Changes in allelic frequency are always driven by natural selection.

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.

What organ is the first to receive nutrients that have been absorbed from the digestive tract?

Which label correctly identifies what x represents in the concept map?