Fertilisation and pollination

L/O: To understand the processes of fertilisation and pollination.

Starter: Draw and label a diagram of a flower.Extension: Write the function of each part.

Success Criteria:A* - Explain in detail the processes of fertilisation and pollination.A – Explain the processes of fertilisation and pollination.B – Explain the importance of pollination in agriculture.C – State what fertilisation and pollination are.

Pollination

• Pollination involves the transfer of pollen (male gamete) from the anther to the stigma (outermost female part)

• If it is in the same flower it is calledself-pollination.

• If between different flowers it is calledcross-pollination

• Plants are pollinated by insects or the wind.

Pollination

Pollination

Sexual reproduction in flowers

Sexual reproduction in flowers

PollinationFeature Insect pollinated plants Wind pollinated flowers

Petals Large, brightly colours; many are patterned to guide insects in

Small, usually brown or green

Scent Often scented to attract insects

Not scented

Nectar A sugary liquid made to attract insects

No nectar

Stigma Found inside the petals so insects brush against it on way to nectar

Large, feathery; hangs outside the petals to collect pollen from the air; may be sticky

Anthers Inside the petals so insects brush past on way to nectar

Hang outside petals so pollen blown away by wind

Pollen grains Relatively few, large and sticky to attach into the insects that visit the flower

Many, small and light to float easily in the wind

Fertilisation

• Fertilisation involves the fusion of the nucleus of the male gamete (in the pollen) with the nucleus of the female gamete (in the ovules).

Fertilisation

• The pollen grain grows a tube.• The tube reaches an ovule.• The gamete nuclei fuse (fertilisation)

and a zygote (seed) forms.

Let´s have a look at some pollen tubes underneath the microscope!

Fertilisation

Fertilisation• Pollen arrives on stigma, pollination takes place• For fertilisation to happen, male nuclei from pollen grain have to

travel down style and into ovary to fuse with nuclei of ovule• Pollen grain and ovules both have more than one nuclei• Ovule- nucleus will go on to form embryo in seed (egg nucleus)• Nuclei that will form the food store for developing embryo is the

endosperm nucleus• All nuclei in ovule have to fuse with male nuclei from pollen

grain for fertilisation to occur• Pollen grain attaches to top of stigma in pollination

Fertilisation

• A pollen tube grows out of pollen grain down style• Pollen tube grows into ovary and into ovule• Here, one male nuclei from pollen grain fertilises the egg nucleus in the ovule to

form a zygote• Variety is introduced when male and female nuclei fuse• Zygote grows and divides to develop into an embryo• Other male nucleus fuses with 2 more female nuclei to form endosperm

nucleus• Fertilised endosperm nucleus and egg cell nucleus of the ovule give rise to a

seed• Endosperm forms food store, while the tissue that results from the female egg

nucleus forms the embryo plant• If there are several ovules, most or all of them are fertilised• As seeds form, the ovary grows into a fruit, which surrounds and protects seeds

Fertilisation

Once fertilisation has taken place the zygote (fertilised ovule)becomes a seed, and the ovary becomes a fruit.The petals die and fall off.The plant seeds are in the fruit.

What are fruits like?The fruits can be:

- soft & fleshy

- hard & dry

• Write the names of as many fruit as you can think of as a group and write them on a card

• Stick them on the correct side of the class

•Everyone pick a fruit card and your job is to bring that piece of fruit in for next lesson!

To finish off…..

• http://www.youtube.com/watch?v=sc6snhtpd4g&playnext=1&list=PL2CD6FD59EA58C94A