Microevolution is occurring when: a bird has a beak of a particular size that shrinks during a drought allele frequencies change
in a population occur over generations gene flow evenly transfers alleles between populations individuals within all species vary in their phenotypic traits
Basically you have hydrophilic (water loving) and hydrophobic (water hating) the heads are hydrophilic and the tails are hydrophobic. this allows the cell to be selectively permeable. this means selectively allows or does not allow substances In or out
