Question

What is true for deuterostomes?
A. Presence of schizocoel
B. NonFormation of the anus from the blastopore
C. Coelom lined by mesoderm on both sides
D. Absence of false coelom

Answer 1

Hint: A coelom is a body cavity. There are three types of organisms based on coelom- acoelomate, coelomate, and pseudocoelomate. A false coelom has internal organs present in the coelom. A deuterostome is an organism whose blastopore develops into an anus.

Complete step by step answer: The above diagram shows deuterostomes and the formation of deuterostomes from the eight-cell stage.

Deuterostomes are organisms that have a mouth that is formed from some opening in the gut and the blastopore forms the anus. The posterior end of the organism is the blastopore. This is a different case from the usual because generally blastopore develops into the mouth.
Now, we will analyze all the options to find the correct answer.
-In option A, the presence of schizocoel is mentioned. Schizocoel is a type of coelom formed through the splitting of the mesodermal mass. The mesodermal mass is referred to as the middle germ layer during embryonic development. A coelom is referred to as the body cavity which lies between the digestive tract and the body wall. There is as such no cavity present in deuterostomes.
-In option B, the nonformation of the anus from blastopore is mentioned. As we can see in the diagram, the blastopore forms the anus of deuterostomes. So option B is incorrect.
-In option C, coelom lined by mesoderm on both sides is mentioned. The statement given is not true.
-In option D, the absence of a false coelom is mentioned. A false coelom or pseudocoelom has alimentary canals and other internal organs in it. But in the case of deuterostomes, the digestive tube lies in the exterior of the coelom. So this means, there is no cavity present.
So, the correct option is option D.

Note: Most of the deuterostomes belong to the phylum Echinodermata and Chordata. Few examples of these are sea urchins, sea stars, lancelets, humans, birds, sand dollars, and tunicates among many others.