How do catalysts affect the energy of reactions?

Explanation:

A catalyst speeds up a chemical reaction, without being consumed by the reaction. It increases the reaction rate by lowering the activation energy for a reaction. ... Remember that with a catalyst, the average kinetic energy of the molecules remains the same but the required energy decreases

one would be wind another would be water density

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).