Pearson Edexcel IAL Biology 6.7 Pathogen entry routes & barriers

Practise naming pathogen entry routes and explaining how skin, stomach acid, gut flora and skin flora reduce infection risk.

Exam points

identify barriers including skin, mucus, cilia, stomach acid, blood clots and normal flora
interpret hand-washing evidence to compare removal or killing of skin microorganisms

[Maximum number: 2]

Methicillin-resistant Staphylococcus aureus (MRSA) is a disease causing worldwide concerns.

Methicillin is one of the antibiotics to which this pathogen has developed resistance.
Castaneroxy A is a molecule extracted from the European chestnut tree, endemic to Southern Europe and Turkey.

The effects of Castaneroxy A have been investigated.
The investigations have found that Castaneroxy A:
- does not affect the natural skin flora
- prevents MRSA from producing toxins
- weakens the MRSA bacteria
- reduces the size of skin infections caused by MRSA.

Explain why it is important that Castaneroxy A does not affect skin flora.

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6.7—Pathogen entry routes and barriers question 1