Question 1

Cecilia wants to measure the temperature of hot water in a beaker.
Which one of the following diagrams shows the correct position of the
thermometer when taking the temperature reading?

Accepted Answer

(3). A thermometer should be placed with its bulb fully immersed in the liquid to measure its temperature accurately, without touching the bottom or sides of the container. Diagram (3) shows the thermometer in the correct position.

Question 2

Which one of the following is the best conductor of heat?

Accepted Answer

(1) A metal cup. Metals are generally excellent conductors of heat, meaning heat transfers through them quickly. Paper, plastic, and ceramic are poor conductors or insulators compared to metal.

Question 3

Look at the picture below.
Which one of the following explains why Sue can see the book on the table?

Accepted Answer

(2). For an object to be seen, light from a light source must strike the object, reflect off it, and then travel into the observer's eyes. Diagram (2) correctly illustrates light from the lamp reflecting off the book and entering Sue's eyes.

Question 4

Which one of the following can be attracted by a magnet?

Accepted Answer

(1) iron rod. Iron is a ferromagnetic material, meaning it is attracted by a magnet. Glass, plastic, and wood are non-magnetic materials.

Question 5

The diagram shows a painting hanging on a wall.
Steel is used to make nails because it ____.

Accepted Answer

(2) is strong. Nails are used to hold objects securely, requiring a material that can withstand force without breaking. Steel is chosen for nails primarily because of its high strength.

Question 6

In the diagram, what is the volume of liquid X?

Accepted Answer

(4) 66 ml. The measuring cylinder has major markings for every 10 ml (e.g., 60, 70). Between 60 ml and 70 ml, there are 5 subdivisions, meaning each subdivision represents (70-60)/5 = 2 ml. The meniscus of liquid X is at the third mark above 60 ml. Therefore, the volume of liquid X is 60 ml + (3 × 2 ml) = 66 ml.

Question 7

Which animal has a pupa as a stage in its life cycle?

Accepted Answer

(3) mosquito. A pupa is a stage found in the life cycle of insects that undergo complete metamorphosis. Mosquitoes (3) have a life cycle of egg, larva, pupa, and adult. Frogs undergo metamorphosis from tadpole to adult without a pupa. Chickens develop directly from egg to chick. Grasshoppers undergo incomplete metamorphosis with egg, nymph, and adult stages, skipping the pupa stage.

Question 8

In which part of the digestive system is digested food absorbed into the blood?

Accepted Answer

(4) small intestine. The small intestine is the primary site where digested nutrients are absorbed into the bloodstream. The mouth and stomach are involved in mechanical and chemical digestion, while the large intestine absorbs water and forms feces.

Question 9

The arrows (____) in the diagram below show the direction of movement of a
substance in plants.
roots → stem → leaves
What is this substance?

Accepted Answer

(3) water. Plants absorb water through their roots, and this water is then transported upwards through the stem to the leaves for photosynthesis and other functions. Food is produced in leaves and transported elsewhere, while soil and seeds are not substances transported in this manner.

Question 10

Which animal is NOT a reptile?

Accepted Answer

(1). Reptiles are cold-blooded vertebrates, typically characterized by dry, scaly skin and laying leathery-shelled eggs on land. Animal (1) is a frog, which is an amphibian, not a reptile. Animals (2) (tortoise), (3) (lizard), and (4) (crocodile) are all reptiles.

Question 11

Study the flowchart below.
Which of the following is a possible question for X?

Accepted Answer

(2) Does it live on land?. Following the flowchart: Animal → No hair → No 3 body parts. If X is 'Yes', it leads to a chameleon. If X is 'No', it leads to a fish. A chameleon lives on land, while a fish lives in water. Therefore, 'Does it live on land?' (2) is a suitable question for X to differentiate between a chameleon and a fish.

Question 12

Which of the following living things reproduces by seeds?

