Question 1

Which one of the following characteristics can be used to differentiate between a reptile and a bird?
(1) The way they breathe
(2) The way they reproduce
(3) The number of body parts
(4) The type of outer covering

Accepted Answer

(4) The type of outer covering. Both reptiles and birds breathe using lungs and reproduce by laying eggs. Both have a head, neck, trunk, and limbs (birds have wings as modified forelimbs). However, reptiles have scales (or scutes), while birds have feathers. The type of outer covering is a key differentiating characteristic.

Question 2

Study the classification chart below.
Which one of the following headings do P, Q and R represent?
P
(1) fungi
(2) fungi
(3) plants
(4) decomposers
Q
bacteria
flowering plants
decomposers
flowering plants
R
non-flowering plants
bacteria
bacteria
fungi

Accepted Answer

(2) fungi, flowering plants, bacteria. P is characterized by 'feed on dead or living organisms', which describes fungi (decomposers). Q is characterized by 'able to make their own food', which describes flowering plants (producers). R is characterized by 'can only be seen under microscope', which describes bacteria. This combination aligns with option (2).

Question 3

Study the plant cell shown below.
Where does photosynthesis take place inside the plant cell?
(1) P
(2) Q
(3) R
(4) S

Accepted Answer

(1) P. P points to the chloroplast, which is the site of photosynthesis in a plant cell. Q is the cell wall, R is the nucleus, and S is the cytoplasm.

Question 4

Study the life cycle shown below.
Which one of the following animals has a life cycle similar to the one shown above?
(1) frog
(2) chicken
(3) mosquito
(4) grasshopper

Accepted Answer

(4) grasshopper. The life cycle shown (egg → nymph → adult) represents incomplete metamorphosis. Among the given options, the grasshopper undergoes incomplete metamorphosis. A frog and mosquito undergo complete metamorphosis, and a chicken undergoes direct development.

Question 5

David studied the graph below.
The graph shows the relationship between the surrounding temperature and the number of adult insect X in a farm.
David stated two reasons to explain the relationship as shown in the graph:
A As the surrounding temperature increases, the number of eggs laid by insect X increases.
B As the surrounding temperature increases, the number of days to complete the life cycle of insect X decreases.
Based on the graph, which reason(s) is/are possible?
(1) A only
(2) B only
(3) A and B
(4) Neither A and B

Accepted Answer

(3) A and B. The graph shows that an increase in surrounding temperature leads to an increase in the number of adult insect X. If the number of eggs laid (A) increases with temperature, it leads to more adults. If the life cycle duration (B) decreases with temperature, it means faster reproduction and more generations, also leading to more adults. Both A and B are possible reasons for the observed trend.

Question 6

The diagram below shows the developmental stages of a flowering plant.
Where do the processes of pollination, fertilisation and germination take place?
Pollination | Fertilisation | Germination
(1) E | E | G
(2) D | E | G
(3) E | E | F
(4) D | F | G

Accepted Answer

(4) D, F, G. Pollination occurs in the flower (D). Fertilisation occurs within the flower, leading to the formation of the seed (F). Germination is the process by which a seed (F) develops into a seedling (G). Therefore, option (4) correctly associates these processes with the indicated stages/structures.

Question 7

Seaweeds are plants that live in the sea. An example of a seaweed is shown below.
Waves pull the seaweed in different directions and the seaweed is adapted to survive the sea waves.
Which properties of the stalk have helped it to adapt in its environment?
(1) Elastic and Flexible
(2) Flexible and Strong
(3) Elastic and Strong
(4) Elastic and Waterproof

Accepted Answer

(2) Flexible and Strong. To withstand strong sea waves, the seaweed stalk must be able to bend without breaking. This requires it to be flexible (to bend easily) and strong (to resist breaking under force). While elasticity is also beneficial for returning to shape, the combination of flexible and strong best describes the properties needed to survive continuous wave action.

Question 8

Which one of the following groups shows a population in a habitat?
(1) adults of animal A, adult plants
(2) young plants, adult plants, plant-eaters
(3) eggs of animal A, larvae of animal B, adults of animal C
(4) eggs of animal X, larvae of animal X, adults of animal X

Accepted Answer

(4) eggs of animal X, larvae of animal X, adults of animal X. A population consists of all individuals of the same species living in a particular area at a specific time. Option (4) includes different life stages (eggs, larvae, adults) of the *same species* (animal X), which correctly defines a population.

Question 9

The diagrams below show the healthy and the infected gills. The infected gills have fungi S growing into them.
Based on the above information, which one of the following graphs correctly shows the effect of fungi S on the amount of oxygen absorbed into the bloodstream of the fish?

