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VICBiologyQuick questions
Unit 4: How does life change and respond to challenges?
Quick questions on Innate and adaptive immunity (barriers, B and T cells, antibodies, memory): VCE Biology Unit 4
15short 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 the innate immune response?Show answer
The innate system is the first line of defence. It is present from birth, acts within minutes to hours, and treats every pathogen the same way.
What is the adaptive immune response?Show answer
The adaptive system is specific (targets one pathogen), takes days to mount on first exposure, and produces memory so the second exposure is much faster and stronger.
What is comparing innate and adaptive?Show answer
The two branches communicate constantly. Antigen-presenting cells of the innate system trigger the adaptive response, and cytokines from adaptive cells amplify innate functions.
What is the inflammatory response?Show answer
When tissue is damaged or infected, mast cells release histamine and cytokines, causing:
What is antigen presentation?Show answer
Dendritic cells, macrophages and B cells engulf pathogens, break them down and display fragments (antigens) on MHC class II molecules on their surface. Infected body cells display fragments of internal pathogens on MHC class I molecules.
What is clonal selection?Show answer
Each B cell and T cell carries one specific receptor. When the receptor matches a presented antigen, the cell is selected, activated and proliferates (clonal expansion).
What is helper T cells?Show answer
Bind antigen on MHC class II. Once activated, they secrete cytokines that coordinate the rest of the adaptive response: activating cytotoxic T cells, stimulating B cell proliferation, and amplifying macrophage activity.
What is cytotoxic T cells?Show answer
Bind antigen on MHC class I (on infected body cells). They release perforin (which makes pores in the target cell membrane) and granzymes (which trigger apoptosis), killing the infected cell. This is cell-mediated immunity.
What is b cells?Show answer
Bind free antigen using their B cell receptor (a membrane-bound antibody). With help from helper T cells, they differentiate into:
What is antibodies?Show answer
Y-shaped proteins with two antigen-binding sites specific to one antigen. They work by:
What is memory and the secondary response?Show answer
After the infection is cleared, most effector cells die. Memory B and T cells persist for years. If the same pathogen is encountered again, the secondary response is:
What is saying B cells make antibodies on first contact within hours?Show answer
B cells need helper T cell signals and several days to differentiate into plasma cells. The first response is slow.
What is confusing cell-mediated and humoral immunity?Show answer
Cell-mediated = cytotoxic T cells kill infected body cells. Humoral = B cells and antibodies act on extracellular pathogens.
What is saying the innate response is "weak"?Show answer
It is non-specific but very effective at clearing most invaders before the adaptive response is needed.
What is calling all white blood cells "lymphocytes"?Show answer
Only B cells, T cells and NK cells are lymphocytes. Neutrophils, macrophages and dendritic cells are not.