What is the role of the circulatory system? A. absorb oxygen from the external environment.
B. Sends electrical signals throughout the body.
C. moves blood around the body for nutrient/waste, and blood gas exchange.
D. Removes toxins and waste from the blood stream.

Which statement best describes the relationship between an allele and a gene? question 1 a. an allele is a variation of a gene that can be expressed as a phenotype. b. an allele is the part of a gene that attaches to messenger rna molecules. c. an allele is a segment of a dna molecule that controls replication of a gene.