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Primary 6 PSLE Science Practice Paper 4

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TuitionGoWhere Practice Paper - Science Primary 6 PSLE

TuitionGoWhere Practice Paper (AI)

Subject: Science Level: Primary 6 (PSLE) Paper: Practice Paper — Diversity (Topic Focus) Version: 4 of 5 Duration: 1 hour 45 minutes Total Marks: 100

Name: ________________________ Class: ________________________ Date: ________________________

Instructions to Candidates

Write your name, class, and date in the spaces provided above.
Answer all questions in the spaces provided.
Write in dark blue or black pen.
You may use a pencil for diagrams or graphs.
Do not use correction fluid.
The number of marks for each question is shown in brackets [ ].
The total mark for this paper is 100.
You are advised to spend about:
- Section A: 25 minutes (20 marks)
- Section B: 50 minutes (50 marks)
- Section C: 25 minutes (30 marks)
- Review: 5 minutes

Section A: Multiple Choice Questions (20 marks)

Questions 1–20: Each question is worth 2 marks. Choose the most accurate answer and write its letter (A, B, C, or D) in the space provided.

1. Which of the following is a characteristic used to classify living things into groups?

A) Colour of the organism B) Number of legs C) Presence of a backbone D) Size of the organism

Answer: ________ [2]

2. The table below shows the classification of four organisms.

Organism	Has backbone	Has feathers	Has scales
W	Yes	Yes	No
X	Yes	No	Yes
Y	No	No	Yes
Z	No	No	No

Which organism is most likely a fish?

A) W B) X C) Y D) Z

Answer: ________ [2]

3. Which of the following is a non-living thing?

A) Mushroom B) Coral C) River D) Moss

Answer: ________ [2]

4. A student grouped a set of objects as shown below.

Group 1: Wood, plastic, rubber Group 2: Copper, iron, aluminium

What was the student most likely classifying the objects by?

A) Whether they are natural or man-made B) Whether they are magnetic C) Whether they are electrical conductors or insulators D) Whether they are transparent or opaque

Answer: ________ [2]

5. Which of the following correctly shows the order of classification from the largest group to the smallest group?

A) Species → Genus → Family → Order → Class → Phylum → Kingdom B) Kingdom → Phylum → Class → Order → Family → Genus → Species C) Kingdom → Class → Phylum → Order → Family → Genus → Species D) Phylum → Kingdom → Class → Order → Family → Species → Genus

Answer: ________ [2]

6. The diagram below shows a classification key for four animals.

                    ┌── Has feathers ──────── Bird
            ┌───┤
            │   └── No feathers ───┐
Start ──────┤                      ├── Has fins ──── Fish
            │                      │
            └───┬── Has moist skin ─┘
                │
                └── Has dry scales ─── Reptile

Using the key above, which animal would be classified as a fish?

A) Animal with feathers and fins B) Animal with no feathers and moist skin C) Animal with no feathers and fins D) Animal with dry scales and no feathers

Answer: ________ [2]

7. Which of the following is a characteristic of all living things?

A) They can fly. B) They can photosynthesise. C) They can reproduce. D) They have legs.

Answer: ________ [2]

8. The table below shows some properties of four materials.

Material	Density (g/cm³)	Floats in water?
P	0.6	Yes
Q	1.0	No
R	1.5	No
S	0.9	Yes

(The density of water = 1.0 g/cm³)

Which material has a density greater than that of water but less than 1.3 g/cm³?

A) P B) Q C) R D) None of the above

Answer: ________ [2]

9. A student sorted a collection of items into two groups:

Group A: Glass marble, metal coin, ceramic tile Group B: Cotton cloth, tissue paper, sponge

Which property did the student most likely use to sort the items?

A) Hardness B) Flexibility C) Transparency D) Electrical conductivity

Answer: ________ [2]

10. Which of the following is an example of a natural material?

A) Nylon rope B) Plastic bottle C) Cotton fabric D) Rubber tyre (synthetic)

Answer: ________ [2]

11. The diagram shows a Venn diagram with two overlapping circles.

    ┌─────────────┐   ┌─────────────┐
    │  Conducts   │   │  Magnetic   │
    │ electricity │   │             │
    │             │   │             │
    │  Copper     │   │  Iron       │
    │  Aluminium  │   │  Nickel     │
    │             │   │             │
    └─────────────┘   └─────────────┘
         Overlap: Steel

Which material belongs in the overlap region?

A) Copper B) Steel C) Aluminium D) Nickel

Answer: ________ [2]

12. Which of the following groups contains only animals with backbones (vertebrates)?

A) Frog, shark, ant B) Eagle, lizard, dolphin C) Spider, crab, snail D) Earthworm, jellyfish, starfish

Answer: ________ [2]

13. A plant has the following characteristics:

It produces flowers.
It has seeds enclosed in fruits.
It has broad leaves with network veins.

