Question

Assertion:- Nematodes exhibit eutely
Reason:- In nematodes cell division case near the end of embryonic development so that the number of the cells if the adult is constant
A)Both assertion and reason are correct and reason is the correct explanation for assertion.
B)Both assertion and reason are correct but reason is not the correct explanation for assertion.
C)Assertion is correct but reason is incorrect
D)Both assertion and reasons are incorrect

Answer 1

Hint: Nematodes are very small slender worms which are microscopic and free living , they are worms of phylum nematoda.

Complete answer:
The nematodes or roundworms consist of the phylum Nematoda which are also called Nemathelminthes. Among plant parasitic nematodes being known as eelworms. They are a dissimilar animal phylum inhabiting a broad variety of environments. Taxonomically they are differentiated along with insects and the other moulting animals. Unlike flatworms they have tubular digestive systems with openings at each end. Similar to tardigrades they contain a reduced number of Hox genes. Eutelic organisms have a fixed number of somatic cells when they reach maturity, the exact number being constant for any one species. Development proceeds by cell division until maturity; further growth occurs via cell enlargement only.
Most of the eutelic organisms are microscopic in nature. The examples for this include the rotifers, ascaris, many species of nematodes which includes the model organism Caenorhabditis elegans in which their male individuals have 1031 cells tardigrades, larvacea and dicyemida

Eutely occurs when the early embryonic cells each one come with a limit for total divisions. When this limit is reached the organism is able to only become larger because of the cell enlargement somewhat than cell division. Eutelic organisms encompass a fixed number of somatic cells while they reach maturity, the original number being stable for any one species. Development continues by the cell division awaiting maturity. Additional growth occurs through the cell enlargement only. In nematodes the number of nuclei is also invariable. There is growth in the dimension of the body but this is because of the growth in the size of the cells which is known as hypertrophy. Most of the eutelic organisms are microscopic in nature.

Hence, the correct answer is option (A)

Note: Nematodes play an important role in nutrient recycling and in the release of nutrients for plants growth and development. Some of them attack insects and helps in controlling the insect pest.