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Immunology (Module 3)

4 dot points across 4 inquiry questions, in syllabus order. Each dot point has a focused answer, with exam-style questions and worked answers where available.

What causes infectious disease, and how do pathogens spread between hosts?

Pathogens: biological pathogens include prions, viruses, bacteria, fungi, protists and parasites; infectious disease is caused by invasion of a pathogen, which can be transmitted from one host to another; adaptations of pathogens for entering cells and tissues and for transmission (direct contact, body fluids, contaminated food or water, vectors); the physical or chemical changes that stimulate immune responses; factors affecting the spread of disease

TASC Biology Level 3 (BIO315124, criterion 7): the six types of pathogen with examples, how infectious diseases are transmitted, pathogen adaptations for entry and spread, the malaria parasite's life cycle, how pathogens trigger immune responses, and the factors that affect and control the spread of disease.

9 min read →

How does the innate immune system defend the body against any pathogen?

Immune response: vertebrates have innate (non-specific) and adaptive (specific) immune responses in three lines of defence; the first line is innate, non-specific physical and chemical barriers; the second line is innate, non-specific cellular, chemical and inflammatory responses involving phagocytes; cell specialisation (phagocytic cells) and the role of the cell membrane in endocytosis, including phagocytosis

TASC Biology Level 3 (BIO315124, criterion 7): the three lines of defence, the physical, chemical and biological barriers of the first line, and the second line: the inflammatory response with mast cells and histamine, phagocytosis by neutrophils, macrophages and dendritic cells, and antigen presentation.

8 min read →

How does the adaptive immune system target specific pathogens and remember them?

The third line of defence is adaptive and specific: persistent adaptive responses to specific antigens, including humoral immunity through the production of antibodies by B lymphocytes and cell-mediated immunity provided by T lymphocytes, with memory cells giving long-term immunity; the roles of antigen-presenting cells (dendritic cells and macrophages), mast cells, neutrophils, B lymphocytes, memory B cells, T lymphocytes, helper T cells, cytotoxic T cells, regulatory T cells and memory T cells

TASC Biology Level 3 (BIO315124, criterion 7): antigens and antibodies, how antigen-presenting cells activate helper T cells, the humoral response (B cells, plasma cells, antibodies, memory B cells), the cell-mediated response (cytotoxic, regulatory and memory T cells), and why a second exposure produces a faster, stronger response.

10 min read →

How can immunity be gained, and how does vaccination protect a whole population?

Vaccination and the concept of herd immunity: analyse the similarities and differences between passive immunity (for example antibodies acquired via the placenta or via antibody serum injection) and active immunity (acquired through the actions of the immune system as a result of natural exposure to a pathogen or through the use of vaccines)

TASC Biology Level 3 (BIO315124, criterion 7): natural and artificial active immunity, natural and artificial passive immunity, why only active immunity is long-lasting, how vaccines work, and how herd immunity protects people who cannot be vaccinated.

7 min read →