This plant is most likely a

A) fern. B) moss. C) monocotyledon. D) dicotyledon.

Answer: ________ [2]

14. Which of the following is the best reason why scientists classify living things?

A) To give every organism a unique name B) To make it easier to study and understand the diversity of life C) To arrange organisms from smallest to largest D) To count the number of organisms in an area

Answer: ________ [2]

15. The table below shows the properties of four substances.

Substance	Boiling point (°C)	Melting point (°C)	State at room temp
W	−183	−218	Gas
X	100	0	Liquid
Y	357	−39	Liquid
Z	2800	1538	Solid

Which substance is a liquid at room temperature (25 °C)?

A) W only B) X only C) X and Y only D) W, X, and Y

Answer: ________ [2]

16. Which of the following is a man-made material?

A) Wood B) Silk C) Concrete D) Wool

Answer: ________ [2]

17. A student found an unknown organism. It has the following features:

It has six legs.
It has three body parts.
It has one pair of antennae.

This organism most likely belongs to which group?

A) Arachnids B) Crustaceans C) Insects D) Myriapods

Answer: ________ [2]

18. Which of the following materials is a good thermal insulator?

A) Copper B) Aluminium C) Steel D) Wood

Answer: ________ [2]

19. The diagram shows a simple classification key.

                    ┌── Produces seeds ──── Seed plants
            ┌───┤
            │   └── No seeds ───────── Ferns / Mosses
Start ──────┤
            │
            └───┬── Has flowers ────── Flowering plants
                │
                └── No flowers ─────── Conifers

An organism produces seeds but does not have flowers. According to the key, it is classified as a

A) fern. B) moss. C) flowering plant. D) conifer.

Answer: ________ [2]

20. Which of the following statements about biodiversity is correct?

A) Biodiversity refers only to the number of animal species in an area. B) Greater biodiversity means an ecosystem is less stable. C) Biodiversity includes the variety of living things and their habitats. D) Biodiversity is not affected by human activities.

Answer: ________ [2]

Section B: Structured Questions (50 marks)

Questions 21–30: Answer all questions in the spaces provided. Show your working where necessary.

21. The table below shows the characteristics of four organisms (A, B, C, and D).

Characteristic	Organism A	Organism B	Organism C	Organism D
Has backbone	Yes	Yes	No	No
Has feathers	No	Yes	No	No
Has moist skin	Yes	No	No	Yes
Has dry scales	No	No	Yes	No
Lives on land & water	Yes	No	Yes	Yes

(a) Identify the group to which Organism B belongs. Give one reason for your answer. [2]

(b) Which organism is most likely an insect? Give one reason for your answer. [2]

(c) Organism A is most likely a frog. State two characteristics from the table that support this. [2]

[Total: 6 marks]

22. A student was given four materials: copper, glass, rubber, and iron. She tested each material for three properties and recorded her results in the table below.

Material	Conducts electricity?	Magnetic?	Flexible?
Copper	Yes	No	Yes
Glass	No	No	No
Rubber	No	No	Yes
Iron	Yes	Yes	Yes

(a) Which material(s) would be most suitable for making the wire of an electrical cable? Explain your answer. [3]

(b) Which material would be least suitable for making a cooking pan handle? Explain your answer. [2]

(c) The student wants to sort the four materials into two groups based on whether they are natural or man-made. Complete the table below. [2]

Natural material(s)	Man-made material(s)

[Total: 7 marks]

23. The diagram below shows a classification key for five animals: P, Q, R, S, and T.

                         ┌── Has feathers ──────────────────── P
                 ┌───┤
                 │   └── No feathers ───┐
          ┌───┤                        ├── Has fins ────────── Q
          │   │                        │
          │   └── Has legs ───┐        └── No fins ────────── R
Start ────┤                  │
          │                  └── No legs ──────────────────── S
          │
          └── No legs, no fins, no feathers ──────────────── T

(a) Animal P is a parrot. State one characteristic that all animals in group P share. [1]

(b) Animal Q could be a shark. Explain why the shark is placed in group Q and not in group R. [2]

(c) Name one animal that could belong to group S. Give a reason. [2]

(d) Animal T is a jellyfish. State two characteristics of animal T shown in the key. [2]

[Total: 7 marks]

24. The bar chart below shows the number of different types of organisms found in two habitats, Forest X and Garden Y.

Organism type	Forest X	Garden Y
Birds	12	5
Insects	45	30
Mammals	8	2
Reptiles	6	1
Amphibians	4	0
Plants	80	25

(a) Which habitat has greater biodiversity? Give one reason for your answer. [2]

(b) Calculate the total number of organism types recorded in Garden Y. [1]

(c) Give one possible reason why Garden Y has fewer amphibians than Forest X. [2]

