How many chromosomes do sex cells have compared with the original?

In dna, only the_ varies from one nucleotide to another. base phosphate sugar amino acid

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.

Plsss > .< compare and contrast the characteristics of flatworms rounds worms and earthworms