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Primary 6 PSLE Science Life Cycles Quiz
Free P6 PSLE Science Life Cycles quiz, Nemo3 AI version, with questions, answers, and PSLE-focused practice for Singapore students.
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Questions
Primary 6 PSLE Science Quiz - Life Cycles
Name: ________________________
Class: Primary 6 ______
Date: ________________________
Score: ______ / 50
Duration: 45 minutes
Total Marks: 50
Instructions:
- Answer all questions.
- For Section A, choose the correct option and write its letter (A, B, C, or D) in the brackets provided.
- For Section B and C, write your answers in the spaces provided.
- The number of marks for each question is shown in brackets [ ].
- Read each question carefully before answering.
Section A: Multiple-Choice Questions (10 × 1 mark = 10 marks)
1. Which of the following animals undergoes a four-stage life cycle?
A. Grasshopper
B. Chicken
C. Butterfly
D. Frog
[ ]
2. The diagram below shows the life cycle of a mosquito.
Generated diagram for Q2.
At which stage does the mosquito breathe through a siphon at the water surface?
A. Egg
B. Larva
C. Pupa
D. Adult
[ ]
3. A mealworm beetle undergoes a four-stage life cycle. Which stage comes immediately after the larva?
A. Egg
B. Pupa
C. Adult
D. Nymph
[ ]
4. Which of the following statements about the nymph stage in a three-stage life cycle is correct?
A. The nymph looks very different from the adult.
B. The nymph lives in water while the adult lives on land.
C. The nymph resembles a smaller version of the adult without wings.
D. The nymph is a non-feeding, inactive stage.
[ ]
5. The diagram below shows the life cycle of a flowering plant.
Generated diagram for Q5.
Which process occurs between pollination and fruit formation?
A. Germination
B. Fertilisation
C. Seed dispersal
D. Photosynthesis
[ ]
6. In the life cycle of a frog, which stage breathes through gills?
A. Egg
B. Tadpole
C. Froglet
D. Adult frog
[ ]
7. Which of the following is not a characteristic of animals that undergo a three-stage life cycle?
A. The young resemble the adults.
B. There is no pupal stage.
C. The young and adults usually live in the same habitat.
D. The young undergo complete metamorphosis.
[ ]
8. A student observed an insect that hatched from an egg into a nymph, which moulted several times before becoming an adult. This insect most likely undergoes a:
A. Four-stage life cycle
B. Three-stage life cycle
C. Two-stage life cycle
D. Five-stage life cycle
[ ]
9. The diagram below shows a seed germinating.
Generated diagram for Q9.
What is the function of the cotyledon during germination?
A. Protects the embryo
B. Absorbs water from the soil
C. Provides stored food for the seedling
D. Carries out photosynthesis
[ ]
10. Which of the following animals lays its eggs in water and has a larval stage that lives in water?
A. Butterfly
B. Grasshopper
C. Frog
D. Chicken
[ ]
Section B: Structured Questions (8 × 2 marks = 16 marks)
11. The diagram below shows the life cycle of a butterfly.
Generated diagram for Q11.
(a) Name the stage labelled X in the diagram.
[1]
(b) State one difference between the larva and the adult butterfly in terms of feeding method.
[1]
12. The table below shows the number of days each stage lasts in the life cycle of a mosquito at 25°C.
| Stage | Number of Days |
|---|---|
| Egg | 2 |
| Larva | 10 |
| Pupa | 2 |
| Adult | 30 |
(a) What is the total number of days from egg to adult?
[1]
(b) The mosquito spends the longest time in which stage?
[1]
13. The diagram below shows a young grasshopper (nymph) and an adult grasshopper.
Generated diagram for Q13.
(a) Based on the diagram, state one visible difference between the nymph and the adult grasshopper.
[1]
(b) Explain why the grasshopper is said to undergo incomplete metamorphosis.
[1]
14. A student placed some mealworms in a container with oats and observed them over several weeks. She recorded the following observations:
- Day 1: Small, white, cylindrical eggs seen.
- Day 10: Worm-like larvae moving and eating oats.
- Day 30: Larvae stop moving, become curved and pale.
- Day 40: Adult beetles emerge.
(a) Name the stage the mealworm is at on Day 30.
[1]
(b) State one reason why the larva stops moving and eating before becoming a pupa.
[1]
15. The diagram below shows the reproductive parts of a flower.
Generated diagram for Q15.
(a) Name the part labelled Y that produces pollen grains.
[1]
(b) After pollination, the pollen grain grows a tube down the style to reach the ovule. Name this process.
[1]
16. The diagram below shows a frog's life cycle.
Generated diagram for Q16.
(a) State one change in the breathing method as the tadpole develops into an adult frog.
