1. Life Cycles and Metamorphosis

2. Life Cycles and Metamorphosis
You have not always looked like you do today. Your body has gone through many changes in your life. These changes are a part of the human life cycle, which includes being a baby, toddler, child, teenager, adult, and an elder.

3. Life Cycles and Metamorphosis
Every living thing has a life cycle.
A life cycle is all of the changes an organism goes through in its life.
Members of a species go through similar life cycles.
In this lesson, you will learn about different life cycles.

4. Plant Life Cycle
Giant oak trees begin their lives as small acorns.

5. Plant Life Cycle
Other plants begin as small seeds. The seeds change to seedlings and then go through many stages in the plant life cycle.

6. Plant Life Cycle
The tree does not start to reproduce until it reaches the last stages of its life cycle. Then it will produce acorns and the life cycle will begin again.

7. Plant Life Cycle
Other plants have similar life cycles. The plants begin as seeds. The seeds germinate, or begin to grow. Roots sprout, then a tiny stem. As the stem pushes its way through the soil, leaves begin to grow. The mature flowers produce seeds to start the life cycle all over again.

8. Plant Life Cycle

9. Metamorphosis
Even when the oak tree is small, it still has a stem and leaves like the adult tree.
Some animals have a different life cycle.
These organisms look nothing like adults when they are in the middle stages of their life cycle.

10. Metamorphosis
These organisms, such as frogs, insects, and lobsters, go through metamorphosis.
Metamorphosis occurs when an egg goes through distinct stages on its way to become an adult.

11. Metamorphosis

12. Metamorphosis
The frog’s life cycle goes from being an egg to a tadpole to a frog.
This life cycle is an example of a complete metamorphosis.
The metamorphosis is complete because the tadpole stage (larva) is different from the adult stage.

13. Metamorphosis
A tadpole can breathe under water and has a tail, while frogs breathe air and have no tails.

14. Metamorphosis

15. Metamorphosis
The life cycle of many insects is also a complete metamorphosis.
Some insects go through their life cycles in four stages: egg, caterpillar (larva), chrysalis, and butterfly. This is a complete metamorphosis because a caterpillar is very different from the adult butterfly.

16. Metamorphosis

17. Metamorphosis Other insects go through incomplete metamorphosis.
Incomplete metamorphosis occurs when the larvae look similar to the adults.
These insects have a stage called the nymph stage. A nymph looks like a smaller version of the adult.

18. Metamorphosis
Grasshoppers and lobsters both go through incomplete metamorphosis.
A grasshopper nymph looks like an adult grasshopper.

19. When an egg goes through distinct stages on its way to becoming an adult, what takes place?
A. Larval stage
B. Metamorphosis
C. Reproduction
D. Nymph stage

20. When an egg goes through distinct stages on its way to becoming an adult, what takes place?
B. metamorphosis

21. An insect has the following stages in its life cycle: egg – nymph – adult Which kind of change does this insect undergo?
A. Complete metamorphosis
B. Incomplete metamorphosis
C. Interrupted metamorphosis
D. An incomplete life cycle

22. An insect has the following stages in its life cycle: egg – nymph – adult Which kind of change does this insect undergo?
B. Incomplete metamorphosis

23. What do a seed and an egg have in common?
A. Both are adult stages in life cycles.
B. Both are larval stages in life cycles.
C. Both are the first stages in life cycles.
D. Both are the last stages in life cycles.

24. What do a seed and an egg have in common?
C. Both are the first stages in life cycles.