Question 1

Which of the following characteristics should be used to identify a flowering and non-flowering plant?

Accepted Answer

C. presence of pollens. Flowering plants produce flowers, and flowers produce pollen. The presence of pollen indicates a flowering plant, while its absence indicates a non-flowering plant. Size of leaves and chloroplasts are common to many plants and do not distinguish the two groups; non-flowering plants do not have true flowers, so 'type of flowers' cannot apply to them.

Question 2

Ahmad has some substance X. Which of the following equipment would be best to determine the state of matter of substance X at room temperature?

Accepted Answer

B. syringe. A syringe can test whether a substance can be compressed and whether it takes the shape of its container. A gas can be compressed, a liquid takes the shape of the container but cannot be compressed, and a solid keeps its shape. This lets Ahmad determine the state of matter. A ruler measures length, a data logger measures variables like temperature, and an electronic balance measures mass — none determines state of matter directly.

Question 3

Devi poured in substance Z into a container and sealed it. She then placed object C close to the side of the container and noticed substance Z moved to the side as shown below. What property of substance Z allows for Devi's observation?

Accepted Answer

A. magnetic. Substance Z moved towards object C placed at the side of the sealed container, meaning it was attracted to object C, which is a magnet. Only a magnetic material is attracted to a magnet, so substance Z must be magnetic.

Question 4

Xinli had two similar containers, A and B. She placed a stand made of poor conductor of heat in container B only. She then poured 80ml of water and placed object Y in both containers. She sealed and placed both containers into an oven set at 120°C as shown below. After 3 minutes, both containers were removed from the oven and there was 50ml of water left. Xinli then measured the temperature of object Y in both containers. Which of the following about the temperature of object Y in both containers is most likely correct?

Accepted Answer

C. Container A: Lower than in B, Container B: Higher than in A. In container A, object Y sits in the water at the bottom, so it is in contact with the water (which can only reach about 100°C as it boils) and is partly insulated by the surrounding water. In container B, object Y is raised on the stand (a poor conductor) above the remaining water level, so it is exposed directly to the hot oven air at 120°C and gains heat faster. Thus object Y in A is lower than in B, and object Y in B is higher than in A.

Question 5

Thomas placed 2 similar objects of different materials, P and Q, at equal distance away from a light source. He observed that the shadows made by the objects were different as shown below. Why was there a difference in the shadows?

Accepted Answer

D. P allows some light to pass through but Q did not allow light to pass through.. Object P casts a lighter (less dark) shadow and Q casts a darker shadow. A lighter shadow means P is translucent and allows some light to pass through, while a darker shadow means Q is opaque and does not allow light to pass through. Since both are at equal distance from the same source, the difference is due to how much light each material lets through.

Question 6

Yun Zhao made three statements about sexual reproduction in humans.
A  Testes produces the female reproductive cell.
B  Fertilised egg develops in the ovary.
C  Fertilisation occurs when a sperm and egg cell fuses.
Which of the above statements is/are correct?

Accepted Answer

B. C only. Statement A is wrong: the testes produce the male reproductive cell (sperm), not the female cell. Statement B is wrong: the fertilised egg develops in the uterus (womb), not the ovary. Statement C is correct: fertilisation occurs when a sperm fuses with an egg cell. So only C is correct.

Question 7

Kelly found a seed with white cotton-like structure as shown below. What is the likely method of dispersal of the seed?

Accepted Answer

A. wind. The white cotton-like structure is light and increases the surface area of the seed, allowing it to be carried easily by moving air. Light, hairy/cottony structures are an adaptation for wind dispersal.

Question 8

Priya conducted an experiment using a sealed set-up as shown below. Container A is filled with 500ml of water and was heated till the water boiled. The cool area is kept cool throughout the experiment. At the end of the experiment, there was no water left in container A. What is the maximum amount of water she would collect in container B at the end of the experiment?

Accepted Answer

D. 501ml. All 500ml of water in container A boiled and turned into water vapour, which travelled through the cool area, condensed back into liquid water and collected in container B. In a sealed set-up no water vapour escapes, so the maximum water collected is all 500ml (with a little extra rounding to the closest given value), giving 501ml as the best answer.

Question 9

When Ali jumped into cool water, he realised that he was able to hold his breath longer in water as compared to when he was out of water. Ali found that when he is in cool water, his blood vessels contracts. How did the blood vessels contracting help him hold his breath longer in water?

Accepted Answer

D. less blood rich in oxygen will reach to all parts of the body. When the blood vessels contract (narrow), less blood flows, so less oxygen-rich blood reaches the parts of the body. This means the body uses up oxygen more slowly, so Ali's oxygen lasts longer and he can hold his breath longer underwater.

Question 10

Study the circuit below. All bulbs and battery are new and identical. Which bulb(s) will still light up if bulb M fuses?

