State two ways in which viruses are different from bacteria.

Describe two ways in which antiviral drugs work.

Discuss three of the difficulties associated with solving the AIDS problem.

bacteria are a single cell / viruses are not cellular;

bacteria have cell walls/nuclei / viruses have no nucleus/cell wall;

bacteria larger than viruses / viruses smaller than bacteria;

viruses need host cell to reproduce / viruses take over another cell;

bacteria are organisms/living / bacteria metabolise/can grow/feed/excrete / viruses are not living / viruses do not metabolise/grow/feed/excrete ;

Allow “bacteria have both DNA and RNA / viruses have either RNA or DNA only (but not both)”.

alter cell’s genetic material;

block enzyme activity within host cell;

(changes cell membrane so that it) inhibits virus entry/bonding to cell;

prevents virus from leaving cell (after reproduction);

becomes part of DNA of virus / alters virus / blocks enzyme (polymerase) which builds DNA;

prevents virus from using cell to multiply/reproduce/replicate / prevents virus from using cell’s metabolism;

HIV retrovirus attacks immune system / binds to white blood cells/T-cells;

virus has ability to mutate;

virus makes people vulnerable to other infections;

metabolism of virus is linked closely to metabolism of the (host) cell / OWTTE;

antiretroviral agents are expensive / availability dependent on wealth of community/nation / lack of education/knowledge;

(social) “stigma” of diagnosis leads to not getting treatment / OWTTE;

The ways in which viruses differ from bacteria were well answered but, in (b), how antiviral drugs work was less well described. The AIDS problem had clearly been discussed but some of the answers lacked focus.

The ways in which viruses differ from bacteria were well answered but, in (b), how antiviral drugs work was less well described. The AIDS problem had clearly been discussed but some of the answers lacked focus.

The ways in which viruses differ from bacteria were well answered but, in (b), how antiviral drugs work was less well described. The AIDS problem had clearly been discussed but some of the answers lacked focus.