Quick questions on Adaptive immune response, humoral and cell-mediated immunity: HSC Biology Module 7

All lymphocytes mature into one of three classes.

Targets infected, cancerous or abnormal host cells.

Mature in the bone marrow. Each B cell has a unique surface antibody (B-cell receptor) that recognises one antigen.

Mature in the thymus. Each T cell has a unique T-cell receptor (TCR) that recognises one antigen displayed on MHC. Two main subtypes:

A subset of activated B and T cells become long-lived memory cells.

Y-shaped proteins with two antigen-binding sites. Functions:

First exposure to a pathogen. Takes 5 to 14 days to produce significant antibody. Symptoms may develop while immunity is building.

Re-exposure to the same pathogen. Memory cells recognise the antigen within hours. Antibody production is faster, higher and longer-lasting.

For "explain how antibodies are produced", markers want the chain in order: antigen recognised as non-self → specific B cell binds it → helper T-cell activation → clonal expansion → plasma cells secrete specific antibody. Skipping helper T cells or clonal selection loses marks.

For a primary-vs-secondary graph, state the differences in speed, peak height and duration, then give the cause (memory cells). "Calculate the fold increase" means peak2 divided by peak1 - show the working.

"Outline" wants brief points; "describe" wants steps in order; "explain" wants cause and effect; "evaluate" wants a justified judgement (e.g. about a vaccine) weighing strengths and limitations.