(d) A student claims: "Forest X is healthier because it has more organisms." Explain one limitation of this claim. [2]

[Total: 7 marks]

25. The table below shows the properties of five substances at room temperature (25 °C).

Substance	Melting point (°C)	Boiling point (°C)	Density (g/cm³)	Soluble in water?
A	−114	78	0.79	Yes
B	0	100	1.00	—
C	660	2470	2.70	No
D	115	445	1.97	Yes
E	1538	2800	7.87	No

(a) Which substance is water? How do you know? [2]

(b) Which substance is a solid at room temperature but dissolves in water? [1]

(c) Substance C is aluminium. Explain why aluminium is suitable for making aircraft bodies. Refer to two properties from the table. [3]

(d) Substance A is ethanol. State its state of matter at room temperature. Explain your answer. [2]

[Total: 8 marks]

26. A student was asked to classify a group of eight organisms using the following characteristics:

Presence or absence of a backbone
Method of reproduction (lays eggs / gives birth to live young)
Body covering (hair, feathers, scales, moist skin)

The results are shown below.

Organism	Backbone?	Reproduction	Body covering
W	Yes	Lays eggs	Feathers
X	Yes	Lays eggs	Scales
Y	Yes	Gives birth	Hair
Z	Yes	Lays eggs	Scales
P	No	Lays eggs	Moist skin
Q	No	Lays eggs	Dry scales
R	No	Lays eggs	Moist skin
S	No	Lays eggs	No covering

(a) How many organisms in the table are vertebrates? [1]

(b) Organisms P and R are both amphibians. State one characteristic from the table that supports this. [1]

(c) Organism Y is a dolphin. Explain why a dolphin is classified as a mammal and not a fish, using two pieces of evidence from the table. [3]

(d) Organism S is a jellyfish. State two characteristics from the table that show it is very different from the vertebrates. [2]

[Total: 7 marks]

27. The diagram shows a simple food chain in a pond ecosystem.

Algae → Water flea → Small fish → Large fish → Heron

(a) Which organism in the food chain is the producer? [1]

(b) Explain why the water flea is classified as a consumer. [2]

(c) If the number of algae decreased greatly, explain what would happen to the large fish population. Give two reasons. [3]

(d) The heron is a bird. State two characteristics of birds that help them survive in this ecosystem. [2]

[Total: 8 marks]

28. A student grouped a set of materials as shown below.

Group 1: Cotton, wool, silk, linen Group 2: Nylon, polyester, acrylic, PVC

(a) What property did the student use to classify the materials? [1]

(b) State one advantage of using materials from Group 1 over Group 2. [2]

(c) State one advantage of using materials from Group 2 over Group 1. [2]

(d) A shirt is made from a blend of cotton and polyester. Explain why a blend might be used instead of pure cotton. Give one reason. [2]

[Total: 7 marks]

29. The table below shows the adaptations of four organisms to their habitats.

Organism	Habitat	Adaptation
A	Desert	Stores water in its stem
B	Arctic	Has a thick layer of blubber
C	Rainforest	Has broad leaves
D	Pond	Has gills for breathing underwater

(a) Organism A is a cactus. Explain how the adaptation helps it survive in the desert. [2]

(b) Organism B is a seal. Explain how blubber helps it survive in the Arctic. [2]

(c) Organism C is a tropical plant. Explain how broad leaves help it survive in the rainforest. [2]

(d) Organism D is a fish. Name one other adaptation a fish has for living in water. [1]

[Total: 7 marks]

30. The diagram shows a classification of living and non-living things found in a garden.

                        ┌── Living ───┐
                        │             │
                        │  ┌── Can move on its own ── Animals
                        │  │
                        │  └── Cannot move on its own ── Plants
                        │
All things in garden ───┤
                        │
                        └── Non-living ───┐
                                          │
                                          ├── Natural (e.g., rocks, soil, water)
                                          │
                                          └── Man-made (e.g., bench, fence)

(a) Name one thing in the garden that would be classified as a natural non-living thing. [1]

(b) Name one thing in the garden that would be classified as a man-made non-living thing. [1]

(c) A student says: "A plant is non-living because it cannot move on its own." Explain why this statement is incorrect. Give two characteristics of living things that plants have. [3]

(d) Explain why it is important for scientists to classify living and non-living things. [2]

[Total: 7 marks]

Section C: Free-Response Questions (30 marks)

Questions 31–35: Answer all questions in the spaces provided. Use complete sentences where appropriate. Marks are awarded for scientific accuracy, clarity, and use of evidence.

31. A scientist discovered a new organism in a cave. The organism has the following characteristics:

It has no backbone.
It has eight legs.
It has two body parts.
It produces silk.
It has no antennae.

