Question

what fearure do ctenophores have that placazoans and sponges lack?

a. nervous system

b. cilla

c. ability to coordinate cell activities

d. cadherins

Answer 1

Correct answers is

a Nervous sytem.

Explanation: Placazoans and sponges do not have nervous system. Sponge is the only multicellular animal which do not have sensory organ and nervous system. Ctenophores has a nervous system in the form of web (net) which forms ring around the mouth. Ctenophores do not have brain or central nervous system.

Explanation for wrong answers

All three do have cilia which helps in the movement ans attachment. All three has ability to coordinate cell activities, same as that of other organisms. Though tight junctions is not present in placazoans and sponges, however, cadherins are reported in all three and help in cell to cell binding or attachment.