Describe measles as a highly infectious viral disease characterised by a fever and a red skin rash, noting its potential to be fatal if complications arise.
Understand that the widespread vaccination of young children is a primary, effective defense against the measles virus.
Explain that the measles virus is extremely contagious and spread primarily through the inhalation of droplets from sneezes and coughs.
Describe HIV as a severe viral infection initially presenting as a flu-like illness that progressively attacks the body's immune cells if not actively managed with antiretroviral drugs.
Explain that late-stage HIV infection, or AIDS, occurs when the immune system becomes so severely damaged it can no longer defend against other routine infections or cancers.
Understand that HIV is transmitted exclusively through direct sexual contact or the direct exchange of bodily fluids, such as blood sharing among intravenous drug users.
Identify Tobacco mosaic virus (TMV) as a widespread plant pathogen that negatively affects many plant species, specifically including tomatoes.
Describe the physical symptoms of TMV, specifically the distinctive 'mosaic' pattern of discolouration on leaves, and explain how this directly affects plant growth by fundamentally inhibiting photosynthesis.
