Radioactive isotopes are used to tag proteins in the cell membranes of mouse cells. these cells are then fused with human cells in cultures. what is the likely outcome of the tagged mouse proteins?

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.

her affection for her parents makes her an especially sympathetic character.