Question

Explain the detailed process for a cell taking in water from the periphery. What are the dangers associated with taking in water, and how are they overcome?

Answer 1

Explain the detailed process for a cell taking in water from the periphery. What are the dangers associated with taking in water, and how are they overcome?

A cell is made up of phospholipids having a polar head group and non-polar lipid tail which is embedded inside forming lipid bilayer. Water molecules are small in size hence can easily cross the cell membrane.

The movement of water inside a cell occurs through different passive processes called osmosis, depending upon the concentration of water present.

Osmosis is a type of diffusion of solvent (mainly water) from a region of high concentration to a region of low concentration through a semi-permeable membrane.

The region where the concentration of water is high, water moves from that region to region where concentration of water is low.

In this way a cell uptakes water from the surrounding. A cell always uptake water only when there is an osmotic potential due to imbalance of solutes across the cell. the osmotic potential is high in the region where water concentration is low and solute concentration is high. Water moves from low osmotic pressure region to high osmotic pressure region.

Depending upon the tonicity, solutions are of three types

Isotonic – When the concentration of water is equal both inside and outside of a cell (equal osmotic potential). It means the number of water molecule entering a cell equals the number of water molecules leaving the cell.

Hypertonic- when concentration of water is high inside a cell and low outside the cell, the water moves out of cell and the cell becomes flaccid.

Hypotonic solution- when concentration of water is high outside the cell, the water moves inside the cell and the cell becomes turgid.

How the dangers associated with taking in water, and how are they overcome?

Movement of water from outside to inside of water makes the cell to increase in size and become turgid.

In animal cells - When water moves into the cell as a result the cell membrane stretches and the cell gets bigger. If water intake continues, the cell membrane will eventually burst – the process is called lysis.

e.g. Red blood cell- excess intake of water could result in lysis of RBCs resulting into haemolysis and loss of blood.

Plant cells- When water moves into a plant cell, the vacuole absorb water and gets bigger putting a pressure on the cell membrane against the cell wall. The turgor pressure generated within the cell makes it firm or turgid. But if the excess water enters the cell the pressure increases beyond control and the cell eventually bursts.

Prevention- The cells have their own way of preventing entry of excess water into the cell. as the cell applies turgid pressure on the cell wall, the cell wall counter-balance the pressure and prevents the cell from lysis or bursting.