Question 1

A group of students conducted some research on sources of energy and recorded the following statements.
Mary: Plants only need sunlight, water and oxygen to make food.
John: I get energy from the food I eat to do my daily work.
Jason: The Sun is our primary source of heat and light energy.
Matthew: The grass the cow eats is its source of energy.
Which of the following students made the correct statement?

Accepted Answer

C. John, Jason and Matthew only. Mary is wrong because plants need carbon dioxide (not oxygen) to make food. John (food gives energy), Jason (Sun is primary source of heat and light) and Matthew (grass is the cow's energy source) are all correct.

Question 2

Wendy set up an experiment to demonstrate how light affects the rate of photosynthesis of plants. She prepared set-ups A and B as shown below. Plants A and B were destarched before the start of the experiment. Which one of the following should Wendy do, after 2 days, to obtain her results?

Accepted Answer

B. Test for presence of starch in the leaves of each plant.. Photosynthesis produces starch. To show that light affects photosynthesis, Wendy must test the leaves for starch — the plant in light (A) makes starch while the plant in the dark (B) does not.

Question 3

Which of the following statements about energy is/are true?
A. Only plants use energy from the Sun.
B. Organisms need energy to carry out life processes.
C. Energy from the Sun can be transferred from one organism to another.

Accepted Answer

D. B and C only. A is false — animals also depend on the Sun's energy (through food). B is true — all organisms need energy for life processes. C is true — energy is passed along food chains from one organism to another. Hence B and C only.

Question 4

The diagram below shows parts of a plant. Which one of the following gives the correct functions of the parts P, Q, R and S in the diagram above?

Accepted Answer

D. P: contains seeds for reproduction; Q: transports food, water and mineral salts; R: takes in water and mineral salts; S: contains small openings for the exchange of gases. P points to the flower/fruit (contains seeds for reproduction), Q points to the stem (transports food, water and mineral salts), R points to the roots (takes in water and mineral salts), and S points to a leaf (has stomata — small openings for exchange of gases). Option D matches all four.

Question 5

The flow chart below shows the processes involved in the human digestive system. Based on the information given in the flow chart, what are A, B, P and Q?

Accepted Answer

C. A: small intestine; B: large intestine; P: digestive juice; Q: water. Digestion is completed at A (the small intestine). Undigested food is passed into B (the large intestine), where water (Q) is absorbed. Churning of food into a partly-digested form in the stomach involves the production of digestive juice (P). Option C is correct.

Question 6

Sally planned to study the shadows formed by two identical metal cones. The cones were placed in different positions directly under identical light sources in a dark room. Shadows were formed on screens A and B as shown below. Which of the following shadows would be observed for each screen?

Accepted Answer

B. Screen A: triangle (pointing left); Screen B: circle. In set-up A the cone lies on its side (axis horizontal) with light from above, so its shadow is a triangle. In set-up B the cone stands upright (point up) with light from directly above, so its shadow is a circle (the outline of its circular base). Option B matches.

Question 7

Susan dropped her ball that glowed in the dark into a deep drain. She was unable to see her ball when she looked into the drain. She decided to lower a mirror and place it at position R to help her see the ball. At which angle should Susan place the mirror so that she will be able to see the ball in the drain?

Accepted Answer

D. Mirror at R tilted with reflective side facing down. The mirror must be tilted at an angle so that light from the glowing ball reflects off the reflective surface and travels up to Susan's eye at the drain opening. Option 4 shows the mirror tilted with its reflective face angled correctly to redirect the light from the ball up out of the drain.

Question 8

The graph below shows how the length of Linda's shadow changes over a period of time as she walks in a straight line near a street lamp at night. Which of the following statements are correct?
A. Linda is walking directly below the lamp at the 4th second.
B. Linda is walking towards the lamp during period X and away from the lamp during period Y as shown in the graph.
C. Linda is walking at a faster speed during the period Y compared to the period X.
D. Linda is walking towards the lamp during period Y and away from the lamp during period X as shown in the graph.

Accepted Answer

C. A, B and C only. The shadow is shortest around the 4th second, meaning she is closest to (directly below) the lamp then (A correct). During X the shadow shortens (walking towards the lamp) and during Y it lengthens (walking away) (B correct). The shadow lengthens more steeply in Y over the same time, so she is faster during Y (C correct). D contradicts B and is wrong. Hence A, B and C only.

