IB Biology HL 2.3.2 Diversity of Virus Structure

a. variation in size/shape

OR

helical versus spherical / spikes versus no spikes / other contrasting shapes;

b. head and tail in bacteriophage (lambda) and polyhedral/spherical in HIV/COVID-19;

c. DNA or RNA as genetic material;

d. retroviruses/HIV has reverse transcriptase (but other viruses do not);

e. DNA in bacteriophage lambda and RNA in HIV/COVID-19;

f. single-stranded or double stranded DNA/RNA/nucleic acid;

g. bacteriophage lambda with double stranded and HIV/COVID-19 with single stranded;

h. circular or linear DNA / linear DNA in bacteriophage lambda;

i. variation in number of DNA/RNA/nucleic acid molecules

OR

HIV/other virus example with more than one molecule (of DNA/RNA);

j. some viruses are enveloped (in plasma membrane from the host cell);

k. bacteriophage lambda is a naked virus and HIV/COVID-19 is enveloped;

I. rapid evolution due to short generation time/rapid mutation rate/no proofreading/intense natural selection;

m. changes in influenza coat proteins/coronavirus spike proteins;

Marking guidance:

Accept other verified and valid examples in marking points b, e, g, i, k and m.

Accept coronavirus instead of COVID-19.

Accept diagrams to show examples of structural differences for marking points b, e, g, i, k and m. Reject statements that some viruses have plasma membranes.

7
max