Summary Unit 4 notes biology IAL edexcel, Immunity
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Module
Biology
Institution
Bachillerato
Book
Edexcel A level Biology B Student Book 2 ActiveBook
- Biology notes that will help international a level students prepare for their unit 4 exam.
- Consist of Chapter 5B: Ecology.
- 90% typed notes with the other 10% being hand written usually in tables.
- Useful tools to help learn and memorise them like emojis, diagrams, tables and shortcuts
, 1) Tuberculosis
• A disease is an illness or disorder of the body or mind associated with a set of
symptoms that leads to poor health
• Infectious diseases are caused by pathogens (bacteria, , viruses) and are
transmissible
• Mycobacterium tuberculosis causes TB
People who contain the active form of TB or
, so bacteria enters the air in tiny droplets of
liquid from the lungs and uninfected people
inhale these.
Spreads faster in overcrowded conditions
1. Once inside the , TB bacteria are engulfed by phagocytes. primary infection
2. Bacteria survives and reproduce inside these.
3. Infected phagocytes will become encased in structures called
tubercules where bacteria remains dormant.
4. Bacteria becomes activated and overpowers the immune system later active
(e.g. during HIV infection → immune system compromised → person phase of TB
dvps TB)
• Symptoms: , , coughing and lung inflammation. If untreated → extensive
damage to lungs → death due to respiratory failure. Or can spread across body →
organ failure.
2) HIV
= human immunodeficiency virus which contains RNA and is a retrovirus
• Transmitted via
From mother to child across placenta,
Sexual Blood Sharing of
mixing blood during birth and
intercourse donation needles
through breast milk
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