Well matter is basically any substance that has mass and takes up space. Example, you have a ball, or a table, or anything really. That is mass. But anything that doesn't take up space or has mass isn't matter. So, anything that doesn't have a mass or take up space is not matter. Hope this helped you understand. :D
Answer:
Innate immunity is a non-specific immune system which provides defence against any pathogenic microorganism in early stages. It includes physical barrier such as skin, chemical barriers such as saliva, tears, et cetera, phagocytic cells such as macrophages, et cetera.
Acquired immune system is the one which develops after exposure to pathogen or antigen. It is highly specific in nature. It includes B-lymphocytes and T-lymphocytes. It includes the production of antibodies.
Vaccines are used to develop acquired immunity in people. The process is termed as vaccination or immunisation. Heat-killed or weakened pathogen or antigen is inserted into a person after which a person develops antibodies and memory cells against that pathogen or disease. So, the immune system acts more vigorously against that pathogen in secondary infection.
Thus, a person becomes immunised.
Takes place in <span>two stages</span>
