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Primary 6 PSLE Science Semestral Assessment 2 (End of Year) Paper 3
Free P6 PSLE Science SA2 Paper 3, Nemo3 Exam version, with questions, answers, and PSLE-focused practice for Singapore students.
These static practice materials are generated from the site's syllabus and paper-generation workflow, with source and model context shown so students and parents can evaluate the material before use.
Questions
TuitionGoWhere Practice Paper - Science Primary 6 PSLE
TuitionGoWhere Exam Practice (AI)
Subject: Science
Level: Primary 6 PSLE
Paper: SA2 Version 3
Duration: 1 h 45 min
Total Marks: 100
Name: ________________________
Class: Primary 6 ________
Date: ________________________
INSTRUCTIONS TO CANDIDATES
- Do not open this booklet until you are told to do so.
- Follow all instructions carefully.
- Answer all questions.
- The total marks for this paper is 100.
- Booklet A (Questions 1–28): 56 marks
Booklet B (Questions 29–44): 44 marks - For Booklet A, shade your answers on the Optical Answer Sheet (OAS) provided.
- For Booklet B, write your answers in the spaces provided in this booklet.
BOOKLET A (56 marks)
Questions 1 to 28 carry 2 marks each. For each question, four options are given. Choose the correct answer and shade the correct oval (1, 2, 3 or 4) on the Optical Answer Sheet.
1
Which of the following groups of living things are all classified as fungi?
(1) Mould, yeast, mushroom
(2) Fern, moss, mushroom
(3) Bacteria, virus, mould
(4) Algae, yeast, bacteria
2
Study the classification chart below.
Generated diagram for Q2.
Which of the following correctly describes how the organisms in Group X and Group Y obtain food?
| Group X | Group Y | |
|---|---|---|
| (1) | Make their own food | Feed on dead or living organisms |
| (2) | Feed on dead or living organisms | Make their own food |
| (3) | Feed on dead or living organisms | Feed on dead or living organisms |
| (4) | Make their own food | Make their own food |
3
Which of the following statements about microorganisms is correct?
(1) All microorganisms are harmful to humans.
(2) All microorganisms can be seen with the naked eye.
(3) Some microorganisms are useful in food production.
(4) Microorganisms do not need air, water, or food to survive.
4
The diagram below shows a plant cell and an animal cell.
Generated diagram for Q4.
Which part is present in the plant cell but absent in the animal cell?
(1) Nucleus
(2) Cytoplasm
(3) Cell wall
(4) Cell membrane
5
Four students made the following statements about bacteria.
| Student | Statement |
|---|---|
| Ali | Bacteria are plants because they have cell walls. |
| Bala | Bacteria are animals because they can move. |
| Cindy | Bacteria are fungi because they reproduce by spores. |
| Devi | Bacteria are microorganisms that are neither plants nor animals. |
Whose statement is correct?
(1) Ali
(2) Bala
(3) Cindy
(4) Devi
6
The table below shows the characteristics of four organisms, P, Q, R, and S. A tick (✓) indicates the presence of the characteristic.
| Characteristic | P | Q | R | S |
|---|---|---|---|---|
| Has cell wall | ✓ | ✓ | ✓ | ✗ |
| Has chloroplasts | ✓ | ✗ | ✗ | ✗ |
| Reproduces by spores | ✗ | ✓ | ✓ | ✗ |
| Feeds on decaying matter | ✗ | ✓ | ✓ | ✗ |
Which organism is most likely a flowering plant?
(1) P
(2) Q
(3) R
(4) S
7
Which of the following is not a characteristic of all living things?
(1) They need air, food, and water.
(2) They can reproduce.
(3) They can move from place to place.
(4) They respond to changes around them.
8
Study the flowchart below.
Generated diagram for Q8.
An organism does not make its own food, feeds on dead and decaying matter, and reproduces by spores. Which group does it belong to?
(1) Flowering plant
(2) Non-flowering plant
(3) Fungi
(4) Bacteria
9
Which of the following groups contains only vertebrates?
(1) Frog, snake, earthworm
(2) Bird, fish, mammal
(3) Insect, spider, crab
(4) Snail, jellyfish, starfish
10
The diagram below shows an animal.
Generated diagram for Q10.
Based on the observable features, which animal group does it belong to?
