Building Blocks of Nucleic acids are polynucleotides- <span>long chainlike molecules composed of a series of nearly identical building blocks called nucleotides</span>
Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues
In the case of chronic bronchitis or chronic inflammation of the airways, cyanosis or the bluish discoloration of the skin results from the reduced levels of oxygen in the blood. With reduced oxygen levels, the blood in the arteries will not be bright red in color but rather be brownish just like venous blood and this reflects in the skin as bluish in color.
Species change over time due to natural selection.