12. Updates from NH paper 2024

Question 1

Name the process for when a new virus infects a different species

Answer 1

Zoonosis

Question 2

Outline the functions of complement proteins

Answer 2

Chemotaxis – complement proteins gather near a pathogen and attract phagocytes to it making phagocytosis easier/
Opsonisation - attach to non-self-antigen on cells making them easier to identify and making phagocytosis easier. [1]
Lyse B cell plasma membranes by forming a membrane attack complexes [2]
Promote inflammation by recruiting inflammatory cells which destroy the cell. [3]

Question 3

Define epidemic

Answer 3

An epidemic is a significant rise in the level of incidence of a disease in a population with more people affected in a short time

Question 4

Define endemic

Answer 4

The normal level of incidence of a disease always present in a population with a limited number of people affected.

Question 5

Compare antigenic shift with antigenic drift

Answer 5

Antigenic shift produces a new viral strain suddenly (by two viruses merging in a host cell) whereas antigenic drift can produce a new viral strain more gradually (it would be more closely related to the original strain)

Antigenic shift may result in the infection of a new species whereas antigenic drift will more likely result in infection in the same species.