Plz help. doing how due at 12

Which of th following best describes how genes produce traits in an organism?

The structure of a dna molecule is best described as a. one long strand of nucleic acids b. two strands of dna nucleotides joined by hydrogen bonds c. two strands of amino acids joined by hydrogen bonds d. one long strand of amino acids

Why do the circulatory systems of land vertebrates have separate circuits to the lungs and to the rest of the body?