Practise IB Biology HL A2.3.2 by comparing viral nucleic acids, capsids, envelopes, shapes and vaccine targets as evidence of structural diversity.
At all levels of biological organization there is diversity.
Describe, with examples, the diversity of structure in viruses.
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.
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