Unit 1 Biology and Disease 3.1.1 Pathogens and Lifestyle

This word document summarises chapter 1 of the AQA text book, 3.1.1 on the specification.

I made the notes with reference to the specification so hopefully everything is there.

If any one has any questions or corrections for me please let me know in the comments and I'll do my best to help :)

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Revision: Unit 1 Biology and Disease 3.1.1 Pathogens and Lifestyle


Communicable diseases (infectious diseases) are caused by microorganisms.
Microorganisms Single celled organisms.
Microorganisms that cause disease are called pathogens.
The most common pathogens are
o Viruses
o Bacteria
o Fungi

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Infection occurs when a pathogen
o Enters the host
o Colonises the tissues of the host
o Resists the defences of the host
o Causes damage to the host tissues.
Transmission When a pathogen is transferred from one individual to another.
Transmission may occur through
o Air
o Water

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o Immunisation

How pathogens cause disease
o Pathogen must attach itself to host tissues.
o Penetrate the host cells.
o Colonise and reproduce within the host tissue.
Pathogens enter the host cell by
o Endocytosis
o Or by producing enzymes that breach the host cell membrane.
Colonisation depends on the…

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o Physical activity
Reduced activity leads to an increased risk.
o Sunlight
The more someone is exposed to sunlight or light from sun beds, the greater the risk of skin

Risk factors and CHD (coronary heart disease)

Genes, age and sex are beyond our individual control.
Lifestyle factors can…


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