Purines are adenine and guanine. So the answer should be D (Pyrimidines). besides, phosphate group and pentose sugar are a part of a nucleotide.
Answer:
Explanation: Mendeleev arranged the elements on the basis of their atomic mass. Melting and boiling point were used as the physical characteristics in deciding the position of elements. He arranged the elements and wrote the formula of their oxides and hydrides which seemed to possess same chemical formula.
Explanation:
The structure of proteins is ultimately determined by the sequence of nucleic acids.
The answer for the question above is A. the gravitational pull of the moon on the water near the coast. The sun and and the moon are responsible for the rising and falling of the ocean tides. The gravitational pull of the moon and the sun makes the water in the oceans bulge, causing a continuous change between high and low tide.