section 3 (1) explain why the concentration of water in cells should be maintained within a narrow range for optimal function

Question 1

What is water’s role in living organisms?

Answer 1

• Water is the solvent that forms the basic aquatic medium of cytoplasm in cells and body fluids. It is also the transport medium in plants.
• Water provides the necessary medium in which all chemical reactions of metabolism can occur
• makes up 2/3 of the body

Question 2

How is water concentration and solute concentration related?

Answer 2

• Water enters and leaves cells through osmosis and it follows the osmotic gradient (water moves from high concentration to low concentration). Hence the movement of water into and out of the cell depends directly on the concentration of solutions both inside and outside the cell.

Question 3

Why must water concentration be maintained within a relatively small range?

Answer 3

• so that chemical reactions in the cells are able to continue as a result of water being the main solvent for all chemical reactions in cells

Question 4

What are some of the problems associated with a change in water concentration?

Answer 4

• If the balance of water and solutes in cells is not maintained at an optimal concentration, too much water may enter the cell causing it to burst, or too much water may move out causing the cell to shrink and the cytoplasm too concentrated for cell functioning.
• The osmotic pressure of living tissue can also affect the pH in cells – for example, too little water leads to an increase in the concentration of solutes such as carbon dioxide thus reducing the pH.
• lack of structural support- osmotic pressure provides structural support
• may dilute concentration of solutes