Nitrogen - 14 and nitrogen - 15 are isotopes of the same element. How do these isotopes differ

Hurry which of these is true about index fossils? a) are very scarcely found b) used as guides in relative dating c) found in the youngest layer of the rock d) used as reference points in absolute dating

Ais a group of individuals of the same that exist together in the same place at the same time

Make a claim about the factors that cause inherited genetic variations within populations. also make a claim about the effects of mutations.