§-Quick questions
NSWBiologyModule 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. The figure below maps the main physical, chemical and biological barriers onto the body.
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. The figure below follows the cascade from tissue damage to phagocytosis and fever.
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 tie each sign of inflammation to its cause?Show answer
Don't just list heat, redness, swelling, pain - say histamine → vasodilation (heat/redness) and increased permeability (swelling). The mechanism is where the marks are.
What are use precise verbs?Show answer
Phagocytes "engulf/enclose" then "digest/destroy"; NK cells "lyse"; complement "opsonises" and "lyses". Precise terminology lifts a Band 4 answer to Band 6.
What is match depth to the command word?Show answer
"Identify/state" wants the component and its job; "describe" wants the ordered steps; "explain" wants the mechanism; "evaluate" wants a justified judgement (e.g. innate vs adaptive).