IGCSE Biology Paper-4: Specimen Questions with Answers 272 - 272 of 279


Type 1 diabetes is caused by the immune system destroying body cells.

Question 272 (2 of 2 Based on Passage)


Write in Short

Short Answer▾

Antibodies are part of the immune system.

Describe how antibodies function.


Antibodies Have Three Main Functions

  • Antibodies are secreted into the blood and mucosa, where they bind to and inactivate foreign substances such as pathogens and toxins (neutralization) .
    • (Neutralizing antibodies not only to bind to a virus, they bind in a manner that blocks infection. A neutralizing antibody might block interactions with the receptor. )

  • Antibodies activate the complement system to destroy bacterial cells by lysis (punching holes in the cell wall) .

    • (The complement system, also known as complement cascade, is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promote inflammation, and attack the pathogen’s cell membrane. )

  • Antibodies facilitate phagocytosis of foreign substances by phagocytic cells (opsonization) .

    • (Opsonization is the molecular mechanism whereby pathogenic molecules, microbes, or apoptotic cells (antigenic substances) are connected to antibodies, complements, or other proteins to attach to the cell surface receptors on phagocytes and NK cells. )

Phagocytic Cells