Which is likely to be the most important contribution of genetic engineering to the practice of selective breeding?
making pets that are more docile
producing plants that grow same-sized fruit
reducing genetic diversity to make harvesting easier
developing crops that are more resistant to attack by pests

Lactase is essential for digesting lactose in milk. this enzyme is specific for this sugar. why? molecules and active sites vary in size; only properly sized molecules can fit.there is a precise compatibility between the active site and the lactose molecule.specificity refers to the action of the enzyme, such as hydrolysis, and relatively few molecules can be hydrolyzed.reaction-specific enzymes assume a fit by folding around the most numerous substrate molecules.