[1]
(b) The tadpole has a long tail but the adult frog does not. State the function of the tail in the tadpole.
[1]
17. Seeds need water, air (oxygen), and suitable temperature to germinate. A student set up four experiments as shown:
| Set-up | Conditions |
|---|---|
| A | Water + Air + Suitable temperature |
| B | No water + Air + Suitable temperature |
| C | Water + No air + Suitable temperature |
| D | Water + Air + Low temperature (4°C) |
In which set-up(s) will the seeds germinate?
[2]
18. The diagram below shows the dispersal of seeds by wind.
Generated diagram for Q18.
(a) Name the structure on the fruit that helps it disperse by wind.
[1]
(b) Explain how this structure helps in wind dispersal.
[1]
Section C: Open-Ended Questions (4 × 6 marks = 24 marks)
19. The diagram below shows the life cycles of a butterfly and a grasshopper.
Image pending generation: diagram for Q19.
(a) State one similarity between the life cycles of the butterfly and the grasshopper.
[1]
(b) State two differences between the life cycles of the butterfly and the grasshopper.
[2]
(c) The caterpillar (larva) moults several times before becoming a pupa. Explain why moulting is necessary for the caterpillar.
[1]
(d) The grasshopper nymph also moults several times. State one difference in the outcome of moulting between the caterpillar and the grasshopper nymph.
[1]
(e) A farmer finds that grasshoppers are eating his crops. He sprays a chemical that prevents moulting. Explain how this would affect the grasshopper population over time.
[1]
20. The diagram below shows an experiment to investigate the conditions needed for seed germination. Three set-ups were prepared:
Generated experimental_setup for Q20.
(a) What is the aim of this experiment?
[1]
(b) Which tube is the control set-up? Explain your answer.
[1]
(c) In which tube(s) will the seeds germinate? Explain why.
[2]
(d) A student suggests adding a fourth tube with boiled water and a layer of oil on top, kept at room temperature. What condition is this tube testing for?
[1]
(e) If the seeds in Tube 1 germinate, the student observes that the radicle emerges first, followed by the plumule. State the function of the radicle in the young seedling.
[1]
End of Quiz
Answers
Primary 6 PSLE Science Quiz - Life Cycles (Answer Key)
Total Marks: 50
Section A: Multiple-Choice Questions (10 marks)
1. C – Butterfly undergoes a four-stage life cycle (egg, larva, pupa, adult). Grasshopper and chicken have three-stage life cycles; frog has a distinct metamorphosis but is not classified as four-stage in the same way.
2. B – The larva (wriggler) of a mosquito breathes through a siphon at the water surface. The pupa also breathes at the surface but through trumpets; the question specifies "siphon" which is characteristic of the larva.
3. B – In a four-stage life cycle (complete metamorphosis), the sequence is: Egg → Larva → Pupa → Adult.
4. C – In a three-stage life cycle (incomplete metamorphosis), the nymph resembles a smaller version of the adult without fully developed wings. It lives in the same habitat and feeds on the same food.
5. B – Fertilisation occurs after pollination (pollen reaches stigma) and before fruit formation. The fertilised ovule develops into a seed, and the ovary develops into the fruit.
6. B – The tadpole breathes through gills (external then internal). The froglet and adult frog breathe through lungs and skin.
7. D – Animals with three-stage life cycles undergo incomplete metamorphosis, not complete metamorphosis. Complete metamorphosis (four-stage) involves a pupal stage where the young look very different from the adult.
8. B – Hatching into a nymph that moults several times before becoming an adult is characteristic of a three-stage life cycle (incomplete metamorphosis).
9. C – The cotyledon (seed leaf) stores food (starch, proteins, oils) that provides energy and building materials for the growing seedling until it can photosynthesise.
10. C – Frog lays eggs in water (spawn), and the tadpole (larva) lives in water with gills. Butterflies lay eggs on leaves; grasshoppers lay eggs in soil; chickens lay eggs on land.
Section B: Structured Questions (16 marks)
11.
(a) Pupa (or Chrysalis) [1]
(b) The larva (caterpillar) has chewing mouthparts and eats leaves, while the adult butterfly has a proboscis (siphoning mouthpart) and feeds on nectar. [1]
Accept: Larva eats solid food (leaves); adult sucks liquid food (nectar).
12.
(a) 2 + 10 + 2 = 44 days [1]
(b) Adult stage (30 days) [1]
13.
(a) The nymph is smaller and has wing buds, while the adult is larger and has fully developed wings. [1]
Accept: Nymph lacks wings / has wing buds; adult has full wings. Or size difference.
(b) The grasshopper undergoes incomplete metamorphosis because the young (nymph) resembles the adult, lives in the same habitat, and there is no pupal stage. [1]
Key points: Resemblance, same habitat, no pupa.
