A Level Biology Practice Exam

Which component of the immune system is mainly responsible for antibody production?

1. T lymphocytes

2. B lymphocytes

3. Macrophages

4. Eosinophils

The correct answer is: B lymphocytes

B lymphocytes, also known as B cells, play a crucial role in the immune system, primarily responsible for the production of antibodies. When B cells encounter an antigen, which is a substance that the immune system recognizes as foreign, they can activate and differentiate into plasma cells. These plasma cells are specialized for the secretion of large quantities of antibodies specific to that antigen. Antibodies are proteins that bind to antigens, marking them for destruction by other immune cells and neutralizing their harmful effects. This process is central to the adaptive immune response, allowing the body to remember previous infections and respond more effectively upon subsequent exposures to the same pathogens. In contrast, T lymphocytes primarily function to help regulate the immune response and to kill infected host cells, while macrophages play a role in phagocytosing pathogens and presenting antigens, and eosinophils are mainly involved in combating multicellular parasites and certain infections, as well as mediating allergic responses. Understanding the specific roles of these immune cells is essential for grasping how the immune system operates cohesively to protect the body.