Question 1

Which of the following characteristic is found in insects, but not in other animals?

Accepted Answer

D. They have three body parts.. Insects are defined by a body divided into three parts (head, thorax, abdomen). Laying eggs, wings and feelers are also found in some other animals, so the unique insect feature is three body parts.

Question 2

The graph below shows the change in the population of zebras in a grassland habitat over a period of time. Zebras feed on grass only. Which of the following events most likely could have led to the change in the zebra population from Point A to Point B?

Accepted Answer

D. There was a decrease in the population of the zebra's predators.. From Point A to Point B the zebra population increases. A drought, a new disease, or overeating of grass (less food) would all reduce the population. Only a decrease in the zebra's predators would allow more zebras to survive, increasing the population.

Question 3

Which of the following shows how the carbon dioxide is removed from a human body?

Accepted Answer

B. bloodstream → lungs → windpipe → nose. Carbon dioxide is carried by the bloodstream to the lungs, where it diffuses into the air sacs. It then travels up the windpipe and out through the nose during exhalation.

Question 4

The following relationships were observed among five organisms, A, B, C, D and E living in a habitat. C feeds on A, B and D. B feeds on A. E feeds on C. Which one of the following is correct?

Accepted Answer

A. Producer: A,D | Prey: B | Prey and predator: C | Predator: E. A and D are not eaten as prey of an animal-hunting chain and feed on nothing, so they are producers (plants). B eats only the producer A (so it is a consumer/prey) and is eaten by C, making it prey. C eats the animal B (and A, D) and is eaten by E, so C is both prey and predator. E eats C and is not eaten, so E is the top predator.

Question 5

The diagram below shows a rotting log. Based only on the diagram, which one of the statements is correct?

Accepted Answer

C. There is only one population of insect living on the rotting log.. The diagram shows ants (insects), fungus and spiders. Spiders are arachnids, not insects, so among the organisms shown only the ants are insects — one population of insects. The log is dead matter (not a living plant population) and more than two populations of organisms are present.

Question 6

A farmer has two different types of soil, G and H. Each soil was taken from two different layers, top or bottom soil. He predicted that plants will grow more healthily in soil G while his friend predicted that plants will grow more healthily in the top soil of soil H. Which of the following set-ups should the farmer use to provide a correct test for both their predictions?

Accepted Answer

B. Top soil G and Top soil H; Bottom soil G and Bottom soil H — each with the same number of plants.. To test 'soil G vs soil H' the same layer of both soils must be compared, and to test 'top vs bottom soil of H' both layers of H are needed. So all four combinations (top G, bottom G, top H, bottom H) are required, each planted with the SAME number of plants for a fair test — only set-up B does this.

Question 7

Which one of the following causes increased greenhouse effect?

Accepted Answer

C. Deforestation. Deforestation removes trees that absorb carbon dioxide, so more carbon dioxide remains in the atmosphere, increasing the greenhouse effect. Global warming is the result of an increased greenhouse effect, not its cause.

Question 8

Dennis wanted to find out if plant takes in water through its roots. Which one of the following should Dennis use as an experimental set-up?

Accepted Answer

A. Plant with its roots in the water and aluminium foil covering the container opening.. To show that water is taken in through the roots, the roots must be in the water and the aluminium foil must cover the water surface to prevent evaporation. Any fall in water level can then only be due to the roots absorbing water.

Question 9

What is the function of cytoplasm in animal cell?

Accepted Answer

C. Controls the movement of substances within the cell. The cytoplasm is the jelly-like substance where cell processes occur and through which substances move within the cell. Controlling cell activities/inheritance is the nucleus's job, and controlling movement in and out of the cell is the cell membrane's job.

Question 10

Wei Liang prepared two set-ups, X and Y for an experiment. In Set-up X, he put a plant into a container of red coloured water and covered the plant with a plastic bag. In Set-up Y, he replaced the plant with a stick instead and covered it with a plastic bag. The two set-ups were placed in the same location. An hour later, the water level in Set-up X was less than before. Wei Liang also found tiny water droplets on the inner surface of the plastic bag in Set-up X but not in Set-up Y. Based on Wei Liang's observation, what conclusion could he make from his experiment?

Accepted Answer

C. Water droplets formed is due to the presence of the plant.. Set-up Y (with a stick, no plant) is the control and formed no droplets, while Set-up X (with a plant) formed droplets. The only difference is the plant, so the water droplets (from transpiration) must be due to the presence of the plant.

Question 11

Study the diagram below which shows the movement of substances in the plant. Which one of the following shows the correct movement of substances in the plant?

Accepted Answer

B. solid arrow: sugar; dotted arrow: water. The dotted arrow traces water moving up from the roots, through the stem, into the leaf and out (transpiration), so it represents water. The solid arrows show the transport of food made in the leaf — food is moved as dissolved sugar (starch is insoluble and not transported), so the solid arrow represents sugar.

