A) DESCRIBE THE PROCESS OF FERTILIZATION IN FLOWERING PLANT. (15 MKS) B) STATE THE CHANGES THAT TAKE PLACE IN A FLOWER AFTER FERTILIZATION. (5 MKS)
a) Describe the process of fertilization in
flowering plant. (15mks)
Ø
Pollen grains stick to the stigma surface; surface of the
stigma produces a chemical substances; which stimulates the pollen grain
to produce a pollen tube; the pollen tube germinates;
Ø
The
pollen tube grows down into the tissues of the style from which it derives
nutrients;
Ø The generative nucleus divides giving
rise to two male nuclei;
Ø The embryosac has eight nuclei; 2
synergids ; egg cell ; two polar nuclei ; three antipodal cells;
Ø When the pollen tube reaches the micropyle
the vegetative nucleus/pollen tube nucleus in the tip of the pollen tube
degenerates/disintegrates ;
Ø One male nucleus fuses with eggs
cell; and forms a zygote; which develops into embryo;
Ø The other male nucleus fuses with two
polar nuclei ; to form triploid nucleus; which develops into endosperm;
Ø The process involves double
fertilization;
b)
State the changes that take place in a flower after fertilization. (5 mks)
structures
and what they change into:
Ø Interguments of ovule – seed coat
/ testa
Ø Zygote – embryo ;
Ø Triploid nucleus – endosperm ;
Ø Ovary wall – pericarp;
Ø Ovary - fruit;
Ø Ovule – seed
Ø Any other
part/style/petal/calyx/stamen/corolla/stigma – dry/falls off;
5mks
thanks for your informative post.its helpful to understand it.
ReplyDeletesynergid and egg cell