page 05 6. Transcription of gene Z only occurs when its transcription factor is dephosphorylated. The distribution of the transcription factor together with the activities of a protein kinase and protein phosphatase specific to this transcription factor are shown in the table. Tissue Transcription factor present Protein kinase activity Protein phosphatase activity Muscle – – + Heart + + – Brain + – + Gene Z is transcribed in the A brain only B heart only C muscle and brain only D heart and brain only. 7. The effect of changing the concentration of extracellular potassium ions on the function of sodium potassium pumps was investigated. Starting with an extracellular solution containing no potassium ions, as the concentration of potassium ions is increased the pumps would be expected to A pump out potassium ions at a faster rate B stay in their phosphorylated conformation for longer C pump in sodium ions at a faster rate D hydrolyse ATP at a faster rate. [Turn over