The first three are the same as those found in DNA, but in RNA thymine is replaced by uracil as the base complementary to adenine. This base is also a pyrimidine and is very similar to thymine. Uracil is energetically less expensive to produce than thymine, which may account for its use in RNA.
Raynaud's phenomenon refers to an ailment featured by blood vessel unusuality resulting due to overactivity of the smooth muscle in the wall of arteries, causing spasms (vasospasms with constriction) of the small vessels, which supply blood to the legs, arms, feet, and hands, and sometimes the nose and ears.
Thromboangiitis obliterans, also known as Buerger's disease and vasculitis, is characterized by thrombosis and inflammation of the small and medium arteries of the feet and legs that recurs and advances in phases.
Natural selection act directly upon <u>Alleles</u>
Explanation:
Genes, such as that of fur color, have many variants called alleles. Natural selection act on the alleles and chooses the best fit for an environment and eliminates the disadvantageous ones from the population over generations. Mutations are a rare occurrence that increases the number of allelic variants of a genes on which natural selection can act upon.
I believe its large blue vessel also known as vena cava
