Chapter 19, Problem 13A

Summary Introduction

To write:

About test.

Introduction:

Structures in a living organism are either an extension of a cell, some kind of formation of different macromolecules (like proteins) or can be an arrangement of different cells that are aligned to perform a particular function. Different organisms are adapted to form different structures that help them to perform their life functions. Some structures may seem similar in different organisms but have different internal structures.

Explanation of Solution

The test is a structure generally seen in protozoa. Protozoa are animal-like protists that follow a heterotrophic mode of nutrition and are thus characterized as heterotrophs. Protozoans generally ingest other protozoans, algae, and bacteria to obtain energy and nutrition.

The test is a hard and porous covering that surrounds the cell membrane of the organism. Organisms possessing tests generally live in the marine environment. Some may also be found in a freshwater environment. The test is responsible for protecting the organisms from the outside environment and the pores present in it allow the organism to extend its cytoplasm for activities

like locomotion. Radiolarians are a type of amoeba that possesses a test.

Conclusion

The test is a hard and protective covering present outside the cell membrane of organisms like Radiolarians.