© 2014 Marshall Cavendish International (Singapore) Pte Ltd
Questions to think about…
What are the stages
of a life cycle?
What is a
life cycle?
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
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.
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
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.
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
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.
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
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.
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
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.
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
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
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
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
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
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
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
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
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
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
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
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
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
© 2014 Marshall Cavendish International (Singapore) Pte Ltd
© 2014 Marshall Cavendish International (Singapore) Pte Ltd