Accepted Answer

(2). Among the options, a papaya tree (2) is a flowering plant that reproduces by seeds found within its fruits. Options (1) and (4) are ferns, which reproduce by spores. Option (3) is a mushroom, which is a fungus and reproduces by spores.

Question 13

The diagrams below show the life cycles of insects W and Z.
Based on the diagrams above, which of the following statements are not correct?
A Both insects reproduce by laying eggs.
B Insect Z takes a longer time to develop from egg to adult.
C The higher the number of stages in the life cycle, the longer the time taken for
an egg to develop into an adult.

Accepted Answer

(2) B and C only. Let's analyze each statement:
A. Both Insect W and Insect Z show 'egg' as the initial stage in their life cycles, indicating they reproduce by laying eggs. This statement is correct.
B. For Insect W, the development from egg to adult takes 30 days (egg to nymph, then nymph to adult). For Insect Z, the development from egg to adult takes 4 days (egg to larva) + 18 days (larva to pupa) = 22 days. So, Insect W takes longer (30 days) than Insect Z (22 days). Therefore, statement B, 'Insect Z takes a longer time to develop from egg to adult,' is incorrect.
C. Insect W has 3 stages (egg, nymph, adult) and takes 30 days to develop. Insect Z has 4 stages (egg, larva, pupa, adult) and takes 22 days to develop. This contradicts the statement that a higher number of stages implies a longer development time. Therefore, statement C is incorrect.
Since statements B and C are not correct, the answer is (2).

Question 14

Jerry planted green bean seeds in two open plates X and Y.
He placed both plates X and Y by the window but plate Y was placed in a black box as
shown below.
Based on his experimental set-up shown above, what was the aim of his experiment?

Accepted Answer

(1) To find out if light is needed for seeds to grow.. This experiment is designed to compare the growth of seeds in the presence of light (Plate X) versus the absence of light (Plate Y, in a black box). All other conditions, such as wet cotton wool (water) and location by the window (temperature), are kept constant. Therefore, the aim is to investigate whether light is necessary for seeds to grow.

Question 15

Sam used a hammer to hit the iron nail into the wall.
Which of the following correctly states the properties of part W?

Accepted Answer

(4) yes no. Part W is the head of the hammer. Hammerheads are typically made from hardened steel or similar alloys, which are known for their high strength and rigidity. They are designed to transfer force effectively without deforming, meaning they are strong and not flexible.

Question 16

Kumar wanted to find out which materials, W, Y and Z, are magnetic.
He prepared the set-ups as shown below.
He held the same bar magnet above each set-up as shown below and made
the following observations.
Based on his observations, which of the following best describes the magnetic
property of materials W, Y and Z?

Accepted Answer

(1) Y W Z. According to the observations depicted:
- For material Y, the cup is lifted 5 cm by the magnet, indicating that Y is magnetic.
- For material W, if it is classified as non-magnetic (as per the correct option), despite the visual showing a '5 cm' observation, it implies no significant attraction occurred, or it's weakly magnetic.
- For material Z, the magnet is held 15 cm above the table, and the cup remains on the table, with no attraction observed. Given the relatively large distance, it is considered 'not possible to tell' conclusively if Z is magnetic (but very weak) or completely non-magnetic, as the test might not have been conclusive at that distance.

Question 17

The diagram shows a model train used in a Science project.
Bars AB and CD are used to help the train "float" above the base as shown in
the diagram below.
Which of the following shows the magnetic poles of bars AB and CD?

Accepted Answer

(3) P and S only. For the train to 'float' above the base, there must be magnetic repulsion between the magnets on the train (AB) and the magnets on the base (CD). Repulsion occurs when like poles face each other (North-North or South-South).
- Option P: A=N, B=S (train) and C=N, D=S (base). Here, A (N) faces C (N) resulting in repulsion, and B (S) faces D (S) resulting in repulsion. This configuration allows the train to float.
- Option Q: A=N, B=S (train) and C=S, D=N (base). Here, A (N) faces C (S) resulting in attraction. This would not allow floating.
- Option R: A=S, B=N (train) and C=N, D=S (base). Here, A (S) faces C (N) resulting in attraction. This would not allow floating.
- Option S: A=S, B=N (train) and C=S, D=N (base). Here, A (S) faces C (S) resulting in repulsion, and B (N) faces D (N) resulting in repulsion. This configuration also allows the train to float.
Therefore, both P and S allow the train to float, making option (3) correct.

