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Primary 3 Science Life Cycles Quiz

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Questions

Primary 3 Science Quiz - Life Cycles

Name: ________________________
Class: Primary 3 _____
Date: _______________
Score: _____ / 40

Duration: 45 minutes
Total Marks: 40

Instructions:

Answer all questions.
Write your answers in the spaces provided.
For multiple-choice questions, write the letter (A, B, C, or D) in the brackets provided.
For open-ended questions, write your answers in complete sentences.
Check your work carefully before handing in.

Section A: Multiple-Choice Questions (10 × 1 mark = 10 marks)

For each question, choose the correct answer and write its letter in the brackets provided.

1. Which of the following animals has a three-stage life cycle?
A. Butterfly
B. Mosquito
C. Grasshopper
D. Frog

[ ]

2. The diagram below shows the life cycle of a flowering plant.
<image_placeholder> id: Q2-fig1 type: diagram linked_question: Q2 description: Life cycle of a flowering plant with four stages labelled A, B, C, D in clockwise order. Stage A: seed. Stage B: seedling with two small leaves. Stage C: young plant with more leaves. Stage D: adult plant with flower and fruit. labels: A, B, C, D values: None must_show: Seed, seedling, young plant, adult plant with flower and fruit; arrows showing direction of cycle </image_placeholder>

At which stage does the plant start to make its own food?
A. Stage A
B. Stage B
C. Stage C
D. Stage D

[ ]

3. Mealworms are the young of darkling beetles. The table below shows the number of days a mealworm spends at each stage of its life cycle.

Stage	Number of Days
Egg	10
Larva	60
Pupa	14
Adult	90

How many days does it take for a mealworm to develop from an egg to an adult?
A. 74
B. 84
C. 94
D. 174

[ ]

4. Which of the following statements about the life cycle of a mosquito is correct?
A. The pupa stage does not move.
B. The larva breathes through gills.
C. The adult mosquito lays eggs in soil.
D. The egg hatches into a pupa.

[ ]

5. Study the flowchart below.
<image_placeholder> id: Q5-fig1 type: diagram linked_question: Q5 description: Flowchart for classifying animals by life cycle stages. Start: Does the young look like the adult? Yes → 3-stage life cycle. No → Does it have a pupa stage? Yes → 4-stage life cycle. No → 3-stage life cycle (incomplete metamorphosis). labels: None values: None must_show: Decision diamonds with yes/no branches, three end boxes: 3-stage life cycle (complete), 4-stage life cycle, 3-stage life cycle (incomplete) </image_placeholder>

Animal X has a young that does not look like the adult and has a pupa stage.
Which life cycle does Animal X have?
A. 3-stage life cycle (complete metamorphosis)
B. 3-stage life cycle (incomplete metamorphosis)
C. 4-stage life cycle
D. Cannot be determined

[ ]

6. The diagram below shows a seed germinating.
<image_placeholder> id: Q6-fig1 type: diagram linked_question: Q6 description: Cross-section of a seed germinating. Seed coat split open. Radicle (root) growing downwards. Plumule (shoot) growing upwards with two seed leaves (cotyledons). Root hairs visible on radicle. labels: Seed coat, Radicle, Plumule, Cotyledons, Root hairs values: None must_show: Split seed coat, radicle growing down, plumule growing up, two cotyledons, root hairs </image_placeholder>

Which part absorbs water and mineral salts from the soil?
A. Seed coat
B. Radicle
C. Plumule
D. Cotyledons

[ ]

7. A student observed a plant over several weeks and recorded the following:

Week 1: Seed planted in soil
Week 2: Tiny root and shoot appear
Week 3: First pair of leaves appear
Week 4: More leaves grow; plant gets taller
Week 5: Flower buds form
Week 6: Flowers bloom
Week 7: Fruits develop with seeds inside

At which week does the plant first become able to reproduce?
A. Week 5
B. Week 6
C. Week 7
D. Week 4

[ ]

8. Which of the following animals does not have a nymph stage in its life cycle?
A. Cockroach
B. Grasshopper
C. Dragonfly
D. Beetle

[ ]

9. The graph below shows the height of a bean plant over 6 weeks.
<image_placeholder> id: Q9-fig1 type: graph linked_question: Q9 description: Line graph. X-axis: Week (1 to 6). Y-axis: Height (cm) from 0 to 30. Points: Week 1: 2 cm, Week 2: 5 cm, Week 3: 12 cm, Week 4: 20 cm, Week 5: 25 cm, Week 6: 28 cm. Steady upward curve. labels: Week, Height (cm) values: (1,2), (2,5), (3,12), (4,20), (5,25), (6,28) must_show: Axes labelled, points plotted, line connecting points, title "Growth of a Bean Plant" </image_placeholder>

Between which two weeks did the plant grow the most?
A. Week 1 to Week 2
B. Week 2 to Week 3
C. Week 3 to Week 4
D. Week 4 to Week 5

[ ]

10. Why do most plants produce many seeds but only a few grow into adult plants?
A. Seeds are too heavy to travel far.
B. Many seeds are eaten or do not get suitable conditions to germinate.
C. Plants do not need many adults.
D. Seeds cannot grow without fertiliser.

