Question

Lab #4 Osmosis Experiment 1 – Tonicity and the Animal Cell

Answer 1

Osmosis is the movement of solvent molecules like water along the concentration gradient through semipermeable membrane.

It is a type of passive transport because it does not require energy in the form of ATP hydrolysis.

It also does not require any membrane proteins which act as transporters.

Solutions can be of three types on the basis of their concentration with respect to the cell.

1. If the concentration of the external solution and the cell is equal then, it is said to be isotonic In this case, the rate of movement of water inside the cell is equal to the rate of movement of water leaving the cell and therefore there is no change in the shape of the cell.

2. If the concentration of external solution is greater as compared to the cell then the solution is said to be hypertonic. In this case, water molecules leave the cell and enter into the external solution resulting in the shrinkage of the cell.

3. If the concentration of external solution is lesser as compared to the cell then, the solution is said to be hypotonic and water molecules enter inside the cell resulting in the swelling of the cell. If it is an animal cell, then it may even burst because animal cell does not contain cell wall.