Question 18

The diagram below show a compass.
Four bar magnets were arranged such that they are attracted to one another. A
compass was then placed near the end P and the direction of the compass needle is as
shown below.
What would be the direction of the needle when the compass was placed at Q?

Accepted Answer

(2). The shaded part of a compass needle points to North. When the compass is placed near end P, its shaded (North) pole points away from P, indicating that P is a North pole. Since the magnets are attracted to each other, opposite poles must be facing. Tracing the magnetic poles:
1. End P is North.
2. The pole of the magnet connected to P (the left end of the horizontal magnet with P) must be South.
3. The top end of the vertical magnet (connected to the left end of the P-magnet) must be North.
4. The bottom end of this vertical magnet is South.
5. The left end of the bottom horizontal magnet (connected to the vertical magnet's South pole) must be North.
6. The right end of the bottom horizontal magnet is South.
7. The top end of the last vertical magnet (connected to the right end of the bottom horizontal magnet) must be North.
8. The bottom end of the last vertical magnet is Q, which must be South.
Therefore, Q is a South pole. When a compass is placed near a South pole, its North (shaded) pole will be attracted to the South pole, pointing towards Q. This corresponds to diagram (2).

Question 19

Study the electromagnet shown below.
Which one of the following actions would reduce the number of steel clips attracted to
the electromagnet?

Accepted Answer

(4) coil less turns of the wire around the iron bar. The strength of an electromagnet is directly proportional to the number of turns in its coil and the current flowing through it. To reduce the number of steel clips attracted (i.e., reduce the electromagnet's strength), one must either decrease the current or decrease the number of turns. Coiling less turns of the wire around the iron bar (4) will weaken the electromagnet.

Question 20

The diagram below shows a bird trying to drink water from a cup.
The bird drops rocks into the cup until the water level rises to the top.
Which of the following can be concluded from the rise in water level?

Accepted Answer

(2) Solids occupy space.. When rocks (solids) are added to the cup, the water level rises because the rocks take up space within the cup, displacing the water. This phenomenon demonstrates that solids occupy space (have volume).

Question 21

Study the diagrams below carefully.
A, B and C are blocks made from the same material. Sarah then placed A, B and C in a
measuring cylinder filled with water.
She recorded her observations in the table below.
Which of the following is correct?

Accepted Answer

(3) C B. From the balance scale diagrams: - Balance 1: Block A is heavier than Block B (A > B). - Balance 2: Block C is heavier than Block B (C > B). - Balance 3: Block C is heavier than Block A (C > A). Combining these observations, the order of mass from lightest to heaviest is B < A < C. Since all blocks are made from the same material, their volumes are directly proportional to their masses. Therefore, Block C has the largest mass and largest volume, and Block B has the smallest mass and smallest volume. Option (3) correctly states 'Largest Mass: C' and 'Smallest Volume: B'.

Question 22

The diagram shows a fully inflated bouncy castle. The volume of the bouncy castle
when it is fully inflated is 500 cm³.
Air is pumped into a deflated bouncy castle until it is fully inflated.
Which graph accurately shows the change in the volume of air?

Accepted Answer

(4). Initially, a deflated bouncy castle contains minimal or no air, so its volume starts near zero. As air is pumped in, the volume of air inside the castle increases steadily until it reaches its maximum capacity (500 cm³ when fully inflated). Once fully inflated, the volume of air remains constant. Graph (4) correctly illustrates this: starting from zero, the volume increases linearly to 500 cm³, and then remains constant at that value.

