Topic 4.1 Communicable diseases, prevention and the immune system Flashcards
(36 cards)
What is a pathogen?
A pathogen is a microorganism that causes disease by infecting a host
Name the four types of pathogens
Bacteria
Viruses
Protoctista
Fungi
How do bacteria cause disease?
Bacteria cause disease by producing toxins and damaging host tissues
What is tuberculosis and how is it transmitted?
Tuberculosis is a bacterial infection affecting the lungs, transmitted via airborne droplets
Describe the symptoms and transmission of bacterial meningitis
Bacterial meningitis causes headache, fever, stiff neck, and light sensitivity.
It spreads via respiratory droplets and close contact
What does Ring Rot affect and what are its symptoms?
Ring Rot affects tomatoes, potatoes, and aubergines.
It causes leaf wilting, yellowing, and ring decay in tubers
How do viruses reproduce and damage host cells?
They reproduce by hijacking host cells and forcing them to produce more viruses, leading to cell lysis
What is Tobacco Mosaic Virus (TMV) and how does it affect plants?
TMV causes mosaic leaf patterns, stunted growth, and reduced yield.
It spreads via plant contact and contaminated tools.
How is HIV/AIDS transmitted and what does it affect?
HIV/AIDS spreads through bodily fluids and destroy white blood cells, weakening the immune system.
How is malaria transmitted and what are the symptoms?
Malaria is caused by protoctista transmitted by female mosquitoes.
Symptoms include fever, chills, and fatigue.
Describe Black Sigatoka and its method of transmission
A fungal disease in bananas causes dark leaf streaks and reduced yield.
It spreads through airborne droplets
Why do plants rely on chemical and physical defences against pathogens?
Because plants cannot move, they depend on internal mechanisms to detect and defend against infection
What is the role of saponins in plant defence?
Saponins are antifungal compounds that disrupt fungal cell membranes
How does callose deposition protect plants?
Callose is deposited in cell walls and sieve plates to block pathogen movement
What is lignification and how does it prevent infection?
Lignification involves adding lignin to cell walls, making them tougher and impermeable to pathogens
What is necrosis in plant defence?
Necrosis is deliberate cell death around infection sites to limit pathogen access to water and nutrients
How does the skin act as a primary defence against pathogens?
The skin acts as a physical barrier and secretes sebum, which inhibits microbial growth
Describe the role of platelets in blood clotting
Platelets activate upon injury, forming a clot by converting fibrinogen to insoluble fibrin, which traps blood cells
What are histamines and their function in inflammation?
Histamines cause vasodilation and increase capillary permeability to promote localised heat and swelling
How does mucous membranes defend against pathogens?
They produce mucus that traps pathogens; cilia waft the mucus to be expelled or swallowed
What is opsonin and what is its role in phagocytosis?
Opsonins are molecules that bind to pathogens to enhance recognition and engulfment by phagocytes.
What is the difference between neutrophils and macrophages?
Neutrophils are short-lived and respond quickly; macrophages present antigens on their surface after engulfing pathogens.
What happens in clonal selection of T cells?
A T helper cell binds to an APC presenting a complimentary antigen, activating the T cell
What is the function of T killer cells?
T killer cells destroy infected host cells by releasing perforin
