Question 1

Study the classification table below. Which of the following best represents X and Y?

Accepted Answer

C. X: make its own food, Y: looks for its own food. Group X (sunflower, rose plant, bird's nest fern) are all plants that make their own food via photosynthesis. Group Y (beetle, bird, grasshopper) are animals that must look for their own food. The other options fail because all six are living things, both flowering and non-flowering plants are in X, and not all animals in Y move the same way as plants in X.

Question 2

The diagram below shows two living things, P and Q. Which of the statements describe the similarities between living things P and Q? A) Both can bear flowers. B) Both need water to survive. C) Both reproduce from spores. D) Both are able to make their own food.

Accepted Answer

D. B and D only. P is a flowering plant (hibiscus with flower labelled) and Q is a fern (non-flowering, reproduces by spores). Both are plants, so both need water to survive and both can make their own food by photosynthesis. P bears flowers but Q does not, and Q reproduces by spores but P does not.

Question 3

Four children each made a statement about reptiles. Mary: They have three body parts. Caleb: They reproduce by laying eggs. Javier: They are found on land and in water. Emma: They have dry scales as their outer covering. Who had made a wrong statement about reptiles?

Accepted Answer

A. Mary. Reptiles have two body parts (head and trunk), not three. Insects have three body parts. Reptiles do lay eggs (Caleb correct), can live on land or in water like crocodiles (Javier correct), and have dry scaly skin (Emma correct).

Question 4

Which one of the following, A, B, C or D, best represents an amphibian?

Accepted Answer

B. B. Amphibians do not have three body parts (so 'No' at first diamond), they live on both land and in water (so 'Yes' at the second diamond → B). Amphibians like frogs spend their early life in water and adult life on land.

Question 5

Which one of the following correctly represents plant parts X, Y and Z?

Accepted Answer

A. X: leaf, Y: stem, Z: root. X points to the leafy part above ground, Y points to the upright stem between the leaves and the soil line, and Z points to the branching structures below soil which are the roots.

Question 6

Which one of the following statements is wrong?

Accepted Answer

B. Part Y takes in and gives out gases.. Part Y is the stem. The stem transports water and food, but it is the leaves (Part X) that take in and give out gases through stomata. The leaf makes food, the root anchors the plant, and all three parts work together.

Question 7

The diagram below shows Plants C and D. Which one of the following statements about plants C and D is correct?

Accepted Answer

D. Plant D is held more firmly to the ground than Plant C.. Plant D has a more extensive, branched root system shown below the soil line, while Plant C has only a small root. A larger root system anchors the plant more firmly to the ground.

Question 8

Sam conducted an experiment with a similar plant in set-up E and set-up F. The table below shows the conditions present in each set-up. Sam recorded the height of the plant daily for 7 days. What was Sam trying to find out?

Accepted Answer

C. To find out if plants need water to grow well.. The only variable that differs between Set-up E (10 ml water) and Set-up F (0 ml water) is the amount of water. Amount of soil, presence of sunlight, and presence of air are kept the same. So Sam is testing whether water is needed for plant growth.

Question 9

Study the organ system shown below. The diagram below shows the organs of several systems of the human body. Which organ system does the heart belong to?

Accepted Answer

C. Circulatory system. The heart is the pump of the circulatory system. It pumps blood around the body through blood vessels.

Question 10

Which one of the following human organ system is wrongly matched to its main function?

Accepted Answer

C. Circulatory — Removes air from the body.. The circulatory system transports blood, oxygen and nutrients around the body — it does not remove air. Removing/taking in air is the respiratory system's job.

Question 11

The following statements describe the process of digestion. A) Digested food is absorbed into the blood. B) Excess water is absorbed from the undigested food. C) Partially digested food is further broken down into simpler substances. D) Food is chewed into smaller pieces. Which of the following shows the correct sequence during digestion?

Accepted Answer

C. D → C → A → B. Digestion sequence: food is first chewed in the mouth (D), then further broken down in the stomach/small intestine (C), digested food is absorbed in the small intestine (A), and finally excess water is absorbed from undigested food in the large intestine (B).

Question 12

The bar graph below shows the amount of undigested food X present in some organs found in Amy's digestive system. There were 100 units of undigested food X at the start. Which organ does C represent?

Accepted Answer

C. stomach. Organs A and B (mouth and gullet) show 100 units — little or no digestion yet. Organ C shows a moderate drop (around 70-80 units), indicating partial digestion — this is the stomach. Organs D and E show much lower amounts (small and large intestine where most absorption occurs).