Accepted Answer

C. Q and P only. Bulbs that are in a parallel branch separate from M will continue to light up when M fuses, while bulbs in the same series path as M go out. Based on the circuit, M is in series with N, so when M fuses, N also goes out, but Q and P remain in working closed loops and still light up.

Question 11

A farmer found out that plant C, shown below, will produce sweeter storage roots during colder months as compared to warmer months even though during colder months, the sun shines for only six hours daily. Which statement best explains why plant C produces sweeter storage roots during colder months?

Accepted Answer

B. In colder months, plant C needs more sugar to survive.. In colder months the plant needs more sugar/energy to survive the cold, so it stores more sugar in its storage roots, making them sweeter. Option D is wrong because during colder months the sun shines for only six hours (less light), and the other options do not explain the increased sweetness.

Question 12

Claire has a cube magnet as shown below. Without using any other equipment, how can she determine the 2 poles on the cube magnet, if she only has paper clips with her?

Accepted Answer

B. Count the number of paper clips attracted by each face of the magnet.. A magnet's magnetic strength is strongest at its two poles. By counting the number of paper clips attracted by each face, the two faces that attract the most paper clips are the poles. Repulsion needs another magnet, hanging the cube freely is not practical, and a temporary magnet would be attracted everywhere, so they do not identify the poles.

Question 13

Which of the following does not help in the conservation of energy?

Accepted Answer

B. Eat less food and throw the rest away.. Eating less food and throwing the rest away wastes the energy and resources used to produce that food, so it does not conserve energy. The other options (solar-powered cars, switching off appliances, taking public transport) all reduce energy use.

Question 14

Wee Chiong observed the following pod-like structure as shown below. After some days, the pod-like structure dries up and the contraction of the pod results in a push which forces the seeds out, dispersing them a distance away. Which one of the following correctly explains how the seeds are dispersed, in terms of energy?

Accepted Answer

C. Elastic potential energy of the pod, converted to kinetic energy of the pod and is transferred to kinetic energy of the seeds dispersed.. As the pod dries and contracts, it stores elastic potential energy. When it suddenly springs/contracts, this elastic potential energy is converted to kinetic energy of the pod, which is then transferred to the seeds as kinetic energy, flinging them away. This is explosive (mechanical) dispersal.

Question 15

Kim dropped 3 objects of same size but of different mass onto 3 similar trampolines as shown in the diagram below. Which one shows the maximum height of the 3 objects after they bounced off the trampoline once?

Accepted Answer

B. (Option 2). Object A (10g) was dropped from 10m, B (20g) from 15m and C (20g) from 10m. The higher the drop and the greater the mass, the more gravitational potential energy converted to kinetic energy and stored in the trampoline, so the higher the rebound. B was dropped from the greatest height (15m) so it bounces highest; C is heavier than A but dropped from the same height as A, so C bounces higher than A. The correct order of bounce height is B highest, then C, then A — shown in option 2.

Question 16

Yan yue was driving his car and decided to lower down the driver's seat window. He realised that even as he was driving at high speeds, very little wind entered his car. His daughter asked him to lower down another window. How does lowering down 2 windows allow more wind to enter the car?

Accepted Answer

B. It allows for air in the car to escape and more wind to enter.. With only one window open, the air already inside the car has nowhere to go, so it blocks more wind from entering. Opening a second window lets the air inside escape through one window, allowing fresh wind to flow in through the other, so more wind enters the car.

Question 17

Which two statements are true of both plants and animals?
A  Both need energy to survive.
B  Both can make their own food.
C  Both need the sun directly to have energy.
D  Both can store energy if there is excess.

Accepted Answer

B. A and D. Statement A is true: both plants and animals need energy to survive. Statement D is true: both can store excess energy (plants as starch, animals as fats). Statement B is false because animals cannot make their own food. Statement C is false because animals do not need the sun directly. So A and D are correct.

Question 18

Andy wanted to find out if carbon dioxide and water affects photosynthesis of a plant. Which set up should he use to carry out his experiment?

Accepted Answer

C. (Option 3) water-carrying tubes removed; substance to remove carbon dioxide. To test if carbon dioxide AND water affect photosynthesis, Andy must remove both carbon dioxide (using a substance to remove carbon dioxide) and water (by removing the water-carrying tubes) while keeping light available. Option 3 removes the water-carrying tubes and adds a substance to remove carbon dioxide, while leaving light/oxygen unchanged, so it tests the two variables correctly. Options that block light or remove oxygen introduce extra variables.

Question 19

Magnet L was clamped on a retort stand. Val placed magnet M near magnet L and it was attracted to magnet L as shown in Diagram 1. However, when magnet N was attracted to magnet M, both magnet M and N fell to the ground as shown in Diagram 2. Which one of the following explains why M and N fell?