(1) Mammals
(2) Birds
(3) Reptiles
(4) Amphibians
11
Which of the following statements about the classification of animals is correct?
(1) All animals with wings are birds.
(2) All animals that lay eggs are reptiles.
(3) Mammals feed their young with milk.
(4) Amphibians have dry, scaly skin.
12
Study the table below.
| Animal | Body Covering | Breathing Method | Reproduction |
|---|---|---|---|
| W | Scales | Lungs | Lays eggs |
| X | Moist skin | Gills (young), Lungs (adult) | Lays eggs in water |
| Y | Feathers | Lungs | Lays eggs |
| Z | Hair/Fur | Lungs | Gives birth to live young |
Which animal is a mammal?
(1) W
(2) X
(3) Y
(4) Z
13
The diagram below shows three types of microorganisms viewed under a microscope.
Generated diagram for Q13.
Which of the following correctly identifies the microorganisms?
| View A | View B | View C | |
|---|---|---|---|
| (1) | Bacteria | Yeast | Mould |
| (2) | Yeast | Mould | Bacteria |
| (3) | Mould | Bacteria | Yeast |
| (4) | Bacteria | Mould | Yeast |
14
Which of the following is a useful microorganism?
(1) Salmonella bacteria causing food poisoning
(2) Yeast used in bread making
(3) Virus causing the common cold
(4) Mould growing on spoiled food
15
The diagram below shows a food relationship.
Image pending generation: diagram for Q15.
Which organism is both a predator and a prey?
(1) Grass
(2) Grasshopper
(3) Frog
(4) Eagle
16
Which of the following shows the correct order in a food chain?
(1) Producer → Decomposer → Consumer
(2) Consumer → Producer → Decomposer
(3) Producer → Consumer → Decomposer
(4) Decomposer → Producer → Consumer
17
Study the food web below.
Generated diagram for Q17.
If the population of grasshoppers decreases significantly, which of the following is most likely to happen?
(1) The population of plants will decrease.
(2) The population of frogs will increase.
(3) The population of mice will decrease.
(4) The population of snakes may decrease.
18
Which of the following best describes the role of decomposers in an ecosystem?
(1) They make their own food using sunlight.
(2) They feed on living plants and animals.
(3) They break down dead organisms and waste, returning nutrients to the environment.
(4) They hunt and eat other animals.
19
The diagram below shows a plant.
Generated diagram for Q19.
Based on the features shown, this plant is a:
(1) Non-flowering plant
(2) Monocotyledon
(3) Dicotyledon
(4) Fungus
20
Which of the following adaptations helps a water lily survive in its aquatic habitat?
(1) Deep roots to absorb water
(2) Broad, flat leaves that float on water
(3) Thick, waxy leaves to reduce water loss
(4) Spines instead of leaves to reduce water loss
21
The diagram below shows the life cycle of a mosquito.
Generated diagram for Q21.
At which stage(s) does the mosquito live in water?
(1) Egg only
(2) Larva and pupa only
(3) Egg, larva, and pupa
(4) All four stages
22
Which of the following is not a method of seed dispersal?
(1) By wind
(2) By water
(3) By animals
(4) By photosynthesis
23
The diagram below shows a fruit.
Generated diagram for Q23.
How is the seed of this fruit most likely dispersed?
(1) By wind
(2) By water
(3) By splitting action (explosive dispersal)
(4) By animals
24
Which of the following statements about the human digestive system is correct?
(1) Digestion starts in the stomach.
(2) The small intestine absorbs water from undigested food.
(3) The large intestine absorbs digested nutrients into the blood.
(4) Digestion of food is completed in the small intestine.
25
The diagram below shows the human respiratory system.
Generated diagram for Q25.
Where does gaseous exchange take place?
(1) Trachea
(2) Bronchi
(3) Alveoli
(4) Nose
26
Which of the following shows the correct path of air during inhalation?
(1) Nose → Trachea → Bronchi → Bronchioles → Alveoli
(2) Nose → Bronchi → Trachea → Bronchioles → Alveoli
(3) Nose → Trachea → Bronchioles → Bronchi → Alveoli
(4) Nose → Alveoli → Bronchioles → Bronchi → Trachea
27
The table below shows the composition of inhaled and exhaled air.
| Gas | Inhaled Air (%) | Exhaled Air (%) |
|---|---|---|
| Oxygen | 21 | 16 |
| Carbon Dioxide | 0.04 | 4 |
| Nitrogen | 78 | 78 |
| Water Vapour | Variable | Higher |
Which statement correctly explains the difference?
