DNA is composed of long strings of nucleic acid sequences, but not all of them code for proteins.But the ones that do are called genes.
Alleles are different versions of a certain gene.As an example, the gene that codes for blood type has 3 different alleles, A, B, an O. The genes that code for hair and eye color also have many different alleles.
Answer: B. Smoking not only produces negative effects on human health but also on the environment.
The Right Answer Is Exoskeleton.
