What is osmosis?
To understand osmosis, first you need to understand water potential. Pure water has a water potential of 0, and as it becomes less pure (due to things dissolving in the water) the water potential goes down into the minus numbers. Osmosis describes the tendency for water to want to move from a high water potential where is purer to a lower water potential. Water does this because it is trying to create an equilibrium - where the water is the same purity on both sides.
Related Biology A Level answers
All answers ▸Describe how phagocytosis of a virus leads to presentation of its antigens and how presentation of this antigen leads to the secretion of an antibody against this virus antigen.
Explain how an electrochemical gradient is formed in the mitochondria, and how this gradient is used to synthesise ATP.
What is the difference between mitosis and meiosis?
When a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism. Describe how. (5 marks)