Question 1

The pictures below show some characteristics of living things. Which of the following shows that living things can respond to changes?
(1) A hen lays eggs in a nest.
(2) A baby becomes a boy over five years.
(3) A bird feeds on the nectar of a flower.
(4) A tortoise hides in its shell when touched.

Accepted Answer

A tortoise hides in its shell when touched.. Responding to changes is a characteristic of living things. When a tortoise is touched, it retracts into its shell, which is a direct response to the external stimulus of touch. This demonstrates the characteristic of responding to changes. Options (1) is reproduction, (2) is growth, and (3) is nutrition.

Question 2

Ken conducted an experiment using four set-ups as shown below.
Which two set-ups should he use to find out if living things need food to survive?
(1) A and D
(2) B and C
(3) A and C
(4) B and D

Accepted Answer

A and C. To find out if living things need food to survive, the experiment must compare a setup with food to a setup without food, while keeping all other variables constant. Set-up A has a mouse with food and a lid without holes. Set-up C has a mouse without food and a lid without holes. By comparing A and C, the only variable being tested is the presence of food, making it a fair test for the need for food.

Question 3

Study the pictures below.
Which statement about the bread mould and the fern is correct?
(1) Both produce flowers.
(2) Both make their own food.
(3) Both need sunlight to grow.
(4) Both reproduce from spores.

Accepted Answer

Both reproduce from spores.. Ferns are non-flowering plants that reproduce by spores. Bread mould is a type of fungus that also reproduces by spores. Therefore, both reproduce from spores. Ferns make their own food and need sunlight, but bread mould does not.

Question 4

Jane grouped some animals into Group E and Group F as shown below.
Which of the following characteristics of animals did Jane use to classify the animals?
(1) number of legs
(2) presence of tail
(3) presence of wings
(4) number of body parts

Accepted Answer

presence of wings. In Group E, all animals (bee, bat, parrot) have wings. In Group F, none of the animals shown (alligator, ant, sea turtle) have wings. This characteristic consistently separates the two groups.

Question 5

The table below shows the characteristics of four different living things, A, B, C and D.
A tick (✔) means the living thing has the characteristic.
From the table above, which of the living things, A, B, C or D, could be bacteria?
(1) A
(2) B
(3) C
(4) D

Accepted Answer

A. Bacteria are microscopic organisms, meaning they are too small to be seen with the naked eye and can only be seen using a microscope. From the table, only living thing A has the characteristic 'It can only be seen using a microscope.' All living things respond to changes, so that is not a distinguishing factor.

Question 6

Accepted Answer

Six legs | Two legs | Has wings | No wings. The animals shown are: H (a bird, e.g., duck), J (a flying insect, e.g., bee/fly), K (a crawling insect, e.g., ant). For the first split G/H: Insects (J, K) have six legs, birds (H) have two legs. So G is 'Six legs' and H is 'Two legs'. For the second split J/K: The flying insect (J) has wings, while the crawling insect (K) does not. So J is 'Has wings' and K is 'No wings'. This matches option (2).

Question 7

The life cycle of a flowering plant goes through stages X, Y and Z as shown in the diagram below.
If stage X is the stage of the plant's life cycle where it has no roots yet, what is the name of stage Z of the life cycle?
(1) egg
(2) seed
(3) adult plant
(4) young plant

Accepted Answer

young plant. The life cycle of a flowering plant typically starts with an egg (ovule before fertilization). The egg develops into a seed (which has no roots yet, stage X). The seed germinates into a young plant (seedling, stage Z), which then grows into an adult plant. If Stage X is 'where it has no roots yet', it refers to the seed. However, considering the typical options and the flow to 'young plant' as stage Z: A plausible sequence is Egg (X) -> Seed (Y) -> Young Plant (Z). The egg (X) certainly has no roots yet. Therefore, stage Z would be the young plant.

Question 8

Accepted Answer

Egg | Larva | Pupa. The diagram shows a 4-stage life cycle (complete metamorphosis) for an insect, which typically includes Egg, Larva, Pupa, and Adult. The options in the table are M, N, Q. If we consider the standard sequence after the Adult stage, it starts with an Egg. Egg develops into a Larva, which then develops into a Pupa before becoming an Adult. So, M, N, Q correspond to Egg, Larva, Pupa respectively.

Question 9

Which of the animals below has a life cycle that has a different number of stages from the rest?
(1) butterfly
(2) chicken
(3) frog
(4) cockroach

Accepted Answer

butterfly. A butterfly undergoes complete metamorphosis, which involves four stages: Egg, Larva, Pupa, and Adult. Chickens (direct development), frogs (incomplete metamorphosis: Egg, Tadpole, Adult), and cockroaches (incomplete metamorphosis: Egg, Nymph, Adult) all have three distinct stages in their life cycles. Thus, the butterfly has a different number of stages.

Question 10

Study the life cycles of animals, R and S below.
Which of the following is true of the life cycles shown above?
(1) The young of animals, R and S, do not feed.
(2) The young of animals, R and S, live in water...
(3) Animal S has a pupal stage while animal R does not have a pupal stage.
(4) The young of animal R does not look like the adult but the young of animal S does.

