Answer:
Read the explanation section.
Step-by-step explanation:
The increase in the mass of the potato, which is strip in water, happens because of the movement of the water molecules into the potato cells. It occurs via the osmosis process.
Water molecules in the petri dish are at a higher concentration than water molecules in the cytoplasm of cells of the potato and so move along their concentration gradient into the cells.
As the cells of the potato get more water, its mass becomes increase.