How do plasma cells form, and how do they fight pathogens?

• Adaptive immunity depends on two types of lymphocytes that recognize and respond to specific invading pathogens.

• Like all blood cells, lymphocytes originate from stem cells in the bone marrow.

B cells fully develop and become specialized in the bone marrow.

Immature T cells migrate via the blood to the thymus, a gland in the chest, where they mature and become specialized.

Both B cells and T cells eventually make their way to the lymph nodes and other lymphatic organs and wait to encounter an invader.

it has one origin of replication, but it proceeds in two directions - d)