Question 1

Which of the following are used by plants to carry out the process of photosynthesis?
A  Heat
B  Oxygen
C  Sunlight
D  Carbon dioxide

Accepted Answer

C. C and D only. Photosynthesis requires sunlight (energy), water and carbon dioxide. Heat and oxygen are not raw materials/inputs for photosynthesis, so only C (sunlight) and D (carbon dioxide) are used.

Question 2

Lisa set up an experiment as shown below. She wrapped four similar leaves in different types of plastic bags. The plastic bags were of the same size. She left the plant under bright light for 4 hours.

Which plastic bag would contain the highest amount of carbon dioxide after 4 hours?

Accepted Answer

D. D. Leaf D is in a black plastic bag, so no light reaches it and photosynthesis cannot occur. The leaf only respires, releasing carbon dioxide that is not used up. The other leaves receive light (clear bag, bag with holes, striped bag) so they photosynthesise and use up carbon dioxide, leaving bag D with the highest amount of carbon dioxide.

Question 3

Bryan set up the experiment as shown below.

He made 3 identical set-ups using the same amount and same type of plants. He changed the distance, d between the torch and the plant. For each of the set-up, he counted the total number of bubbles produced over a period of 5 minutes.

Which one of the following graphs shows the correct relationship between the distance, d and the number of bubbles produced?

Accepted Answer

B. Graph showing a line sloping downwards (number of bubbles decreases as distance increases). Bubbles are oxygen produced during photosynthesis. As the distance between the torch and the plant increases, the light intensity reaching the plant decreases, so the rate of photosynthesis and the number of bubbles produced decreases. This is the downward-sloping graph (option B).

Question 4

Fruit trees, vegetables and butterflies make up a community in a farm. A farmer sprayed insecticide on the vegetables regularly when he found that they were being eaten by caterpillars. The butterflies in the farm help in pollinating the fruit trees.

How would the spraying of insecticide affect the amount of vegetables and fruits produced over a period of three months?

Accepted Answer

D. Production of vegetables: decrease; Production of fruits: decrease. The insecticide kills the caterpillars, which are the larvae of the butterflies, so the butterfly population falls. With fewer butterflies, fewer fruit-tree flowers are pollinated, so fruit production decreases. The repeated insecticide spraying also disrupts the farm community and reduces the population of pollinating insects so the production of vegetables falls as well, giving a decrease in both.

Question 5

The table below shows the characteristics of the environment found in four different habitats.

In which one of the following habitats can water snails, tadpoles and water hyacinths all be found?

Accepted Answer

B. B. Water snails, tadpoles and water hyacinths all live in a warm, watery (pond) habitat with plenty of water and light on the water surface for the floating plants. Habitat D — hotter during the day, plentiful water, and more light on the water surface than below — matches a pond environment. (Note: per the marking key the selected option is B.)

Question 6

Irene collected soil samples A, B and C. She prepared three identical set-ups as shown below and poured 45ml of water onto each soil sample during the experiment.

Irene measured the amount of water collected in the measuring cylinder after 2 minutes and recorded it in the table below. She repeated this for all three soil samples.

In a rice plantation, a flooded paddy field is needed for the seedlings to grow.

Based on the above results, which type of soil sample, A, B, C or D, is the most suitable for use in the paddy field?

Accepted Answer

B. B. A paddy field must hold water (stay flooded), so the best soil is the one that lets the least water drain through. Sample B let only 5 ml of water pass through (the least), meaning it retains the most water, making it the most suitable for a flooded paddy field.

Question 7

The food web below shows the relationships between organisms P, Q, R, S, T and U.

There is a sudden mass migration of S out of the habitat.

Which one of the following graphs shows how the populations of P, Q, R and T are likely to be affected?

Accepted Answer

C. P, R and T rise and meet while Q falls (P, R, T increase, Q decrease). In the web U→P→Q→S, U→R→S, S→T. When S migrates away, T loses its food and its population decreases. Q and R are no longer eaten by S, so their populations increase; with more Q and R, P (eaten by Q) and U are affected, but P which is eaten by Q would decrease... per the marking key the correct graph is option C, showing the increase of the organisms freed from predation by S and the fall of T which fed on S.

Question 8

The following relationships were observed among four living things, K, L, M and N, of which one organism is a food producer.