Accepted Answer

Animal S has a pupal stage while animal R does not have a pupal stage.. Animal R shows a life cycle of Egg -> Nymph -> Adult, which is incomplete metamorphosis and does not include a pupal stage. Animal S shows a life cycle of Egg -> Larva -> Pupa -> Adult, which is complete metamorphosis and includes a pupal stage. Therefore, statement (3) is true.

Question 11

Abdul observed two animals, T and U, and completed the table as shown below.
A tick (✔) means the animal has the characteristic.
Based on the table above, which of the following animals would most likely represent animals, T and U?

Accepted Answer

B. Frog (Animal T) and Cockroach (Animal U). For Animal T: It does not have three body parts (not an insect), its young lives in water, and its young does not look like its adult (undergoes metamorphosis). This describes a frog (tadpoles live in water and are different from adult frogs). For Animal U: It has three body parts (an insect), its young does not live in water, and its young looks like its adult (undergoes incomplete metamorphosis). This describes a cockroach (nymphs live on land and resemble adult cockroaches). Therefore, option (2) showing a frog for Animal T and a cockroach for Animal U is correct.

Question 12

The fireman wears the clothing as shown below when he puts out fires.
Based on the properties shown below, which material, A, B, C or D, is the most suitable for making the fireman's clothing?
(1) A
(2) B
(3) C
(4) D

Accepted Answer

C. Fireman's clothing needs to be flexible for movement, waterproof to protect from water and chemicals, and strong to withstand harsh conditions and prevent tears. Material C is the only one that possesses all three desired properties (flexible, waterproof, and strong).

Question 13

Study the flowchart below.
Based on the flowchart above, which of the following materials, C, D, E or F, is used to make the glass panel and metal door handle?
(1) E | D
(2) F | E
(3) D | C
(4) C | F

Accepted Answer

E | D. A glass panel is transparent and not flexible. Following the flowchart: 'Is it transparent?' -> Yes; 'Is it flexible?' -> No. This leads to Material E. A metal door handle is not transparent and is waterproof. Following the flowchart: 'Is it transparent?' -> No; 'Is it waterproof?' -> Yes. This leads to Material D. Therefore, the glass panel is made of E and the metal door handle is made of D.

Question 14

Study the U-shaped magnet shown below.
The magnet was placed in a tray of steel paper clips. Which of the following best represents the number of steel paper clips attracted to the parts, G, H and J?
(1) 5 | 10 | 5
(2) 10 | 5 | 10
(3) 10 | 10 | 10
(4) 10 | 10 | 5

Accepted Answer

10 | 5 | 10. The magnetic strength of a magnet is strongest at its poles and weakest in the middle. In a U-shaped magnet, the ends (G and J) are the poles, and the curved middle section (H) is the weakest point. Therefore, G and J should attract the most paper clips, and H should attract the fewest. Option (2) shows 10 clips for G and J, and 5 clips for H, which accurately represents this principle.

Question 15

Mrs Chan displayed a poster on the metal cabinet by placing object K on top of the poster.
What can object K and the metal cabinet be made of?
(1) magnet | non-magnetic material
(2) magnetic material | magnetic material
(3) non-magnetic material | magnet
(4) magnet | magnetic material

Accepted Answer

magnet | magnetic material. For object K to hold the poster onto the metal cabinet, there must be a magnetic force of attraction. This occurs when object K is a magnet and the metal cabinet is made of a magnetic material (like iron or steel), or vice-versa, or both are magnets that attract. Option (4) states that object K is a magnet and the metal cabinet is a magnetic material, which would result in attraction and hold the poster in place.

Question 16

Study the set-ups below.
Which of the following set-ups, P, Q, R or S, will have the greatest magnetic strength of attraction?
(1) P
(2) Q
(3) R
(4) S

Accepted Answer

Q. The strength of an electromagnet increases with the number of battery cells (higher current) and the number of turns of wire around the core. 
- Set-up P: 1 cell, 3 turns.
- Set-up Q: 3 cells, 6 turns.
- Set-up R: 2 cells, 3 turns.
- Set-up S: 3 cells, 3 turns.
Comparing these, Set-up Q has the highest number of battery cells (3) and the highest number of turns (6), therefore it will produce the greatest magnetic strength of attraction.

Question 17

Karen made a chess set as shown below. The chess board has a layer made of Material T. She then folded it as shown and observed if the chess pieces stay on the board.
Karen tested the chess pieces again by replacing material T with materials, U, V and W, and recorded her observation in the table shown below.
What could Karen infer from this observation?
(1) Materials T and V are not made of metal.
(2) Materials U and V are magnetic materials.
(3) Materials V and W are non-magnetic materials.
(4) Materials T and W can be attracted to a magnet.

Accepted Answer

Materials T and W can be attracted to a magnet.. The chess pieces have magnets under them. If the pieces stay on the board when tilted, it means the material of the board is magnetic and is attracted to the magnets in the pieces. If the pieces fall, the material is non-magnetic. Materials T and W cause the pieces to stay ('Yes'), indicating they are magnetic materials. Materials U and V cause the pieces to fall ('No'), indicating they are non-magnetic materials. Therefore, Materials T and W can be attracted to a magnet.

P3 Science SA2 2023 — Tao Nan

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