Answer:
Without an oxygen atmosphere very few things could live on the early Earth. Anaerobic bacteria were probably the first living things on Earth. The early Earth had no oceans and was frequently hit with meteorites and asteroids.
Explanation:
In the Hardy-Weinberg formula, 2pq represents the frequency of the Aa genotype (heterozygous).
This is a type III hypersensitivity reaction mediated by immune complex deposits. Immune complexes are antigen-antibody (commonly IgG) complexes that are soluble and prone to deposition in multiple organs. Once immune complexes are deposited in an organ, neutrophils and macrophages will then attack the organ causing organ damage and eventually failure. Type III hypersensitivity reactions are characteristic in SLE and other autoimmune diseases such as rheumatoid arthritis, etc.
Other types are type I hypersensitivity which are mediated by mast cells and histamine with the involvement of IgE and this commonly happens in allergic reactions. Type II hypersensitivity is cytotoxic hypersensitivity wherein antibodies directly attack organs (not forming immune complexes). Type IV hypersensitivity (or cell-mediated toxicity) involves T-lymphocytes. This is a delayed type of hypersensitivity exemplified by reactions from <em>M. tuberculosis</em> bacilli in tuberculous disease.
I believe the answer you are seeking is feedback loop
Due to a reduction in blood volume due to blood donation, the stroke volume will decrease. However, to compensate for this, your heart rate will increase so as to maintain your cardiac output. Cardiac output is stroke volume multiplied with heart rate.
Maintaining normal cardiac output is critical so the whole body receives enough nutrients and oxygen.
