Question

Choose the incorrectly matched pair from the choices given below.

• A. Platyhelminthes - incomplete digestive system
• B. Sponges - cellular level of organization
• C. Aschelminthes - metamerism
• D. Radial symmetry - coelenterates

Answer 1

The correct option is C Aschelminthes - metamerism

Metamerism is the phenomenon in which a body is divided into segments externally and internally and there is linear repetition of some organs in every segment. This type of segmentation is true segmentation. Annelids show metameric segmentation. Example: Earthworm.
The body of aschelminthes (e.g., tapeworms) is not divided into segments.

Platyhelminthes, also known as flatworms, have an incomplete digestive system, which means that the digestive tract has only a single opening. Here, digestion takes place in the gastrovascular cavity.

Sponges (phylum Porifera) have a cellular level of organization where each cell performs a particular function. But these cells are not organized to form tissues.

Coelenterates have a radially symmetrical body form, i.e., the body is arranged around a central axis. Example: Sea anemone.