1.  Fill in the gaps in the following sentences: Radiation dose is measured in            . We are exposed to             radiation all the time. When radiation reaches the body, the body is said to be            . When radiation gets inside the body, the body is said to be            .             radiation dose kills cells..             radiation dose damages the DNA of cells. The risk of cancer increases if the exposure to ionising radiation            .    2.  What happens when gamma radiation strikes a living cell.    3.  Cancer treatment sometimes involves the use of gamma radiation to kill cancerous cells.         How is the risk to the healthy cells from the use of gamma radiation reduced?