Question 1

Study the table below. Which animal group is matched with the correct body covering?

Accepted Answer

B. reptile — scales. Reptiles are covered with scales. Birds have feathers, mammals have hair/fur, and amphibians have moist skin.

Question 2

The diagram below shows the different parts of a plant. Which of the following are the functions of part X?
A produces fruits
B makes food for the plant
C absorbs water for the plant
D holds the plant firmly to the soil

Accepted Answer

D. C and D only. Part X is the root. Roots absorb water (and minerals) for the plant and hold the plant firmly to the soil. Fruits are produced by flowers and food is made by leaves.

Question 3

The diagram below shows the human digestive system and its organs. Digestion does not take place at one of the organs. Which organ is that?

Accepted Answer

B. (2). Label (2) points to the oesophagus (gullet), which only transports food from the mouth to the stomach and does not carry out digestion. Mouth (1), stomach (3) and small intestine (4) all carry out digestion.

Question 4

The graph below shows the amount of digested and undigested food in the different parts of the digestive system just before it leaves each organ. Which bar graph correctly represents the large intestine?

Accepted Answer

B. (2). The large intestine absorbs water from the undigested food, so the food leaving it should be mostly undigested with very little digested food remaining. Bar (2) shows only a small amount of undigested food (water removed) and no digested food.

Question 5

The diagram below shows the life cycle of an animal. Which animal undergoes the similar life cycle as shown above?

Accepted Answer

D. cockroach. The diagram shows a 3-stage life cycle: egg → nymph → adult. Cockroaches undergo this incomplete (3-stage) metamorphosis. Beetles, butterflies and mosquitoes have a 4-stage life cycle (egg, larva, pupa, adult).

Question 6

Siti observed the life cycle of the chicken and the frog. She recorded the number of days taken for some of the stages in the life cycles below. At which stage would each animal be on Day 22?

Accepted Answer

B. chicken: young, frog: egg. Chicken egg hatches into young on Day 21, so on Day 22 the chicken is at the young stage. The frog egg only hatches into the young stage on Day 24, so on Day 22 the frog is still at the egg stage.

Question 7

Study the flow chart below. Which of the following represents living thing A and Question B?

Accepted Answer

D. Living thing A: plant; Question B: Does it lay eggs in water?. The first question separates 3-stage life-cycle animals from others. A plant does not have a 3-stage life cycle (plants undergo seed → seedling → adult stages, not the insect 3-stage metamorphosis), so 'yes' leads to A (plant). At Question B, the 'yes' branch leads to mosquito and 'no' leads to butterfly; mosquito lays eggs in water but butterfly does not, so Question B is 'Does it lay eggs in water?'.

Question 8

Ben released object Q into a basin of water and observed the following as shown in the diagram. Based on the diagram above, which of the following correctly states the material object Q could be made of and the reason for his observation?

Accepted Answer

D. wood — It can float on water.. Object Q is floating on the water. Of the materials listed, wood typically floats on water; metal and ceramic sink. The strength, waterproofness or transparency of a material does not determine whether it floats.

Question 9

Joshua pours a beaker of water into a basin as shown in the diagram below. Based on the diagram above, which of the following correctly shows the property of water? The water ____.

Accepted Answer

C. has no definite shape. When water is poured from the tall beaker into the wider basin, it takes the shape of its new container. This shows that water (a liquid) has no definite shape. Liquids do have mass and a definite volume, and they cannot be compressed.

Question 10

Study the classification table below. How are the above items classified?

Accepted Answer

B. Group M: non-matter; Group N: matter. Group M (sound, light, shadow) are non-matter — they have no mass and do not occupy space. Group N (oxygen, cooking oil, sand) are all matter — they have mass and occupy space.

Question 11

Which of the following instruments can be used to measure exactly 35 cm³ of water?

Accepted Answer

A. measuring cylinder. Volume of water is measured with a measuring cylinder, which has fine graduations for accurate readings. A beaker can hold water but is not accurate. A weighing scale measures mass, and a thermometer measures temperature.

Question 12

Sam has two identical beakers each containing 200 ml of water. He then places solid objects, Y and Z, into each beaker and the water levels rise as shown in the diagram below. What can Sam conclude from his observation?

Accepted Answer

C. Object Z occupies less space than object Y.. The water level rises more when object Y is placed in than when object Z is placed in, so Y displaces more water and therefore has a larger volume than Z. This means object Z occupies less space than object Y. Mass cannot be concluded from the displacement.

Question 13

Rosa conducted an experiment using the set-up as shown below. She removed 50 cm³ of water from the container and pumped in another 100 cm³ of air. What is the final volume of air in the container?

Accepted Answer

C. 250 cm³. Air is a gas with no definite volume and fills any container it occupies. Starting air = 100 cm³ and another 100 cm³ pumped in = 200 cm³ of air. When 50 cm³ of water is removed, the air expands to fill that extra space too, giving a final air volume of 200 + 50 = 250 cm³.