[ ]

Section B: Structured Questions (6 × 2 marks = 12 marks)

Answer all questions in the spaces provided.

11. The diagram below shows the life cycle of a frog.
<image_placeholder> id: Q11-fig1 type: diagram linked_question: Q11 description: Life cycle of a frog in four stages arranged in a circle. Stage 1: Eggs (frogspawn) in water. Stage 2: Tadpole with gills and tail, no legs. Stage 3: Tadpole with hind legs, then front legs, tail shrinking. Stage 4: Adult frog on land with lungs, no tail. labels: Eggs, Tadpole (no legs), Tadpole (with legs), Adult frog values: None must_show: Arrows connecting stages, eggs in water, tadpole with gills, tadpole developing legs, adult frog on land </image_placeholder>

(a) Name the stage labelled X in the diagram.
________________________________________________________________________ [1]

(b) State one difference between the tadpole and the adult frog in terms of where it lives and how it breathes.

________________________________________________________________________ [1]

12. The table below shows the life cycles of three animals.

Animal	Number of Stages	Young Looks Like Adult?	Has Pupa Stage?
Chicken	3	Yes	No
Butterfly	4	No	Yes
Grasshopper	3	No	No

(a) Which animal has a three-stage life cycle with incomplete metamorphosis?
________________________________________________________________________ [1]

(b) Explain why the chicken is said to have a three-stage life cycle.

________________________________________________________________________ [1]

13. A farmer wants to grow a new type of plant. He collects seeds from the parent plant and plants them.
<image_placeholder> id: Q13-fig1 type: diagram linked_question: Q13 description: Two seeds side by side. Seed A: large, with a fluffy tuft. Seed B: small, with a hard shiny coat and a hook. labels: Seed A, Seed B values: None must_show: Seed A with fluffy tuft (wind dispersal), Seed B with hook (animal dispersal) </image_placeholder>

(a) Seed A has a fluffy tuft. How is Seed A most likely dispersed?
________________________________________________________________________ [1]

(b) Seed B has a hook. How is Seed B most likely dispersed?
________________________________________________________________________ [1]

14. The diagram below shows a young plant growing from a seed.
<image_placeholder> id: Q14-fig1 type: diagram linked_question: Q14 description: Young plant with roots in soil, stem, and two green leaves. Sun shining above. Water droplets on soil. Arrow pointing from sun to leaves labelled "light". Arrow pointing from soil to roots labelled "water and mineral salts". labels: Roots, Stem, Leaves, Sun, Soil values: None must_show: Roots in soil, green leaves, sun, water in soil, arrows for light and water/mineral salts </image_placeholder>

(a) The leaves are green. What is the function of the green leaves?
________________________________________________________________________ [1]

(b) The roots have root hairs. Why are root hairs important?
________________________________________________________________________ [1]

15. Study the life cycle of a flowering plant below.
<image_placeholder> id: Q15-fig1 type: diagram linked_question: Q15 description: Life cycle of flowering plant in 5 stages: 1. Seed, 2. Germination (root and shoot emerge), 3. Seedling (first true leaves), 4. Adult plant (vegetative growth), 5. Flowering and fruiting (pollination, fertilisation, seed formation). Arrows connect in a cycle. labels: Seed, Germination, Seedling, Adult plant, Flowering and fruiting values: None must_show: Five distinct stages in cycle, pollination and fertilisation shown in flowering stage </image_placeholder>

(a) At which stage does pollination occur?
________________________________________________________________________ [1]

(b) After fertilisation, the ovary develops into the fruit and the ovules develop into seeds. Why is the fruit important for the plant?