Accepted Answer

(3) [graph 3]. Fungi S growing in the gills would damage them, reducing their efficiency in absorbing oxygen. Therefore, as the amount of fungi S increases, the amount of oxygen absorbed into the bloodstream of the fish should decrease. Graph (3) shows this inverse relationship.

Question 10

Amanda carried out an experiment using the set-ups as shown below.
Amanda kept the torch and the distance of the torch from the hydrilla the same to ensure a fair test.
What could she change in the above set-up to increase the amount of gas produced?
(1) Use pond water.
(2) Use green light.
(3) Use 20g of hydrilla.
(4) Use bigger beakers.

Accepted Answer

(3) Use 20g of hydrilla.. The gas produced is oxygen from photosynthesis. To increase the rate of photosynthesis, one can increase the amount of plant material (hydrilla) or the availability of limiting factors like carbon dioxide or light intensity. Using 20g of hydrilla (more plant biomass) would provide more photosynthetic cells, directly increasing the amount of oxygen produced. Green light would decrease photosynthesis, while bigger beakers might not change limiting factors significantly.

Question 11

The diagram below shows a part of the circulatory system of a fish. The arrows represent the movement of blood in a fish.
The blood flowing through _____
(1) P and Q are rich in oxygen
(2) P and Q are rich in carbon dioxide
(3) P is rich in oxygen while Q is poor in oxygen
(4) P is poor in oxygen while Q is rich in oxygen

Accepted Answer

(2) P and Q are rich in carbon dioxide. In fish, blood is pumped from the heart to the gills (P). In the gills, oxygen is picked up, and carbon dioxide is released. Therefore, blood arriving at the gills (P) is rich in carbon dioxide and poor in oxygen. After passing through the gills, the oxygenated blood flows to other parts of the body, where oxygen is delivered and carbon dioxide is picked up. So, blood returning from the 'other parts of the body' to the heart (Q) is also rich in carbon dioxide and poor in oxygen. Thus, both P and Q are rich in carbon dioxide.

Question 12

Four plants were placed into identical jars, each containing the same level of water at first. They were then left near a window for an hour, The height 'h' in each jar was measured at the end of the experiment.
Which one of the following correctly shows the height 'h' from the greatest to the smallest?
(1) B, A, D, C
(2) B, A, C, D
(3) C, D, A, B
(4) C, D, B, A

Accepted Answer

(4) C, D, B, A. The height 'h' represents the remaining water level, so a greater 'h' means less water loss. All setups are near a window, promoting transpiration.
- **C (no plant, oil layer):** Minimal water loss (only very slight evaporation through oil or errors), thus the highest 'h'.
- **D (plant, no oil layer):** Water loss due to transpiration and evaporation from the exposed water surface. This should typically result in the most water loss, and thus the lowest 'h'.
- **B (plant, roots wrapped in plastic bag):** If roots are wrapped, they cannot absorb water from the jar. The plant would transpire using its stored water and eventually wilt, leading to minimal water loss *from the jar*. Thus, 'h' should be very high, close to C.
- **A (plant, oil layer):** Water loss primarily due to transpiration. Less than D, more than B and C.

Based on scientific principles, the order from greatest 'h' to smallest 'h' (least water loss to most water loss) should be C > B > A > D. This corresponds to option (1).

However, following the provided answer key (4) C, D, B, A implies a different order for B, D, and A. Assuming the provided answer key is correct, C has the highest 'h' (least loss). The relative order of D, B, A is unconventional given standard interpretations of transpiration experiments, where D (transpiration + evaporation) would typically have the most water loss. For the purpose of providing the answer key's intended response, we follow (4).

Question 13

Study the food chain below.
Z X Y W
Which one of the following is correct?
Population size | Effect
(1) Z increases. | X, Y and W will decrease.
(2) Z decreases. | X, Y and W will decrease.
(3) W increases. | X, Y and Z will decrease.
(4) W decreases. | X, Y and Z will increase.

Accepted Answer

(3) W increases., X, Y and Z will decrease.. The food chain is Z → X → Y → W (Z is eaten by X, X by Y, Y by W).
Let's analyze option (3) as per the provided answer key:
- If W (top predator) increases:
  - W eats Y, so Y will decrease.
  - Y eats X, so if Y decreases, X will likely increase (less predation pressure on X).
  - X eats Z, so if X increases, Z will likely decrease (more predation pressure on Z).
Therefore, if W increases, Y decreases, X increases, and Z decreases. The statement in option (3) says 'X, Y and Z will decrease', which contradicts the expected increase in X. However, based on the provided answer key, (3) is the correct option. This suggests a potential misinterpretation or a more complex ecological interaction than a simple linear food chain, or an error in the option itself from a strictly scientific standpoint.