Question 9

Mrs Tan went to a café and ordered a cup of tea. When she received the tea she realised it was very hot and she was in a hurry. Which of the following way(s) will enable her to cool her tea faster?
A. Stir the tea with a spoon.
B. Add some ice cubes to the tea.
C. Cover the cup of tea with the saucer.
D. Pour the tea from the cup into the saucer.

Accepted Answer

D. A, B and D only. Stirring (A) speeds heat loss to the surroundings; adding ice (B) draws heat from the tea; pouring into a saucer (D) increases the exposed surface area for faster heat loss. Covering with a saucer (C) traps heat and slows cooling. Hence A, B and D only.

Question 10

Janet recorded the temperature of water in two beakers, X and Y, and she plotted the graphs as shown below. The graph shows how the temperature of water in each beaker changed over time as the water in both beakers were heated. Based on the graph above, which of the following statements are possible explanations of the graph?
A. Both beakers of water were heated for the same amount of time.
B. Beaker X was heated over a stronger flame than beaker Y.
C. Both the beakers had water at the same temperature at the start of the experiment.
D. The temperature of water in beaker Y took a longer time to reach its boiling point.

Accepted Answer

D. A, B and D only. The graph shows X starting at a lower temperature but rising faster and reaching boiling point (the plateau) first, while Y starts higher but rises more slowly. A is possible (same total time shown). B is possible (X heats faster, suggesting a stronger flame). D is correct (Y reaches boiling point later). C is wrong because they started at different temperatures. Hence A, B and D only.

Question 11

Tom wanted to allow the metal ball to pass through the metal ring. However, the metal ball was bigger than the metal ring. What should Tom do to allow the metal ball to pass through the metal ring?
A. Heat the ball over a flame.
B. Heat the ring over a flame.
C. Dip the ball into cold water.
D. Dip the ring into cold water.

Accepted Answer

D. B and C only. The ball must become smaller or the ring larger relative to each other. Heating the ring (B) makes it expand and its hole widen; dipping the ball in cold water (C) makes it contract and shrink. Both allow the ball to pass through. Hence B and C only.

Question 12

Joe jogged round the track 6 times in the morning on a sunny day. Which one of the following correctly describes his source of energy and the energy changes during his jog?

Accepted Answer

B. Source: Food; Energy changes: Chemical potential energy in his body was converted to heat energy and kinetic energy.. Joe's energy comes from the food he eats (chemical potential energy). When he jogs, this is converted into kinetic energy (movement) and heat energy. Option B is correct.

Question 13

Aishah observed the activity below in order to classify the energy changes during the activity. The flow chart below shows the possible energy changes for the above activity. Which one of the following correctly represents P, Q and R?

Accepted Answer

D. P: Potential energy; Q: Kinetic energy; R: Sound energy. In the arm the muscle has (chemical) potential energy P, which becomes kinetic energy as the arm moves. The moving arm gives the ball kinetic energy Q. When the ball hits the pins, the pins gain kinetic energy plus sound energy R plus heat energy. So P = potential energy, Q = kinetic energy, R = sound energy. Option D.

Question 14

Janice listed some processes involving energy changes as shown below.
A. Charging the hand phone.
B. Turning on an electrical fan.
C. Burning firewood to keep warm.
D. Rubbing a rubber seed on the ground.
Which one of the following diagrams correctly shows the energy changes in the processes above?

Accepted Answer

D. Diagram 4. A (charging phone) = electrical energy → potential (chemical) energy. B (electrical fan) = electrical energy → kinetic energy. C (burning firewood) = (chemical) potential energy → heat energy. D (rubbing seed) = kinetic energy → heat energy. Diagram 4 correctly maps A: Electrical→Potential, B: Electrical→Kinetic, C: Potential→Heat, D: Kinetic→Heat.

Question 15

James is playing tennis. When the ball comes towards him, he will hit it hard with his racket as shown below. Which of the following will change after James hits the ball with his racket?
A. mass of the tennis ball
B. speed of the tennis ball
C. volume of the tennis ball
D. direction of the moving tennis ball

Accepted Answer

D. B and D only. A force from the racket changes the ball's speed (B) and its direction of movement (D). The mass (A) and volume (C) of the ball do not change. Hence B and D only.

Question 16

Study the diagram below. Which one of the following represents activities P and Q correctly?