Question 12

The chart below shows the characteristics of different organisms J, K and L. (Start → 'Does the young resemble the adult?' Yes → L; No → 'Does it have a 4-stage life cycle?' Yes → K; No → J.) Which of the following represents the life cycle of organisms J, K and L?

Accepted Answer

B. J: Frog, K: Butterfly, L: Cockroach. L: young resembles the adult → cockroach (incomplete metamorphosis, nymph looks like adult). K: young does not resemble adult and has a 4-stage life cycle → butterfly (egg, larva, pupa, adult). J: young does not resemble adult and does NOT have a 4-stage life cycle → frog (3-stage: egg, tadpole, adult).

Question 13

Meng Li placed a plant in the dark for 48 hours and then partially covered one of the leaves with black paper. After doing so, he placed the plant under the sun for another 5 hours. He tested the leaf for starch by using iodine solution and observed the leaf as: the covered middle region turned brown while the two uncovered regions turned dark blue. Which of the following can be deduced from the above experiment? A: Air is needed for photosynthesis. B: Sunlight is needed for photosynthesis. C: Chlorophyll is needed for photosynthesis.

Accepted Answer

B. B only. The only variable changed is light (covered vs uncovered part of the same leaf). The covered part (no light) had no starch (brown) while the uncovered parts (light) had starch (dark blue), showing sunlight is needed for photosynthesis. The experiment does not test air or chlorophyll, so only B can be deduced.

Question 14

Study the life cycle of a housefly (housefly → egg → maggot → pupa → housefly). A beaker containing a piece of uncooked meat was left in a room for a week. After a week, maggots were observed on the meat. Edina wanted to set up the experiment which would show that the maggots did not come from the meat. Which set-up should Edina use?

Accepted Answer

C. A beaker containing uncooked meat with a sealed cover.. To show maggots do not arise from the meat itself, only one variable should change — flies' access. Keep the same uncooked meat but seal the beaker so flies cannot land and lay eggs. If no maggots appear in the sealed beaker, the maggots must have come from flies, not the meat.

Question 15

Jim noted down the properties of two objects, A and B. He put a tick for the property each object has. Object A: fragile, opaque, able to sink in water. Object B: flexible, opaque, able to sink in water. Which one of the following best identifies objects A and B?

Accepted Answer

D. A: ceramic spoon, B: rubber boots. Object A is fragile (breaks easily), opaque and sinks — a ceramic spoon fits all three (metal/wood are not fragile; wood floats; newspaper is not really fragile). Object B is flexible, opaque and sinks — rubber fits (plastic ruler is often transparent; plastic scissors are not flexible). So A is a ceramic spoon and B is rubber boots.

Question 16

Bob placed an iron toy car on a board made from three different materials, X, Y and Z, which were glued together. He used a magnet to move the car from point A to point D. However, the car came to a stop at point C. What could materials X, Y and Z be made of?

Accepted Answer

C. X: copper, Y: plastic, Z: steel. The magnet's force passes through non-magnetic materials to attract the iron car, so the car moved across X and Y (which must be non-magnetic — copper and plastic). The car stopped at C, the start of Z, because Z is a magnetic material (steel); the magnet is attracted to/blocked by Z so the car cannot be pulled over it.

Question 17

Roy threw a ball and it landed in the roof gutter. To find the ball, he attached a mirror to a pole at Point Z. Which one of the following diagrams shows the correct position of the mirror that will allow Roy to see the ball in the gutter?

Accepted Answer

B. Mirror tilted at an angle ('/') on top of the pole at Z, reflective surface facing up toward the ball and down toward the eye.. The ball is above the pole and Roy's eye is below it. A mirror must be tilted at an angle (about 45°) so that light from the ball strikes the mirror and is reflected down to Roy's eye. A flat horizontal mirror would not redirect the light from the ball to his eye.

Question 18

Martin shone a torch onto two objects, A and B. Objects A and B were placed at equal distance from the torch. The shadows cast by objects A and B are of similar size but the shadow of object A is darker than the one cast by object B. Martin wanted the shadow formed to be a single dark circle on the screen. Which one of the following changes should he do before he aligns the objects in a straight line?

Accepted Answer

C. Move object B nearer to the screen. Object A is opaque (dark shadow); object B is translucent (lighter shadow). To get a single dark circle the same size as before, object A must stay where it is (so its shadow size is unchanged) and be in front, with object B tucked behind it. Moving object B nearer the screen places it behind A, where it falls inside A's shadow and contributes nothing, leaving one dark circle.

Question 19

Study the diagram below. When the plunger is pushed all the way in, all the air from the pump goes into the metal container. Which one of the following shows what happens to the volume and mass of air in the metal container when the plunger is pushed all the way in?

Accepted Answer

C. Volume remains the same; Mass increases. The metal container is rigid, so the air inside still fills the same fixed space — its volume stays the same (1000 cm³). However, the extra 100 cm³ of air from the pump adds more air particles, so the mass of air in the container increases.

