SQA National 5 Biology Practice Exam

Antibodies play a critical role in the immune system by specifically targeting and neutralizing pathogens such as bacteria and viruses. When a pathogen enters the body, the immune system recognizes it as foreign. Antibodies are produced by B cells and bind to specific antigens on the surface of these pathogens. This binding can neutralize the pathogen directly, preventing it from infecting cells, or mark it for destruction by other immune cells through a process known as opsonization. In contrast, structural support, transportation of oxygen, and regulation of metabolism are not functions of antibodies. Structural support is typically provided by proteins such as collagen and keratin. Hemoglobin, found in red blood cells, is responsible for transporting oxygen, while metabolic regulation is managed by enzymes and hormones, none of which involve antibodies. Thus, the correct understanding of the role of antibodies is essential to comprehend how the immune system protects the body.