(1) The body uses oxygen and produces carbon dioxide during respiration.
(2) The body uses carbon dioxide and produces oxygen during respiration.
(3) Nitrogen is used by the body for respiration.
(4) Water vapour is removed from the body during respiration.
28
Which of the following activities increases the rate of heartbeat the most?
(1) Sleeping
(2) Reading a book
(3) Running
(4) Sitting quietly
BOOKLET B (44 marks)
Questions 29 to 44 carry 2 to 4 marks each. Write your answers in the spaces provided.
29
The diagram below shows two organisms, A and B.
Generated diagram for Q29.
(a) State one similarity between Organism A and Organism B. [1]
(b) State one difference between Organism A and Organism B. [1]
(c) Which group of living things does Organism A belong to? [1]
30
The flowchart below shows the classification of some plants.
Generated diagram for Q30.
(a) Based on the flowchart, state the two main groups of plants. [1]
(b) Plant X reproduces by spores and does not bear flowers. Which group does Plant X belong to? [1]
(c) Give an example of a gymnosperm. [1]
31
The diagram below shows a food web in a garden community.
Generated diagram for Q31.
(a) Name two food chains from the food web, each with at least three organisms. [2]
Food chain 1: ________________________________________________________________
Food chain 2: ________________________________________________________________
(b) If a disease kills all the ladybirds, explain what will happen to the population of aphids. [2]
32
The diagram below shows a cell.
Generated diagram for Q32.
(a) Is this a plant cell or an animal cell? [1]
(b) Name the part that controls all activities in the cell. [1]
(c) State the function of the chloroplasts. [1]
(d) The diagram does not show mitochondria. Does this mean the cell has no mitochondria? Explain. [1]
33
Study the table below showing the characteristics of four organisms.
| Organism | Nucleus | Cell Wall | Chloroplasts | Mode of Nutrition |
|---|---|---|---|---|
| W | Yes | Yes (cellulose) | Yes | Autotrophic |
| X | Yes | Yes (chitin) | No | Saprotrophic |
| Y | No | Yes (peptidoglycan) | No | Heterotrophic |
| Z | Yes | No | No | Heterotrophic |
(a) Which organism is a bacterium? [1]
(b) Which organism is a fungus? [1]
(c) Which organism is a plant? [1]
(d) Which organism is an animal? [1]
34
The diagram below shows the life cycle of a flowering plant.
Generated diagram for Q34.
(a) Name the process where pollen grains are transferred from the anther to the stigma. [1]
(b) After pollination, the pollen tube grows down the style to the ovary. What happens during fertilisation? [1]
(c) The ovary develops into the fruit. What does the ovule develop into? [1]
(d) State one way in which the fruit shown below is dispersed.
Generated diagram for Q34.
35
The diagram below shows a human circulatory system.
Generated diagram for Q35.
(a) Name the blood vessel that carries oxygenated blood from the lungs to the heart. [1]
(b) In which chamber of the heart does deoxygenated blood enter first? [1]
(c) Explain why the walls of the left ventricle are thicker than the walls of the right ventricle. [2]
36
An experiment was set up to investigate the conditions needed for seed germination. Four set-ups were prepared as shown.
Generated experimental_setup for Q36.
(a) Which two set-ups should be compared to show that water is needed for germination? [1]
(b) Which two set-ups should be compared to show that a suitable temperature is needed for germination? [1]
(c) What is the purpose of Set-up D? [1]
(d) In Set-up A, the seeds germinated after 3 days. State the process that provides energy for the seedling to grow before it develops leaves. [1]
37
The diagram below shows a cross-section of a leaf.
Generated diagram for Q37.
(a) Name the part labelled X (palisade mesophyll). [1]
(b) State the function of the stomata. [1]
(c) Explain why the palisade mesophyll cells contain more chloroplasts than the spongy mesophyll cells. [2]
38
The table below shows the number of different organisms found in a pond community.
| Organism | Number |
|---|---|
| Water lily (producer) | 50 |
| Pond snail (herbivore) | 200 |
| Small fish (carnivore) | 50 |
| Large fish (top carnivore) | 5 |
| Water flea (herbivore) | 500 |
(a) Draw a pyramid of numbers for this community in the space below. Label each level. [2]
Generated diagram for Q38.
