Life Cycles

Grade 3 · Science · Study Guide

Explore how living things grow and change through their life cycles from birth to death.

A life cycle is the series of changes a living thing goes through from the beginning of its life to the end. All living things — plants, insects, frogs, and even humans — have life cycles. Each stage in a life cycle looks different and has a specific job to do.

Butterflies have one of the most dramatic life cycles, called complete metamorphosis. It has four stages: egg, larva (caterpillar), pupa (chrysalis), and adult butterfly. The caterpillar eats and grows, then the chrysalis is a resting stage where the body completely transforms. Frogs go through a similar process: egg, tadpole, froglet, adult frog.

Plants have life cycles too! A flowering plant starts as a seed. The seed germinates (sprouts) and grows into a seedling, then a full plant. The plant flowers, gets pollinated, and produces new seeds — starting the cycle again. Some cycles take weeks, like a bean plant, and others take years, like an oak tree. Understanding life cycles helps us know how to care for living things and why they look the way they do at different stages of life.

Key terms

Life Cycle
The series of stages a living thing passes through from birth to death and reproduction.
Metamorphosis
A dramatic change in body form as an animal grows, like a caterpillar becoming a butterfly.
Larva
The worm-like stage of an insect after hatching from an egg (like a caterpillar).
Germinate
When a seed sprouts and begins to grow into a new plant.
Pupa
The resting stage in an insect's life cycle where it transforms inside a cocoon or chrysalis.

Flashcards

Life Cycle
All the stages a living thing goes through from birth to death.
Egg
The first stage in many animal life cycles where a new organism begins to develop.
Larva
The worm-like young form of an insect (like a caterpillar or maggot).
Pupa
The transforming stage inside a cocoon or chrysalis.
Metamorphosis
A big change in body form as an animal develops.
Germinate
When a seed sprouts and begins to grow.
Seedling
A young plant that has just sprouted from a seed.

Questions

  1. What are the four stages of a butterfly's life cycle in order?

    1. Egg, larva, pupa, adult
    2. Larva, egg, pupa, adult
    3. Egg, pupa, larva, adult
    4. Adult, egg, larva, pupa
    Show answer

    Answer: Egg, larva, pupa, adult

    A butterfly's complete metamorphosis goes: egg → larva (caterpillar) → pupa (chrysalis) → adult butterfly. This order is always the same.

  2. All living things go through a life cycle.

    Show answer

    Answer: True

    Every living thing — animals, plants, fungi — has a life cycle. They are all born, grow, reproduce, and eventually die.

  3. What is a tadpole?

    1. A baby bird
    2. A young frog
    3. A type of insect
    4. A plant seedling
    Show answer

    Answer: A young frog

    A tadpole is the young (larval) stage of a frog. It lives in water and gradually grows legs and loses its tail to become a frog.

  4. When a seed sprouts and starts growing, it is called ___.

    Show answer

    Answer: germination

    Germination is when a seed absorbs water, splits open, and sends out a tiny root and shoot to become a new plant.

  5. During which stage of a butterfly's life cycle does the most dramatic change happen?

    1. Egg
    2. Larva
    3. Pupa
    4. Adult
    Show answer

    Answer: Pupa

    During the pupa stage, the caterpillar's body completely reorganizes inside the chrysalis to form an adult butterfly — the most dramatic transformation.

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