(a) To which group of animals does this organism most likely belong? Give two characteristics to support your answer. [3]

(b) The scientist wants to classify this organism using a dichotomous key. Complete the key below by filling in the blanks (i) and (ii). [2]

1a. Has backbone ................................................ Go to 2
1b. No backbone ................................................. Go to 3

2a. Has feathers ............................................... Bird
2b. No feathers ............................................... Mammal

3a. Has six legs ............................................... Insect
3b. (i) ........................................................ Go to 4

4a. Has eight legs ............................................. (ii)
4b. Has more than eight legs .................................. Myriapod

(c) Explain why this organism is not an insect. [2]

[Total: 7 marks]

32. The table below shows the properties of six materials.

Material	Density (g/cm³)	Conducts electricity?	Melting point (°C)	Natural or Man-made?
W	0.92	No	115	Natural
X	2.70	Yes	660	Natural
Y	1.38	No	200	Man-made
Z	7.87	Yes	1538	Natural
P	0.001	No	−259	Natural
Q	1.05	No	160	Man-made

(a) Which material is most likely polythene (a type of plastic)? Give two properties to support your answer. [3]

(b) Material X is aluminium. Explain why aluminium is used to make overhead power cables. Refer to two properties from the table. [3]

(c) Material P is hydrogen gas. Explain why hydrogen gas has a very low density. Use the particle model in your answer. [2]

[Total: 8 marks]

33. Read the following passage and answer the questions that follow.

Mangrove forests are found along tropical coastlines. They are home to a wide variety of organisms, including mudskippers, crabs, herons, monitor lizards, and various species of fish and insects. The mangrove trees have special roots that grow above the water surface, allowing the trees to breathe in the waterlogged soil. The roots also trap soil and reduce coastal erosion. However, in recent years, many mangrove forests have been cleared to make way for housing and aquaculture farms.

(a) The passage mentions mudskippers, crabs, herons, monitor lizards, fish, and insects. Classify these organisms into two groups: vertebrates and invertebrates. [3]

Vertebrates	Invertebrates

(b) Explain how the special roots of mangrove trees are an adaptation to their environment. [2]

(c) Mangrove forests support a high biodiversity. Explain two reasons why it is important to conserve mangrove forests. [3]

(d) State one way in which human activities have negatively affected the mangrove ecosystem. [1]

[Total: 9 marks]

34. A student conducted an experiment to test the strength of four different materials. She hung equal weights from strips of each material and measured how much each strip stretched. The results are shown below.

Material	Amount of stretch (cm)
Rubber	8.5
Nylon	2.0
Cotton	3.5
Steel	0.1

(a) Which material is the strongest? Explain your answer. [2]

(b) The student wants to make a bungee cord. Which material should she choose? Explain why. [2]

(c) Explain why steel is used to build bridges. Refer to the results and one other property of steel. [3]

(d) State one limitation of this experiment. Suggest how the student could improve it. [2]

[Total: 9 marks]

35. The diagram shows a food web in a grassland ecosystem.

         ┌──────────────────────────────────┐
         │                                  │
         ▼                                  ▼
      Grass ──→ Grasshopper ──→ Frog ──→ Snake
        │                          ▲
        │                          │
        └──→ Rabbit ──────────────┘
                  │
                  ▼
                Hawk

(a) Identify two consumers in the food web. [2]

(b) Which organism is both a predator and prey? Explain your answer. [2]

(c) If a disease killed all the grasshoppers, explain what would happen to the frog population and the grass population. [3]

(d) Explain why the grass is essential to this food web. [2]

[Total: 9 marks]

END OF PAPER

This practice paper was generated by TuitionGoWhere (AI) for educational purposes. It is aligned with the MOE Primary Science syllabus and is not derived from any actual PSLE or school examination paper.

Answers

TuitionGoWhere Practice Paper — Science Primary 6 PSLE

Answer Key — Version 4 of 5

Subject: Science (Primary 6, PSLE) Paper: Practice Paper — Diversity (Topic Focus) Total Marks: 100

Section A: Multiple Choice Questions (20 marks)

1. C — Presence of a backbone

Reasoning: Classification of living things is based on shared structural characteristics. The presence or absence of a backbone (vertebral column) is a key characteristic used to divide animals into vertebrates and invertebrates. Colour, size, and number of legs are not reliable classification criteria because they can vary widely within a group. [2]

2. B — X

Reasoning: A fish is a vertebrate (has a backbone) and has scales but does not have feathers. Organism X matches these characteristics. Organism W is a bird (has feathers). Organisms Y and Z lack backbones. [2]

3. C — River

Reasoning: A river is a body of water and is non-living. Mushrooms (fungi), coral (animals), and moss (plants) are all living organisms. [2]

4. C — Whether they are electrical conductors or insulators

Reasoning: Group 1 (wood, plastic, rubber) are all electrical insulators. Group 2 (copper, iron, aluminium) are all electrical conductors (metals). This is the most consistent property that separates the two groups. [2]

