Chapter 24, Problem 27A

Summary Introduction

To write:

The correct term that does not belong and explain why it does not belong.

Introduction:

Sponges and cnidarians were the first animals to evolve from a multicellular ancestor. Most sponges and cnidarians live in marine water. Sponges have no tissues, no organs, and most have no symmetry. Most cnidarians have two layers of cells and one opening of the body. Such two layers are divided into tissues with different functions.

Explanation of Solution

The term spongin does not belong to alternation of generations, polyp, and medusa. Polyp and medusa are the body forms of cnidarians. A polyp is a tube-shaped body and a mouth surrounded by tentacles. A medusa is an umbrella-shaped body and tentacles that hang down. The polyp and medusa are found in the life cycle of jellyfish. The polyps reproduce asexually to form medusa. They show alternation of generation. Alternation of generations is a type of life cycle that occurs mostly in those plants that have haploid and diploid stages in the process of reproduction. Spongin is a tough fibrous protein. It is a type of protein and polyp, medusa, alternation of generation does not belong to this.

Conclusion

Thus, the spongin does not belong to polyp, medusa, and alternation of generation as spongin is a type of protein.