Question

Which of the following are characteristics of deuterostomes?
A. Spiral cleavage, blastopore becoming mouth
B. Radial cleavage, blastopore becoming anus
C. Spiral cleavage, blastopore becoming anus
D. Radial cleavage, blastopore becoming mouth

Answer 1

Hint: Deuterostomes are also known as enterocoelomates. In Deuterostomes, the zygote develops into a hollow ball of cells called a blastula.

Complete step by step answer: The two characteristics of deuterostomes are radial cleavage and the blastopore becoming anus. In deuterostomes, the early divisions occur parallel or perpendicular to the polar axis. This pattern of cleavage is called radial cleavage. The other special characteristic of the deuterostome is the fact that the blastopore, i.e. the opening at the bottom of the forming gastrula becomes the anus, whereas, in the case of protostomes, the blastopore becomes the mouth. Most of the deuterostomes belong to one of the two groups that include echinoderms and the chordates. Protostomes are the primitive invertebrates. It is a superphylum of the kingdom Animalia with all animals having bilateral symmetry and a blastopore developing into the anus during embryonic development. The name deuterostome means "mouth second", and refers to one of the important developmental features unique to this group. It is the sister clade of Protostomes. Bilateria is the group under subkingdom Eumetazoa, which has the triploblastic animals with bilateral symmetry. On the basis of this difference in embryonic development, they are further divided into superphylum, Protostomia and Deuterostomia.
Hence, the correct answer is option B.

Note: Chordata, Cephalochordata and Echinodermata are the examples of deuterostomes, while annelids are the protostome in which the first opening in the embryo becomes the mouth. Most deuterostomes show indeterminate cleavage, in which the developmental fate of the cells in the developing embryo is not determined by the identity of the parent cell.