Accepted Answer

C. P: Closing a drawer; Q: Lifting a box from the floor. The left group (kicking a ball, flicking a coin, P) are examples of forces that need contact/direct push (pushing/pulling), so P is 'Closing a drawer'. The right group (removing a plug, magnet attracting iron) are forces acting at a distance or requiring effort like lifting; Q is 'Lifting a box from the floor'. Option C fits both categories.

Question 17

An iron bar AB was magnetised using the stroking method as shown in Diagram 1 below. Diagram 2 shows the magnetised poles of bar AB after it was magnetised. Another iron bar, XY, was magnetised using two magnets as in Diagram 3. Which one of the following diagrams shows a possible arrangement of the two bars after they were magnetised?

Accepted Answer

C. Y–X horizontal on top and B–A vertical below at the X end. From Diagram 2, bar AB has S at end A and N at end B. In Diagram 3, the magnet's N pole faces X (inducing S at X) and the S pole faces Y (inducing N at Y), so X is a S pole and Y is a N pole. Attraction occurs between unlike poles, so the bars arrange so unlike poles meet. Option 3 shows a valid arrangement where the poles align to attract.

Question 18

Angela set up an experiment on a table top as shown in the diagram below. When she released a steel ball from Point Y down the ramp, it hit object A causing it to move to its observed position, which was further than the expected position. What could she possibly do to the above set-up to ensure that Object A reached the expected position?
A. Lower the height of the support.
B. Release the steel ball at Point Z.
C. Increase the height of the support.
D. Replace the steel ball with a ping-pong ball.

Accepted Answer

C. A, B and D only. Object A moved too far, so the ball must hit it with less energy. Lowering the support (A) reduces the ball's height and gravitational potential energy; releasing from the lower Point Z (B) also reduces its starting height/energy; replacing with a lighter ping-pong ball (D) gives less kinetic energy. Increasing the height (C) would make it go even further, which is wrong. Hence A, B and D only.

Question 19

Four balls were dropped onto a box of sand. The diagram below shows from the side view the depressions by each ball after they had been dropped onto the sand. If the above experiment was conducted to show the effect of dropping the balls at different height from the ground, which one of the following variables must be kept the same in order for the experiment to be a fair test?
A. mass of each ball
B. material of the balls
C. distance of the balls from the sand

Accepted Answer

B. A and B only. The variable being changed is the drop height (distance of balls from the sand), so that must vary — C cannot be kept the same. For a fair test the mass (A) and material (B) of the balls must be kept the same. Hence A and B only.

Question 20

The toy below consists of a box with a toy figure attached to a spring. When the lid is opened, the toy figure will pop out of the box as shown below. Which of the following statements are correct to describe the popping out effect of the toy figure once the lid is opened?
A. The toy figure pops out as the stretched spring return to its original length once the lid is opened.
B. The compressed spring exerts a force on the closed lid which causes the toy figure to pop out once the lid is opened.
C. The elastic potential energy in the compressed spring is converted to kinetic energy as the spring returns to its original length once the lid is opened.

Accepted Answer

B. B and C only. The spring inside the closed box is compressed (not stretched), so A is wrong. B is correct — the compressed spring pushes against the lid. C is correct — the elastic potential energy stored in the compressed spring changes to kinetic energy as it returns to its original length. Hence B and C only.

Question 21

The diagram below shows a catapult made of rubber bands and ice-cream sticks. A small container is attached at the end of the inclined stick to hold a pebble. When the inclined stick is pushed down and released, the pebble will move forward and travel in the air for a certain distance before dropping to the ground. Which one of the following statements about the experiment is correct?

Accepted Answer

D. The kinetic energy in the dropping pebble had been converted to sound energy and heat energy when it hit the ground.. A is wrong — the pebble still has energy. B is wrong — a pebble in the air has gravitational potential energy. C is wrong — the rubber band stores elastic (not chemical) potential energy. D is correct — when the pebble hits the ground its kinetic energy is converted to sound and heat energy.

Question 22

Which of the following statements about gravitational force are correct?
A. Gravitational force is a force that acts at a distance.
B. The Earth's gravitational force is the force that pulls objects to the ground.
C. Our weight is less on the Moon than on the Earth because the Moon has less gravitational force than the Earth.

Accepted Answer

D. A, B and C. All three statements are true: gravity acts at a distance (A), Earth's gravity pulls objects to the ground (B), and weight is less on the Moon because the Moon exerts a weaker gravitational force (C). Hence A, B and C.