5. B — Kingdom → Phylum → Class → Order → Family → Genus → Species

Reasoning: The standard biological classification hierarchy proceeds from the broadest (largest) group, Kingdom, down to the most specific (smallest) group, Species. [2]

6. C — Animal with no feathers and fins

Reasoning: Following the key: Start → Has feathers? No → Has fins? Yes → Fish. An animal with no feathers and fins is classified as a fish. [2]

7. C — They can reproduce

Reasoning: All living things carry out life processes, which include reproduction, respiration, nutrition, excretion, growth, and response to stimuli. Flying, photosynthesis, and having legs are not universal characteristics of all living things. [2]

8. D — None of the above

Reasoning: A density greater than 1.0 g/cm³ but less than 1.3 g/cm³ is required. P = 0.6 (less than 1.0), Q = 1.0 (not greater than 1.0), R = 1.5 (greater than 1.3). None of the materials meet the criteria. [2]

9. B — Flexibility

Reasoning: Group A (glass marble, metal coin, ceramic tile) are all hard and rigid (not flexible). Group B (cotton cloth, tissue paper, sponge) are all soft and flexible. Hardness is also plausible, but flexibility is the most consistent distinguishing property across all six items. [2]

10. C — Cotton fabric

Reasoning: Cotton is a natural fibre obtained from the cotton plant. Nylon rope and plastic bottles are synthetic (man-made). Rubber tyres are typically made from synthetic rubber (man-made), though natural rubber exists. Cotton fabric is the clearest example of a natural material. [2]

11. B — Steel

Reasoning: Steel is an alloy of iron and carbon. It conducts electricity (like all metals) and is magnetic (because it contains iron). Copper and aluminium conduct electricity but are not magnetic. Nickel is magnetic but the overlap region requires both properties. Steel fits both criteria. [2]

12. B — Eagle, lizard, dolphin

Reasoning: Eagles (birds), lizards (reptiles), and dolphins (mammals) are all vertebrates. Option A includes an ant (invertebrate). Option C contains only invertebrates. Option D contains only invertebrates. [2]

13. D — Dicotyledon

Reasoning: Flowering plants with broad leaves and network (reticulate) veins are dicotyledons. Monocotyledons have parallel veins. Ferns and mosses do not produce flowers or seeds. [2]

14. B — To make it easier to study and understand the diversity of life

Reasoning: Classification helps scientists organise the vast diversity of life into manageable groups based on shared characteristics, making it easier to study, identify, and understand relationships between organisms. [2]

15. C — X and Y only

Reasoning: A substance is a liquid at room temperature (25 °C) if its melting point is below 25 °C and its boiling point is above 25 °C. Substance X: melts at 0 °C, boils at 100 °C → liquid. Substance Y: melts at −39 °C, boils at 357 °C → liquid. Substance W is a gas (boiling point −183 °C). Substance Z is a solid (melting point 1538 °C). [2]

16. C — Concrete

Reasoning: Concrete is manufactured by mixing cement, water, sand, and gravel. It does not occur naturally. Wood, silk, and wool are natural materials obtained from plants or animals. [2]

17. C — Insects

Reasoning: Insects are characterised by having six legs, three body parts (head, thorax, abdomen), and one pair of antennae. Arachnids have eight legs. Crustaceans have more than six legs. Myriapods have many legs. [2]

18. D — Wood

Reasoning: Wood is a poor conductor of heat (good thermal insulator). Copper, aluminium, and steel are all metals and are good thermal conductors. [2]

19. D — Conifer

Reasoning: Following the key: produces seeds → yes; has flowers → no → conifer. Ferns and mosses do not produce seeds. Flowering plants have flowers. [2]

20. C — Biodiversity includes the variety of living things and their habitats.

Reasoning: Biodiversity refers to the variety of living organisms (plants, animals, microorganisms) and the ecosystems/habitats they inhabit. It is not limited to animals (A is wrong). Greater biodiversity generally means a more stable ecosystem (B is wrong). Human activities do affect biodiversity (D is wrong). [2]

Section B: Structured Questions (50 marks)

21.

(a) Organism B is a bird. [1] It has feathers [1] and a backbone, which are characteristics of birds. [2]

(b) Organism D is most likely an insect. [1] It has no backbone (invertebrates), and insects are invertebrates. (Note: Organisms C and D are both invertebrates; D is the better answer as it has moist skin, which could suggest a soft-bodied invertebrate, but the key point is that it lacks a backbone.) [2]

Marking note: Accept Organism C or D with a valid reason (no backbone = invertebrate). Full marks for identifying an invertebrate organism with a correct explanation.

(c) Two characteristics supporting that Organism A is a frog:

It has a backbone (frogs are vertebrates/amphibians). [1]
It has moist skin (amphibians have moist, permeable skin). [1]
It lives on land and water (amphibians are adapted to both habitats). [1]

Accept any two of the above. [2]

[Total: 6 marks]

22.

