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Primary 6 PSLE Science Life Cycles Quiz
Free Exam-Derived Owl Alpha Primary 6 PSLE Science Life Cycles quiz with questions and answers for Singapore students. This page is rendered as a direct URL so the questions and answers can be discovered without pressing in-page buttons.
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Questions
Primary 6 PSLE Science Quiz - Life Cycles
Name: ______________________________
Class: ______________________________
Date: ______________________________
Score: ________ / 40
Duration: 40 minutes
Total Marks: 40
Instructions
- Answer all questions.
- Write your answers in the spaces provided.
- Marks for each question are shown in brackets [ ].
- You are advised to spend no more than 40 minutes on this paper.
- The use of calculators is not required.
Section A: Multiple Choice Questions (10 marks)
Questions 1–10: Choose the most correct answer. Write the letter (A, B, C, or D) in the space provided.
1. Which of the following shows the correct order of the life cycle of a butterfly?
A) Egg → Pupa → Larva → Adult B) Egg → Larva → Adult → Pupa C) Egg → Larva → Pupa → Adult D) Larva → Egg → Pupa → Adult
Answer: ________ [1]
2. During which stage of a frog's life cycle does it develop lungs?
A) Egg B) Tadpole C) Adult frog only D) Young frog (froglet)
Answer: ________ [1]
3. Which of the following animals undergoes incomplete metamorphosis?
A) Butterfly B) Mosquito C) Grasshopper D) Beetle
Answer: ________ [1]
4. What is the main difference between complete and incomplete metamorphosis?
A) Complete metamorphosis has an egg stage; incomplete does not. B) Complete metamorphosis has a pupa stage; incomplete does not. C) Incomplete metamorphosis has four stages; complete has three. D) Incomplete metamorphosis involves a larva; complete involves a nymph.
Answer: ________ [1]
5. A plant produces seeds that grow into new plants. Which part of the plant's life cycle do the seeds represent?
A) The beginning of a new generation B) The end of the parent plant's life C) The flowering stage only D) The germination stage
Answer: ________ [1]
6. Which of the following is a characteristic of a nymph in incomplete metamorphosis?
A) It looks very different from the adult. B) It lives in water. C) It resembles a smaller version of the adult. D) It is enclosed in a cocoon.
Answer: ________ [1]
7. The diagram below shows the life cycle of a mealworm beetle.
Egg → Larva → ? → Adult
What is the missing stage?
A) Nymph B) Pupa C) Caterpillar D) Cocoon
Answer: ________ [1]
8. Which of the following statements about the life cycle of a flowering plant is true?
A) The seed is produced before pollination. B) Germination occurs after the seed is dispersed. C) The flower appears after the fruit. D) Fertilisation occurs before pollination.
Answer: ________ [1]
9. A student observed that a caterpillar moults several times during its larval stage. Why does the caterpillar moult?
A) To change into a pupa B) To replace damaged skin C) To grow bigger as its outer skin does not stretch D) To prepare for hibernation
Answer: ________ [1]
10. Which organism has a life cycle that includes a pupal stage?
A) Cockroach B) Dragonfly C) Housefly D) Grasshopper
Answer: ________ [1]
Section B: Short Answer Questions (20 marks)
Questions 11–16: Write your answers in the spaces provided.
11. The diagram shows the life cycle of a frog.
Egg → Tadpole → Froglet → Adult Frog
(a) State one way in which a tadpole is different from an adult frog. [1]
(b) Explain why the tadpole must live in water but the adult frog can live on land. [2]
12. Complete the table below to compare the life cycles of a butterfly and a grasshopper. [4]
| Feature | Butterfly | Grasshopper |
|---|---|---|
| Type of metamorphosis | (a) _______________ | (b) _______________ |
| Number of stages | (c) _______________ | (d) _______________ |
| Name of young stage | (e) _______________ | (f) _______________ |
| Pupal stage present? | (g) _______________ | (h) _______________ |
13. The diagram shows the life cycle of a flowering plant.
Seed → Germination → Seedling → Adult Plant → Flowering → Pollination → Fertilisation → Seed Formation → Seed Dispersal
(a) Name the process by which the seed begins to grow into a seedling. [1]
(b) State two conditions necessary for the process named in (a) to occur. [2]
(c) Explain the importance of seed dispersal in the life cycle of a plant. [2]
14. A student placed some bean seeds on wet cotton wool in a sealed plastic bag and left it in a warm place. After five days, the seeds germinated.
(a) Explain why the seeds were able to germinate even though they were not planted in soil. [1]
(b) The student then opened the bag and planted the seedlings in soil near a window. Predict what would happen to the seedlings after two weeks and give a reason for your answer. [2]
15. The diagram shows four organisms at different stages of their life cycles.
- W: A caterpillar eating leaves
- X: A chrysalis hanging from a branch
- Y: A butterfly emerging from the chrysalis
- Z: A butterfly laying eggs on a leaf
(a) Arrange the letters W, X, Y, Z in the correct order of the butterfly life cycle. [1]
________ → ________ → ________ → ________
(b) State one important change that occurs inside the chrysalis (Stage X). [1]
16. Explain why some insects, such as mosquitoes, are considered harmful during their larval stage. [2]
Section C: Structured / Application Questions (10 marks)
Questions 17–20: Answer all questions. Show your reasoning clearly.
