Question

Arrange the following in the ascending order based on their chromosome number (i) Primary endosperm cell of maize (ii) Meristematic cell of Apple (iii) Xylem parenchyma cell of Potato (iv) Aleurone layer cell of Rice
1. iv, i, ii, iii
2. iii, iv, i, ii
3. i, ii, iv, iii
4. ii, iii, i, iv

Answer 1

Hint:-The chromosomes can be described as the nuclear compounds of special organization and function. They are capable of self-replication and play a very important role in heredity, mutation, variation, and evolutionary development of the species.

Complete answer:
- Primary endosperm cell of maize :
Endosperm is a characteristic storage tissue that supplies nutrition to the developing embryo, Development of endosperm is from primary endosperm nucleus (i.e. PEN). It is formed by the process of triple fusion which involves the fusion of one of the male gametes with the two polar nuclei or with their fusion product present in the central cell. So the primary endosperm cell of maize is triploid and has a total of 30 chromosomes.
- Meristematic cell of Apple :
Meristematic cells are the somatic cells. These are a group of cells that are preparing to divide or are in a continuous state of division. So they have the capacity to divide mitotically i.e. through equational division. The cells are diploid and have 34 chromosomes (i.e. 2n=34).
- Xylem parenchyma cell of Potato :
Xylem is a complex tissue that helps in the transport of water and minerals in the plant body. It is a complex tissue and is composed of four different kinds of elements- tracheids, vessels, xylem fibres and xylem parenchyma. So the xylem parenchyma cells are somatic cells and thus are diploid in nature and have 48 chromosomes (i.e. 2n=48)
- Aleurone layer cell of Rice :
The Aleurone layer is present in the monocot seeds. The endosperm in the seeds is separated from the embryo by a distinct layer known as aleurone layer. This layer synthesizes amylase and breaks down starch into maltose and glucose. The cells of this layer are triploid in nature and have a total 36 chromosomes (i.e. 3n=36).
Thus, the right option is 3.

Note:- The chromosome number in a somatic cell for a diploid organism is diploid while it reduces to half in the gametes due to meiosis. The endosperm nucleus is formed by the fusion of three nuclei so it is triploid in most angiosperms.