(a) Copper would be most suitable for making the wire of an electrical cable. [1] Copper conducts electricity [1] and is flexible, so it can be drawn into thin wires. [1] [3]

(b) Copper (or iron) would be least suitable for making a cooking pan handle. [1] Copper conducts electricity and is a good thermal conductor, meaning it would become very hot and burn the user's hand. (The question asks about a pan handle, so thermal conductivity is the relevant property. Copper and iron are good thermal conductors.) [2]

Marking note: Accept copper or iron. Award 1 mark for identifying the material, 1 mark for explaining that it conducts heat well / would become hot.

(c)

Natural material(s)	Man-made material(s)
Copper, Iron	Glass, Rubber

[2] — 1 mark for each column correctly completed.

Marking note: Copper and iron are natural (mined from the earth as ores). Glass is man-made (manufactured by heating sand). Rubber can be natural or synthetic; in this context, rubber is treated as man-made. Accept reasonable alternatives with justification.

[Total: 7 marks]

23.

(a) All animals in group P have feathers. [1]

(b) The shark is placed in group Q because it has no feathers [1] and has fins. [1] It is not in group R because the shark has fins, whereas group R animals do not have fins. [2]

(c) A snake could belong to group S. [1] A snake has no legs, no fins, and no feathers. [1] (Accept any valid animal, e.g., worm, eel, snake.)

(d) Two characteristics of animal T (jellyfish) from the key:

It has no legs. [1]
It has no fins. [1]
It has no feathers. [1]

Accept any two. [2]

[Total: 7 marks]

24.

(a) Forest X has greater biodiversity. [1] Forest X has more types of organisms (6 types) and a greater number of individuals across most organism types compared to Garden Y. [1] [2]

Marking note: Accept any valid reason, e.g., "Forest X has more species" or "Forest X has organisms from more groups."

(b) Total number of organism types in Garden Y = 5 + 30 + 2 + 1 + 0 + 25 = 63 [1]

Marking note: The question asks for the total number of organism types recorded. If interpreted as "number of categories," the answer is 5 (amphibians = 0, so 5 types present). If interpreted as total count, it is 63. Award the mark for 63 (total organisms counted). Clarification: The table shows counts, not types. The total count is 63.

(c) Garden Y has fewer amphibians because:

Garden Y may lack a water source (pond, stream) that amphibians need. [1]
Garden Y may have less moisture/humidity, which amphibians require for their moist skin. [1]
Garden Y may have more predators or less shelter for amphibians. [1]

*Accept any one valid reason. [2]

(d) One limitation: The number of organisms does not necessarily indicate the health of an ecosystem. [1] A habitat could have many organisms but be polluted or unbalanced (e.g., an overpopulation of one species could indicate a lack of predators). [1] Health depends on the balance and diversity of species, not just the total number. [2]

[Total: 7 marks]

25.

(a) Substance B is water. [1] Its melting point is 0 °C and boiling point is 100 °C, which are the known melting and boiling points of water. [1] [2]

(b) Substance D is a solid at room temperature (melting point 115 °C > 25 °C) and dissolves in water. [1]

Marking note: Substance D has a melting point of 115 °C, so it is solid at 25 °C, and it is soluble in water.

(c) Aluminium is suitable for making aircraft bodies because:

It has a low density (2.70 g/cm³), making the aircraft lightweight. [1]
It has a high melting point (660 °C), so it remains solid at high temperatures. [1]
It is a metal, so it is strong and durable. [1] [3]

Marking note: Award marks for any two relevant properties from the table with correct explanation.

(d) Ethanol (Substance A) is a liquid at room temperature. [1] Its melting point is −114 °C (below 25 °C) and its boiling point is 78 °C (above 25 °C), so it exists as a liquid at 25 °C. [1] [2]

[Total: 8 marks]

26.

(a) 4 organisms are vertebrates (W, X, Y, Z). [1]

(b) Organisms P and R both have moist skin and no backbone, which are characteristics of amphibians. [1]

Marking note: Accept "moist skin" or "no backbone" or "lays eggs."

(c) A dolphin is classified as a mammal because:

It gives birth to live young (does not lay eggs). [1]
It has hair (body covering is hair). [1]
It has a backbone (is a vertebrate). [1]

Fish lay eggs and have scales. The dolphin gives birth to live young and has hair, which are mammalian characteristics. [3]

(d) Two characteristics showing the jellyfish (S) is different from vertebrates:

It has no backbone. [1]
It has no body covering (no hair, feathers, or scales). [1] [2]

Marking note: Accept "lays eggs" as an additional difference, but the key differences are no backbone and no body covering.

[Total: 7 marks]

27.