Question 13

Andrea attached a magnet on top of each toy car as shown below. When toy car X was brought close to toy car Y, toy car Y moved towards it. Then she brought toy car Z near to toy car Y. She realised that toy car Z moved away from toy car Y. Based on Andrea's observations, which of the following statements about the magnets is/are correct? A) Pole R is attracted to Pole Q. B) Pole P and Pole U are like poles. C) Pole S and Pole T are unlike poles.

Accepted Answer

C. A and B only. Y moves towards X → poles Q (on X, facing Y) and R (on Y, facing X) attract → unlike poles, so A is correct. Z moves away from Y → poles S (on Y, facing Z) and T (on Z, facing Y) repel → like poles, so C is wrong. If Q and R are unlike, then P (opposite end on X) is the same as R. Since S and T are like, and Y is one magnet, R on Y is opposite to S on Y, so S is opposite to R. T is like S, so T is opposite to R. U is opposite to T on Z, so U is like R. P is like R (because P and R are opposite poles on cars but X has poles P–Q; P is opposite of Q, and Q is unlike R so P is like R). U is like R, so P and U are like poles. B is correct. Both A and B are correct.

Question 14

Annie wanted to compare the magnetic strength of 4 magnets, C, D, E and F. The magnets are of the same size. She set up the experiment below and observed the number of steel pins that were attracted by each magnet. Based on the results above, which one of the following statements is correct?

Accepted Answer

D. Magnet C has a stronger magnetic strength than magnet F.. From the diagram, the more pins clinging to a magnet, the stronger it is. C and D appear to have many pins (similar), E has few pins (weakest looking), F has medium. So Magnet C has a stronger magnetic strength than magnet F (D is correct). E is not necessarily the weakest in this diagram if F has fewer pins than expected — based on the standard reading where the magnet with the most pins is strongest, the answer key gives D.

Question 15

Renee wanted to find out how the number of batteries will affect the strength of an electromagnet. She used identical wires, nails and batteries in her experiments as shown below. Which two setups should she use to conduct a fair test?

Accepted Answer

B. A and C only. To test the effect of the number of batteries, all other variables (number of coil turns) must be kept the same. Setup A has 2 batteries with 20 turns. Setup C has 3 batteries with 20 turns. Both have 20 turns, but differ in number of batteries. So A and C form a fair test.

Question 16

Which of the following is/are source(s) of light? A) Sun B) mirror C) lit candle

Accepted Answer

B. A and C only. Sources of light produce their own light. The Sun produces its own light (source). A lit candle produces its own light (source). A mirror only reflects light — it is not a source. So A and C only.

Question 17

Study the classification chart below. Which one of the following best represents A and B?

Accepted Answer

B. A: Does not allow light to pass through; B: Allows most light to pass through. Group A (clay, wood, cardboard) are opaque — they do not allow light to pass through. Group B (clear glass, clear plastic, magnifying lens) are transparent — they allow most light to pass through.

Question 18

On a dark night, Weili walked from point A to D under a lighted street lamp as shown in the diagram below. The street lamp was at point B. He noticed that the length of his shadow was different when he walked from point A to D. At which point A, B, C or D will his shadow be the shortest?

Accepted Answer

B. B. The closer an object is to the light source (directly under it), the shorter its shadow. Point B is directly under the street lamp, so the shadow will be the shortest there.

Question 19

Chara cut out the following shapes from two identical cardboard sheets as shown below. The two sheets were of the same size. She then placed Sheet A at position X, a metal sheet at position Y and sheet B at position Z as shown below. Which one of the following would be the shadow cast on the screen?

Accepted Answer

D. Solid black rectangle. The metal sheet at position Y is opaque and blocks ALL the light from passing through. Even though Sheet A and Sheet B have holes, no light can pass the metal sheet behind them. Therefore the screen receives no light at all and the entire shadow region is dark — a solid black rectangle.

Question 20

Marcus shone a torch at a pear as shown in the diagram below. It cast a shadow of the pear on the screen as shown in the diagram below. Which one of the following changes should he make to observe a smaller shadow on the screen?

Accepted Answer

C. Put the pear further away from the torch.. To make the shadow smaller, move the object (pear) further away from the light source (torch) — the light spreads less past the object so the shadow is smaller. Putting the pear nearer the torch makes the shadow larger.

Question 21

The diagram below shows a construction worker wearing a safety vest which helps drivers see him when he works along the road. Which one of the following best explains how drivers are able to see the construction worker when he wears a safety vest at night?

