Reproduction of flower plants
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IB ASSESSMENT STATEMENT
9.3.1 Draw and label a diagram showing the structure of
dicotyledonous animal-pollinated flower and plants.
Know the location and function of following structures
•Sepal
•Petal
•Anther
•Filaments
•Stigma
•Style
•ovary
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Structure of Flowers
Function of Flowers
Flowers are reproductive organs.
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Structure of Flowers
Sepals enclose the bud before it opens and
protect the flower while it is developing.
Sepal
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Structure of Flowers
Petals are often brightly colored and are found just
inside the sepals.
Petals attract insects and other pollinators to the
flower.
Petal
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Structure of Flowers
The male parts of a flower consist of an anther and
a filament, which together make up the stamen.
Anther
Stamen
Filament
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Structure of Flowers
An anther is an oval sac where meiosis takes place,
producing pollen grains (male sex cells).
Anther
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Structure of Flowers
The filament is a long, thin stalk that supports an
anther.
Filament
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Structure of Flowers
The innermost floral parts are carpels, also called
pistils, which produce the female gametophytes.
Stigma
Style
Ovary
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Carpel
Structure of Flowers
Each carpel has a broad base forming an ovary.
The ovary contains one or more ovules where female
sex cells are produced.
Ovary
Ovule
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Structure of Flowers
The narrow stalk of the carpel is the style.
Style
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Structure of Flowers
At the top of the style is the stigma—a sticky portion
where pollen grains frequently land.
Stigma
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Structure of Flowers
Parts of a Typical Flower
Stamen
Stigma
Anther
Filament
Style
Ovary
Ovary
Petal
Sepal
Ovule
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Carpel
Flower structure
Stigma
Style
Ovary
Petal
Anther
Sepal
Filament
© 2008 Paul Billiet ODWS
IB ASSESSMENT STATEMENT
9.3.1 Draw and label a diagram showing the structure of
dicotyledonous animal-pollinated flower and plants.
Know the location and function of following structures
Sepal
Petal
Anther
Filaments
Stigma
Style
ovary
Copyright Pearson Prentice Hall
IB Assessment Statement
Distinguish between pollination,
fertilization, and seed dispersal.
Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall
IB Assessment Statement
9.3.2 Distinguish between pollination,
fertilization and seed dispersal
• Pollination – pollen is transferred from
anther to a stigma
• Fertilization- After pollination a zygote is
formed by the fusion of a male gamete with a
female gamete inside the plants ovule.
•Seed Dispersal – Ovaries develop into a fruit.
The function of a fruit is to disperse seeds.
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Pollination
Pollen grains contain the male
gametes of the plant
They are picked up by a
pollinator and transferred to
another flower
Plants tend to specialise in
pollinators
This ensures the pollen is
delivered to same species of
plant
Yellow archangel Lamiastrum
galobdolon being pollinated by a bumble
bee Bombus hortorum
© 2008 Paul Billiet ODWS
Pollination
Small skipper Thymelicus flavus on marsh thistle Cirsium palustris
© 2008 Paul Billiet ODWS
Pollination
The honey bee Apis melifera on marsh thistle Cirsium palustris
© 2008 Paul Billiet ODWS
Pollination
Most species of flowering plants are
hermaphroditic
Pollen from a flower could land on the stigma
of the same flower or another flower on the
same plant = self pollination
Pollen transferred from the anther on one
flower to the stigma of another flower on a
different plant = cross pollination
© 2008 Paul Billiet ODWS
Fertilisation
Pollination ≠ Fertilisation
The male gamete (the male nucleus) has to
get to the egg cell
The egg cell lies in an ovule in an ovary at the
centre of the plant
The pollen grain germinates on the stigma
It grows a pollen tube down the style
It male nuclei travel down the pollen tube to
the ovule
© 2008 Paul Billiet ODWS
Fertilisation
The pollen grain
germinates on the
stigma
Pollen grains (N)
(male gametophyte)
It grows a pollen tube
down the style
It male nuclei travel
down the pollen tube
to the ovule
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Stigma
Fertilisation
The egg cell lies in an ovule in an ovary at the centre
of the plant
.
Haploid cell
(N)
Ovule
Ovary (2N)
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Fertilisation
Embryo sac (N)
(female gametophyte)
Pollen grows a pollen
tube down the style
It male nuclei travel down
the pollen tube to the
ovule
Sperm
Pollen tube
Egg cell
Polar nuclei
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Fertilisation
Embryo sac (N)
(female gametophyte)
The sperm moves from
the pollen tube to
combine with the egg of
the ovule to forma zygote
(seed).
Sperm
Pollen tube
Egg cell
Polar nuclei
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Fertilisation
The sperm moves from the pollen tube to combine
with the egg of the ovule to forma zygote (seed).
As the seed develops around the ovary will develop
into a fruit. Fruit protects the seed
Endosperm
(3N)
Zygote (2N)
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Fertilisation
Pollen grain
Stigma
Style
Ovule
Embryo sac
Ovary
© 2008 Paul Billiet ODWS
Pollen tube
IB ASSESSMENT STATEMENT
9.3.3 Draw and label a diagram showing the external
and internal structure of a named dicotyledonous
seed. Know the following location and function of the
following structures:
•Testa
•Micorphyle
•Embryo root
•Embryo shoot
• cotyledons
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Seed Germiination
The seed is the means by which an embryo can be
dispersed to distant locations.
It is a protective structure for the embryo.
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Seed Structure
a) Testa protects the plant embryo and the cotyledon food stores
b) Radicle is the embryonic root
c) Plumule is the embryonic stem
d) Cotyledons contain food store for the seed
e) Micropyle is a hole in the testa ( from pollen tube fertilisation)
through which water can enter the seed prior to germination
f) Scar is where the ovule was attached to the carpel wall.
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LE 38-8a
Seed coat
(Testa)
Radicle
(Embryo
root)
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Embryo
Shoots
(plumule)
Cotyledons
Copyright Pearson Prentice Hall
IB ASSESSMENT STATEMENT
9.3.3 Draw and label a diagram showing the external
and internal structure of a named dicotyledonous
seed. Know the following location and function of the
following structures:
•Testa
•Micorphyle
•Embryo root
•Embryo shoot
• cotyledons
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IB Assessment Statements
9.3.4.Explain the conditions needed for germinaton of
a typical seed.
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Seed Germination
Conditions for the germination of a typical seed.
Seeds require a combination of:
• Oxygen for aerobic respiration
• Water to metabolically activate the cells
• temperature for optimal function of enzymes
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IB Assessment Statement
9.3.5 Outline the metabolic processes
during seed germination of a starchy seed,
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Metabolic processes during germination of a starchy seed.
The metabolic events of seed
germination:
a) Water absorbed and the
activation of cotyledon cells
b) Synthesis of gibberellin
which is a plant growth
substance. (Hormone is some
text longer a term used to
describe such compounds).
c) The gibberellin brings about
the synthesis of the
carbohydrase enzyme
amylase
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Metabolic processes during germination of a starchy seed.
The metabolic events of seed
germination:
d) Starch is hydrolysed to
maltose before being absorbed
by the embryonic plant
e) The maltose can be further
hydrolysed to glucose for
respiration on polymerised to
cellulose for cell wall formation.
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Metabolic processes during germination of a starchy seed.
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