Question

Bilateral symmetry is a common feature of phylum

• A. Platyhelminthes, Aschelminthes, Annelida and Arthropoda
• B. Porifera, Aschelminthes, Annelida and Arthropoda
• C. Porifera, Ctenophora, Platyhelminthes, Arthropoda
• D. Coelenterata, Ctenophora, Aschelminthes, Arthropoda

Answer 1

The correct option is A Platyhelminthes, Aschelminthes, Annelida and Arthropoda

Symmetry refers to a correspondence of body parts, in relative position, size and shape, on opposite sides of a dividing line or distributed around a central point or axis. There are two types of symmetry: radial and bilateral. Radial symmetry means that the body can be divided into two identical halves in any plane passing through the centre. Bilateral symmetry means that the body can be divided into identical halves in only one plane.

Organisms in phylum Porifera are asymmetrical. Organisms in phylum Cnidaria and Ctenophora are radially symmetrical. Bilateral symmetry is seen in phylum Platyhelminthes and all the following phyla.