Download Reproduction 3 - P5 Diligent Science

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Questions to think about…
What are
the parts of
a flower?
How do flowering
plants
reproduce?
How do non-flowering
plants reproduce?
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Reproduction in flowering plants
• Flowering plants can reproduce
from seeds.
• To reproduce, plants produce
flowers which develop into fruits
and seeds.
• For fruits and seeds to be
produced, the flowers must be
pollinated and fertilised.
a tomato seed
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Parts of a flower
Male
parts
Female
parts
This flower has
both male and
female parts.
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Parts of a flower
• The male parts of the flower are the anther and
filament.
o
The anther contains pollen sacs which produce pollen
grains.
• The female parts of the flower are the stigma,
style, ovary and ovule.
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Parts of a flower
• Some plants like the papaya have the
male and female parts in separate flowers.
male flower of the
papaya plant
female flower of the
papaya plant
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Pollination
• Pollination is the transfer of pollen grains
from the anther to the stigma of a flower.
o The pollen grains can be transferred within
the same flower.
stigma
pollen grains
from anther
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Pollination
• Pollination is the transfer of pollen grains
from the anther to the stigma of a flower.
o The pollen grains can also be transferred from
one flower to another.
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Fertilisation
• When a pollen grain lands
on the surface of a
stigma, it produces a tube.
• The inside of the tip of the
tube contains the male
cells of the flower.
• These tubes grow down
the style to reach the
ovules in the ovary.
• Inside each ovule is an
egg cell.
stigma
pollen
tubes
pollen
grains
style
ovary
ovule
egg
cell
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Fertilisation
• When a pollen tube reaches the ovule, the
female egg cell and male cell combine.
• This process is called fertilisation.
yellow pollen grains
on a flower
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From flower to fruit
flower (after fertilisation)
After fertilisation, most
Inside
the
ovary,
the
The
ovary
then
grows
of the
flower
parts
ovules
begin
tooff
bigger
until
itdrop
becomes
wither
and
developfor
except
theseeds.
ovary.
ainto
fruit.
petals wither
ovary begins
to swell
seeds develop inside the
fruit, fruit grows bigger
petals drop off
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From flower to fruit
• Sexual reproduction involves a male and a
female.
• The process of producing new plants from
seeds involves both male and female
cells.
• Thus, sexual reproduction takes place in
plants.
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Dispersal of fruits and seeds
Well,
if the
seeds
grow
too
That’s
Also,
some
In
order
forright.
seeds
to
closely
together, while
fruits
scattered
grow
at are
a suitable
overcrowding
might
occur.
the
seeds
remain
inside
place,
they
must
be
I see! So if this happens,
them.
scattering
Soyoung
what The
are
the
ways
inof
scattered.
the
plants
may
not
seeds
orand
fruits
is called
which
fruits
seeds
are
get
enough
water,
dispersal.
mineralsdispersed?
and
sunlight to
Why
is that
so?
grow
well.
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Dispersal of fruits and seeds
• Wind
o
o
o
Fruits and seeds dispersed
by wind are often dry and
light.
Some of them have wing-like
structures.
They are easily carried by
wind.
angsana
lalang
dandelion
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Dispersal of fruits and seeds
• Animals
Some fruits can be eaten by animals.
o Their seeds are thrown away or passed out in
the animals’ droppings if swallowed.
o
kiwi
watermelon
papaya
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Dispersal of fruits and seeds
• Animals
o
Other fruits and seeds attach themselves to
animals’ bodies or our clothes by using hooks
or stiff hairs.
mimosa
lovegrass
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Dispersal of fruits and seeds
• Water
o
o
Fruits dispersed by water usually float and are
carried along rivers, streams or at sea.
They often have waterproof coverings or fibrous
husks to help them float in water.
coconut
lotus plant
mangrove
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Dispersal of fruits and seeds
• Splitting open forcefully
o
Some fruits split open
when ripe to shoot their
seeds away.
lady’s finger
cotton
rain tree
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Germination
• Parts of a seed
seed leaf
baby plant
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Germination
germinates
disperse
seed
ripe fruit and seeds
Photo of
tomato
seedling, p.
48, P5A
grows
seedling
leaves
During
this stage,
the seedling
A
seed
starts
to
Next,the
the
shoot
appears
and
First,
root
of
the
baby
cannot
make
its
own
food,
but
germinate
when
it
the
first
leaves
unfold.
The
plant
grows
out
of the
gets
it
energy
from
the
foodroot
lands
on
a
place
with
young
now leaves.
able to
seed
to plant
form
aisseed
seedling.
stored
in
its
enough
and
makewarmth
itsbaby
ownplant
food.
water.
shoot
young plant
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Germination
germinates
disperse
Photo of
tomato
seedling
seed
grows
ripe fruit and seeds
pollination and
fertilisation
occurs
When the flower of an adult
plant gets pollinated and
fertilised, the cycle of
reproduction repeats itself.
The young plant
develops into an adult
plant.
seedling
leaves
shoot
develops into
root
adult plant with flowers
young plant
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Non-flowering plants
ferns
• While flowering plants
reproduce from seeds,
non-flowering plants
reproduce in other ways.
• Spores
o
For example, ferns
reproduce from spores,
and do not produce seeds
like flowering plants.
spore bag of a fern
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Asexual Reproduction
• Underground stems
bud
The potato is an example of an
underground stem.
o It can be identified as a stem
because of the buds and leaf
scars.
o The buds can grow into new
plants when the potato in buried
in soil.
shoot
o
A potato
To grow a potato plant from
a cut piece of potato, each
piece must contain at least
one bud.
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Asexual Reproduction
• Underground stems
o
More examples:
buds growing into
new shoots
shoot
scale leaf
bud
fleshy leaf
scale leaf
bud
stem
bud
root
waterstem
chestnut
underground
onion
ginger
root
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Asexual Reproduction
• Suckers
Plants like banana and
pineapple reproduce by
developing upright
shoots called suckers.
o These shoots develop
from a certain part of the
stem.
o
heliconia
plant
sealing
wax palm
sucker
sucker of aplant
banana
pineapple
plant on the ground
sucker of a sealingsucker of a
wax palm heliconia plant
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Asexual Reproduction
• The leaves of plants like the bryophyllum,
begonia, and African violet can produce new
plants.
• Such leaves are often thick and fleshy.
leaf of
new plant
root of
new plant
bryophyllum
plant
bryophyllum leaf
© 2009 Marshall Cavendish International (Singapore) Private Limited
© 2009 Marshall Cavendish International (Singapore) Private Limited