LIFE SCIENCE

Detailed explanation-1: -Answer. Osmosis is the movement of water through a plasma membrane from a region of low concentration to a region of high solute concentration. Here, the protozoan loses water when its put in a solution of lower water concentration as water always move from high concentration to low concentration.

Detailed explanation-2: -When a freshwater protozoan is placed in marine water then the protozoan dies. Freshwater protozoans have the ability to produce contractile vacuole which helps in the survival of protozoan from osmosis. It means, the contractile vacuole disappears.

Detailed explanation-3: -A fish that lives in salt water will have somewhat salty water inside itself. Put it in the freshwater, and the freshwater will, through osmosis, enter the fish, causing its cells to swell, and the fish will die.

Detailed explanation-4: -When the saltwater fish is placed in a freshwater aquarium, the fish will take too much water in its cells causing it to swell and then rapture causing the fish to die. The freshwater is a hypotonic solution therefore, the water molecule will move from the place of high concentration to the place of low concentration.

Detailed explanation-5: -Freshwater is hypotonic to Elodea A hypotonic solution is a solution that contains less (hypo) solutes than the cytoplasm of the cell. Thus, a hypotonic solution has more water than the cell and water has a tendency to move (diffuse) into the cell.