What are the species that no longer exist on earth known as

What links the two strands in a dna helix together in the middle? a. phosphate groups b. sugar rings bonded together c. proteins d. bases with hydrogen bonds

The rapid decomposition of organic matter produces evidence which supports: the slow accumulation of coal deposits long ages of the earth rapid burial of vast amounts of vegetation biblical account of noah's flood

Veins have a much lower blood pressure than arteries. which of these prevents backflow of blood in veins? a. pressure applied by the heart b. one–way valves in veins c. thin muscular walls of veins