________________________________________________________________________ [1]

16. The diagram below shows the life cycle of a mosquito.
<image_placeholder> id: Q16-fig1 type: diagram linked_question: Q16 description: Mosquito life cycle in 4 stages: Egg raft on water surface → Larva (wriggler) hanging at water surface with breathing tube → Pupa (tumbler) comma-shaped at water surface → Adult mosquito flying away. labels: Egg, Larva, Pupa, Adult values: None must_show: Egg raft on water, larva with breathing tube at surface, pupa at surface, adult emerging </image_placeholder>

(a) Both the larva and pupa live in water. State one similarity in how they breathe.
________________________________________________________________________ [1]

(b) The adult female mosquito sucks blood. Why does she need blood?
________________________________________________________________________ [1]

Section C: Open-Ended Questions (4 × 4 marks = 16 marks)

Answer all questions in the spaces provided. Write in complete sentences.

17. Mei Ling observed the life cycle of a butterfly and recorded the number of days for each stage:

Stage	Number of Days
Egg	4
Larva (caterpillar)	14
Pupa	10
Adult	21

(a) How many days does the butterfly spend in the larva and pupa stages combined?
________________________________________________________________________ [1]

(b) The caterpillar eats a lot of leaves during the larva stage. Why is this important?

________________________________________________________________________ [1]

(d) The adult butterfly lives for 21 days. State one main purpose of the adult stage in the life cycle.
________________________________________________________________________ [1]

18. The diagram below shows two plants, Plant A and Plant B, growing in a garden.
<image_placeholder> id: Q18-fig1 type: diagram linked_question: Q18 description: Two flowering plants side by side. Plant A: tall, many flowers, bees visiting. Plant B: short, few flowers, no insects. Both have fruits developing. labels: Plant A, Plant B, Bees, Flowers, Fruits values: None must_show: Plant A with many flowers and bees, Plant B with few flowers and no insects, fruits on both </image_placeholder>

(a) Plant A has many bees visiting its flowers. How do bees help the plant?

________________________________________________________________________ [1]

(b) Plant B has few flowers and no insects visiting. Suggest one reason why Plant B has fewer fruits than Plant A.

________________________________________________________________________ [1]

(c) The fruits of both plants split open when ripe to scatter seeds. Name this method of seed dispersal.
________________________________________________________________________ [1]

(d) Why is seed dispersal important for plants?

________________________________________________________________________ [1]

19. A group of students conducted an experiment to find out the conditions needed for seed germination. They used four set-ups:

Set-up	Seeds	Water	Air	Temperature	Light
W	5	Yes	Yes	Room temp (25°C)	Yes
X	5	No	Yes	Room temp (25°C)	Yes
Y	5	Yes	No	Room temp (25°C)	Yes
Z	5	Yes	Yes	Cold (4°C)	Yes

After 5 days, only the seeds in Set-up W germinated.

(a) What is the aim of this experiment?
________________________________________________________________________ [1]

(b) Which two set-ups should be compared to show that water is needed for germination?
________________________________________________________________________ [1]

________________________________________________________________________ [1]

(d) The students concluded that light is not needed for germination. Do you agree? Explain using the results.

________________________________________________________________________ [1]

20. The diagram below shows the life cycle of a flowering plant and the life cycle of a butterfly.
<image_placeholder> id: Q20-fig1 type: diagram linked_question: Q20 description: Two life cycles side by side. Left: Plant - Seed → Germination → Seedling → Adult plant → Flower → Fruit with seeds → back to Seed. Right: Butterfly - Egg → Caterpillar (larva) → Pupa → Adult butterfly → lays eggs → back to Egg. labels: All stages labelled on both cycles values: None must_show: Complete plant cycle with 5-6 stages, complete butterfly cycle with 4 stages, arrows showing cyclic nature </image_placeholder>

(a) State one similarity between the life cycle of a flowering plant and the life cycle of a butterfly.
________________________________________________________________________ [1]

(b) State one difference between the two life cycles.
________________________________________________________________________ [1]

________________________________________________________________________ [1]

(d) The adult butterfly lays many eggs but only a few survive to become adults. Give one reason why many eggs do not survive.
________________________________________________________________________ [1]

End of Quiz

Answers

Primary 3 Science Quiz - Life Cycles (Answer Key)

Total Marks: 40

Section A: Multiple-Choice Questions (10 marks)

1. Answer: C
Explanation: Grasshoppers have a three-stage life cycle (egg → nymph → adult) with incomplete metamorphosis. Butterflies and mosquitoes have four-stage life cycles (complete metamorphosis). Frogs have a life cycle with distinct larval (tadpole) and adult stages but are not classified as three-stage in the same way as insects with incomplete metamorphosis.
Mark: 1

2. Answer: B
Explanation: At Stage B (seedling), the first leaves (cotyledons or true leaves) appear and begin photosynthesis, allowing the plant to make its own food. At Stage A (seed), the plant relies on stored food in the cotyledons.
Mark: 1