(b) Explain why the number of organisms decreases at each higher trophic level. [2]
39
The diagram below shows two similar plants, P and Q, grown under different conditions.
Generated diagram for Q39.
(a) State the difference in the colour of the leaves between Plant P and Plant Q. [1]
(b) Explain why Plant Q has yellow leaves. [1]
(c) Plant Q has a taller but thinner stem than Plant P. Explain why. [2]
40
The diagram below shows the human digestive system.
Generated diagram for Q40.
(a) Name the organ where most absorption of digested food takes place. [1]
(b) State the function of the large intestine. [1]
(c) The liver produces bile which is stored in the gall bladder. State the function of bile in digestion. [1]
(d) Explain why food moves along the digestive tract even when a person is upside down. [1]
41
Study the food web below.
Generated diagram for Q41.
(a) How many food chains are there in this food web? [1]
(b) If the population of phytoplankton decreases due to pollution, explain how this will affect the shark population. [2]
(c) State the original source of energy for this food web. [1]
42
The diagram below shows a microorganism viewed under a microscope.
Generated diagram for Q42.
(a) Identify this microorganism. [1]
(b) State two characteristics of this microorganism that show it is a living thing. [2]
(c) How does this microorganism obtain food? [1]
43
The diagram below shows a plant growing towards light.
Generated diagram for Q43.
(a) What is this response of the plant to light called? [1]
(b) Explain how the plant benefits from this response. [1]
(c) Name the plant hormone responsible for this growth response. [1]
44
The table below shows the breathing rate and heart rate of a student before and after exercise.
| Before Exercise | After Exercise | |
|---|---|---|
| Breathing Rate (breaths/min) | 16 | 32 |
| Heart Rate (beats/min) | 72 | 144 |
(a) Describe the change in breathing rate after exercise. [1]
(b) Explain why both breathing rate and heart rate increase during exercise. [2]
(c) After resting for 10 minutes, the student's heart rate returned to 72 beats/min. What process in the body cells requires the increased oxygen supply during exercise? [1]
END OF PAPER
Answers
TuitionGoWhere Practice Paper - Science Primary 6 PSLE (Answer Key)
TuitionGoWhere Exam Practice (AI)
Subject: Science
Level: Primary 6 PSLE
Paper: SA2 Version 3
Total Marks: 100
BOOKLET A (56 marks)
1
Answer: (1) Mould, yeast, mushroom
Marks: 2
Explanation: Mould, yeast, and mushroom are all fungi. Fern and moss are non-flowering plants. Bacteria and viruses are microorganisms but not fungi. Algae are plant-like protists.
2
Answer: (3) Feed on dead or living organisms | Feed on dead or living organisms
Marks: 2
Explanation: Group X (Bacteria, Amoeba, Paramecium) are microorganisms that obtain food by feeding on other organisms (heterotrophic). Group Y (Mushroom, Mould, Yeast) are fungi, which are saprotrophs that feed on dead and decaying matter. Neither group makes its own food.
3
Answer: (3) Some microorganisms are useful in food production.
Marks: 2
Explanation: Yeast is used in bread making and brewing. Bacteria are used in yoghurt, cheese, and fermented foods. Not all microorganisms are harmful (many are beneficial), most cannot be seen with the naked eye, and all microorganisms need air, water, and food to survive.
4
Answer: (3) Cell wall
Marks: 2
Explanation: Plant cells have a cell wall made of cellulose, chloroplasts, and a large central vacuole. Animal cells lack a cell wall, chloroplasts, and have only small vacuoles. Both have a nucleus, cytoplasm, and cell membrane.
5
Answer: (4) Devi
Marks: 2
Explanation: Bacteria are prokaryotic microorganisms classified in their own domain (Bacteria). They are neither plants (no chloroplasts, different cell wall composition), nor animals (unicellular, no ingestion), nor fungi (different cell wall, no chitin).
6
Answer: (1) P
Marks: 2
Explanation: Organism P has a cell wall and chloroplasts (photosynthetic) but does not reproduce by spores or feed on decaying matter — characteristics of a flowering plant. Q and R have chitin cell walls, reproduce by spores, and feed on decaying matter — fungi. S lacks a cell wall — likely an animal.
