1. (a) 1. (In latency) there is a delay between infection and {symptoms / lysis} / eq ; 2. (In latency) viral genetic material is incorporated into hosts DNA / eq ; 3. Reference to a trigger / eq ; 2 (b) Reverse transcriptase ; 1(c) Makes DNA ; Using viral RNA as template / eq ; 2

2. (a) Genetic material incorporated into host cell genome / provirus; Cell is not destroyed / no interference with cell function; Trigger (to cell) needed for replication to occur; Reverse transcriptase needed; Delay before particle made; 33. (a) 1. {Microorganism / named organism} enters {tissues / organs / cells}; 2. Because microorganism penetrates hosts natural barriers / eq; 3. Multiplies; 4. Damages {tissues / cells} / releases toxins; 2 (b) 1. Reference to heat fixation; 2. Add crystal violet and iodine; 3. {Decolourise / eq} in alcohol / eq; 4. Reference to counter-staining / description; 5. Purple bacteria indicate Gram positive and red bacteria indicate Gram negative bacteria; 3 (c) (i) Invade cells in the lung; {Lung tissue / alveoli} destroyed; Blood vessels ruptured; Coughing to remove debris from lungs; 2 (ii) Reason for existence of resistant bacteria; Any resistant bacteria will multiply; And pass on resistance gene / plasmid / eq; 2 [9]