[Payal Tekwani]

Physical change is a temporary process which can be reversed or bring back to its original state. So , it a reversible process. No new products or substances are formed in this change . It brings change in only physical properties of matter like shape , size etc. It has no effect on the change of chemical bonds of atoms or molecules and due to this no energy is produced during this change. In this composition of matter is not changed.

While a Chemical change is a permanent change which cannot be reversed. So, it is an irreversible process. In a chemical change always new substances and products are formed . In contrast to physical change and as the name clarifies it has direct effect on chemical bonds of molecules or atoms and due to this energy is produced during this change. In this composition of matter is changed.

Let us understand completely with the help of example –

* Melting of an ice is an excellent example to explain physical change.

* Burning of wood is an excellent example for chemical change.

[Payal Tekwani]

Our immunological responses are governed by various cells but majorly cells which are involved in generating immune response in our body are B-cells and T-cells. B cells are known as B-Lymphocytes produced by bone marrow and T-cells known as T-Lymphocytes are produced by Thymus. Both the cells work together and generate antibodies to fight from microorganisms or we can say pathogens. Apart from these cells our body produces Macrophages , Interleukins , Monocytes and many other cells for providing immunity.

• This reply was modified 1 year, 10 months ago by  Payal Tekwani.