Chapter 37, Problem 19A

Summary Introduction

Introduction:

The body has two lines of natural defense against infectious disease. It helps us and protect us from the infectious disease.

Answer to Problem 19A

Correct answer:

The correct answer is option (C) your skin.

Explanation of Solution

Explanation/justification for the correct answer:

Option (C) your skin. The skin is the most important the body has in our body. It is the most important mechanical barrier in our body. The outer layer of the skin is very difficult as well as tough for pathogens to penetrate. So, this is the correct answer.

Explanation for incorrect answer:

Option (A) the helper T-cell. They are the most important cells in adaptive immunity as they are required for almost all adaptive immune responses. But they are not the first defense of our body against infectious disease. So, option (A) is incorrect.

Option (B) an antibody. An antibody is also called as immunoglobulin, a protective protein produced by the immune response to the presence of a foreign substance, called antigen. But they are not the first defense of our body against infectious disease. So, option (B) is incorrect.

Option (D) phagocytosis. A phagocyte is a free-living one-celled organism, such as an amoeba, or one of the body cells, such as a white blood cell. But they are not the first defense of our body against infectious disease. So, option (D) is incorrect.