1. Which statement best describes the immune system? The immune system produces gametes. The immune system exchanges gases between the blood (a) (b) and lungs. (c) (d) The immune system protects the body from pathogens. The immune system digests food into usable nutrients. 2. The immune system is comprised of lines of defense. (a) (b) (c) two three four (d) five 3. Which statement best describes the first line of defense? The first line of defense consists of different types of (a) barriers that keep most pathogens out of the body. The first line of defense includes the inflammatory (b) response. (c) defense. Leukocytes are the cells responsible for the first line of (d) The first line of defense includes the skin, mucous membranes and biological barriers such as white blood cells. 4. Which statements are true about mechanical barriers? (1) Mechanical barriers physically block pathogens from entering (3) Mechanical barriers are living organisms that help protect the body. (4) Mechanical barriers destroy pathogens on the outer body surface. I and 2 (b) 3 and 4 1, 2, and 3 (c) (d) 1, 2, 3, and 4 (a) 5. Which statement describes the second line of defense? The second line of defense includes biological and (a) chemical barriers. The skin is the major organ of the second line of (b) defense. (c) the body. (d) that enter the body. The second line of defense keeps most pathogens out of The second line of defense is encountered by pathogens