Chemical potential energy → Electrical energy → Sound energy. When S1 is opened the bulb is switched out of the circuit (no light produced). When S2 is closed, current flows through the bell only. The battery's chemical potential energy is converted to electrical energy, which the bell converts to sound energy. Hence: chemical potential energy → electrical energy → sound energy.

P6 Science CA1 2016 — Nanyang

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P6 Science CA1 2016 — Nanyang

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