Question 1

What is the common characteristic of all birds?

Accepted Answer

C. They reproduce by laying eggs.. Not all birds can fly (e.g. penguins), birds have two body parts (head and trunk with wings), and young birds look like adults. The defining common trait of birds is that they reproduce by laying eggs.

Question 2

Which characteristic(s) can be used to classify a tomato plant, a bird nest fern and a mushroom into two groups?
A: Ways of reproduction
B: Ways of obtaining food
C: Flowering or non-flowering plants

Accepted Answer

B. A and B only. A mushroom is a fungus, not a plant, so it cannot be classified by flowering/non-flowering (C is invalid). Reproduction method (tomato by seeds, fern by spores, mushroom by spores) and ways of obtaining food (tomato/fern make their own food; mushroom is a decomposer) can both classify them into two groups.

Question 3

A group of living things was observed under a microscope over three days. Which characteristic of living things was shown over the three days?

Accepted Answer

C. Living things can respond.. Across Day 1 to Day 3, sunlight is shown shining on the organisms and they have moved/oriented towards the sunlight. This shows response to a stimulus (light).

Question 4

Which cell shows the position of the nucleus correctly?

Accepted Answer

B. Diagram 2. A typical animal cell has its nucleus located near the centre of the cell (within the cytoplasm), surrounded by the cell membrane. Diagram 2 shows the dark oval nucleus centrally placed inside the cell.

Question 5

Study the life cycle of an animal. Which of the following correctly shows the animal and stage Q?

Accepted Answer

A. butterfly — egg. The cycle shows P → (fertilisation) → Q → R → S → P, with fertilisation occurring between P (adult) and Q. After fertilisation, the next stage is the egg. The butterfly has a four-stage life cycle (egg → larva → pupa → adult), so Q = egg fits the butterfly.

Question 6

The diagram below shows a seedling of a plant. What is the direction of the transport of water and food in the seedling?

Accepted Answer

D. water: upwards; food: upwards and downwards. Water absorbed from the moist soil by the roots is transported upwards through the water-carrying tubes (xylem). Food made by the leaves is transported in both directions (upwards and downwards) through the food-carrying tubes (phloem) to all parts of the plant.

Question 7

The diagram below shows the parts of a female reproductive system of a human and a flower. Which part of the female human reproductive system has a similar function as Y?

Accepted Answer

D. S. Y is the ovary of the flower, which produces ovules (female sex cells). In the human female reproductive system, S labels the ovary, which produces eggs (female sex cells). They have the same function.

Question 8

Noel pruned an overgrown tree by cutting off some of the branches. Compared to Diagram 1, the cutting of branches in Diagram 2 reduces competition for ____.

Accepted Answer

C. sunlight. Pruning removes branches and leaves, so the remaining leaves on the tree are less crowded. With fewer leaves in the way, the remaining leaves face less competition for sunlight.

Question 9

____ is the primary source of energy.

Accepted Answer

A. Sun. The Sun is the primary source of energy for all living things. Plants capture light energy from the Sun to make food, and this energy is passed along the food chain.

Question 10

Olsen wanted to find out how much water plants will take in. Which set-up should she choose to get the most accurate result?

Accepted Answer

D. Plant in a measuring cylinder with scale. A measuring cylinder has the narrowest, most uniform diameter and the finest scale markings of the apparatus shown, so the change in water level is largest and easiest to read accurately when the plant takes in water.

Question 11

The diagram shows a watermelon plant. The plant stores sugar in the watermelon and farmers add mineral salt K to the soil to make the watermelon even sweeter. Which of the following describes the movement of sugar and mineral salt K?

Accepted Answer

C. mineral salt K: water-carrying tube; sugar: food-carrying tube. Mineral salts dissolved in water are absorbed by the roots and transported up through the water-carrying tubes (xylem). Sugar (food) made by the leaves is transported through the food-carrying tubes (phloem) to the fruit.