7
Answer: (3) They can move from place to place.
Marks: 2
Explanation: Not all living things move from place to place (locomotion). Plants are living but are generally fixed in one place. All living things need air, food, water; can reproduce; and respond to stimuli.
8
Answer: (3) Fungi
Marks: 2
Explanation: Following the flowchart: Does not make own food → feeds on dead/decaying matter → Fungi. Fungi are saprotrophs that reproduce by spores.
9
Answer: (2) Bird, fish, mammal
Marks: 2
Explanation: Birds, fish, and mammals are all vertebrates (have backbones). Frog is a vertebrate but earthworm is an invertebrate. Insect, spider, crab are arthropods (invertebrates). Snail, jellyfish, starfish are invertebrates.
10
Answer: (2) Birds
Marks: 2
Explanation: The animal has feathers, wings, beak, lays eggs, and has two legs with claws — all characteristic features of birds. Mammals have hair/fur and produce milk. Reptiles have dry scaly skin. Amphibians have moist skin.
11
Answer: (3) Mammals feed their young with milk.
Marks: 2
Explanation: This is a defining characteristic of mammals. Not all winged animals are birds (e.g., bats are mammals, insects have wings). Not all egg-layers are reptiles (birds, monotremes, amphibians, fish lay eggs). Amphibians have moist skin, not dry scaly skin.
12
Answer: (4) Z
Marks: 2
Explanation: Animal Z has hair/fur, breathes with lungs, and gives birth to live young — all mammalian characteristics. W has scales and lays eggs (reptile). X has moist skin and metamorphosis (amphibian). Y has feathers and lays eggs (bird).
13
Answer: (1) Bacteria | Yeast | Mould
Marks: 2
Explanation: View A shows rod-shaped single cells (typical bacteria). View B shows oval cells with buds (yeast budding reproduction). View C shows thread-like hyphae with spores (mould structure).
14
Answer: (2) Yeast used in bread making
Marks: 2
Explanation: Yeast ferments sugar to produce carbon dioxide, which causes bread dough to rise. Salmonella causes food poisoning, viruses cause diseases, mould on spoiled food indicates spoilage.
15
Answer: (3) Frog
Marks: 2
Explanation: The frog eats grasshoppers (predator) and is eaten by snakes (prey). Grass is a producer. Grasshopper is a primary consumer (prey only in this chain). Eagle is a top predator.
16
Answer: (3) Producer → Consumer → Decomposer
Marks: 2
Explanation: Energy flows from producers (plants) to consumers (herbivores, then carnivores) to decomposers (bacteria, fungi) which break down dead matter and recycle nutrients.
17
Answer: (4) The population of snakes may decrease.
Marks: 2
Explanation: Grasshoppers are prey for frogs and snakes. Fewer grasshoppers → less food for frogs and snakes → their populations may decrease. Plants may increase (less herbivory). Mice are not directly affected.
18
Answer: (3) They break down dead organisms and waste, returning nutrients to the environment.
Marks: 2
Explanation: Decomposers (bacteria, fungi) are saprotrophs that externally digest dead organic matter and absorb nutrients, recycling them back into the ecosystem for producers to use.
19
Answer: (3) Dicotyledon
Marks: 2
Explanation: The plant has broad leaves with network (reticulate) veins, a taproot system, flowers with 5 petals (multiple of 4 or 5), and seeds in a fruit — all characteristics of dicotyledons. Monocots have parallel veins, fibrous roots, flower parts in multiples of 3.
20
Answer: (2) Broad, flat leaves that float on water
Marks: 2
Explanation: Water lilies have broad floating leaves to capture sunlight on the water surface. Deep roots (1) are for dry habitats. Thick waxy leaves (3) and spines (4) are adaptations to reduce water loss in dry (xerophytic) habitats.
21
Answer: (3) Egg, larva, and pupa
Marks: 2
Explanation: Mosquito eggs are laid in water. Larvae (wrigglers) and pupae (tumblers) are aquatic stages. Only the adult mosquito is terrestrial and flies.
22
Answer: (4) By photosynthesis
Marks: 2
Explanation: Photosynthesis is the process by which plants make food, not a method of seed dispersal. Wind, water, and animals are the three main agents of seed dispersal.
