Question

name the process by which unicellular fresh water organisms and most plant cells tend to gain water

Answer 1

The process by which unicellular freshwater organisms and most plant cells tend to gain water is Osmosis.
Osmosis is the passage of water from region of high water concentration through  a semi permeable membrane to a region of low water concentration.
Osmosis is purely a mechanical process where cell absorb water without spending any amount of energy.

Answer 2

Osmosis is the process by which unicellular freshwater organisms and most plant cells tend to gain water. for example raisins