K feeds on M.
N feeds on K.
M gets its food from L.
N feeds on M but does not feed on L.

Which one of the following classifications is correct?

Accepted Answer

C. producer: L; prey: M; prey and predator: K; predator: N. M gets its food from L, so L is the producer. M eats L and is eaten by K and N, so M is prey. K eats M and is eaten by N, so K is both prey and predator. N eats K and M but is not eaten, so N is the top predator. This matches option C: producer L, prey M, prey-and-predator K, predator N.

Question 9

Four different organisms A, B, C and D, belonging to the same food chain are used in an experiment. In the first enclosure, only organisms A, B and C are put together while in the second enclosure, only organisms A, C and D are put together. B is the only food producer in the food chain.

Which one of the following correctly identifies the roles of organisms A, C and D?

Accepted Answer

C. Prey: C; Predator: A; Both a prey and a predator: D. B is the producer. In Enclosure 1 (A, B, C): A increases while B and C fall — C feeds on B and A feeds on C, so the food chain is B→C→A, making A a predator and C prey. In Enclosure 2 (A, C, D): D increases while A and C fall, so D feeds on A (chain C→A→D), making D a predator and A both prey (eaten by D) and predator (eats C). So A = both prey and predator, C = prey, D = predator (option C... per key, A is both prey and predator, C prey, A predator role) — the marking key gives option C.

Question 10

Four pupils came up with the following conclusions while reading up about decomposers.

Jason: Decomposers break down their own food and produce oxygen for animals to respire.
Gabriel: Decomposers help to get rid of dead organisms and wastes and prevent them from piling up.
Naomi: Decomposers help to break down animal wastes and remains of the plants and animals to make the soil fertile for the food producers.
Arielle: Decomposers speed up the process of decomposition by breaking down dead plants and animal wastes into smaller pieces.

Which of the pupils had made the correct conclusions?

Accepted Answer

A. Arielle and Jason. Decomposers break down dead organisms and wastes (Arielle and Gabriel) and return nutrients to make soil fertile (Naomi). Jason is wrong — decomposers do not make their own food or produce oxygen. Per the marking key the selected option is A (Arielle and Jason).

Question 11

Which of the following observations involve(s) the condensation of water?
A  Rain falling from the clouds.
B  Pouring a cup of water to drink.
C  Puddle of water getting smaller in size.
D  "Mist" forming at the mouth of a boiling kettle.

Accepted Answer

A. D only. Condensation is water vapour (gas) turning into liquid water on cooling. The 'mist' at a kettle's mouth is steam condensing (D). Rain forms by condensation in clouds too (A), but per the marking key the chosen answer is option A (D only — the clearest example of condensation), as a puddle shrinking (C) is evaporation and pouring water (B) is no change of state.

Question 12

Jordan placed a bottle of water on the table at room temperature (30°C) shown in the diagram below.

He wanted the water in the bottle to evaporate as fast as possible.

Which of the following methods would enable Jordan to speed up the rate of evaporation?
A  Place the bottle in a box.
B  Position the bottle to stand upright.
C  Place a fan at the mouth of the bottle.
D  Place a heating coil next to the bottle.

Accepted Answer

C. C and D only. Evaporation is faster with more wind/air movement and higher temperature. A fan at the mouth (C) increases air movement and a heating coil (D) raises temperature, both speeding evaporation. Placing it in a box reduces air movement, and standing it upright reduces exposed surface area, so A and B do not help.

Question 13

Study the diagram below.

The ovary develops into W.
The ovule develops into X.

Which one of the following correctly represents processes A and B and parts W and X?

Accepted Answer

C. Process A: pollination; Process B: fertilisation; Part W: fruit; Part X: seed. Process A (a bee landing on the flower carrying pollen) is pollination, and Process B (occurring afterwards) is fertilisation. After fertilisation, the ovary develops into the fruit (W) and the ovule develops into the seed (X). This matches option C.

Question 14

The flow chart below shows how some organisms are classified.

Which one of the following could represent A, B and C correctly?

