The organ system that obtains oxygen from the air and disposes of waster carbon dioxide back into the air is the system. What is the blank answer?

The  central dogma  of molecular biology is centered upon the process of protein synthesis, in which the information from dna is transcribed and translated, resulting in multiple amino acids being joined to form a)lipidsb)proteinsc)carbohydratesd)nucleic acids

One function of the poly-a tail on eukaryotic mrna sequences is to the mrna be transported from the nucleus to the cytoplasm. prokaryotic mrna also has a poly-a tail. choose the best explanation of the prokaryotic poly-a tail. a. prokaryotic poly-a tails are composed of a different molecular structure compared with eukaryotic poly-a tails. b. prokaryotic poly-a tails have the same functions as eukaryotic poly-a tails, because this process is highly conserved throughout different species. c. prokaryotic poly-a tails aren't important, because prokaryotes don't have nuclei. d. prokaryotic poly-a tails have other functions,because prokaryotes don't have nuclei.

What is the one part of the nucleotide  that differs among the other different nucle  tides?