Sexual Reproduction in Flowering Plants. What are flowering plants?. -The flowering plants, also known as angiosperms are seed-producing plants.
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What are flowering plants?
-The flowering plants, also known as angiosperms are seed-producing plants.
-The characteristics of angiosperms includehaving flowers, endosperm within the seeds, and the production of fruits that contain the seeds.
Formation of male and female gametes in flowering plants
- Male and female gametes are produced in flowers
Egg Cell (1)
Polar Nuclei (2)
Join stigma to ovary
Place where pollen grains are produced
- The egg. A small structure in a seed plant that contains the embryo sac and develops into a seed after fertilization
E.S.M cell (2n)
Forms 4 (n) megaspores, 3 die
3 antipodal cells
2 synergid cells
1 egg cell
The nucleus of the functional megaspore
A process in which ripe pollen from an anther are transferred to a stigma
Fertilisation starts when pollen grains land on stigma
Formation of pollen tube
The formation of pollen tube is stimulated by the sugar on the stigma. The pollen grain on the stigma will germinate and form pollen tube, grow into style towards ovule.
The pollen grain forms a tube known as ; POLLEN TUBE
The generative nucleus divide by mitosis forming 2 GAMETE NUCLEI
2 male gamete nuclei
The tube nucleus lead the 2 male gamete nuclei down the pollen tube
The pollen tube penetrates the ovule through the micropyle
The tube nucleus disintegrates giving a clear passage for 2 male gamete nuclei
1 male nucleus
1 male nucleus
Fuse with egg cell
Fuse with 2 polar nuclei
+ 1 male nucleus
Diploid Zygote (2n)
+ 1 male nucleus
*Protects the embryo and endosperm*
*protects the seeds and may function to disperse them
Triploid Nucleus (3n)
*provides nourishment to the developing embryo*
*a nutrient-rich tissue
Fertilisation in Flowering Plants is called “Double Fertilisation”.
The process that takes place in ovule occurs twice
1st : The fertlisation of egg cell and 1 male gamete nucleus to form a diploid zygote
2nd : The fertlisation of 1 male gamete and 2 polar nuclei s to form a triploid nucleus
The importance of Double Fertilsation for the Survival of Flowering Plants
Give rise to endosperm
-Endosperm formed when 2 polar nuclei are fertilised
by 1 male gamete nucleus
-Endosperm is a nutritive cell, it stores food in form of
starch and protein as well as fat
-After a fertlisation in an ovule, there are 1 embryo and
1 triploid nucleus (which later develops into
endosperm). It means each embryo has its own
temporary food store in the endosperm
-Therefore, each embryo in each ovule feeds on its own
stored food in endosperm for survival
-Food stored in endosperm enable embryo lives longer
when the conditions are unfavourable