Question 14

A scientist carried out an investigation to find out how the amount of dissolved oxygen in water will affect the number of two types of organisms.
The organisms were placed in two different containers of water. The water in each containers had different amount of dissolved oxygen.
Based on results, he concluded that organism A is not affected by the amount of dissolved oxygen in water while organism B is affected by the amount of dissolved oxygen in water.
Which one of the following shows a possible result for his conclusion?

Accepted Answer

(4) More: ΔΔ, Less: Δ. Organism A (triangles Δ) is not affected by dissolved oxygen, meaning its number should remain constant regardless of oxygen levels. Organism B (squares □) is affected by dissolved oxygen, meaning its number should change. Let's analyze the options based on the diagram counts:
(1) More O2: 3Δ, 3□. Less O2: 3Δ, 3□. (A constant, B constant – B not affected, so incorrect)
(2) More O2: 3Δ, 3□. Less O2: 3Δ, 2□. (A constant, B changes – B affected, correct)
(3) More O2: 3Δ, 3□. Less O2: 3Δ, 4□. (A constant, B changes – B affected, correct)
(4) More O2: 2Δ, 5□. Less O2: 1Δ, 1□. (A changes 2->1, B changes 5->1 – A is affected, so incorrect)

Both (2) and (3) fit the conclusion. Typically, 'affected' by less oxygen means a decrease. However, according to the provided answer key, (4) is the correct option. This contradicts the conclusion that organism A is not affected, as the number of triangles decreases from 2 to 1. There appears to be an inconsistency in option (4) given the stated conclusion. If we strictly follow the given answer key (4), despite the contradiction for organism A, no logical explanation can be provided to reconcile the conflicting information.

Question 15

Which one of the following is a good conductor of heat?
(1) metal
(2) wood
(3) fabric
(4) plastic

Accepted Answer

(1) metal. Metals are known for being good conductors of heat due to the presence of free electrons that can easily transfer thermal energy. Wood, fabric, and plastic are generally poor conductors or insulators of heat.

Question 16

Three bars were freely suspended on a rod as shown in the diagram below.
Based on the above observation, which bars are definitely magnets?
(1) X and Y only
(2) Y and Z only
(3) X and Z only
(4) X, Y and Z

Accepted Answer

(1) X and Y only. Observing only attraction between bars does not definitively prove both are magnets, as a magnet can attract a magnetic material (e.g., iron). Only repulsion between two objects proves that both are magnets. Given the options and typical interpretations in simplified physics questions, if X and Y are magnets, they can attract each other (opposite poles). If Y is a magnet, it can attract Z, which could be a magnetic material or another magnet. The answer key states (1) X and Y only. This implies a scenario where X and Y are magnets and Z is a magnetic material, which is consistent with the attractions shown, even though other scenarios are also possible.

Question 17

The picture below shows a tree and its reflection in the water.
Which one of the following correctly shows the path of light for the reflection of the tree in the water to be seen?

Accepted Answer

(3) [diagram 3]. For an object's reflection in water to be seen, light from the object (the tree) must travel to the surface of the water, reflect off the surface, and then travel to the observer's eye. Option (3) correctly illustrates this path: light originates from the tree, strikes the water surface, and is reflected upwards to the eye.

Question 18

Victor wanted to find out if the number of pieces of paper would affect the amount of light that could pass through it. He set up an experiment as shown below.
He increased the number of pieces of paper and recorded the amount of light that passed through in the table below.
Based on the information Victor collected, which one of the following is definitely true?
(1) The amount of light blocked by six pieces of paper was 12 units.
(2) The amount of light detected for one piece of paper would be 40 units.
(3) The amount of light detected for nine pieces of paper would be 0 units.
(4) The amount of light blocked by seven pieces of paper would be 48 units.

Accepted Answer

(3) The amount of light detected for nine pieces of paper would be 0 units.. The total amount of light without any paper (0 pieces) is 48 units. Light blocked = Total light - Light detected.
(1) For 6 pieces, light detected = 12 units. Light blocked = 48 - 12 = 36 units. (False)
(2) Data for 1 piece is not provided; extrapolation is not definite. (Not definitely true)
(3) For 8 pieces, light detected = 0 units. For 10 pieces, light detected = 0 units. This implies that 8 or more pieces of paper completely block all light. Therefore, 9 pieces would also block all light, resulting in 0 units detected. (Definitely true)
(4) For 7 pieces, we don't have data. While it's likely very little light passes through, we cannot definitively say 48 units are blocked without data for 7 pieces showing 0 units detected. (Not definitely true)

Question 19

Air is pumped into the balloon as shown below using an air pump.
What happens to the total volume and the mass of air in the balloon after 2 more pumps of air is given?
Total volume of air in the balloon | Total mass of air in the balloon
(1) increases | increases
(2) remains the same | increases
(3) remains the same | remains the same
(4) increases | remains the same

Accepted Answer

(1) increases, increases. When more air is pumped into the balloon, additional air particles are added, which increases the total mass of air inside the balloon. Since the balloon is elastic, the increased amount of air will also cause the balloon to expand, thus increasing its total volume.

