Barriers and non-specific defencesEdexcel A-Level Biology A: Flashcards
What these 15 flashcards ask
- Name four routes of entry for pathogens.
- How does skin protect against infection?
- How does stomach acid protect the body?
- What is meant by gut flora?
- Why can antibiotics lead to gut infection?
- How do mucus and cilia protect the airways?
- What chemical starts inflammation and what does it do?
- What causes redness and warmth in inflammation?
- What causes swelling in inflammation?
- What is pus?
- What does lysozyme do?
- What is interferon and what does it do?
- Describe the steps in phagocytosis.
- Which two cell types carry out phagocytosis?
- Why are these defences called non-specific?
Exam questions on Barriers and non-specific defences
- Pathogens can enter the body by several routes and the body has barriers against each one. In hospital, patient 1 has taken a broad-spectrum antibiotic for ten days and has developed severe diarrhoea caused by Clostridium difficile in the gut. Patient 2 takes a drug that raises the pH of the stomach contents from about pH 2 to about pH 5.Explain why taking a broad-spectrum antibiotic could lead to the infection in patient 1.2 marks
- A student cuts her finger on broken glass. Within a few minutes the area around the cut becomes red, warm, swollen and painful, although the cut was cleaned straight away.Explain how inflammation helps the body to fight an infection in the cut.2 marks
- Interferon is released by cells infected with a virus. In an experiment, two dishes of cultured cells were exposed to the same dose of influenza virus. One dish had been treated with interferon for six hours beforehand and one was untreated. After 48 hours the untreated dish had 120 plaques (areas of dead cells) and the interferon-treated dish had 18 plaques.Describe how interferon protects cells from viral infection.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).