Question

How many chromosomes are present in the nucellus?

Answer 1

Hint: The nucellus is present in the ovary of the plants. It is the inner structure of the ovule which forms a layer of cells in the integuments. It is similar to a megasporangium in function and structure.

Complete answer:
The ovule is the important part of the plant which takes part in fertilisation. The male gametes fuse with the ovule to bring about fertilisation. The ovule has three parts-the integuments, the inner nucellus and the female gamete. The nucellus is the layer of tissue that protects the embryo. The nucellus contains the megaspore mother cell which undergoes meiosis and forms female gametes. The megaspore present in the nucellus is haploid and the female gametes are haploid.

Additional information:In the case of angiosperms, double fertilisation or triple fusion takes place. In this, the megagametophyte or the embryo sac fuses with two male gametes. One of the male gametes fuses with the egg cell and forms a zygote. The second male gametes fertilise with the polar nuclei (2 in number) in the embryo sac and form the endosperm. The endosperm provides nutrition to the growing embryo. It increases the viability of the angiosperms. All the male gametes and female eggs are utilised in this process.

Thus, the correct answer is Haploid (n).

Note: The number of chromosomes in an organism is known as ploidy. An organism has 2 sets of chromosomes referred to as 2N or diploid. If an organism/gametes has a single set of chromosomes (N) then it is known as haploid. The ploidy of nucellus is 2N.