In thick skin, there is an extra layer of epidermal cells. this layer is called the stratum .

Which statement describes characteristics of planarians? a they live in oceans, are parasites, and reproduce only sexually. b they live in fresh water, are parasites, and reproduce only asexually. c they live in oceans, are free living, and reproduce sexually and asexually. d they live in fresh water, are free living, and reproduce sexually and asexually.

Nucleic acids offer variability because they contain alternate forms of genes called .

What is gene expression control that occurs after the generation of rna