What happens to animal cells if they are put in fresh water?
If your animal cells are placed in fresh water, the water will diffuse rapidly into your cells. This is known as osmosis
Well, you have less concentration of water in your cells than outside of the cells. Hence, water will want to travel into the cell to make the concentration of water equal inside and outside the cell.
However, as water enters continuously into the cell to make the concentration equal, the cell may expand to the point that it will burst. This is known as lysing.
They would burst...
When we put animal cells into pure, fresh water
Water will move from a high concentration (the solution) to a region of low concentration (inside the cell). This will make the cell expand greatly. Since animal cells do not have a cell wall, when too much of this water enters to make the concentration of water on both sides even, the animal cell may eventually burst, and die out.