A Level Biology Practice Exam

What does clonal expansion refer to?

1. The creation of differentiated cells

2. The proliferation of antibody-producing cells

3. The reduction of cell sizes

4. The formation of unresponsive cells

The correct answer is: The proliferation of antibody-producing cells

Clonal expansion refers to the process by which specific lymphocytes, such as B cells or T cells, multiply in response to an antigen. When a naïve B cell encounters an antigen that matches its specific receptor, it undergoes activation and starts to divide, producing a large number of identical daughter cells, or clones. These clones can differentiate into plasma cells that produce antibodies, or they can become memory cells that contribute to long-term immunity. In the context of the immune response, this process is crucial because it amplifies the response to a particular pathogen by generating a large population of cells that can effectively target and eliminate the invading organism. This mechanism ensures that the body has a robust and faster response upon subsequent exposures to the same antigen. The other options do not accurately reflect the concept of clonal expansion; they refer to different biological processes.