Chapter 21, Problem 10STP

Summary Introduction

To explain:

The two membranes that make up an amoeba and why it is beneficial for the amoeba to have two membranes.

Introduction:

Amoeba is a member of the phylum Sarcodina. The organisms of this phylum are animal-like protists that use pseudopods for locomotion and feeding. A pseudopod is a temporary and blunt extension of cytoplasm. These extensions surround and envelop a smaller organism, forming a food vacuole. Most amoebas are found in fresh water having a lot of vegetation, decaying matter and bacteria. It has an irregular or asymmetric body. Some amoebas are parasites that live inside an animal host.

Explanation of Solution

The structure of an amoeba is simple. Amoebas are enveloped in an outer cell membrane called endoplasm and inner thickened cell membrane called ectoplasm. Inside the ectoplasm, the cytoplasm contains food vacuoles, a contractile vacuole, a nucleus, and other cell organelles. The waste products and undigested food particles are excreted by diffusion through the endoplasm into the surrounding water. The oxygen need for cellular processes also enters into the cell through endoplasm from the surrounding water.

Conclusion

Thus, the two cell membrane endoplasm and ectoplasm help amoeba to maintain the function of the body and locomotion properly.