flowers as reproductive structures abbotts page 53
TRANSCRIPT
FLOWERS AS REPRODUCTIVE STRUCTURES
ABBOTTS
PAGE 53
FLOWER STRUCTURE PAGE 53
Parts of a Flower
Stigma
Style
Ovary
Carpel/Pistil
(female) Anther
Filament
Stamen (male)
petals
ovule
sepal
DIAGRAM PAGE 53
Parts of the Flower
Peduncle: flower stalk Receptacle: part of stalk bearing the floral organs, at base
of flower Sepal: leaflike structures at flower base, protects young
flower bud Calyx: all the sepals together form the calyx Petal: located inside and above the sepals, often large and
colourful, sometimes scented, sometimes producing nectar Stamen: male part of the flower, consist of the anther and
filament, makes pollen grains Pollen: grains containing the male gametes Pistil/Carpel: female part of the flower, consist of the
stigma, style and ovary Ovule: located in the ovaries, carry female gametes
FLOWER ANATOMY
Anther
Sepal
Filament
Petal
Stigma
Pollen Tube
Ovary
Style
Ovule
Stamen
Carpel
PURPOSE OF EACH FLOWER PART
A. Carpel:
1. Stigma- Covered in a sticky substance that pollen grains can stick to
2. Style- Raises the stigma away from the ovary to decrease pollen contamination
3. Ovary- Protects the ovule after fertilization; becomes the fruit
4. Pollen Tube- What the pollen travels through to reach the eggs in the ovule
5. Ovule- Like the egg in animals; once fertilization takes place it will become the seed.
PURPOSE OF EACH FLOWER PART
B. Stamen:
Anther- Contain pollen sacs. The sacs release pollen on to the outside of the anthers where wind or other organisms can transfer the pollen to the carpel for fertilization.
Filament- Stalk of the anther
C. Petal: Petals are used to attract insects into the flower, they may have guidelines on them and be scented.
D. Sepal: Sepals protect the flower whilst the flower is developing from a bud.
FLOWER FUNCTIONS
Flowers contain the reproductive organs Stamens – male parts Carpel – female part
Flowers attract pollinators who transport pollen from the anther to the stigma
PAGE 54
TO DO
DRAW FLOWER IN YOUR
WORKBOOKPAGE 53
DRAWING11
Use a sharp HB pencil Drawing must be big enough e.g. Half a page Leave enough space around the drawing for labels Labels must be written in ink and not cover the diagram
itself Label lines must be in ink, drawn with a ruler and must
not cross each other The line must not end with an arrow and it must indicate
the exact part that is being labelled The drawing should have a heading stating what the
diagram shows
POLLINATION BY POLLINATORS
Pollinators are organisms that aid in the transfer of pollen from anther to stigma, to allow for fertilization
Flowers get pollinated and pollinators get food
ADD TO WORKBOOK
Pollination takes place through:
insectswindbirdswater
POLLINATION
13
Is the transfer of ripe pollen containing the male gametes from the anthers to the stigma to allow for fertilization
PAGE 54
14
Self Pollination = when the pollen from one flower is used to fertilize the eggs produced by that same flower; true-bred flowers
15
Cross Pollination = when the pollen from one flower is used to fertilize a different flower of the same type
POLLINATION BY POLLINATORS
Pollinators are animals that move pollen from anther to stigma, to allow for fertilisation
Pollinators visit flowers to get food (pollen and nectar)
Flowers get pollinated and pollinators get food Pollinators are mostly insects (some are
vertebrates)
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ADAPTATIONS OF INSECT-POLLINATED FLOWERS
The flowers have large conspicuous petals in bright colours
Sweet scent to attract moths and butterflies Offer a reward of nectar and/pollen Anthers and stigma are often inside the flower Pollen grains are often sticky or spiky (stick to the
insects Large quantities of pollen are produced Flowers have nectar guides to help the insect find
the centre of the flower
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SOUTH AFRICAN INSECT-POLLINATED FLOWER
Bluish in colour – bees pollinate blue and yellow flowers
Delicate sweet scent Sturdy with a landing platform
on which the bee lands Have nectaries which secrete
nectar (sweet liquid) to attract and feed pollinators
Flowers are open in the daytime
Pollen grains stick to the bodies of bees
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Salvia africana-caerulea
ADAPTATIONS OF BIRD POLLINATED FLOWERS
Flowers produce a large quantity of dilute nectar Flowers are bigger than insect pollinated flowers Flowers are red and open in the daytime Flowers are sturdy – birds are rough Flowers have little or no scent – birds have a poor
sense of smell Ovules are protected from the probing beaks Pollen grains stick together in clumps – bird picks up
a lot of pollen in one visit Flowers are erect with a landing platform
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SOUTH AFRICAN BIRD-POLLINATED FLOWER
Flowers stand at the tips of long stalks
Flowers have a sturdy landing place for sunbirds
Flowers have three orange sepals and three blue petals
Two of the petals join together to form a dart to hold the stamens, style and nectary
Dart provides a perch for the sunbird
PAGE 57
strelitzia reginae
The structure and pollination of the flowers is fascinating. The hard, beak-like sheath from which the flower emerges, is called the spathe. This is held at right angles to the stem, and has the appearance of a bird's head. Each spathe contains 4 to 6 flowers, and these emerge one at a time from the spathe. Each flower consists of 3 clear yellow sepals and 3 deep purple petals. The yellow sepals give the appearance of a crest on the 'bird's' head. Two of the purple petals are joined together around the stamens and the style to form an arrow-like structure. The third purple petal is visible as a small scale.