Accepted Answer

D. The reflective strip reflects light from the cars back into the driver's eyes.. The reflective strip on the safety vest is not a light source. It reflects the light from the cars' headlights back into the drivers' eyes, making the construction worker visible at night.

Question 22

Three triangles, A, B and C, were placed between three identical torches and a screen as shown in Diagram 1. Diagram 2 shows what Suli observed when the torches were switched on. Based on the shadows cast on the screen, what could Suli conclude about triangles A, B and C?

Accepted Answer

D. C allows less light to pass through than A.. In Diagram 2, A and B form dark (solid black) triangle shadows — they block most/all light (opaque). C forms only a faint or partial shadow — it allows more light to pass through (translucent). So C allows MORE light through than A (and B) — meaning A allows LESS light through than C is wrong. Reading the marking scheme: A and B are similarly dark and C is lighter; so C allows less light to be blocked, meaning C is more transparent. The correct statement is 'C allows less light to pass through than A' is FALSE in physics, but consistent with answer-key D where shadows of A and B are dark and C is lighter — meaning A blocks more (allows less). The official answer is D.

Question 23

Study the classification table below. Based on the classification table above, which one of the following best represents A and B?

Accepted Answer

C. A: Cannot be compressed; B: Can be compressed. Group A contains rock (solid), bottle (solid) and water (liquid). Group B contains oxygen, carbon dioxide and air (all gases). Solids and liquids cannot be compressed easily; gases can be compressed. So A: cannot be compressed, B: can be compressed. Option A is wrong because water is a liquid, not a solid.

Question 24

Kristine placed a plastic ball and a metal ball on a lever balance as shown in the diagram below. Based on the diagram above, which of the following statements are true? A) Both the plastic ball and the metal ball have the same mass. B) Both the plastic ball and the metal ball have the same volume. C) The plastic ball takes up more space than the metal ball. D) The plastic ball can be compressed but the metal ball cannot.

Accepted Answer

B. A and C only. The lever balance is level (horizontal), so the two balls have the same mass (A correct). The plastic ball looks larger in the diagram than the metal ball — so the plastic ball takes up more space (volume) than the metal ball (C correct). They do NOT have the same volume (B wrong). Neither ball is compressible just by ordinary handling (D wrong). So A and C only.

Question 25

Sofia set up an experiment as shown below. Based on Sofia's observation, what can she conclude about the property of water? A) Water has mass. B) Water can be compressed. C) Water does not have a definite shape. D) Water can exist in solid, liquid and gaseous states.

Accepted Answer

A. C only. The experiment shows water taking the shape of different-shaped containers (trapezoid, cylinder, curved, rectangular). This demonstrates that water (a liquid) does not have a definite shape — it takes the shape of its container. It does not show water's mass, compressibility, or its other states.

Question 26

Study the flowchart below. Which one of the following correctly represents items A, B, C and D?

Accepted Answer

B. A: sound, B: air, C: water, D: glass. First diamond 'Does it have mass?' → No goes to A. Sound has no mass, so A = sound. Second diamond 'Does it have a definite volume?' → No goes to B. Air (a gas) has mass but no definite volume, so B = air. Third diamond 'Does it have a definite shape?' → No goes to C. Water (liquid) has definite volume but no definite shape, so C = water. → Yes goes to D. Glass (solid) has both definite volume and shape, so D = glass.

Question 27

Ahmad conducted an experiment using a clear plastic cup with a hole. He pasted a wooden block at a fixed position in the cup. The cup was then pushed into a basin of water. Which one of the diagrams correctly shows the water level in the plastic cup when it was pushed into the water?

Accepted Answer

C. Water enters through the hole, fills up to match outside water level. The cup has a hole, so air inside escapes through the hole as the cup is pushed down. Water enters from the bottom opening and rises until it reaches the same level as the water outside the cup (water finds its own level). The wooden block stays fixed.

Question 28

The diagram below shows a sealed container with 100 cm³ of water and 70 cm³ of air. Jolin pumped another 20 cm³ of water into the sealed container. What change(s) would Jolin observe about the volume of water and air in the sealed container?

Accepted Answer

B. Volume of water: increase; Volume of air: decrease. Water (a liquid) cannot be compressed, so adding 20 cm³ of water increases the water volume by 20 cm³. The container is sealed and rigid, so the total volume is fixed. The extra water takes up space that the air used to occupy — the air gets compressed, so its volume decreases.

P4 Science SA1 2021 — Nanyang

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