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Module 7: Infectious Disease
Quick questions on Innate immune response in animals, first and second lines of defence: HSC Biology Module 7
9short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is first line of defence?Show answer
The first line prevents pathogens from entering the body. It is always active and requires no recognition.
What is second line of defence?Show answer
If a pathogen breaches the first line, the second line activates within minutes to hours. It is still non-specific but now involves cells and signalling molecules.
What is the inflammatory response?Show answer
Inflammation is the most visible part of the innate response. It has four cardinal signs: heat, redness, swelling and pain.
What are natural killer cells?Show answer
Lymphocytes that recognise virus-infected and cancerous cells by their reduced MHC class I expression. They release perforin (forms pores in membranes) and granzymes (induce apoptosis).
What is complement system?Show answer
A cascade of around 30 plasma proteins that:
What are interferons?Show answer
Cytokines released by virus-infected cells that signal neighbouring cells to enter an antiviral state, slowing viral spread.
What is q1?Show answer
Identify three components of the first line of defence in humans and state the function of each. [3 marks]
What is q2?Show answer
A graph shows neutrophil count at a wound site rising from 100 cells per mm cubed at time 0 to 2500 at 6 hours, then declining to 800 by 24 hours. Describe the response over time and explain why neutrophil numbers decline after the peak. [3 marks]
What is q3?Show answer
Compare innate and adaptive immunity. (a) State two features that distinguish them. (b) Describe one example of how innate immunity initiates an adaptive response.