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

What is an animal that lives by preying on other animals

Which organelle breaks down sugar molecules that supply energy to the cell ?

Which of the following factors would not contribute to allopatric speciation? a) a population becomes geographically isolated from the parent population.b) the separated population is small, and genetic drift occurs.c) the isolated population is exposed to different selection pressures than the ancestral population.d) different mutations begin to distinguish the gene pools of the separated populations.e) gene flow between the two populations is extensive.