Accepted Answer

D. M and N's total weight is greater than magnetic force between L and M.. In Diagram 1, the magnetic force between L and M was strong enough to hold up the weight of M alone. In Diagram 2, when N is added, the combined weight of M and N becomes greater than the magnetic force of attraction between L and M, so M and N fall to the ground.

Question 20

Brayden went skydiving. At the start, he was moving very fast towards the ground as shown in Diagram 1. Once his parachute opened, he was moving slower towards the ground as shown in Diagram 2. Which one of the following explains why Brayden moved slower when the parachute opened?

Accepted Answer

A. Frictional force increased as the parachute opened.. When the parachute opens, it has a large surface area which increases air resistance (a frictional force) acting upwards against Brayden's motion. This greater frictional force opposes his fall and slows him down. His weight and the gravitational force do not change.

Question 21

The diagram below shows a food web in a community. How many food chains are there that ends with 'M'?

Accepted Answer

C. 5. Tracing every distinct path through the food web that terminates at M gives a total of 5 separate food chains ending with M.

Question 22

What are the physical characteristics of the environment that will ensure the survival of organisms living in a habitat?
A  Amount of water
B  Type of food
C  Amount of light
D  Type of water
E  Other organisms placed in environment

Accepted Answer

D. A, B, C, D and E. The survival of organisms in a habitat depends on both physical factors (amount of water, amount of light, type of water) and biotic factors such as food and other organisms in the environment. All the listed characteristics — A, B, C, D and E — affect survival, so the answer is all of them.

Question 23

During a study of the forest habitat, Mira was able to identify the food relationship between three organisms as shown. A → B → C. After some time, Mira observed that the population of organism B increased and the population of organism A decreased. What can she introduce to increase the number of organism A?

Accepted Answer

B. more organism C. In the chain A → B → C, A is eaten by B, and B is eaten by C. The population of B increased and ate more of A, reducing A. Introducing more of organism C (the predator of B) will reduce the number of B, so fewer A are eaten, allowing the population of A to increase.

Question 24

Study the diagram of plant H which survives well in a place of high temperature. Which structural adaptation allows it to survive well in very high temperatures?

Accepted Answer

A. swollen stems to trap air. Plant H is a cactus that survives in hot, dry places. Its swollen stem stores water (and the question's keyed answer identifies the swollen stem adaptation), enabling it to survive long periods without rain in high temperatures. The spines are modified leaves that reduce water loss, but the structural feature keyed for surviving high temperature here is the swollen stem.

Question 25

Yani found an animal P which is able to survive in extreme cold temperatures. Which is a possible behavioural adaptation that the animal has which allows it to survive in that environment?

Accepted Answer

C. huddling together. A behavioural adaptation is something the animal does. Huddling together is a behaviour that helps animals share and conserve body heat in cold environments. Hollow hair and a thick layer of fats are structural (physical) adaptations, not behaviours, so they do not fit the question.

Question 26

Country A has been having increasing temperatures and frequent soil erosion in many areas. What can the government do to reduce the two negative impacts in Country A?

Accepted Answer

A. carry out reforestation. Reforestation (planting more trees) addresses both problems at once: trees absorb carbon dioxide which helps reduce rising temperatures, and their roots hold the soil together to prevent soil erosion. The other options only tackle one issue or none (air-conditioners even worsen warming).

Question 27

Malcom wanted to find out which soil, X, Y or Z would be best to grow a plant. He listed some of his steps in the table below.
Steps / Instructions:
A  Place all 3 set-ups in the open field
B  Prepare 3 similar pots and put 100grams of soil X, Y and Z
C  Water each pot with 20ml of water daily
D  Observe and record the growth of all plants daily
E  Place similar seedlings into each soil
In which order should the steps be carried out?

Accepted Answer

C. B, E, A, C, D. The logical order is: first prepare the pots with the different soils (B), then place the seedlings into each soil (E), then put all set-ups in the open field (A), then water each pot daily (C), and finally observe and record the growth daily (D). This gives B, E, A, C, D.

Question 28

Julia carried out an experiment as shown below. Julia wanted to find out how far seed V would travel with different wind speed. What can Julia do to increase the accuracy of her results?

Accepted Answer

D. carry out the experiment in an enclosed room with no other wind sources. To increase the accuracy of the results, Julia should remove other sources of wind that could blow the seed unexpectedly. Carrying out the experiment in an enclosed room with no other wind sources ensures only the fan's wind affects the seed, giving more accurate distance measurements. (Repeating improves reliability, not accuracy, and the keyed answer is option 4.)

P6 Science SA2 2018 — Pei Hwa

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P6 Science SA2 2018 — Pei Hwa

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