Explain how HIV causes a person to become more susceptible to other infections over time.

Edexcel GCSE Biology (1BI0) — 5.2 Pathogens and immunity · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

HIV is a communicable disease spread through direct contact with infected body fluids. It is known to target specific cells of the immune system.

Model answer (4 marks)

HIV infects and destroys CD4+ T‑helper cells, which are white blood cells essential for coordinating immunity.

The loss of these cells weakens the immune system.

With fewer CD4+ cells, B‑lymphocytes receive less stimulation, so antibody production falls.

Consequently the body cannot mount an effective immune response to other pathogens, making the person increasingly susceptible to infections, eventually leading to AIDS.

Examiner tips

Use the term CD4+ T‑helper cells; link loss to weakened immunity. Show the chain: cell loss → reduced B‑cell help → fewer antibodies → susceptibility. Keep answer concise, 4 points, no extra words.

Common mistakes

Confusing CD4+ cells with B‑cells; not mentioning antibody production. Using vague terms like "immune cells" instead of CD4+. Adding irrelevant details about transmission or symptoms.

Mark scheme (4 marks)

HIV destroys / attacks white blood cells
This weakens / damages the immune system
Fewer B-lymphocytes means fewer antibodies can be produced
The body cannot mount an effective immune response to other pathogens / infections, leading to AIDS

Key terms in this question

HIV