AP BIOLOGY

Detailed explanation-1: -The first line of defence (or outside defence system) includes physical and chemical barriers that are always ready and prepared to defend the body from infection. These include your skin, tears, mucus, cilia, stomach acid, urine flow, ‘friendly’ bacteria and white blood cells called neutrophils.

Detailed explanation-2: -Answer and Explanation: Fever is not the first line of defense; it is considered the second line of defense. Suppose the first line of defense couldn’t protect the body, and the pathogen still enters the body. In that case, the second line of defense protects the body, including fever, inflammation, and phagocytosis.

Detailed explanation-3: -The body’s third line of defense is the immune response. This involves the lymphatic system. This system filters pathogens from lymph and produces lymphocytes.

Detailed explanation-4: -The human body has three primary lines of defense to fight against foreign invaders, including viruses, bacteria, and fungi. The immune system’s three lines of defense include physical and chemical barriers, non-specific innate responses, and specific adaptive responses.