C.2
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Frogs do have lungs but they are small and rarely used, frogs mostly take in moisture through the skin in process called cutaneous gas exchange.
The answer is C. This is because nucleotide elongation involves the addition of a nucleotide to the 3 prime carbon of the previous nucleotide carbon ring. This involves a dehydration reaction between the phosphate group on the 5 prime carbon of the last nucleotide to the hydroxyl group of the 3 prime carbon of the previous nucleotide.
The answer is B). Genetic screening basically testing for the genetic traits of an individual. Therefore the answer would be B).
Developing a coelom made nutrients more easily absorbed by roundworms. A coelom is a fluid filled cavity developed in the mesoderm and it is the main body of a roundworm. It contains the digestive tract and many other organs.
