A researcher conducted an experiment on a fruit fly species in which a single population of the flies was split into two separate groups. One group was fed with a starch-based food source, and the other group was fed with a maltose-based food source. The populations remained separated with their different food sources for many generations. When the two groups were finally reunited with each other, it was observed that the fruit flies still preferred to mate with members of their original population over members of the other population that had been fed a different food source.

What process is illustrated by this experiment?

A. coevolution

B. convergent evolution

C. gene flow

D. speciation

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

hope this .. .

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.