Primary 3 Science · Answers and explanations
Life Cycles of Some Animals
Use this page to check the worksheet together. Talk about why each answer is right. Total: 20 marks.
Section A · Multiple choice 8 marks
1. Look at Table 1. Which two animals both have four stages in their life cycles?1 mark
Table 1 (for Questions 1 to 4)| Animal | Stages in life cycle | Name of young | Does the young look like the adult? | Where the young lives | Where the adult lives |
|---|
| Chicken | 3 | chick | Yes | on land | on land |
| Frog | 3 | tadpole | No | in water | on land and in water |
| Grasshopper | 3 | nymph | Yes | on land | on land |
| Butterfly | 4 | caterpillar | No | on land (on leaves) | flies in the air |
| Mosquito | 4 | wriggler | No | in water | flies in the air |
| Mealworm beetle | 4 | mealworm | No | on land | on land |
(A) Chicken and frog(B) Butterfly and mosquito(C) Frog and grasshopper(D) Chicken and butterfly
Answer: (B) Butterfly and mosquitoButterfly and mosquito are both marked 4. The other pairs each include an animal with 3 stages.
2. How many of the animals in Table 1 have a pupa stage in their life cycles?1 mark
(A) 3(B) 2(C) 4(D) 6
Answer: (A) 3Only animals with four stages (egg, larva, pupa, adult) have a pupa: butterfly, mosquito and mealworm beetle, which makes 3.
3. Which animal in Table 1 has a young that lives in water and an adult that flies in the air?1 mark
(A) Frog(B) Butterfly(C) Chicken(D) Mosquito
Answer: (D) MosquitoThe mosquito wriggler lives in water and the adult flies. The butterfly young lives on land, and a frog does not fly.
4. Which two animals in Table 1 have young that look like their adults?1 mark
(A) Frog and chicken(B) Mosquito and grasshopper(C) Chicken and grasshopper(D) Butterfly and frog
Answer: (C) Chicken and grasshopperOnly the chicken and grasshopper rows say Yes.
5. Figure 2 shows four pictures of a butterfly in different stages. Which choice puts the stages in the correct order, starting with the egg?1 mark
(A) B, C, D, A(B) B, D, C, A(C) B, D, A, C(D) A, B, D, C
Answer: (B) B, D, C, AB is the egg, D the caterpillar (larva), C the pupa and A the adult butterfly.
6. A caterpillar eats a lot of leaves, grows bigger and sheds its outer covering. Which stage is it in?1 mark
(A) Larva(B) Egg(C) Pupa(D) Adult
Answer: (A) LarvaThe larva is the stage that feeds, grows and moults.
7. Which stages of the mosquito live in water?1 mark
(A) Only the adult(B) Egg and adult(C) Larva, pupa and adult(D) Egg, larva and pupa
Answer: (D) Egg, larva and pupaThe first three stages are in water. The adult mosquito flies.
8. Which sentence about the pupa stage is correct?1 mark
(A) It eats leaves all day long.(B) It lays eggs.(C) It does not eat and develops into an adult.(D) It looks like a smaller adult.
Answer: (C) It does not eat and develops into an adult.A pupa does not feed. It stays still while its body changes into an adult.
Section B · Show what you know 12 marks
9. Figure 3 shows the life cycles of two animals, X and Y. State one similarity and one difference between the two life cycles.2 marks
Answer: Similarity: both start as an egg (or both have an adult stage). Difference: Y has 4 stages including a pupa, but X has 3 stages and no pupa.1 mark for a correct similarity (both begin with an egg, both end with an adult, both go round in a cycle). 1 mark for a correct difference (4 stages versus 3 stages, or Y has larva and pupa while X has a nymph).
10. Ravi found a tadpole in a pond. (a) Name the adult animal the tadpole will become. (b) State one way the tadpole is different from the adult.2 marks
Answer: (a) Frog. (b) The tadpole has a tail and lives only in water, but the adult frog lives on land and in water.1 mark for frog. 1 mark for one correct difference (has a tail, lives only in water, does not look like the adult).
11. Kim says, "A grasshopper has a pupa stage." Is she correct? Give a reason for your answer.2 marks
Answer: No. A grasshopper has only 3 stages: egg, nymph and adult. It has no pupa stage.1 mark for No. 1 mark for the reason (only 3 stages, egg, nymph, adult, no pupa).
12. The stages of a mosquito are listed below in the wrong order: adult, pupa, egg, larva. Write them in the correct order, starting with the egg.2 marks
Answer: egg, larva, pupa, adult2 marks for all four in the correct order. 1 mark if egg is first and adult last but the middle two are swapped.
13. Write each of these animals in the correct column of Table 2: butterfly, frog, mosquito, chicken.2 marks
Table 2| Animals with 3 stages | Animals with 4 stages |
|---|
| frog, chicken | butterfly, mosquito |
Answer: 3 stages: frog, chicken. 4 stages: butterfly, mosquito.2 marks for all four correct. 1 mark for two or three correct.
14. Mei Ling watched a butterfly grow. Read her notes in Table 3. (a) Which stage was the animal in from Day 11 to Day 18? (b) Explain why the leaves stayed untouched on these days.2 marks
Table 3: Mei Ling's notes on a butterfly| Days | What Mei Ling saw |
|---|
| Day 1 to Day 10 | The caterpillar ate many leaves. It grew longer and fatter. It shed its skin three times. |
| Day 11 to Day 18 | It hung from a twig inside a hard case. It did not move. The leaves stayed untouched. |
| Day 19 | A butterfly came out of the case and flew away. |
Answer: (a) Pupa. (b) The pupa does not eat.1 mark for pupa. 1 mark for the pupa does not eat (it is still while its body changes).
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