Does the palisade and spongy mesophyll have the same functions/do they both have a role that includes photosynthesis? Or is it just the palisade? if yes, is it safe to say: when CO2 enters the leaf, through the stomata, it goes through air space, into the spongy mesophyll and palisade mesophyll?

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.