Question 12

An experiment is set up as shown. The volume of gas collected is measured after 20 minutes. The experiment is repeated several times. Each time the light intensity is increased. Which graph shows the result?

Accepted Answer

A. Graph rising then levelling off (plateau). As light intensity increases, the rate of photosynthesis (and hence volume of oxygen gas produced) increases. However, beyond a certain point another factor (e.g. carbon dioxide) becomes limiting, so the volume of gas levels off — graph (1) shows this rise-then-plateau curve.

Question 13

Which one of the following is a similarity between the small intestine and large intestine?

Accepted Answer

C. Undigested food can be found in both of them.. Only the small intestine produces digestive juices and absorbs digested food. Both organs contain undigested food at some point — it passes from the small intestine into the large intestine where water is then absorbed from it.

Question 14

When starch is mixed with saliva, it is broken down into sugar. Tom prepared four set-ups, F, G, H and J as shown below. Using two of the above set-ups, which one of the following could be the aim of Tom's investigation?

Accepted Answer

D. F and J — To find out if the number of stirs of mixture affects the rate starch is broken down into sugar.. F and J differ only in the number of stirs (F=0 stirs, J=10 stirs); all other variables (starch 25 ml, saliva 30 ml, temperature 40°C) are identical. So only F vs J is a fair test for the effect of number of stirs.

Question 15

The diagram shows a pair of shoes. To wear comfortably, it is most important for part C of the shoe to have the property of ____.

Accepted Answer

B. flexibility. Part C is the upper portion of the shoe that wraps around the foot. For comfortable wear, this part must be flexible so it can bend with the foot during walking and not chafe.

Question 16

A compass has a small magnet that can move freely. Which diagram shows the directions of the small magnets in the compass correctly?

Accepted Answer

C. Two compasses on either end of a magnet — left needle points right (towards magnet), right needle points right (away from magnet). A magnet has a north and a south pole. The compass needles will both point in the same direction along the magnet's field — the north pole of each compass needle is attracted to the magnet's south pole and repelled by the magnet's north pole. So both needles point the same way (one needle towards the magnet, the other away from it).

Question 17

There is a lighted candle and a toy behind a screen. Which of the following explains why Nadiah cannot see the toy?

Accepted Answer

D. No light is reflected from the toy into Nadiah's eyes.. Nadiah can see other things because light from the candle is entering her eyes. She cannot see the toy because the screen blocks the light reflected from the toy from reaching her eyes.

Question 18

Mala set up an experiment as shown below in a dark room. The light sensor gave a reading of 30 units. When Mala moved one object in the set-up, the reading on the light sensor increased to 50 units and dropped to 0 units suddenly. Which object did Mala move and in which direction?

Accepted Answer

C. Moved torch towards the screen.. When the torch is moved closer to the screen, it first moves past the book so more light reaches the sensor (reading increases to 50). When the torch is on the same side as the screen / past the book and then the screen finally blocks the light, the reading drops suddenly to 0.

Question 19

The diagram below show four identical syringes. Which syringe can be pushed in the most?

Accepted Answer

D. cotton. Cotton contains many air pockets (gas). Gases can be compressed because their particles are far apart, so the syringe with cotton (and trapped air) can be pushed in the most. Water, sand and honey are essentially incompressible.

Question 20

The diagram below shows Jyak blowing air into a balloon. The inflated balloon is bigger because air ____.

Accepted Answer

B. occupies space. When air is blown into the balloon, it pushes against and fills the inside of the balloon, making it bigger. This shows that air (a gas) occupies space.

Question 21

Simon wanted to compare the heat conductivity of metals using the set-up as shown below. A piece of wax of the same size was placed on each end of the rods which was supported by the wooden ring. The rods were then heated at position X of the set-up. The table shows the information regarding the metal rods, P, Q, R and S. Simon observed that the wax on rod S dropped first, followed by that on rod R, P and Q. Based on the results, which of the following conclusion is correct?