17. A farmer noticed that his cabbage plants were being eaten by caterpillars. He also found some cabbage white butterflies flying around his farm.
(a) Using your knowledge of the butterfly life cycle, explain how the butterflies are related to the caterpillars eating the cabbages. [2]
(b) The farmer decided to remove all the caterpillars by hand. Predict and explain what would happen to the number of butterflies on the farm. [2]
18. The table below shows the average duration (in days) of each stage in the life cycles of two insects at 25°C.
| Stage | Insect P | Insect Q |
|---|---|---|
| Egg | 4 | 5 |
| Larva | 14 | — |
| Nymph | — | 21 |
| Pupa | 10 | — |
| Adult | 30 | 25 |
(a) Identify which insect (P or Q) undergoes complete metamorphosis. Give a reason for your answer. [2]
(b) Calculate the total length of the life cycle of Insect P from egg to the end of the adult stage. [1]
(c) A scientist found that when the temperature was lowered to 15°C, the larval stage of Insect P lasted 28 days instead of 14 days. Suggest a reason for this observation. [1]
19. A student wanted to investigate whether light is needed for the germination of seeds. She set up the experiment as shown below.
- Setup 1: 10 bean seeds on wet cotton wool, placed in a bright cupboard.
- Setup 2: 10 bean seeds on wet cotton wool, placed in a dark cupboard.
- Both cupboards were kept at the same temperature.
After 7 days, 8 seeds germinated in Setup 1 and 7 seeds germinated in Setup 2.
(a) Identify the variable that the student changed (independent variable). [1]
(b) Identify two variables that were kept the same (controlled variables). [2]
(c) Based on the results, what conclusion can the student draw? [1]
20. Read the following passage and answer the questions.
The mayfly is an insect with a unique life cycle. The nymph lives in freshwater streams for up to two years, feeding on algae. When it is ready, the nymph rises to the surface and emerges as a winged adult. The adult mayfly does not feed and lives for only one to two days. Its sole purpose is to mate and lay eggs in the water before it dies.
(a) Does the mayfly undergo complete or incomplete metamorphosis? Explain your answer. [2]
(b) Explain why the adult mayfly does not need to feed. [1]
(c) Suggest one reason why the nymph stage lasts much longer than the adult stage. [1]
End of Quiz
Answers
Primary 6 PSLE Science Quiz – Life Cycles
Answer Key
Section A: Multiple Choice Questions (10 marks)
1. C [1]
- Explanation: Complete metamorphosis in a butterfly follows the sequence: Egg → Larva (caterpillar) → Pupa (chrysalis) → Adult.
- Common mistake: Students may confuse the order of larva and pupa (choosing A).
2. D [1]
- Explanation: The froglet (young frog) stage is when the tadpole undergoes significant changes, including the development of lungs and legs, allowing it to live on land. Tadpoles breathe through gills.
- Common mistake: Students may choose B (tadpole) because they associate change with the tadpole, but lungs develop during the froglet stage.
3. C [1]
- Explanation: Grasshoppers undergo incomplete metamorphosis (egg → nymph → adult). Butterflies, mosquitoes, and beetles undergo complete metamorphosis.
- Common mistake: Students may select mosquito (B) as it is also a common insect, but mosquitoes undergo complete metamorphosis with a pupal stage.
4. B [1]
- Explanation: Complete metamorphosis has four stages including a pupa stage, while incomplete metamorphosis has three stages with no pupa stage.
- Common mistake: Students may choose D, but it is the reverse — complete metamorphosis involves a larva, while incomplete involves a nymph.
5. A [1]
- Explanation: Seeds contain the embryo of a new plant and represent the beginning of a new generation in the plant life cycle.
6. C [1]
- Explanation: A nymph resembles a smaller version of the adult but lacks fully developed wings and reproductive organs. It does not look drastically different (unlike a larva).
7. B [1]
- Explanation: The mealworm beetle undergoes complete metamorphosis. The missing stage between larva and adult is the pupa.
8. B [1]
- Explanation: Germination occurs after the seed has been dispersed and lands in a suitable environment with water, air, and warmth.
- Common mistake: Students may choose D, but pollination must occur before fertilisation.
9. C [1]
- Explanation: The caterpillar's outer skin (exoskeleton) does not stretch, so it must shed (moult) its skin to grow bigger.
10. C [1]
- Explanation: Houseflies undergo complete metamorphosis (egg → larva/maggot → pupa → adult). Cockroaches, dragonflies, and grasshoppers undergo incomplete metamorphosis.
Section B: Short Answer Questions (20 marks)
11. (a) [1]
- A tadpole has a tail / breathes through gills / has no legs / lives in water, whereas an adult frog has legs / breathes through lungs / has no tail / can live on land.