23
Answer: (3) By splitting action (explosive dispersal)
Marks: 2
Explanation: The pod-like fruit that splits open when dry, flinging seeds away, is characteristic of explosive dispersal (e.g., pea, bean, rubber tree).
24
Answer: (4) Digestion of food is completed in the small intestine.
Marks: 2
Explanation: Digestion starts in the mouth (starch), continues in the stomach (protein), and is completed in the small intestine (all nutrients). The small intestine absorbs digested nutrients. The large intestine absorbs water.
25
Answer: (3) Alveoli
Marks: 2
Explanation: Gaseous exchange (oxygen in, carbon dioxide out) occurs in the alveoli (air sacs) where the walls are one cell thick and surrounded by capillaries. The trachea and bronchi are air passages.
26
Answer: (1) Nose → Trachea → Bronchi → Bronchioles → Alveoli
Marks: 2
<stage3_exam_answers_md>
TuitionGoWhere Practice Paper - Science Primary 6 PSLE (Answer Key)
TuitionGoWhere Exam Practice (AI)
Subject: Science
Level: Primary 6 PSLE
Paper: SA2 Version 3
BOOKLET A (56 marks)
| Question | Answer | Explanation |
|---|---|---|
| 1 | (1) | Mould, yeast, and mushroom are all classified as fungi. Fern and moss are non-flowering plants. Bacteria and viruses are microorganisms but not fungi. Algae are plant-like protists. |
| 2 | (3) | Group X (Bacteria, Amoeba, Paramecium) are microorganisms that feed on dead or living organisms (heterotrophic). Group Y (Mushroom, Mould, Yeast) are fungi which are decomposers feeding on dead or decaying matter (saprotrophic). Neither group makes its own food. |
| 3 | (3) | Some microorganisms are useful in food production (e.g., yeast in bread/beer, bacteria in yogurt/cheese). Not all are harmful (1), most cannot be seen with the naked eye (2), and they need air, water, and food to survive (4). |
| 4 | (3) | The cell wall is a rigid structure made of cellulose found in plant cells but absent in animal cells. Nucleus, cytoplasm, and cell membrane are present in both. |
| 5 | (4) | Devi is correct. Bacteria are prokaryotic microorganisms classified in their own domain (Bacteria/Monera), distinct from plants, animals, and fungi. They have cell walls (peptidoglycan, not cellulose), some can move, but they reproduce by binary fission, not spores. |
| 6 | (1) | Organism P has a cell wall and chloroplasts (photosynthesises) but does not reproduce by spores or feed on decaying matter. This matches a flowering plant. Q and R are fungi (cell wall, spores, saprotrophic). S is an animal (no cell wall). |
| 7 | (3) | Not all living things can move from place to place (locomotion). Plants are living but generally fixed in one place. All living things need air, food, water; can reproduce; and respond to stimuli. |
| 8 | (3) | Following the flowchart: Does not make own food (No) → Feeds on dead/decaying matter (Yes) → Fungi. Reproduction by spores is a characteristic of fungi. |
| 9 | (2) | Vertebrates have a backbone. Bird, fish, and mammal are all vertebrate classes. Frog (amphibian) and snake (reptile) are vertebrates, but earthworm is an invertebrate. Insect, spider, crab are arthropods (invertebrates). Snail (mollusc), jellyfish (cnidarian), starfish (echinoderm) are invertebrates. |
| 10 | (2) | The features described (feathers, wings, two legs with claws, beak, lays eggs) are defining characteristics of Birds. |
| 11 | (3) | Mammals are defined by the presence of mammary glands to feed young with milk. (1) Bats (mammals) and insects have wings. (2) Birds, monotremes, amphibians, fish, reptiles lay eggs. (4) Amphibians have moist, permeable skin; reptiles have dry, scaly skin. |
| 12 | (4) | Animal Z has hair/fur, breathes with lungs, and gives birth to live young – characteristics of Mammals. W is a reptile, X is an amphibian, Y is a bird. |
| 13 | (1) | View A: Rod-shaped single cells = Bacteria. View B: Oval cells with buds = Yeast (budding reproduction). View C: Thread-like structures (hyphae) with spores = Mould. |
| 14 | (2) | Yeast is used in bread making (fermentation produces CO2 to make dough rise). Salmonella, cold viruses, and spoilage mould are harmful. |
