Answer: Leeuwenhoek biggest contribution is to the first tenet of the cell theory.
Explanation: the first tenet of cell theory states that every living being is made of cells and even an organism can be made of just one cell able to reproduce by itself.
Leeuwenhoek observations stablish the existence of microscopic structures alive some with movement. This helped other scientists to determinate this structures were cells that can make vital processes such as feeding, breathing or reproducing which are determinant in biological definition of life.
Thrifty metabolism
Thrifty metabolism is the genetic
tendency toward efficient use of energy that results in below-average energy
requirements and increased storage of calories as fat. Thrifty metabolism
contributes to less weight lost when an obese person reduce the amount of his
calorie intake even though there is changes in metabolism.
Mutations are disruptions in the human body