Question 20

Ravi has three objects, A, B and C. He puts object A into a measuring cylinder containing some water. Then he puts object B and then followed by object C. The diagram below shows how the water level changes after each object is placed in. Using only information from the diagram above, Ravi will be able to find the volume of object(s) ___

Accepted Answer

C. B and C only. Volume by displacement needs the water level before AND after an object is added (and the object fully submerged). The first cylinder already contains A, so there is no 'before A' reading — A's volume cannot be found. B's volume = (level with A+B) − (level with A), and C's volume = (level with A+B+C) − (level with A+B), both readable from the diagram. So only B and C can be found.

Question 21

In the set-up below, a drop of red ink is placed in the glass tube connecting the two conical flasks, Y and Z. Each flask is then placed in a basin of water at different temperatures. In which one of the following arrangements will the drop of red ink move the furthest from flask Z in the shortest time?

Accepted Answer

A. Flask Y: water at 3°C; Flask Z: water at 90°C. For the ink to move furthest away from flask Z (i.e. toward Y), the air in Z must expand the most (heated strongly) while the air in Y contracts the most (cooled strongly). Placing Z in hot water (90°C) makes its air expand greatly and placing Y in cold water (3°C) makes its air contract, pushing the ink furthest from Z in the shortest time.

Question 22

Sue was given a test-tube of water. What should Sue do in order to allow the water in the test-tube to take a shorter time to evaporate?

Accepted Answer

D. Transfer all the water from the test-tube to a tray. Evaporation is faster when the exposed surface area of the water is larger. Pouring the water into a tray spreads it out, giving a much larger surface area, so it evaporates faster. Removing fans, adding ice, or sealing the tube would all slow evaporation.

Question 23

Minnie opened the freezer door and observed white 'clouds' escaping from the freezer. Which one of the following is a true statement about the white 'clouds' seen?

Accepted Answer

D. Warmer water vapour from surrounding air lost heat to the cold air and condensed to form the 'clouds'.. The white 'clouds' are tiny water droplets. The warm water vapour in the surrounding room air comes into contact with the cold air from the freezer, loses heat to it and condenses into visible water droplets. (Steam itself is invisible, and the cold freezer air holds little vapour.)

Question 24

The diagram below shows an electric circuit with four identical bulbs, A, B, C and D, and four switches, S1, S2, S3 and S4. What is the least number of switches that must be closed to light up bulbs A and C?

Accepted Answer

B. 2. Bulb A is in the top branch in series with bulb B through switch S1, so closing S1 completes a circuit through A (also lighting B). Bulb C is in a separate parallel branch with switch S2, so closing S2 lights C. A and C are in different branches needing different switches, so the least number of switches to close is 2 (S1 and S2).

Question 25

The circuit diagram below shows how the various components are connected together. Which one of the following observations is correct?

Accepted Answer

D. When only S2 and S3 were closed, none of the bulbs lit up.. S1 is the main switch in series with the battery, so it must be closed for any current to flow. When only S2 and S3 are closed (S1 open), the battery is disconnected and no bulb lights. (A is wrong because the eraser is an insulator so W never lights; B is wrong because S2/S3 are open; C is wrong because S1 is open.)

Question 26

The diagram below shows 4 cubes of equal mass supported in different ways. Cubes A and C are hung from a support while B and D are balanced on their support. Which one of the following statements is true about the amount of gravitational potential energy the cubes possess?

Accepted Answer

A. A is equal to B. Gravitational potential energy depends on mass and height. The cubes have equal mass, so GPE depends only on height. Cubes A, B and D are at the same height (the dashed reference line, 1 m), so A and B have equal GPE. Cube C hangs lower than D, so C has less GPE than D.

Question 27

When Aziz jumped on the trampoline, he noticed that there was a force which pulled him downwards and then another force which pushed him upwards. Identify the forces which pulled him downwards and pushed him upwards respectively.

Accepted Answer

C. pulled down: Gravitational Force; pushed up: Elastic Spring Force. Gravitational force pulls Aziz downwards toward the trampoline. As he lands, the stretched trampoline acts like a spring and pushes him back up — this is the elastic spring force.

Question 28

Four identical balls, W, X, Y and Z, were hung from a pole using strings of different lengths. Each string was cut 1 cm above each ball. The balls landed in a container of flour placed directly below. Four dents of different depths were created in the flour by the four balls. Which one of the following diagrams shows correctly the four dents in the flour made by the four balls respectively?

Accepted Answer

A. W: deep dent, X: shallow, Y: deep, Z: shallow. After each string is cut 1 cm above its ball, each ball falls a distance equal to its height above the flour. A ball hung higher (shorter string) falls further, hits faster and makes a deeper dent. W and Y are hung higher, so they make deeper dents, while X and Z are lower (Z just above the flour) and make shallower dents — matching option A.

P6 Science SA2 2018 — Rosyth

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P6 Science SA2 2018 — Rosyth

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