Which of the following statements is true? a. all cells contain at least one tissue. b. organs are made up of cells and tissues. c. only some organs contain cells. d. tissues are made up of organs and 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.

What must be done to breed dogs for a partical trait

Which of the following is caused by reproductive isolation within a species? a. a decrease in gene flow b. an increase in genetic flow c. a decrease in genetic drift d. an increase in gene flow