(a) Algae is the producer. [1]

(b) The water flea is a consumer because it feeds on other organisms (algae) for food and cannot make its own food. [2]

Marking note: 1 mark for identifying it as a consumer, 1 mark for explaining that it feeds on other organisms / cannot photosynthesise.

(c) If algae decreased greatly:

The water flea population would decrease because it feeds on algae (less food available). [1]
The small fish population would decrease because there are fewer water fleas to eat. [1]
The large fish population would decrease because there are fewer small fish to eat. [1]

The large fish population would decline due to a reduction in food availability throughout the food chain. [3]

(d) Two characteristics of birds that help them survive:

Feathers for flight and insulation. [1]
Beaks adapted for feeding. [1]
Wings for flying to find food/escape predators. [1]
Lightweight bones for flight. [1]

Accept any two valid characteristics. [2]

[Total: 8 marks]

28.

(a) The student classified the materials by whether they are natural or man-made (synthetic). [1]

(b) One advantage of Group 1 (natural materials):

They are biodegradable and better for the environment. [1]
They are breathable and comfortable to wear. [1]
They are renewable resources. [1]

*Accept any one valid advantage. [2]

Marking note: 1 mark for the advantage, 1 mark for a brief explanation.

(c) One advantage of Group 2 (man-made materials):

They are more durable and last longer. [1]
They are cheaper to produce in large quantities. [1]
They are water-resistant or wrinkle-resistant. [1]

Accept any one valid advantage. [2]

(d) A cotton-polyester blend is used because:

Polyester adds strength and durability to the fabric. [1]
The blend is less likely to wrinkle compared to pure cotton. [1]
It is more affordable and easier to care for. [1]

Accept any one valid reason with explanation. [2]

[Total: 7 marks]

29.

(a) The cactus stores water in its stem, which allows it to survive long periods without rainfall in the desert where water is scarce. [2]

Marking note: 1 mark for identifying the function (stores water), 1 mark for linking it to the desert environment.

(b) The thick layer of blubber insulates the seal, keeping it warm in the freezing Arctic temperatures. [2]

Marking note: 1 mark for insulation, 1 mark for linking to the Arctic environment.

(c) Broad leaves have a large surface area, which allows the plant to absorb more sunlight for photosynthesis in the shaded rainforest. [2]

Marking note: 1 mark for large surface area, 1 mark for absorbing more sunlight / photosynthesis.

(d) One other adaptation of a fish for living in water:

Streamlined body shape to reduce water resistance when swimming. [1]
Fins for swimming and balance. [1]
Scales to protect the body. [1]

*Accept any one valid adaptation. *[1]

[Total: 7 marks]

30.

(a) One natural non-living thing: rock / soil / water / sand. [1]

(b) One man-made non-living thing: bench / fence / path / pot / tool. [1]

(c) The statement is incorrect because plants are living things. Two characteristics of living things that plants have:

Plants can reproduce (produce seeds, fruits). [1]
Plants can photosynthesise (make their own food). [1]
Plants grow and respond to stimuli (e.g., grow towards light). [1]

*Accept any two valid characteristics. *[3] Marking note: 1 mark for stating the statement is incorrect, 1 mark each for two valid characteristics.

(d) It is important for scientists to classify living and non-living things because:

It helps organise and understand the natural world. [1]
It makes it easier to study and identify different things. [1]
It helps us understand relationships between different things. [1]

*Accept any two valid reasons. *[2]

[Total: 7 marks]

Section C: Free-Response Questions (30 marks)

31.

(a) The organism most likely belongs to the group arachnids (or spiders). [1] Two supporting characteristics:

It has eight legs (arachnids have eight legs; insects have six). [1]
It has two body parts (cephalothorax and abdomen; insects have three). [1]
It produces silk (a characteristic of spiders). [1]
It has no antennae (arachnids lack antennae). [1]

Award 1 mark for the group, 1 mark each for two valid characteristics. [3]

(b)

(i) Has more than six legs / Has eight legs / Does not have six legs [1]
(ii) Arachnid (or Spider) [1] [2]

Marking note: For (i), accept any characteristic that distinguishes insects (six legs) from arachnids (eight legs). For (ii), accept "Arachnid" or "Spider."

(c) This organism is not an insect because:

Insects have six legs, but this organism has eight legs. [1]
Insects have three body parts, but this organism has two body parts. [1]
Insects have antennae, but this organism has no antennae. [1]

Award 1 mark for each correct difference, up to 2 marks. [2]

[Total: 7 marks]

32.