Question 20

Two identical containers, A and B, were covered with identical lids. Container A was filled with 250g of ice cubes and Container B was filled with 250g of water at room temperature. They were placed on a balance as shown below.
After ten minutes, the balance tilted downwards on the side of container A.
Which one of the following could be the reason for this observation?
(1) The ice cubes in container A had melted.
(2) The water in container B had evaporated.
(3) Water droplets were formed on the outer surface of container B.
(4) Water droplets were formed on the outer surface of container A.

Accepted Answer

(4) Water droplets were formed on the outer surface of container A.. The balance tilting downwards on side A means container A gained mass. Container A holds ice cubes, making its outer surface cold. Water vapor in the surrounding air would condense on this cold surface, forming water droplets. These external water droplets add mass to container A, causing it to become heavier and tilt the balance downwards. Melting ice (1) or evaporation inside sealed containers (2) do not change total mass. Water droplets on container B (3) would make B heavier, tilting the balance to the right.

Question 21

Susan was given two syringes covered with black paper. Syringe A contained substance S while syringe B contained substance T. The distance d before pushing was kept at 10 cm.
She pushed the plungers and measured the distance'd 'as shown below.
She recorded her results in the table below.
d (cm)
Before pushing | After pushing
Substance S | 10 | 10
Substance T | 10 | 5
Which one of the following could be substances S and T?
Substance S | Substance T
(1) cotton wool | fruit juice
(2) air | cotton wool
(3) water | fruit juice
(4) water | cotton wool

Accepted Answer

(4) water, cotton wool. For Substance S, the distance 'd' remained 10 cm after pushing, meaning it is incompressible. Liquids (like water, fruit juice) are generally incompressible. For Substance T, 'd' changed from 10 cm to 5 cm, meaning it is compressible. Gases (like air) are compressible, and porous solids (like cotton wool) are also compressible due to air gaps. Option (4) provides 'water' for S (incompressible) and 'cotton wool' for T (compressible), which fits the observations.

Question 22

The diagram below shows a water cycle.
Which of the following statement is correct?
(1) Process X occurs at a fixed temperature.
(2) Process X occurs when water in waterbodies loses heat.
(3) Process Y occurs when there is no temperature difference.
(4) Process Y occurs when water vapour loses heat to surrounding air.

Accepted Answer

(4) Process Y occurs when water vapour loses heat to surrounding air.. Process X is evaporation (water bodies to water vapour). Process Y is condensation (water vapour to clouds).
(1) Evaporation occurs over a range of temperatures, not a fixed temperature. (Incorrect)
(2) Evaporation (Process X) occurs when water gains heat, not loses heat. (Incorrect)
(3) Condensation (Process Y) requires water vapour to cool, implying a temperature difference with cooler surroundings. (Incorrect)
(4) Condensation (Process Y) happens when water vapour loses heat to cooler surrounding air, causing it to change back into liquid droplets. (Correct)

Question 23

Lionel wanted to determine the effect of plants on the temperature of air in a room. He set up the experiment as shown below using three different coloured walls.
Which two set-ups should he use in his experiment?
(1) set-ups A and B only
(2) set-ups A and D only
(3) set-ups B and D only
(4) set-ups C and D only

Accepted Answer

(3) set-ups B and D only. To determine the effect of plants on air temperature, the presence/absence of plants should be the only variable. All other factors, such as wall color, must be kept constant. Set-up B has plants with a black wall, and Set-up D has no plants with a black wall. Comparing these two setups isolates the effect of the plants while keeping the wall color controlled.

Question 24

Weiling sets up a circuit as shown. All the bulbs and batteries are working properly.
All four bulbs light up when all four switches are closed.
Which switch should she open if she wants none of the bulbs to light up?
(1) Switch 1
(2) Switch 2
(3) Switch 3
(4) Switch 4

Accepted Answer

(2) Switch 2. To turn off all bulbs, the main circuit that supplies power to all branches must be broken. Switch 2 is located in the main path directly after the battery, before the current branches to the individual bulbs. Opening switch 2 will cut off the electricity supply to the entire circuit, causing all bulbs to go out. Switches 1, 3, and 4 only control individual bulbs or smaller branches.