| 15 | (3) | Frog eats grasshopper (predator) and is eaten by snake (prey). Grass is a producer. Grasshopper is prey (to frog) but not a predator (eats plants). Eagle is a top predator only. |
| 16 | (3) | Energy flows: Producer (makes food) → Consumer (eats producer/other consumers) → Decomposer (breaks down dead matter). |
| 17 | (4) | Grasshoppers are prey for frogs, spiders, birds. If grasshoppers decrease, their predators (frogs, snakes via frogs/birds) have less food, so populations may decrease. Plants may increase (less herbivory). Mice are not directly linked to grasshoppers. |
| 18 | (3) | Decomposers (bacteria, fungi) break down dead organisms and waste, returning nutrients to the environment for producers to reuse. |
| 19 | (3) | Broad leaves with network (reticulate) veins, taproot system, flower parts in 4s/5s, seeds in fruit → Dicotyledon. Monocots have parallel veins, fibrous roots, flower parts in 3s. |
| 20 | (2) | Water lilies have broad, flat leaves that float on water to capture sunlight. They don't need deep roots for water (1), thick waxy leaves are for xerophytes (3), spines are for cacti (4). |
| 21 | (3) | Mosquito eggs are laid in water; larvae (wrigglers) and pupae (tumblers) are aquatic. Only the adult is terrestrial/flying. So Egg, larva, and pupa live in water. |
| 22 | (4) | Photosynthesis is the process of making food, not a method of seed dispersal. Wind, water, and animals are standard dispersal agents. |
| 23 | (3) | A pod that splits open when dry to scatter seeds describes explosive dispersal (splitting action). Examples: pea, bean, rubber tree. |
| 24 | (4) | Digestion starts in the mouth, continues in stomach, and is completed in the small intestine where most absorption of nutrients occurs. Large intestine absorbs water (2, 3 incorrect). |
| 25 | (3) | Gaseous exchange (O2 in, CO2 out) occurs in the alveoli (air sacs) due to thin walls and rich capillary network. |
| 26 | (1) | Correct anatomical path: Nose → Trachea → Bronchi → Bronchioles → Alveoli. |
| 27 | (1) | During respiration, cells use oxygen and produce carbon dioxide. Hence exhaled air has less O2 (16% vs 21%) and more CO2 (4% vs 0.04%). Nitrogen is inert. Water vapour increases due to moist respiratory surfaces. |
| 28 | (3) | Running is vigorous exercise requiring more oxygen/nutrients, increasing heart rate the most. Sleeping, reading, sitting are low activity. |
BOOKLET B (44 marks)
29
(a) Both have a cell wall. (Accept: Both are living things / made of cells)
(b) Organism A is single-celled (unicellular) with no nucleus (prokaryotic); Organism B is multi-cellular with a nucleus (eukaryotic). (Accept: A has flagellum/moves, B is fixed/has chloroplasts)
(c) Bacteria (or Monera / Prokaryotes)
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(a) Flowering plants and Non-flowering plants.
(b) Fern (or Moss / Non-flowering plant that reproduces by spores).
(c) Pine tree / Conifer / Cypress / Ginkgo (any gymnosperm example).
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(a) Food chain 1: Grass → Grasshopper → Frog → Hawk (or Grass → Grasshopper → Bird → Hawk, etc.)
Food chain 2: Shrubs → Aphid → Ladybird → Bird → Hawk (or Trees → Caterpillar → Bird → Hawk, etc.)
(Must start with producer, arrows show energy flow, min 3 organisms)
(b) The aphid population will increase. Ladybirds are predators of aphids. With no ladybirds, fewer aphids are eaten, so their population rises (until limited by food/other predators).
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(a) Plant cell (has cell wall, chloroplasts, large central vacuole).
(b) Nucleus.
(c) Contain chlorophyll to trap light energy for photosynthesis (make food).
(d) No. Mitochondria are too small to be seen under a light microscope / not shown in simplified diagrams. Plant cells have mitochondria for respiration (release energy).
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(a) Y (No nucleus = prokaryote = bacterium; peptidoglycan cell wall).
(b) X (Has nucleus, chitin cell wall, no chloroplasts, saprotrophic = fungus).
(c) W (Has nucleus, cellulose cell wall, chloroplasts, autotrophic = plant).