(a) Material Y is most likely polythene. [1] Two supporting properties:

It has a low density (1.38 g/cm³), which is typical of plastics/polythene. [1]
It does not conduct electricity, which is a property of plastics. [1]
It has a relatively low melting point (200 °C), typical of thermoplastics. [1]
It is man-made, which is consistent with polythene being a synthetic polymer. [1]

Marking note: Award 1 mark for identifying Y, 1 mark each for two valid properties. Accept Q as an alternative with valid reasoning. [3]

(b) Aluminium is used for overhead power cables because:

It conducts electricity well, allowing efficient transmission of electrical energy. [1]
It has a low density (2.70 g/cm³), making it lightweight and reducing the load on support structures. [1]
It is a metal, so it is ductile and can be drawn into wires. [1] [3]

Marking note: Award 1 mark for each valid property with explanation, up to 3 marks.

(c) Hydrogen gas has a very low density because:

The particles in a gas are far apart from each other. [1]
Hydrogen is the lightest element, with the smallest mass per particle, so a given volume has very little mass. [1]
The particles are spread out over a large volume, resulting in very little mass per unit volume. [1]

Award up to 2 marks for a clear explanation using the particle model. [2]

[Total: 8 marks]

33.

(a)

Vertebrates	Invertebrates
Mudskipper (fish)	Crab
Heron (bird)	Insect
Monitor lizard (reptile)
Fish

[3] — 1 mark for each row correctly filled (3 rows × 1 mark = 3 marks).

Marking note: Mudskipper, heron, monitor lizard, and fish are vertebrates. Crab and insect are invertebrates. Award marks for correct classification.

(b) The special roots (aerial/prop roots) of mangrove trees grow above the waterlogged soil, allowing the trees to obtain oxygen for respiration. [1] In waterlogged soil, there is very little air, so the roots that grow above the surface can absorb oxygen directly from the air. [1] [2]

(c) Two reasons to conserve mangrove forests:

Mangroves support high biodiversity, providing habitats for many species of organisms. [1]
Mangrove roots reduce coastal erosion by trapping soil and stabilising the shoreline. [1]
Mangroves act as nurseries for fish and other marine life, supporting fisheries. [1]
Mangroves absorb carbon dioxide and help mitigate climate change. [1]

Accept any two valid reasons. [3]

(d) One negative human impact: Clearing mangrove forests for housing and aquaculture farms, which destroys habitats and reduces biodiversity. [1]

[Total: 9 marks]

34.

(a) Steel is the strongest material. [1] It stretched the least (only 0.1 cm) when the same weight was applied, indicating it has the greatest resistance to deformation. [1] [2]

(b) The student should choose rubber for a bungee cord. [1] Rubber stretched the most (8.5 cm), showing it is highly elastic and can stretch and return to its original shape, which is essential for a bungee cord. [1] [2]

Marking note: Award 1 mark for choosing rubber, 1 mark for explaining elasticity.

(c) Steel is used to build bridges because:

It is very strong (stretched only 0.1 cm in the test), so it can support heavy loads without deforming. [1]
It has a high melting point (1538 °C), so it remains solid under extreme conditions. [1]
It is durable and can withstand weathering and heavy use over long periods. [1] [3]

Marking note: Award 1 mark for strength (referring to results), 1 mark for high melting point, 1 mark for durability or another valid property.

(d) One limitation: The experiment only tested one weight/size of each material, so the results may not be generalisable. [1] Improvement: Test multiple weights and use strips of the same dimensions (length, width, thickness) for a fair comparison. [1] [2]

Marking note: Accept any valid limitation (e.g., only one trial, strips may have different thicknesses) and a corresponding improvement.

[Total: 9 marks]

35.

(a) Two consumers: Grasshopper and Frog (or Rabbit, Snake, Hawk). [2] — 1 mark each.

Marking note: Any two consumers from the food web. The grass is the producer, so it is not a consumer.

(b) The frog is both a predator and prey. [1] It is a predator because it eats grasshoppers, and it is prey because it is eaten by snakes. [1] [2]

Marking note: Accept rabbit (eaten by hawk, eats grass) or snake (eaten by hawk, eats frog) with valid explanation.

(c) If all grasshoppers were killed:

The frog population would decrease because grasshoppers are a food source for frogs. [1]
The grass population would increase because there would be fewer grasshoppers feeding on the grass. [1]
The snake population might also decrease due to fewer frogs to eat. [1] [3]

Marking note: Award 1 mark for each correct consequence with explanation.

(d) Grass is essential to this food web because:

It is the producer, making food (glucose) through photosynthesis. [1]
It is the primary source of energy for all other organisms in the food web (directly or indirectly). [1]
Without grass, the consumers (grasshopper, rabbit, frog, snake, hawk) would have no food source. [1]

Award up to 2 marks for a clear explanation. [2]

[Total: 9 marks]

Mark Summary

Section	Marks
A: Multiple Choice (Q1–20)	20
B: Structured (Q21–30)	50
C: Free Response (Q31–35)	30
Total	100

This answer key was generated by TuitionGoWhere (AI) for educational purposes. It is aligned with the MOE Primary Science syllabus and is not derived from any actual PSLE or school examination paper.