Your heart rate increases when exercising because: a. your muscle cells need more oxygen
b. your muscle cells start growing faster
c. your heart creates more blood
d. your heart sends more blood to the muscle cells

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

The breakdown of food is accomplished by enzymes. a. physical b. chemical c. mechanical d. none of the above

The illustration shown is an ovum, a female sex cell. a mutation in this cell may be passed to the woman’s offspring during a) birth. b) mitosis. c) dna replication. d) sexual reproduction