pllination and fertilization

POLLINATION

&

FERTILIZATION

By

Gideon

POLLINATION

Pollination is the transfer of pollen grains from an anther to the stigma.

– an anther is part of the stamen which is the male part of the flower.

– Stigma is part of the pistilate which is the female part of the flower

DIAGRAM SOWING THE STAMEN AND

THE PISTIL.

TYPES OF POLLINATION

1. Self-pollination:

–transfer of pollen from an anther to the stigma within the same flower or

to a different flower of the same plant.

(a) Autogamy

(b) Geitonogamy

Continuation of the type of pollination

2. Cross-pollination:

– transfer of pollen grains from an anther to the stigma of a

different plant of the same species.

These processes are done by the following agents:

–insects, wind, birds, bats, water and other animals.

DIAGRAM SHOWING SELF AND CROSS-

POLLINATION

CHARACTERISTICS OF FLOWERING

PLANTS POLLINATED BY ANIMALS

Color – Bright colors, mostly yellow and blue

Shape – give room to the pollinators to easily access the pollen

Fragrance – they have nice and strong scents

FERTILIZATION

Fertilization is the union of the sperm cell and the egg to form a zygote which develops into an embryo and finally a seed

Process

Pollen grain at the stigma absorbs a fluid from the stigma,

It bulges and produces a tube(pollen tube) through the aperture

The tube grows down through the style to the ovule in the ovary

Vegetative nucleus stays at the tip as the generative nucleus lags behind and undergoes through mitosis to produce two sperm cells

DIAGRAMS SHOWING THE POLLEN

GRAIN AND A MATURE MALE

GAMETOPHYTE.

Sperm

cells

Vegetative nucleus

Pollen tube

pollen grain

aperture

Pollen grain Matured gametophyte

DEVELOPMENT OF A

MEGASPOROCYTE1

2

3

45

6

7

Double fertilization

One of the sperms unites with an egg to form a zygote.

The other sperm unites with the central nuclei to form a 3n (triploid ) endosperm.

The 3n endosperm surrounds the embryo that develops from the zygote to provide the nutrients.

Eventually the ovary develops into a fruit and the ovule into a seed.

THANK YOU!!!!