Question 25

Gopal set up bulb A in four different electrical circuits P, Q, R and S using identical batteries and identical bulbs. The batteries and bulbs are all working properly.
In which circuits would bulb A have the same brightness?
(1) P and Q only
(2) P and R only
(3) P, R and S only
(4) Q, R and S only

Accepted Answer

(2) P and R only. Brightness depends on the current through the bulb. Assume one battery provides voltage V and one bulb has resistance R.
- **Circuit P:** 1 battery, 1 bulb A. Current I = V/R. Brightness is proportional to I.
- **Circuit Q:** 1 battery, 2 bulbs in series. Total resistance = 2R. Current I_Q = V/(2R) = I/2. (Dimmer)
- **Circuit R:** 2 batteries in series, 1 bulb A. Total voltage = 2V. Current I_R = 2V/R = 2I. (Brighter)
- **Circuit S:** 1 battery, 2 bulbs in parallel. Each bulb has voltage V across it. Current through bulb A = V/R = I. (Same brightness as P)

Based on scientific principles, bulb A would have the same brightness in circuits P and S. However, the provided answer key states (2) P and R only. This implies that the brightness in R (with 2 batteries) is considered 'the same' as in P (with 1 battery), which contradicts the direct relationship between voltage and current/brightness in series circuits. Given the strict instruction to provide the 'correct answer' from the key, we select (2).

Question 26

The diagram below shows the different positions of a bungee jumper who was secured by an elastic rope as he jumped off. At first, the bungee jumper was at the top, position P before he took his jump.
Which one of the following shows the correct conversion of energy as the bungee jumper jumps from position P to S?
(1) potential energy (stretched rope) → kinetic energy (jumper) → potential energy (jumper)
(2) potential energy (jumper) → potential energy (stretched rope) → kinetic energy (jumper)
(3) kinetic energy (jumper) → kinetic energy (stretched rope) → potential energy (jumper)
(4) potential energy (jumper) → kinetic energy (jumper) → potential energy (stretched rope)

Accepted Answer

(4) potential energy (jumper) → kinetic energy (jumper) → potential energy (stretched rope). At position P, the jumper is at a height, so they have gravitational potential energy (jumper). As they fall, this potential energy is converted into kinetic energy (jumper). As the rope begins to stretch and the jumper slows down towards the lowest point S, the kinetic energy (and some remaining potential energy) is converted into elastic potential energy stored in the stretched rope. At position S (fully stretched rope), the jumper momentarily stops, so kinetic energy is zero, and the energy is primarily elastic potential energy in the rope.

Question 27

The diagram below shows the path of object A after the strap has been pulled back and released using device C.
Which of the following statement(s) is/are true?
A Gravity is acting on object A at point Q only.
B The speed of object A decreases as it falls from Q to R.
C A greater force is applied to the strap when it is pulled back further.
D The kinetic energy of object A decreases while its gravitational potential energy increases as it moves from P to Q.
(1) A only
(2) D only
(3) C and D only
(4) B, C and D only

Accepted Answer

(3) C and D only. A: Gravity acts on object A throughout its entire flight path (P to Q to R), not just at Q. So, A is false.
B: As object A falls from Q (highest point) to R, its height decreases, and it accelerates due to gravity, so its speed increases. So, B is false.
C: Pulling the strap back further increases its stretch, storing more elastic potential energy and thus allowing a greater force to be applied upon release. So, C is true.
D: As object A moves from P (launch) to Q (highest point), it moves upwards against gravity. Its height increases, so gravitational potential energy increases. Its speed decreases, so kinetic energy decreases. So, D is true.
Since C and D are true, option (3) is correct.

Question 28

Two groups of people were in a tug-of-war as shown below.
Neither of the groups was able to make the other group move to its side because _____
(1) the force they exerted was not great enough
(2) the friction between their feet and the ground prevented it
(3) each group exerted an equal and opposite force on the other group
(4) the gravitational force was greater than the pulling force exerted by each group

Accepted Answer

(3) each group exerted an equal and opposite force on the other group. In a tug-of-war where there is no movement, the forces are balanced. According to Newton's Third Law, when one group pulls the rope, the other group pulls back with an equal and opposite force. If these forces between the two groups are equal and opposite, the net force on the rope (and thus on each group relative to the rope) is zero, preventing either group from moving the other.

P6 Science SA2 2019 — Rosyth

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P6 Science SA2 2019 — Rosyth

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