IELTS Reading Practice Test 2026 - Free IELTS Reading Practice Questions and Study Guide

The statement about B-lymphocytes that indicates they transform into NK (natural killer) cells when activated is incorrect because B-lymphocytes and NK cells are distinct types of lymphocytes, each with different functions and developmental pathways. When B-lymphocytes are activated, they differentiate primarily into plasma cells, which are responsible for producing antibodies (immunoglobulins). Some of these activated B cells become memory B-cells, which are crucial for long-term immunity, allowing for a quicker and more robust response upon subsequent exposures to the same antigen. In contrast, NK cells are involved in the innate immune response and play a role in the direct killing of virus-infected cells and tumor cells, but they do not arise from B-lymphocytes.