3. Answer: B
Explanation: Egg (10) + Larva (60) + Pupa (14) = 84 days. The adult stage (90 days) is not included because the question asks for development from egg to adult (i.e., until it becomes an adult).
Common mistake: Adding all four stages (174 days) — this would be the total lifespan, not development time.
Mark: 1

4. Answer: A
Explanation: The mosquito pupa (tumbler) is comma-shaped and does not feed; it moves only by tumbling through water but is largely inactive. The larva breathes through a siphon tube at the water surface (not gills). Adult mosquitoes lay eggs in water, not soil. The egg hatches into a larva, not a pupa.
Mark: 1

5. Answer: C
Explanation: Following the flowchart: Young does not look like adult → Has a pupa stage → 4-stage life cycle (complete metamorphosis).
Mark: 1

6. Answer: B
Explanation: The radicle is the embryonic root that grows downward and develops root hairs to absorb water and mineral salts from the soil. The plumule becomes the shoot, and cotyledons store or produce food.
Mark: 1

7. Answer: B
Explanation: The plant can first reproduce when flowers bloom (Week 6), as pollination and fertilisation can then occur, leading to seed formation. Flower buds (Week 5) are not yet open for pollination. Fruits with seeds (Week 7) are the result of reproduction.
Mark: 1

8. Answer: D
Explanation: Beetles have a four-stage life cycle (egg → larva → pupa → adult) with complete metamorphosis. Cockroaches, grasshoppers, and dragonflies have three-stage life cycles with a nymph stage (incomplete metamorphosis).
Mark: 1

9. Answer: C
Explanation: Growth between weeks:
Week 1→2: 5−2 = 3 cm
Week 2→3: 12−5 = 7 cm
Week 3→4: 20−12 = 8 cm ← greatest increase
Week 4→5: 25−20 = 5 cm
Mark: 1

10. Answer: B
Explanation: Plants produce many seeds because most will not survive — they may be eaten by animals, land in unsuitable conditions (no water, light, or soil), or be destroyed by weather. This is a survival strategy to ensure at least some offspring reach adulthood.
Mark: 1

Section B: Structured Questions (12 marks)

11. (a) Answer: Tadpole (with legs) / Tadpole developing legs
Explanation: Stage X shows a tadpole that has developed hind legs and front legs, with the tail shrinking. This is the stage between the legless tadpole and the adult frog.
Mark: 1

11. (b) Answer: The tadpole lives in water and breathes through gills, while the adult frog lives on land and breathes through lungs (and skin).
Explanation: Tadpoles are aquatic with gills for breathing underwater. Adult frogs are amphibious but primarily terrestrial, using lungs to breathe air (and moist skin for gas exchange).
Mark: 1

12. (a) Answer: Grasshopper
Explanation: Grasshopper has 3 stages, young does not look like adult, and no pupa stage — this is incomplete metamorphosis.
Mark: 1

12. (b) Answer: The chicken has three stages (egg → chick → adult), and the young (chick) looks like the adult (both have feathers, beak, two legs, wings), so it is a three-stage life cycle without metamorphosis.
Explanation: In a three-stage life cycle with no metamorphosis, the young resembles the adult in body form, only smaller and not sexually mature.
Mark: 1

13. (a) Answer: By wind
Explanation: The fluffy tuft acts like a parachute, allowing the seed to be carried by air currents.
Mark: 1

13. (b) Answer: By animals (the hook catches on animal fur)
Explanation: The hook attaches to the fur of passing animals, transporting the seed to a new location.
Mark: 1

14. (a) Answer: The green leaves trap light energy from the sun to make food (photosynthesis).
Explanation: Chlorophyll in the leaves absorbs sunlight, which is used to convert carbon dioxide and water into sugar (food) and oxygen.
Mark: 1

14. (b) Answer: Root hairs increase the surface area of the roots, allowing more water and mineral salts to be absorbed from the soil.
Explanation: The tiny extensions of root epidermal cells greatly increase the absorptive surface area, which is essential for efficient uptake.
Mark: 1

15. (a) Answer: Flowering and fruiting stage / Stage 5
Explanation: Pollination (transfer of pollen to stigma) occurs when the plant produces flowers, which is the flowering stage.
Mark: 1

15. (b) Answer: The fruit protects the seeds and helps in seed dispersal (e.g., by animals eating the fruit or by splitting open).
Explanation: Fruits aid in the survival of the species by protecting developing seeds and enabling them to reach new places to grow.
Mark: 1

