Question

Put a drop of blood in three types of liquids :

(a) pure water

(b) salt solution

(c) water containing 5M glucose and 0.9% Nacl

What will happen to blood drop and why ?? Explain your answer.

Answer 1

When you put a drop of blood in a solution that is hypertonic to it the blood cells will undergo what is known as crenation.

On the other hand, when you put a drop of blood, the cells undergo hemolysis.

When the blood is put in isotonic solution, there will be no change occurring to the blood cells.

In both cases, the red blood cells are the cells in the blood being referred to.

A look at the terminologies used above:

1) Hypertonic solution - this refers to a solution that has a higher concentration , has more solutes, than the concentration of the cells cytoplasm.

2) Hypotonic solution - this solution is one which is less concentrated as compared to the concentration of the cell cytoplasm; has a smaller amount of solutes.

3) Crenation - this is the shrinking of cells that is caused when it loses water to its environment when placed in an hypertonic solution through exosmosis.

4) Hemolysis - this happens when cells are placed in hypotonic solution. The cells draw water from this solution through endosmosis and end up bursting - the process of hemolysis.

Therefore you just have to know whether the solutions are hypertonic or hypotonic to the cells in the blood to know whether crenation or hemolysis will take place.

A. Pure water is hypotonic and hence hemolysis will take place.
B. Salt solution is hypertonic to and hence creantion of the cells will take place.
C. Water containing 5M glucose and 0.9% NaCl is isotonic to the concentration of blood cells and there will be no change on the cells.