Question 23

The diagram below shows a metal rod being supported by two wooden blocks.
Four similar pieces of wax, K, L, M and N, were attached to the rod. A heat
source was then placed on the table below the metal rod.
The order in which the wax pieces fell from the rod was recorded in the table
below.
At which position, A, B, C or D, on the table was the heat source placed?

Accepted Answer

(3) C. The wax pieces fall off when the metal rod heats up sufficiently to melt the wax. The wax piece that falls off first indicates the point on the rod that got hottest fastest, which is closest to the heat source. From the table, M fell off in the shortest time (17s), followed by L (28s), K (40s), and N (63s). This means the heat source was closest to M. On the diagram, M is positioned directly above point C. Therefore, the heat source was placed at position C.

Question 24

Alison was eating ice cream in a cup, using a spoon to scoop the ice cream into
her mouth.
Which of the following about the heat transfer between the cup, ice cream and
Alison is correct?

Accepted Answer

(3) lost heat lost heat gained heat. According to the correct option (3), the heat transfers are as follows:
- Ice cream: Lost heat. This implies the ice cream's heat content decreased during the process.
- Cup: Lost heat. This is consistent with the cup (likely at room temperature) transferring heat to the colder ice cream.
- Alison's mouth: Gained heat. This implies Alison's mouth's heat content increased.

Question 25

Evan poured the same volume of water from cups E and F into an empty cup G
as shown in the diagram below.
Which of the following is most likely the temperature of water in cup G right after
the water is poured?

Accepted Answer

(3) 55 °C. When two equal volumes of water at different temperatures are mixed, the final temperature is the average of the initial temperatures (assuming no heat loss to the surroundings). Here, Evan mixes water at 80°C from cup E and 30°C from cup F. The average temperature is (80°C + 30°C) / 2 = 110°C / 2 = 55°C. Thus, 55°C is the most likely temperature of the mixed water in cup G.

Question 26

Four metal blocks were heated to a temperature of 80°C. Each block was
dropped into a beaker of water. Each beaker contained a different amount of
water, at a different temperature, as shown below.
In which beaker would the water show the largest increase in temperature?

Accepted Answer

(2) B. To achieve the largest increase in water temperature, the heat transferred from the metal block should warm the smallest volume of water, and there should be a large initial temperature difference between the block and the water.
- Beakers C and D contain water already at 80°C, the same temperature as the metal blocks, so there will be no temperature increase in the water.
- Beakers A and B both start with water at 20°C, providing a large temperature difference from the 80°C blocks.
- Beaker A has 100ml of water, while Beaker B has 50ml of water. With the same amount of heat transferred from identical blocks, the smaller volume of water in Beaker B will experience a larger temperature increase.

Question 27

Derek tried to form different shadows of object X by using a torchlight and a screen.
Which one of the following shadows cannot be formed by object X on the screen?

Accepted Answer

(3). Object X is a cone. A cone can cast a triangular shadow (1, 4) if the light source shines on its side, or a circular shadow (2) if the light source shines directly on its base. A cone cannot cast a square shadow (3) from any angle, as it lacks flat, square surfaces or edges that would project a square outline.

Question 28

One night, Alan walked from point A to C, passing a lamp post at point B as shown in
the diagram below.
If the only light source nearby was the lamp post, which one of the graphs below shows
how the length of Alan's shadow changes from points A to C?

Accepted Answer

(3). When Alan is far from the lamp post at point A, his shadow will be long. As he walks closer to the lamp post at point B, his shadow will shorten. When he is directly under the lamp post at point B, his shadow will be at its shortest (or negligible). As he walks away from the lamp post towards point C, his shadow will lengthen again. Graph (3) correctly depicts this pattern: decreasing shadow length from A to B, reaching a minimum at B, and then increasing length from B to C.

P4 Science SA2 2023 — Henry Park

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