Question 14

Four identical empty bottles, A, B, C and D, were pushed into a tank filled with water as shown in the diagram below. Two bottles, C and D, were sealed before being pushed into the water. Which bottle shows the correct water level in the bottle?

Accepted Answer

A. A. Bottles A and B have open openings so water can enter and rise inside; bottles C and D are sealed so air is trapped inside, preventing water from entering. A is shown empty (with water entering — wait reconsider). Correct: open bottles allow water to enter to the same level as the tank; sealed bottles trap air so almost no water enters. Bottle A is shown with the same water level inside as the tank, matching this behaviour for an open bottle pushed in.

Question 15

Paul made the following electromagnet to attract some iron nails. Which of the following method(s) can Paul use to attract more iron nails?
A use a shorter wire
B increase the number of batteries
C change the iron rod to a plastic rod
D reduce the number of coils of wire around the iron rod

Accepted Answer

A. B only. The strength of an electromagnet can be increased by increasing the current (more batteries) or increasing the number of coils of wire around an iron core. Only option B increases the strength. A shorter wire is unrelated, plastic is not magnetic so it would weaken the magnet, and reducing the coils would also weaken it.

Question 16

Four magnets are arranged as shown below. A compass is placed near pole H. Which of the following shows the correct observation when the ends of two magnets are placed near to each other and a compass is placed at one end?

Accepted Answer

C. D C H G with compass arrow pointing left. In the original arrangement, the compass near pole H points towards H, so H is a north pole (attracting the compass needle's south end) — or equivalently G is the south end of that bar. Pairing magnets so that the same pole H still faces the compass and pulls the needle left in the same way: the option that keeps H next to the compass with the matching pole orientation (D C / H G with the arrow pointing toward H) is correct.

Question 17

Study the diagram below. Which of the following shows the path of light that enabled Raelyn to see her dog?

Accepted Answer

D. lamp → Raelyn's dog → Raelyn (light from lamp to dog, then from dog to Raelyn). To see a non-luminous object such as the dog, light must travel from the lamp to the dog, be reflected off the dog, and then enter Raelyn's eyes. So the correct light path is lamp → dog → Raelyn's eyes.

Question 18

The diagram below shows an opaque bottle. Which of the following shadows cannot be formed by the bottle?

Accepted Answer

D. dark bottle silhouette showing an unfilled (hollow) loop/handle at the top. Opaque objects cast solid (single colour) shadows that take the outline shape of the object from the angle of the light. Options 1–3 are all possible silhouettes of the opaque bottle viewed from different angles. Option 4 shows a hollow loop/handle inside the shadow, which is impossible because an opaque object cannot produce a shadow with a 'see-through' hole where its solid body is.

Question 19

With the lamp switched on, Ivan could not see his cat when his cat moved to the other side of the room, which is separated by a wall. Which of the following explains why Ivan could not see his cat?

Accepted Answer

C. The wall did not allow light to pass through.. The wall is opaque and does not allow light to pass through. Therefore, light reflected from the cat cannot reach Ivan's eyes, so he cannot see the cat. The cat does reflect light, but the opaque wall blocks it.

Question 20

Cheryl sets up an experiment in a dark room as shown below. The object is made up of different materials as shown below (the object is a rectangle of tracing paper with a heart outline of clear plastic and a circle of black paper inside). When the torch is switched on, which of the following could be seen on the screen?

Accepted Answer

C. dim/grey rectangle with a white heart outline and a black circle inside the heart. Tracing paper is translucent (lets some light through — appears dim/grey on screen). Clear plastic is transparent (lets most light through — appears bright/white on the screen where the heart outline is). Black paper is opaque (blocks light — appears as a dark shape where the circle is). So the screen shows a dim rectangle (tracing paper) with a bright heart (clear plastic) containing a dark circle (black paper).

Question 21

An experiment was conducted to compare the amount of light that passes through four different materials, A, B, C and D. The readings of the light sensor are shown in the bar graph below. Based on the bar graph above, which of the materials, A, B, C or D, is most suitable to make a fish tank as shown below?

Accepted Answer

D. material D. A fish tank should be transparent so people can see the fish clearly, meaning it should let through the most light. From the bar graph, material D has the highest light reading (closest to the 'no material' bar), so it is the most transparent and most suitable for a fish tank.

Question 22

John cut a heart, square and circle with hollow centres out of cardboard, as shown below. The shapes are of equal height. These shapes are placed in front of a torch at positions A, B and C as shown below. The diagram below shows the shadow that is cast on the screen. Which of the following best represents where the different shapes were placed at?

Accepted Answer

D. heart: C, square: B, circle: A. The closer a shape is to the torch, the larger its shadow on the screen. From the shadow, the circle's shadow is largest, then the square, then the heart is smallest. So the circle must be closest to the torch (position A), the square in the middle (position B) and the heart farthest from the torch (position C).

P4 Science SA1 2021 — Tao Nan

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