16. (a) Answer: Both the larva and pupa breathe air through a breathing tube/siphon at the water surface.
Explanation: Mosquito larvae and pupae are aquatic but breathe atmospheric oxygen — they come to the water surface and use a siphon (larva) or respiratory trumpets (pupa) to take in air.
Mark: 1

16. (b) Answer: She needs the protein in blood to develop her eggs.
Explanation: Only female mosquitoes bite; they require a blood meal to obtain proteins and iron necessary for egg production. Males feed on nectar.
Mark: 1

Section C: Open-Ended Questions (16 marks)

17. (a) Answer: 24 days
Working: Larva (14 days) + Pupa (10 days) = 24 days
Mark: 1

17. (b) Answer: The caterpillar eats a lot to store energy and nutrients for the pupa stage, when it does not eat but undergoes major changes to become an adult.
Explanation: The larva is the feeding and growth stage. It must consume enough food to fuel metamorphosis inside the pupa.
Mark: 1

17. (c) Answer: Inside the pupa, the caterpillar's body breaks down and reorganises into the adult butterfly (wings, legs, antennae, compound eyes, etc.).
Explanation: This process is called metamorphosis. Tissues are broken down by enzymes and rebuilt into adult structures using energy stored from the larva stage.
Mark: 1

17. (d) Answer: The main purpose of the adult stage is to reproduce (mate and lay eggs) to continue the life cycle.
Explanation: Adult butterflies focus on finding mates and laying eggs on suitable host plants. Their short lifespan is dedicated to reproduction.
Mark: 1

18. (a) Answer: Bees help pollinate the flowers by transferring pollen from the anther of one flower to the stigma of another, enabling fertilisation and fruit/seed formation.
Explanation: Bees are pollinators. As they collect nectar, pollen sticks to their bodies and is carried to other flowers.
Mark: 1

18. (b) Answer: Plant B has fewer flowers, so fewer flowers are pollinated, resulting in fewer fruits.
Explanation: Fewer flowers mean fewer opportunities for pollination and fertilisation. Other acceptable reasons: lack of pollinators, poor health, insufficient light/water/nutrients.
Mark: 1

18. (c) Answer: Splitting / Explosive dispersal
Explanation: Fruits that split open when ripe (e.g., peas, beans, rubber tree) scatter seeds by mechanical force.
Mark: 1

18. (d) Answer: Seed dispersal spreads seeds away from the parent plant to reduce competition for light, water, nutrients, and space, and to colonise new areas.
Explanation: If seeds fall near the parent, seedlings compete with each other and the parent. Dispersal increases survival chances.
Mark: 1

19. (a) Answer: To find out which conditions (water, air, temperature) are needed for seed germination.
Explanation: The experiment tests the necessity of each condition by changing one variable at a time.
Mark: 1

19. (b) Answer: Set-up W and Set-up X
Explanation: W has water, X does not; all other conditions are the same. Since only W germinated, water is needed.
Mark: 1

19. (c) Answer: The seeds in Set-up Y had no air (oxygen). Oxygen is needed for respiration to release energy for germination.
Explanation: Germinating seeds respire to break down stored food for energy. Without air (oxygen), respiration cannot occur.
Mark: 1

19. (d) Answer: No, I do not agree. The experiment does not test light because all set-ups (W, X, Y, Z) had light. To test light, one set-up should be in darkness.
Explanation: A fair test requires only one changed variable. Since light was kept constant (present in all), no conclusion about light can be drawn.
Mark: 1

20. (a) Answer: Both life cycles are continuous cycles that repeat (egg/seed → young → adult → reproduces → back to egg/seed).
Explanation: Both show a cyclic pattern ensuring the next generation.
Mark: 1

20. (b) Answer: The butterfly has a pupa stage (4 stages, complete metamorphosis), while the plant does not have a pupa stage (seed → seedling → adult → flower/fruit).
OR: The young butterfly (caterpillar) looks very different from the adult, while the young plant (seedling) resembles the adult in basic structure (roots, stem, leaves).
Explanation: Any valid difference comparing stages, metamorphosis, or appearance of young vs adult.
Mark: 1

20. (c) Answer: It means the life cycle allows the species to continue from one generation to the next by producing offspring that grow into adults and reproduce again.
Explanation: Continuity of species = survival of the species over time through reproduction.
Mark: 1

20. (d) Answer: Many eggs are eaten by predators / do not hatch due to unsuitable conditions (e.g., dry weather, no host plant) / are destroyed by rain or wind.
Explanation: High mortality at the egg stage is common; producing many eggs compensates for low survival rates.
Mark: 1

End of Answer Key