Some lizard species contain females only, so there is no sexual reproduction. In these populations, what would be the major source of variation for natural selection?
A. recombination.
B. independent assortment. C. segregation. D. mutation.

Ablastocyst is a group of cells that forms after a human egg is fertilized. the blastocyst consists of two types of cells. some of these cells will become the placenta. what do the other cells develop into?

Which statement describes john tuzo wilson’s contribution to the theory of plate tectonics?

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.