Question

4. Many fresh-water one-celled organisms have structures called contractile vacuoles. These

Answer 1

Answer:

The process through which the water moves inside these cell is called osmosis.

Explanation:

• The one-celled organisms have some structures called contractile vacuoles which help them to remove excess of water from their body.
• The water enters in the body through osmomis.
• Osmosis is the movement or transfer of water or other solvent through a plasma membrane from a region of low solute concentration to a region of high solute concentration, by which equal concentration is achived on the both sides. Osmosis is passive transport which means it does not require any energy.
• There is high solute(cell organels in this case) concentration inside the cell and low solute concentration in surrounding water and hence water enters inside the cell.
• It is necessary to expel excess of water from the cell as if the water is not expled from the body then water will continuously enter inside the cell as a result of which the cell will burst(same as raisins burst in water when they are kept for too long).
• The concentration of salt water is similar to the concentration of the cell hence contractile  vacuoles has a little value in the ocean (salt water).​

Result: the process of movement of water or other solvent through a plasma membrane from a region of low solute concentration to a region of high solute concentration is known as osmosis.