A-Level Biology Specification

AQA 7402

Section 2.4: Cell recognition and the immune system

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#2.4.1

Each type of cell has specific molecules on its surface that identify it. These molecules include proteins and enable the immune system to identify:

- pathogens
- cells from other organisms of the same species
- abnormal body cells
- toxins.

#2.4.2

Definition of antigen. The effect of antigen variability on disease and disease prevention.

#2.4.3

Phagocytosis of pathogens. The subsequent destruction of ingested pathogens by lysozymes.

#2.4.4

The response of T lymphocytes to a foreign antigen (the cellular response).

- The role of antigen-presenting cells in the cellular response.
- The role of helper T cells (TH cells) in stimulating cytotoxic T cells (TC cells), B cells and phagocytes. The role of other T cells is not required.

#2.4.5

The response of B lymphocytes to a foreign antigen, clonal selection and the release of monoclonal antibodies (the humoral response).

- Definition of antibody.
- Antibody structure.
- The formation of an antigen-antibody complex, leading to the destruction of the antigen, limited to agglutination and phagocytosis of bacterial cells.
- The roles of plasma cells and of memory cells in producing primary and secondary immune responses.

#2.4.6

The use of vaccines to provide protection for individuals and populations against disease. The concept of herd immunity.

#2.4.7

The differences between active and passive immunity.

#2.4.8

Structure of the human immunodeficiency virus (HIV) and its replication in helper T cells.

#2.4.9

How HIV causes the symptoms of AIDS. Why antibiotics are ineffective against viruses.

#2.4.10

The use of monoclonal antibodies in:

- targeting medication to specific cell types by attaching a therapeutic drug to an antibody
- medical diagnosis.

Details of the commercial or scientific production of monoclonal antibodies are not required.

#2.4.11

Ethical issues associated with the use of vaccines and monoclonal antibodies.

#2.4.12

The use of antibodies in the ELISA test.

#2.4.13

Students should be able to:

- discuss ethical issues associated with the use of vaccines and monoclonal antibodies
- evaluate methodology, evidence and data relating to the use of vaccines and monoclonal antibodies.