Isotopes of the same element have different
a) positions on the periodic table
b)chemical behavior
c) atomic numbers
d)mass numbers

The organelle pictured is found in cells of and is theorized to have once been an independent organism.

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.

Match the description of each organism to the appropriate category