14.
(a) Pupa [1]
(b) The larva stops moving and eating to undergo internal reorganisation (metamorphosis) into the adult form inside the pupal case. [1]
Accept: To transform into adult / for metamorphosis / to conserve energy for transformation.
15.
(a) Anther [1]
(b) Fertilisation [1]
Note: The growth of the pollen tube is "pollen tube growth"; the fusion of male and female gametes in the ovule is fertilisation. The question asks for the process of the tube growing down to reach the ovule – this is often called "pollen tube growth" but in PSLE context, "fertilisation" is the overall process after pollination. Accept "pollen tube growth" or "fertilisation".
16.
(a) The tadpole breathes through gills (in water), while the adult frog breathes through lungs and moist skin (on land and in water). [1]
(b) The tail is used for swimming in water. [1]
Accept: For locomotion / movement in water.
17. Set-up A only. [2]
Seeds need all three conditions: water (to activate enzymes, swell seed), air/oxygen (for respiration to release energy), and suitable temperature (for enzyme activity). Set-up B lacks water, C lacks air, D has unsuitable (too low) temperature.
18.
(a) Pappus (or parachute / feathery hairs) [1]
(b) The pappus increases the surface area of the fruit, allowing it to be caught by the wind and carried far from the parent plant. [1]
Key: Increases surface area / air resistance; caught by wind; dispersed far away.
Section C: Open-Ended Questions (24 marks)
19.
(a) Both life cycles begin with an egg stage and end with an adult stage. [1]
Accept: Both have egg and adult stages; both involve growth and development; both involve moulting.
(b) Any two of the following: [2]
- Butterfly has four stages (egg, larva, pupa, adult); grasshopper has three stages (egg, nymph, adult).
- Butterfly undergoes complete metamorphosis; grasshopper undergoes incomplete metamorphosis.
- Butterfly has a pupa stage; grasshopper has no pupa stage.
- Butterfly larva looks very different from adult; grasshopper nymph resembles the adult.
- Butterfly larva and adult have different feeding methods/ habitats; grasshopper nymph and adult have similar feeding methods/ habitats.
(c) The caterpillar's exoskeleton (cuticle) is hard and does not stretch, so it must shed it (moult) to allow its body to grow larger. [1]
Key: Exoskeleton is rigid / non-living / cannot expand; moulting allows growth.
(d) After moulting, the caterpillar remains a larva (still looks like a caterpillar), but the grasshopper nymph develops larger wing buds and looks more like the adult with each moult. [1]
Key difference: Caterpillar moults → still larva; Nymph moults → progressively more adult-like (wing development).
(e) If grasshoppers cannot moult, the nymphs cannot grow larger or develop into adults. They will die as nymphs, so the population will decrease over time as no new adults can reproduce. [1]
Key: Moulting essential for growth and development to reproductive adult; no adults → no reproduction → population decline.
20.
(a) To find out which conditions (water, air, temperature) are necessary for seed germination. [1]
Accept: To investigate the conditions needed for germination.
(b) Tube 1 is the control set-up. It has all three conditions (water, air, suitable temperature) present. [1]
Control has all variables present; experimental set-ups each lack one condition.
(c) Seeds will germinate in Tube 1 only. [1]
Tube 1 has water, air, and suitable (warm) temperature – all three conditions needed for germination. Tube 2 lacks water, Tube 3 has unsuitable (too low) temperature. [1]
Mark breakdown: Correct tube (1m), Correct explanation with all three conditions (1m).
(d) This tube tests whether air (oxygen) is needed for germination. [1]
Boiled water removes dissolved air; oil layer prevents atmospheric oxygen from dissolving. So no oxygen available.
(e) The radicle (embryonic root) grows downwards to anchor the seedling in the soil and absorb water and mineral salts from the soil. [1]
Accept: Anchor plant; absorb water and minerals.
Marking Notes for Teachers
- Section A: 1 mark each. No half marks.
- Section B: 2 marks each. Award 1 mark for each correct sub-part.
- Section C: 6 marks each. Follow the mark breakdown shown.
- Common mistakes to watch for:
- Q4: Confusing nymph (incomplete) with larva (complete).
- Q7: Thinking three-stage = complete metamorphosis.
- Q11(b): Vague answers like "eat different food" – must specify chewing vs siphoning / solid vs liquid.
- Q15(b): Confusing pollen tube growth with fertilisation.
- Q19(c): Saying "to grow" without mentioning the rigid exoskeleton.
- Q19(d): Not contrasting the outcome (larva stays larva vs nymph becomes more adult-like).
- Q20(b): Identifying wrong tube as control.
- Q20(d): Not linking boiled water + oil to removal of oxygen.
Total: 50 marks
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