16.3) Sexual reproduction in plants

Wind pollinated flowers

(the left picture)

Describe the growth of a the pollen tube and its entry into the ovule followed by fertilization

-Once a pollen granule is attached to the stigma, a pollen tube begins to grow through the style to the ovary. Once the pollen tube reaches the ovary, the sperm can swim down and fertilise the ovum

Differences between insect-pollinated flowers and wind-pollinated flowers

-Petals: (i) brightly colored, (w) dull in colour -Pollen: (i) sticky and spiky, (w) light and smooth -Nectar: (i) sweet, while insects eat it, they will get covered in pollen, (w) no nectar is produced -Scent: (I) have a pleasant smell, (w) have no smell -Anthers: (i) inside flower, (w) outside flower -Stigma: (i) inside flower, (w) outside flower

Function of anthers

Anthers produce the plant's gametes, known as pollen.

function of sepals in a flower

Sepals develop at the top of the stem, next to the flower. They help to protect the growing flower and stop it drying out.

function of petals in a flower

Petals are usually brightly coloured. They attract insects, birds or mammals to help pollinate the plant.

Differences between the pollen of wind pollinated flowers and insect-pollinated flowers

Insects: -Has a spiky outer layer, so it will stick onto the insect Wind: -Lighter and smoother -Produce more of itself because a lot of the pollen will get lost

function of stigma

Stigmas protrude out of the top of the plant. Each stigma is covered in a sticky, waxy layer that traps the pollen of other plants.

function of the ovary

The ovary contains an ovule (a gamete). When this is fertilised by pollen, it will develop into a seed. The seed contains the developing plant embryo.

Environmental changes on germination is affected by:

enough water; enough oxygen; the correct temperature.

Self-pollination

the transfer of pollen grains from the anther of a flower to the stigma of the same flower or different flower on the same plant

Pollination

the transfer of pollen grains from the anther to the stigma

Cross-pollination

transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species