- Accept any valid difference. Award 1 mark for a clear, correct difference.
(b) [2]
- A tadpole breathes through gills, which can only extract oxygen from water. [1]
- An adult frog has developed lungs (and can also breathe through its skin), which allow it to breathe air on land. [1]
- Award 1 mark for each valid point. Students must link the breathing structure to the habitat.
12. [4]
| Feature | Butterfly | Grasshopper |
|---|---|---|
| Type of metamorphosis | (a) Complete [½] | (b) Incomplete [½] |
| Number of stages | (c) Four / 4 [½] | (d) Three / 3 [½] |
| Name of young stage | (e) Larva / Caterpillar [½] | (f) Nymph [½] |
| Pupal stage present? | (g) Yes [½] | (h) No [½] |
- Award ½ mark for each correct answer. Total: 4 marks.
13. (a) [1]
- Germination
(b) [2]
- Water / moisture [1]
- Warmth / suitable temperature [1]
- Accept also: oxygen / air. Any two valid conditions. Award 1 mark each.
(c) [2]
- Seed dispersal reduces competition between the parent plant and the offspring for resources such as water, sunlight, and nutrients. [1]
- It also allows the species to spread to new areas / colonise new habitats, increasing the chances of survival of the species. [1]
- Award 1 mark for each valid point. Students must explain the benefit, not just define dispersal.
14. (a) [1]
- Seeds contain stored food (in the cotyledons / endosperm) that provides energy for germination, so they do not need soil initially. [1]
- Accept: The wet cotton wool provided water, which is needed for germination.
(b) [2]
- The seedlings would grow into healthy green plants. [1]
- This is because, once planted in soil and placed near a window, the seedlings can obtain water and minerals from the soil and light from the window for photosynthesis, allowing them to make their own food and grow. [1]
- Award 1 mark for the prediction and 1 mark for the reason. Accept reasonable alternatives (e.g., seedlings grow taller/greener).
15. (a) [1]
- W → X → Y → Z [1]
- (Caterpillar → Chrysalis → Emerging butterfly → Butterfly laying eggs)
(b) [1]
- The caterpillar's body is broken down and reorganised into the body of an adult butterfly (wings, legs, antennae, etc.). [1]
- Accept any valid description of the transformation inside the chrysalis.
16. [2]
- Mosquito larvae live in stagnant water and can develop into adult mosquitoes. [1]
- Adult mosquitoes spread diseases such as dengue fever and malaria when they bite humans, causing illness. [1]
- Award 1 mark for linking larvae to the harmful adult stage and 1 mark for naming the harm (disease transmission). Accept other valid reasons (e.g., larvae compete with other aquatic organisms for food).
Section C: Structured / Application Questions (10 marks)
17. (a) [2]
- The butterflies lay eggs on the cabbage plants. [1]
- The eggs hatch into caterpillars (larvae), which feed on the cabbage leaves. [1]
- Award 1 mark for each logical step linking butterflies to caterpillars.
(b) [2]
- The number of butterflies on the farm would decrease. [1]
- This is because removing the caterpillars means they cannot develop into pupae and then into adult butterflies, so fewer butterflies will be produced. [1]
- Award 1 mark for the prediction and 1 mark for the explanation.
18. (a) [2]
- Insect P undergoes complete metamorphosis. [1]
- This is because its life cycle includes a pupal stage, which is characteristic of complete metamorphosis. [1]
- (Insect Q has a nymph stage and no pupal stage, indicating incomplete metamorphosis.)
(b) [1]
- Total = 4 + 14 + 10 + 30 = 58 days [1]
- Award 1 mark for the correct answer. Accept if working is shown.
(c) [1]
- At a lower temperature, the metabolic rate of the larva decreases, so it grows and develops more slowly, taking longer to complete the larval stage. [1]
- Accept any valid explanation linking temperature to the rate of development.
19. (a) [1]
- Light / amount of light / presence or absence of light [1]
(b) [2]
- Temperature [1]
- Amount of water / moisture / wet cotton wool [1]
- Accept also: type of seed, number of seeds, type of container. Award 1 mark each for any two valid controlled variables.
(c) [1]
- Light is not necessary for the germination of bean seeds. [1]
- Accept: Seeds can germinate in both light and dark conditions. Award 1 mark for a conclusion consistent with the results.
20. (a) [2]
- The mayfly undergoes incomplete metamorphosis. [1]
- This is because its life cycle has three stages (egg → nymph → adult) and does not include a pupal stage. [1]
- Award 1 mark for identifying the type and 1 mark for the reason.
(b) [1]
- The adult mayfly lives for only one to two days and its sole purpose is to reproduce (mate and lay eggs). It does not have enough time to feed and does not need energy for long-term survival. [1]
- Accept: It does not have functional mouthparts / it uses stored energy from the nymph stage.
(c) [1]
- The nymph stage lasts longer because the nymph needs time to feed and grow / store enough energy to develop into an adult and reproduce. [1]
- Accept any valid reason. Award 1 mark.
Total: 40 marks