Question 23

Haikal found many of Organism Z under piles of rotting leaves in the garden. He then suggested four possible explanations for this behaviour.
A. Organism Z prefers dark condition.
B. Organism Z feeds on rotting leaves.
C. Organism Z prefers damp condition.
D. Organism Z does not need direct sunlight to live.
He set up an experiment as shown in the diagram below and placed some Organism Z at the centre. Based on his set-up, which one of the explanations (A, B, C or D) for the behaviour of Organism Z was Haikal trying to test?

Accepted Answer

C. C. The set-up offers Organism Z a choice between dry soil (with rotting leaves) on one side and damp soil (with rotting leaves) on the other, with the only difference being dryness/dampness. He is therefore testing whether Organism Z prefers a damp condition (explanation C).

Question 24

The graph below shows the effect of temperature on the number of four different organisms, K, L, M and N. Which organism(s) will most likely survive the longest period if the environment continues to increase slowly from 35°C?

Accepted Answer

A. M only. Above 35°C, the number of organism M continues to rise (or stays high) while K, L and N all decline. Organism M is best able to tolerate the increasing temperature, so M only will survive the longest.

Question 25

Sara found out from the school gardener that ladybirds feed on aphids. She decided to help the gardener find out which type of ladybird is most effective in removing the aphids. She carried out an investigation, repeated it twice and obtained results as shown below. Based on her results, what can she conclude from her experiment?

Accepted Answer

B. The ladybirds in set-up B are most effective in removing the aphids.. Each set-up started with 150 aphids. After 5 days, set-up B had the fewest aphids left (34), meaning the ladybirds in B ate the most aphids and are the most effective at removing them. Option B is correct.

Question 26

An experiment was conducted to find out the effect of light on the growth of hydrilla plant. An experimental set-up was prepared as shown below. Which one of the following should be a control set-up for this experiment?

Accepted Answer

B. Beaker with hydrilla and water, no light source. To test the effect of light, the control set-up must be identical to the experimental one (hydrilla in water) but with the only variable — light — removed. Option 2 shows the hydrilla in water without a light source, making it the correct control.

Question 27

Siew Hong had three rods, P, Q and R made of different materials. She placed them in various positions, X, Y and Z, in the circuit below. The results of the experiment are shown in the table below. Which one of the inferences can she make from the results above?

Accepted Answer

B. Only rods P and R are able to conduct electricity.. Analysing the table, lamps light up only when the rod in the position completing the circuit is a conductor. From the results, rods P and R allow the lamps to light (conduct electricity) while rod Q does not. Hence only rods P and R are able to conduct electricity — option B.

Question 28

After running for 2 rounds in their school field, Siva and his classmates rushed to stand under the ceiling fan when they went back to their classroom. They claimed that by standing under the moving fan, they will cool down faster. Which one of the following statements explains why they cool down faster when standing under the moving fan?
A. their sweat loses heat making them cool down faster
B. wind from the moving fan increases the rate of evaporation
C. heat is removed from their body when their sweat evaporates
D. their sweat droplets are absorbed into their body more quickly

Accepted Answer

B. B and C only. The moving fan blows air (wind) that increases the rate of evaporation of sweat (B), and as sweat evaporates it removes heat from the body (C), cooling them down. A is imprecise and D is wrong (sweat is not absorbed back). Hence B and C only.

Question 29

Which of the following statements is/are correct when water evaporates?
A. Water gains mass.
B. Water evaporates at 100 °C only.
C. Water gains heat and becomes steam.
D. Water changes from a liquid state to a gaseous state.

Accepted Answer

B. D only. During evaporation water changes from liquid to gaseous state (D correct). A is wrong (mass is not gained). B is wrong (evaporation occurs at any temperature, not only 100°C). C describes boiling/steam, not evaporation. Hence D only.

Question 30

Tom breathed onto a mirror and it turned "misty" at first. After a while, the "mist" cleared up and he was able to see himself in the mirror again. What is the explanation for his observation?

Accepted Answer

D. The "mist" is water droplets; the mirror cleared up after the "mist" had evaporated.. The 'mist' is tiny water droplets formed when warm water vapour from Tom's breath condensed on the cool mirror. The mirror cleared when these water droplets evaporated back into the air. Hence option D.

P6 Science SA1 2012 — Henry Park

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P6 Science SA1 2012 — Henry Park

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