(d) Z (Has nucleus, no cell wall, no chloroplasts, heterotrophic = animal).
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(a) Diffusion (of oxygen from alveoli into blood / carbon dioxide from blood into alveoli).
(b) Alveoli have: (1) Thin walls (one cell thick) for short diffusion distance; (2) Large surface area (many alveoli); (3) Rich blood supply (dense capillary network) / Moist lining for gases to dissolve. (Any two)
(c) Haemoglobin in red blood cells binds to oxygen to form oxyhaemoglobin for transport.
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(a) Water-crowfoot (or Hydrilla / Elodea / any submerged aquatic plant).
(b) Narrow / finely divided / dissected leaves to reduce water resistance / prevent tearing by currents; No / reduced stomata on leaves; Flexible stems to move with water; Air spaces (aerenchyma) in stems/leaves for buoyancy/gas exchange. (Any one)
(c) Floating leaves (broad, flat, waxy upper surface, stomata on upper surface only) to absorb sunlight / exchange gases with air; Long, flexible leaf stalks to reach water surface. (Any one)
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(a) Stigma (receives pollen).
(b) Anther (produces pollen).
(c) Ovary (develops into fruit after fertilisation).
(d) Ovule (develops into seed after fertilisation).
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(a) Germination.
(b) Air (oxygen), Water, Warmth (suitable temperature). (All three required)
(c) The seed leaves (cotyledons) store food / provide nutrients for the seedling until the first true leaves can photosynthesise.
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(a) Circulatory system (heart, blood vessels, blood).
(b) Heart (pumps blood).
(c) Arteries carry oxygenated blood away from heart (except pulmonary artery); Veins carry deoxygenated blood back to heart (except pulmonary vein). Arteries have thicker, more muscular walls; higher pressure. Veins have valves; lower pressure. (Any one difference)
(d) Capillaries have walls one cell thick to allow exchange of substances (oxygen, nutrients, waste) between blood and cells by diffusion.
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(a) Evaporation (water changes from liquid to gas/vapour).
(b) Condensation (water vapour changes to liquid droplets).
(c) Heat gain (from surroundings/sun) causes evaporation; Heat loss (to cooler air) causes condensation.
(d) The water cycle ensures continuous supply of fresh water (rain) for living things; distributes water globally; regulates climate/temperature. (Any one)
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(a) Shadow is formed when light is blocked by an opaque/translucent object. Light travels in straight lines.
(b) Move the torch closer to the object (or move object closer to torch / move screen further away).
(c) The shadow becomes sharper / less fuzzy (smaller penumbra) because the light source acts more like a point source / rays are more parallel. (Or: Shadow size increases if screen distance fixed).
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(a) Repel (Like poles face each other: North-North or South-South).
(b) Attract (Unlike poles face: North-South).
(c) Stroke the steel rod with a magnet (stroking method) using one pole, in one direction, repeatedly. (Or: Electrical method - coil wire around rod, pass DC current).
(d) Heat the magnet / Hammer the magnet / Drop it repeatedly / Store it incorrectly (e.g., N-pole to N-pole). (Any one)
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(a) Gravitational potential energy → Kinetic energy + Heat energy + Sound energy.
(b) Some kinetic energy is converted to heat and sound energy due to friction (air resistance, ramp surface) / not all GPE converts to KE.
(c) Increase the height of the ramp (more GPE) / Use a smoother ramp/ball (less friction) / Use a heavier ball (more GPE). (Any one)
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(a) Circuit A: Bulbs are brighter. (Series vs Parallel: In parallel, each bulb gets full battery voltage; in series, voltage is shared).
(b) Circuit B (Parallel). In parallel, if one bulb fuses, the other circuit path remains closed. In series (A), one fused bulb breaks the only path.
(c) Add more batteries in series / Use batteries with higher voltage / Use bulbs with lower resistance (higher wattage). (Any one)
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(a) C (Copper is a good conductor of heat; metal spoon transfers heat fast from hot soup to hand).
(b) A (Plastic/Wood is a poor conductor of heat / good insulator; handle stays cool).
(c) Conduction (Heat travels through the solid spoon from hotter end to cooler end).
(d) Air is a poor conductor of heat (good insulator). The air pockets in the handle reduce heat transfer by conduction.
End of Answer Key
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