A Level Biology Practice Exam

Which of the following statements best describes B lymphocytes?

1. They directly attack pathogens

2. They produce and release antibodies into circulation

3. They store memory of previous infections

4. They convert into red blood cells

The correct answer is: They produce and release antibodies into circulation

The statement that B lymphocytes produce and release antibodies into circulation is correct because B cells are a key component of the adaptive immune response. When activated by encountering specific antigens, B cells differentiate into plasma cells that secrete antibodies. These antibodies are specialized proteins that bind to pathogens or toxins, marking them for destruction by other immune cells or neutralizing their harmful effects. This function is crucial for the immune system’s ability to recognize and respond to pathogens effectively. In contrast, while it is true that some immune cells can directly attack pathogens, this role is primarily filled by T lymphocytes, such as cytotoxic T cells, rather than B cells. B lymphocytes are not involved in the storage of memory in the sense that they act as memory cells for previous infections; although some B cells can become memory B cells after an infection, this is not their primary function. Additionally, B lymphocytes do not convert into red blood cells; this function is carried out by hematopoietic stem cells in the bone marrow. Therefore, the role of B lymphocytes is specifically aligned with antibody production and secretion.