Question

Define isotonic solution. What happens when a blood cell is dipped in a solution containing more than normal saline concentration?

Answer 1

Hint: A solution is said to be hypertonic when salt concentration of the solution is more than the salt concentration inside the cell.

Complete step by step solution:
A solution that has salt concentration exactly equal to that of blood cells is called an isotonic solution.
When the salt concentration outside the cell is more, the cell tends to lose water due to osmosis and shrink. This might cause the cell to die.
Additional information: If we consider cell membrane of an RBC to be a semipermeable membrane,
If the solution surrounding the cell has the same salt concentration as that inside the cell, the surrounding solution will be called an Isotonic solution.
If the surrounding solution has higher salt concentration than that inside the cell, the surrounding solution will be called a hypertonic solution.
If the surrounding solution has slower salt concentration than that inside the cell, the surrounding solution will be called a hypotonic solution.
Isotonic solutions are generally used in IV fluids.
When plant cells have an additional covering of cell walls. When these cells are kept in a hypotonic solution, central vacuole swells by gaining more water and exerts pressure against the cell wall. Due to its rigidity, the cell wall pushes it back and prevents the cell from bursting. This is called Turgor pressure.

Note: In case of a hypertonic solution, the cell will lose water by osmosis and may shrink and die and in case of a hypotonic solution the cell may gain too much water by osmosis and burst.