EXTRA STUFF
DART FORMED BYBLUE PETALS
SEPALS
SPATHE
ADAPATATIONS OF A WIND-POLLINATED FLOWER
Small, inconspicuous flowers without any bright petals
Petals are often absent for better exposure to wind
No nectar or produced No scent Male flowers are often arranged in
catkins (clusters) that move freely in the wind
Long thin filaments hang outside the flower, easily shaken by the wind
Anthers are large and well exposed to catch the wind
Pollen grains are small (non sticky) and light and easily carried by the wind
Stigmas are long and feather- like with a large surface area and outside the flower to trap pollen
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Examples of inflorescence types.
An inflorescence is a group or cluster of flowers arranged on a stem
WORKBOOK
SOUTH AFRICAN WIND POLLINATED FLOWER
Simple flowers with all the features of wind pollinated flowers except the anthers are not visible
PAGE 58
Thamnochortus pellucidus in flower
Female inflorescence Male inflorescence
The male infloresence hangs down on a flexible stalk to shake the pollen free
Wind distributes the pollen to the female infloresence – caught by bracts and directed to hidden female flowers
Insect Bird
Shape of flower Corolla tube wide and often horizontal – suits approach flight of insectsLanding platform present
Corolla tube often long and narrow to suit shape of birds beakNo landing platform
Colour Not red- bee deterrent Often red – bird attraction colour
Corolla Not large or strong Larger and stronger
Nectar Less nectar- stronger concentration
Much dilute nectar
Nectar guides Present – insect vision not good
Absent – bird has excellent vision
Scent yes Never
Night blooming Sometimes – moths pollinate at night
never
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DIFFERENCES BETWEEN BIRD AND INSECT POLLINATED FLOWERS
SIMILARITIES BETWEEN BIRD AND INSECT POLLINATED FLOWERS
Produce less pollen than wind pollinated flowers; there is no wastage as the pollen is taken directly between plants
Both produce nectar Have pollen grains with spikes etc so that they stick
together and can attach easily to the pollinator Have stigmas and anthers either just outside or inside
the flower Might be affected by disease organisms that are
carried to the flower along with pollen Have obvious petals
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Feature Pollinator eg bird/insect
Wind
Shape of flower Conspicuous inconspicuous
Flower ObviousUsually quite large, coloured scented petals
inconspicuous
Stigma Often inside the flower Large feathery stigmas, outside
Stamens Often inside the flower Large stamens, always hang outside
Pollen Fewer pollen grains, which have spikes to stick together in clumps
A lot of small,dry light pollen grains
Pollination process Not wasteful Random and wasteful
Disease transfer Disease organisms can be transferred with the pollen
No disease transfer
Energy expenditure Great – used for pollination, formation of nectar, etc
Less, only used to produce pollen
Scent and nectar Can be present No scent or nectar
PAGE 59DIFFERENCES BETWEEN POLLINATOR AND WIND POLLINATION
TO DO
TEXTBOOK PAGE 61
LEARNING ACTIVITY 18
ADAPTATIONS OF FLOWERS FOR POLLINATION
FERTILISATIONDIAGRAM PAGE 62
Fertilisation is the combining of nuclei of a male and female gamete to form a zygote
POLLINATION
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Is the transfer of ripe pollen containing the male gametes from the anthers to the stigma to allow for fertilization
PAGE 54
WHAT HAPPENS AFTER FERTILISATION?
The zygote forms an embryo inside the ovule
The rest of the ovule forms endosperm (food for the germinating seed)
The outer layer of the ovule forms the testa (hard, dry, protective layer)
The mature ovule = seed
WHAT HAPPENS AFTER FERTILISATION?
The ovary grows and encloses and protects the seeds =fruit
TO DO
TEXTBOOK PAGE 62
LEARNING ACTIVITY 19
POLLINATION AND FERTILISATION
THE END