Biology is referred to as the study of life. It includes the study of all living organisms such as plant, animals and mammals. The study of biology helps us with the basic necessities of food such as wheat, rice, pulses and development of medicines for curing various types of diseases. Without a food and medicines, survival would almost be impossible on the surface of the earth. The most interesting thing about biology is the study of human body. Our body is so complex that sometimes it is hard to believe. It is hard to believe a child who is so small in size compared to the adult has actually more than twice the number of bones than an adult. Human bodies have the same number of hair as the chimpanzee but these are so fine that they are not clearly visible. I find these as the most interesting things in biology.
Fishes need to maintain a balance of salt and water in their body and for this they use the process of osmoregulation. There are always cases when there is a difference between the salinity of the water fishes are in and their own body and hence they must work for attaining a state of equilibrium between salt and water for their survival. For example, consider the example of a freshwater fish. Freshwater fishes have high salt content than the surroundings and hence there is a strong tendency to lose salt. For survival, they have efficient kidneys that help them lose water quickly. They also take salt from the surroundings using special cells. The condition is completely opposite for a marine fish. They have a strong tendency to absorb salt. They maintain equilibrium by drinking lots of water and urinating less. They do not consume salt from the water they drink. They have special gills that help them eliminate salt from their bodies.
There are two different types of cells present. Eukaryotic cells are different from the prokaryotes in a way that they contain membrane structures such as nucleus. They also have more than one chromosome and prokaryotic cells on the other hand only a single chromosome. Eukaryotic cell are usually multi-cellular while prokaryotic cells are unicellular. Prokaryotes are smaller with a maximum size of 2 µm while the eukaryotes can go as large as 100 µm in size. The endosymbiotic theory proposes the organelles present were once the prokaryotic cells. The theory states that eukaryotes evolved from prokaryotes. The theory states prokaryotes were inside host cells. They might have provided the host cells the necessary nutrients and in turn would have had an environment that helped them survive.
Homeostasis is referred to as the maintenance of a constant favorable environment. The maintenance of a healthy environment is essential for the survival of the cell. Every part needs nutrients for its survivals. Nutrients need to be transported to a