Study the diagram given below and answer any four questions from (a) to (e).
(a) The part labelled as A is:
(b) The role of part labelled as B is:
(i) Transport of male gametes to the ovary.
(ii) Transport of female gametes to the ovary
(iii) Contains ovules which develop into seeds.
(iv) All of these
(c) How many male gametes are produced by each pollen grain?
(d) What happens to the label A which falls on a suitable stigma.
(e) List two reasons for the appearance of variations among the progeny formed by sexual reproduction.
The part labelled as A is (iii) pollen.
The part labelled as B is the Style.
Its function is to transport the pollen grains, which contain the male gamete to the ovary.
So, the correct answer is (i) Transport of male gametes to the ovary.
Each pollen grain produces (ii) 2 male gametes.
The part labelled A is pollen . When it falls on a suitable stigma, it germinates and produces the pollen tube . The pollen tube grows into the style and reaches the ovary. The pollen then releases the 2 male gametes into the embryo sac and it fuses with the female gametes.
Reasons for the appearance of variations among the progeny formed by sexual reproduction are:
- Involvement of DNA of 2 parent organisms.
- Variations also take place during DNA replication before cell division.