How does endosymbiosis play a role in the evolution of prokaryotes to eukaryotes, and how are mitochondria important to this evolution?

Which are forms of nitrogen that are usable by humans

Freckles are a dominant trait in humans. both of the girls have the genotype ff for freckles. if either one marries a man with no freckles, what are the chances that their children will have freckles?

What makes a dominant allele different from a recessive allele