Accepted Answer

C. R is a better conductor of heat than P.. Heat conductivity can only be fairly compared between rods of the same length and thickness. R (length 20 cm) vs P (length 10 cm) is NOT a fair comparison, but the question asks which conclusion is correct based on results. The wax on R (longer rod) dropped before P (shorter rod), which means R is a better conductor — heat travelled the longer distance faster, so R conducts heat better than P. S vs P (both 10 cm, 0.5 cm) and R vs Q (both 20 cm, 0.5 cm) are fair comparisons but options A/B/D draw invalid conclusions.

Question 22

The diagram shows the water cycle. Which of the following shows the correct state of matter of water when it is at A and B?

Accepted Answer

C. A: liquid; B: gaseous. A is the cloud, where water droplets exist as liquid (condensed water vapour). B is water vapour rising from the lake by evaporation, which is in the gaseous state.

Question 23

The diagram below shows some bees flapping their wings above a honeycomb to thicken the nectar. At first, the nectar in the honeycomb was watery. The flapping of the wings causes ____.

Accepted Answer

C. the water content to evaporate faster. Flapping wings increases the air movement over the watery nectar. This causes the water content in the nectar to evaporate faster, thickening the nectar. The nectar (sugar) itself does not evaporate.

Question 24

Study the electric circuit below. Which of the following is definitely the reason for the bulb not to light up?

Accepted Answer

C. There is no battery.. The circuit shows material A connected in series with a bulb, but no battery (no source of electrical energy). Without a battery, no current flows, so the bulb cannot light up. A switch is not required for current to flow. The bulb being fused or material A being an insulator are possibilities but the missing battery is the definite reason.

Question 25

Ziming set up two identical bulbs in his toy house. Bulb X is in Room 1 and Bulb Z is in Room 2. The brightness of each room is the same. The two rooms are separated by a wall as shown below. He wanted Room 2 to be brighter than Room 1. What should he do?

Accepted Answer

B. Add in a bulb in parallel to bulb Z.. Adding a bulb in parallel to bulb Z in Room 2 puts two bulbs lighting up Room 2 while Room 1 still has only one bulb, so Room 2 becomes brighter. Adding a bulb in series would make all bulbs dimmer. Adding batteries makes BOTH rooms brighter equally. An extra conductor in series does not increase brightness.

Question 26

The diagram shows a power station. When the sun warms up the surface of the Earth, it causes the air to move, resulting in winds. The wind passes over the ocean, transferring its kinetic energy to the water below, generating waves. Based on the information above, which of the following shows the energy conversion to generate electricity?

Accepted Answer

B. heat energy → kinetic energy → electrical energy. Heat energy from the Sun warms the Earth, producing wind (kinetic energy of the moving air). The wind transfers kinetic energy to the waves, which turns the turbine to drive the electrical generator, producing electrical energy.

Question 27

Ali held a phone by the wire as shown in diagram 1. After a few seconds, the phone dropped to the ground as shown in diagram 2. The phone dropped because the ____.

Accepted Answer

B. friction between the plug and the phone is less than the weight of the phone. The plug holds the phone via friction. The phone falls when its weight (pulled by gravity) exceeds the frictional force between the plug and the phone — so friction is less than the phone's weight, allowing the phone to slip off.

Question 28

Peifen wanted to compare the stiffness of springs of the same length using the set-up as shown below. She placed object A on spring X with a magnet suspended at the same height above it and measured how much the spring decreased. She then repeated the same experiment using springs Y, Z and W. The results are shown in the table below. When the springs are hung from the ceiling using four identical blocks, which of the following shows the correct results?

Accepted Answer

A. From top to bottom: W, Y, X, Z. The smaller the decrease in length when compressed, the stiffer the spring. W (1 cm) is stiffest, then Y (2 cm), X (3 cm), Z (4 cm). When hung from the ceiling with identical blocks (same weight pulling down), the stiffest spring (W) stretches the least and the least stiff (Z) stretches the most. So top to bottom: W (shortest stretch), Y, X, Z (longest stretch).

P6 Science SA2 2021 — Rosyth

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