PLEASE HELP!! Which of these is necessary for gas exchange in the respiratory system?
a. At least 30% oxygen in the air
b. The exchange surface must be moist c. The air must be cooler than body temperature
d. The blood cannot be moving ​

The main role of dna in the  cell is the long-term storage of information. it is often compared to a blueprint, since it contains the instructions to construct other components of the  cell, such as  proteins  and rna molecules.the main function of rna is to carry information of amino acid sequence from the genes to where  proteins  are assembled on  ribosomes  in the  cytoplasm. mark brainliest, my work is good.