Question

Double fertilisation occurs in
A)Riccia
B)Pteridium
C)Cycas
D)Capsella

Answer 1

Fertilisation is the process by which a sperm and egg fuse to form a zygote which gives rise to an offspring. Double fertilisation is the process in which one female gamete unites with 2 male gametes.

Complete answer:
Before finding out which of these plants undergo double fertilisation lets know a little more about the process of double fertilisation. In double fertilisation 2 male gametes unites with a female gamete. In this one male gamete will fertilise the female egg to form the embryo and the other male gamete will fuse with the polar nuclei to form the endosperm. This process will result in the development of ovaries into fruits and ovules into seed. The two male gametes are haploid and the female egg is also haploid. Thus their fusion will result in the formation of a diploid zygote.

Double fertilisation takes place in angiosperms, that are flower bearing plants. They have separate male and female reproductive systems. Pollen grains which are the male gametes will reach the female egg through stigma and style one of the male gamete fuses with egg to diploid zygote,where the other fuses with synergid cells to form triploid primary endosperm nucleus. This is called triploid fusion. Now let's analyse the options.
Option A) Riccia is a plant belonging to the division bryophyta or liverworts. Their reproduction is not characterised by double fertilisation. In them one female and one male gamete fuse to form a zygote. Therefore this is an incorrect option
Option B) Pteridium is commonly known as ferns and they belong to the division pteridophyta. In this also reproduction does not include double fertilisation. Their reproduction takes place through spores. Therefore this is an incorrect option
Option C) Cycas is a plant belonging to the gymnosperm category but their reproduction is not characterised by double fertilisation because their ovules are not covered by fruit like in double fertilisation. Therefore this is an incorrect option
Option D)Capsella is a gymnosperm whose ovules are enclosed with the fruit and their reproduction is characterised by double fertilisation. Therefore this is the correct option

Hence, the correct answer is option (D)

Note: The significance of double fertilisation is that there are chances of polyembryony which gives the plant better chance at survival.As a result of double fertilization endosperm is formed which gives nourishment to the embryo in their developing stage. Thus providing them with viability.