Sourav Pan is the founder and sole author of Biology Notes Online. He holds a Bachelor of Science (B.Sc.) degree and an M.Sc. in Microbiology from the University of Calcutta. He creates educational resources covering microbiology, immunology, biotechnology, genetics, cell biology, botany, zoology, and other life-science subjects.
His goal is to make complex biological concepts easier to understand through well-structured, student-friendly articles based on academic textbooks, peer-reviewed research, and authoritative scientific sources. In addition to writing new content, he regularly reviews and updates articles to improve their accuracy, clarity, and educational value.
Immunotherapy for tumors is a treatment method where the body immune system is used to act against cancer cells. It helps immune cells to identify and kill tumor cells. It is not like chemotherapy, because chemotherapy directly attacks dividing cells. In immunotherapy, immune response is increased or trained against cancer antigen. The main target is … Read more
Chronic granulomatous disease (CGD) is a rare inherited primary immunodeficiency disease. It affects the phagocytic cells mainly neutrophils and macrophages. These cells are normally used to kill the invading bacteria and fungi. It is caused due to mutation in genes which are related with NADPH oxidase enzyme complex. Due to defect in this enzyme complex, … Read more
Immunodeficiency is a condition in which the immune system becomes weak or defective. It may occur due to defect in lymphocytes, phagocytes or complement system. In this condition, the body becomes more susceptible to infections. Immunodeficiency disorders are conditions in which the immune system becomes fully or partly impaired. It occurs due to defect, failure … Read more
Hypersensitivity is an abnormal immune reaction of the body. It is an exaggerated response against an antigen. This reaction causes tissue damage and different physiological disturbances in the body. Normally immune system protects the body from harmful substances. But in hypersensitivity, the same immune system reacts in harmful way. It may react against harmless substances … Read more
Cytotoxic T cells are special type of white blood cells present in the adaptive immune system. These cells are commonly called CD8⁺ T cells. They are mainly used to destroy the body cells which are infected by virus, intracellular pathogens or changed into cancerous cells. Cytotoxic T cells continuously move in the body and check … Read more
Cell mediated immune response is a type of adaptive immune response in which T lymphocytes directly react against the foreign antigen. It does not mainly depend on circulating antibody. It is mostly active against intracellular pathogens, infected cells and some abnormal cells. This immune response is mainly carried out by cytotoxic T cells (CD8⁺) and … Read more
Immunological tolerance is a state of specific unresponsiveness of the immune system against a particular antigen. In this condition, the immune system does not produce destructive reaction against that antigen. It is a normal protective mechanism of the body. It helps the immune system to distinguish between self and non-self substances. The immune system can … Read more
Spirogyra is a filamentous green algae. It is free floating in nature. It is mainly found in freshwater bodies like ponds, lakes and slow moving streams. It is commonly called water silk or pond scum. This name is given because its filament is soft, slimy and slippery. The filament is covered by mucilaginous sheath. The … Read more
Volvox is a freshwater green algae. It forms hollow and spherical colony. It is also known as globe algae or rolling green algae. It is found in ponds, lakes, ditches and puddles. It occurs in freshwater bodies in different parts of the world. Sometimes the colony can be seen by naked eye. The colony of … Read more
Anabaena is a filamentous cyanobacteria. It is commonly known as blue green algae. It is found in freshwater, marine water and soil. It may be present as plankton or mat like form. It is multicellular organism. The cells are arranged in unbranched chain. This chain is called trichome. The cells are bead like. These vegetative … Read more