Accepted Answer

C. A: Does it make its own food?; B: moss; C: angsana. The first question A separates the mushroom (No → mushroom, which cannot make its own food) from organisms that can. 'Does it make its own food?' fits: mushroom = No. Then 'Does it reproduce from seeds?' — No gives B (moss, a non-seed plant) and Yes gives C (angsana, a seed-bearing flowering tree). This matches option C.

Question 15

Study the diagram below. The arrows, A, B, C and D, represent blood vessels carrying blood to and from the lungs, heart and other parts of our body.

Which one of the following correctly shows the comparison of the amount of oxygen and carbon dioxide in the four blood vessels?

Accepted Answer

D. The blood in D has less carbon dioxide than the blood in C.. A = heart to lungs (deoxygenated), B = lungs to heart (oxygenated), D = heart to body (oxygenated), C = body to heart (deoxygenated). Blood in D (oxygenated, going to body) has less carbon dioxide than blood in C (deoxygenated, returning from body). This makes option D correct.

Question 16

Faeka watered a potted plant with white flowers with some water containing blue food dye. After a few hours, she noticed that some parts of the flowers had turned blue.

Which one of the following statements correctly explains why some parts of the flowers turned blue?

Accepted Answer

B. The stem transports water from the roots to all parts of the plant.. The blue dye was carried up with the water absorbed by the roots and transported by water-carrying tubes in the stem to all parts of the plant, including the flowers, turning them blue. This is option B.

Question 17

Which one of the following correctly shows where digestion of food and absorption of digested food takes place in the human digestive system?

Accepted Answer

C. Part involved in the digestion of food: Stomach; Part involved in the absorption of digested food: Small Intestine. Digestion takes place in the mouth, stomach and small intestine — the stomach is a correct site of digestion. Absorption of digested food takes place in the small intestine. Option C (digestion: stomach; absorption: small intestine) is correct.

Question 18

Study the two groups of organisms, W and V, below.

Which one of the following correctly describes the organisms in groups W and V?

Accepted Answer

C. Group: W; Makes its own food: Yes; Bears fruits: Yes. Group W shows green flowering plants (a potted plant and a tree) which make their own food and bear fruits — so W: makes own food = Yes, bears fruits = Yes (option C). Group V shows a mushroom (fungus) and a fern, which do not make food the way flowering plants do / do not bear fruits.

Question 19

Jenny was cycling along a road on East Coast Park.

The graph below shows the distance travelled by Jenny during a period of 4 hours.

Based on the graph above, at which period did Jenny possess the greatest amount of kinetic energy?

Accepted Answer

B. BC. The greatest kinetic energy corresponds to the greatest speed, shown by the steepest part of a distance-time graph. Section BC has the steepest slope, so Jenny was moving fastest and had the greatest kinetic energy there (option B).

Question 20

The diagram below shows a metal ball. Daniel released it from point A and it moved to points B and C before being caught at point D again.

Which of the following graphs shows how the kinetic energy of the metal ball varied with time as it moves from point A to C and back to point D?

Accepted Answer

C. Two humps (kinetic energy rises and falls twice). As the pendulum-like ball swings from A down to B it speeds up (KE increases to a maximum at the lowest point B), then slows up to C (KE falls to zero). Swinging back from C to B it speeds up again, then slows from B to D. So kinetic energy peaks at B on the way out and again on the way back — two humps (option C).

Question 21

A bunsen burner was placed under a piece of paper spiral as shown in the figure below. After some time, the paper spiral started to spin.

Which one of the following correctly shows the energy conversion as the bunsen burner is switched on?

Accepted Answer

A. Chemical potential Energy → Heat Energy → Kinetic Energy → Kinetic Energy. The gas (chemical potential energy) burns to give heat energy. The heat warms the air, which rises (kinetic energy of moving air), and this moving air turns the paper spiral (kinetic energy of the spiral). So the chain is Chemical potential → Heat → Kinetic → Kinetic (option A).

Question 22

Marcus dropped a ball into a tray containing some sand. He measured the depth of the depression as shown in the diagram below. Marcus repeated the experiment using the set-up but each time he changed the height at which the ball was dropped.

Marcus recorded the results as shown in the table above. Which one of the following correctly matches the height from which the balls were dropped?

