What is a life cycle?

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Questions to think about…

What are the stages of a life cycle? What is a life cycle?

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What is a life cycle? • All living things go through a cycle called a life cycle. • A cycle is a pattern that repeats itself continuously.

• Living things may reproduce. They may have young while they are alive. • The young undergo the same life cycle as their parents. • This way, living things of the same kind continue to be found on Earth.

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What are the stages of a life cycle? A stage represents a step in the life cycle of a living thing.

Humans give birth to their young. The young and the adult are the stages in the life cycle of a human.

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What are the stages of a life cycle?

An adult bird does not give birth to its young. It lays eggs instead. The egg, chick and adult bird are the stages in the life cycle of a bird.

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What are the stages of a life cycle? The stages in a life cycle are different for different living things.

In general, the stages are egg, young and adult.

The life cycle of a living thing shows the order of the different stages. © 2014 Marshall Cavendish International (Singapore) Pte Ltd

What are the stages of a life cycle? • Some living things look very similar at different stages. • Some look very different, like that of the ladybird below.

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What are the stages of a life cycle? • Some animals have three-stage life cycles. Some examples are the cockroach and grasshopper.

• Some animals have four-stage life cycles. Some examples are the butterfly, mosquito and beetle.

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Life cycle of a human

The egg grows Theacycle into baby The young repeats The the life itself of a inside mother grows into when the adultto human begins until it is ready anan adult. reproduces. as egg. be born.

Young (Baby)

Adult

Egg

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Life cycle of a chicken Egg

The hard shell The A chick adultlooks chicken a lotis prevents the egg The egg has aAs it like able its to parents. reproduce Ahard chicken begins from drying out, and shell as its grows, and a new itas looks life cycle even its life an egg. protects the growing outer covering. more like begins. parents. animal its inside. Adult

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Young (Chick)

Life cycle of a frog

Egg When a as tadpole grows Known a tadpole, The frog breathes withit An adult frog isfrog into adult frog, it The The young egg isofbreathes covered askin has aan tail and its lungs and A frog’s eggs are able to reproduce. does not have a looks with very a jelly-like different through its gills. instead. tail usually laid in water. and gills anymore. from substance. its parents.

Adult

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Young (Tadpole)

Life cycle of a cockroach

Egg (in egg case) A Anymph nymph eggegg looks case moults is similar left a in AThe An Each female adult cockroach cockroach hatches to a dark few the times and safe except asin place it lays has into itsadult, wings. eggs a small Ifititan is for grows, smaller the eggs before and to does hatch reproduces, egg cockroach case, which acalled new can life a becoming not onhave their anwings. own. adult. contain cycle 16 nymph. to starts. 50 eggs.

Nymph Adult

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Life cycle of a grasshopper egg

An adultcycle grasshopper AA nymph moults several nymph The looks repeats almost A grasshopper Each egg starts can lay about 20 times. Itwhen grows intotoan the itself same as itsahatches parents, female its asain an nymph. egg. 120 eggs soil adult grasshopper but adult it life isinto smaller lays itsthe eggs and has in each time. which has wings. nothe wings. soil. Adult

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Nymph

Life cycle of a butterfly

Egg

Adult

A caterpillar very fast. Each hatches into When When theegg itcase isgrows time breaks for the open, The The pupa female may butterfly look still may As itaadult too big for its The caterpillar The butterfly moults lays askin, its few larva. The larva of abut Itgets then flies off and an caterpillar butterfly to change appears. into alay It many eggs on another are taking plant, itspreads grows athe new skin and times eggs as iton grows the leaves bigger. or butterfly is called adry leaves eggs to pupa, it things stops its wings feeding and starting place a new life cycle. sheds the old one. This is stem of a plant. caterpillar. hatch onto their own. hooks itself before flying ainside. leaf off. or a twig. called moulting.

Pupa © 2014 Marshall Cavendish International (Singapore) Pte Ltd

Larva (Caterpillar)

Life cycle of a mosquito Egg

When AItmosquito thefeeding case larva breaks is called open, a The cycle repeats itself when stops and Aan mosquito larva develops The oval-shaped mosquito wriggler. adult mosquito It lives in appears. water. It It a female adult mosquito lays changes into an adult into a pupa which livesor near eggs are laid in still slow moults waits for several its wings times to as dryit its eggs. mosquito in the pupal case. thebefore water surface. moving water. grows. flying off. Adult

Pupa © 2014 Marshall Cavendish International (Singapore) Pte Ltd

Larva (Wriggler)

Life cycle of a beetle Egg

Adult

The It stops cycleeating repeats and itself Aslowly When Ladybird A ladybird fullythe grown beetle beetle pupal ladybird eggs case larva when changes a female into adult an lives breaks beetle are onladybird laid plants. open, larva in small develops an It lays moults adultits adult ladybird beetle beetle in ladybird clusters several beetle times on a pupa. leaves. appears. as it theinto pupal eggs. case. grows. Larva

Pupa

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© 2014 Marshall Cavendish International (Singapore) Pte Ltd

© 2014 Marshall Cavendish International (Singapore) Pte Ltd