What happens to a cell to specialize as a red blood cell

Which element is found in both dna and proteins

During endocytosis, cells expel what they don't need take in what they need shrink due to loss of water

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.