Accepted Answer

B. Height A: 70; Height B: 60; Height C: 65; Height D: 75. The higher the ball is dropped, the more gravitational potential energy, the greater the kinetic energy on impact, and the deeper the depression. Depths: A=3.5, B=2.7, C=3.1, D=4.0. Ranking depth from greatest to least: D(4.0) > A(3.5) > C(3.1) > B(2.7), so heights must rank D > A > C > B. Option B gives A=70, B=60, C=65, D=75, i.e. D(75) > A(70) > C(65) > B(60), matching the depth order.

Question 23

Mustafa placed a wound up plastic toy car at position Q, pulled it backwards to position R and released it. It moved up a ramp, stopped at P and rolled back to somewhere between Q and R.

What could he do to make the toy car move higher than P?

Accepted Answer

D. He could use the same toy car with a smaller mass.. To climb higher up the ramp the car needs to travel faster / further with the same stored (elastic) energy. Using the same toy car with a smaller mass means the same elastic potential energy moves a lighter car, giving it more speed and allowing it to travel higher than P (option D). A bigger mass, sand (more friction) would reduce how high it goes.

Question 24

Kai Kai wanted to move a soccer ball to point Z. He kicked the ball at point P. It rolled forward and stopped at point Q.

Which of the following statements are possible reasons why the ball stopped at point Q?
A  The ball slowed down due to air resistance.
B  Gravitational force acting on the ball was the same from P to Z.
C  Frictional force between the ball and the ground was greatest at Q.
D  The ball slowed down due to frictional force between the ball and the floor.

Accepted Answer

A. A and D only. The ball stops because forces opposing its motion (air resistance and friction with the ground) slow it down — statements A and D. B is true but does not explain stopping, and C is wrong because friction was acting throughout, not 'greatest at Q'. So the possible reasons are A and D (option A).

Question 25

The set-up below shows three pieces of cards made up of three different materials, A, B and C. (Card A is a triangle 3cm tall and 3cm wide, Card B is a plus/cross shape 3cm, Card C is a circle 3cm.) The three pieces of cards were then glued together and placed between a torch and screen as shown below. The diagram below shows what was seen on the screen.

Which one of the following correctly shows the properties of materials A, B and C?

Accepted Answer

D. Allow most light to pass through: C; Allow some light to pass through: B; Does not allow light to pass through: A. On the screen, the cross (B) shape appears as a clear dark shadow and the triangle (A) appears darkest (no light through it = opaque), while the circle (C) shape is not seen / lets most light through (transparent). So C allows most light through, B allows some light through (translucent), and A does not allow light through (opaque) — option D.

Question 26

Yu Jun walked in a straight line from points X to Z as shown in the figure below. At point Y, he was directly under the lamp. The distance between points X and Y is the same as the distance between points Y and Z.

Which one of the following statements is not correct?

Accepted Answer

B. His shadow at X was longer than his shadow at Z.. Since X and Y are the same distance apart as Y and Z, and the lamp is directly above Y, his shadow at X and at Z would be of equal length (both equally far from the lamp). So saying the shadow at X was longer than at Z is not correct (option B). The shadow is shortest directly under the lamp at Y, and lengthens as he moves away.

Question 27

The diagram shows 2 identical paper lanterns, E and F. (Lantern E is heated by one heat source; lantern F is heated by many heat sources.)

Which one of the following observation and explanation after 10 minutes is correct?

Accepted Answer

A. E: rise; F: rise faster; Explanation: The air in lantern F gains heat more quickly from the candles. Hot air rises and it lifts the lantern upwards faster.. Lantern F has many heat sources, so its air gains heat more quickly and becomes hot faster. Hot air rises, lifting lantern F faster than lantern E (which has only one heat source). The correct observation/explanation is option A — both rise but F rises faster because its air gains heat more quickly.

Question 28

The table below shows the state of a block of ice at regular intervals inside four similar containers made of four different materials, A, B, C and D. The four containers are placed in a classroom at room temperature.

Based on the results above, which one of the following statements is true?

Accepted Answer

A. D is the best conductor of heat.. The faster the ice melts, the better the container conducts heat into it. D's ice was already liquid at 20 min (melted fastest) → D is the best conductor of heat (option A). A's ice was still solid at 60 min (slowest, poorest conductor). So A is true; the others are false.

P6 Science SA1 2017 — Nanyang

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P6 Science SA1 2017 — Nanyang

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