Different species of heterotrophic Unicellular organisms such as amoeba and actually actinobacteria are found in fresh water sources .the future of distinguishes amoeba from actinobacteria is the-

Cells tend to have a relatively small and uniform size. why aren’t cells larger?

Does the sun release radiant energy?

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.