Which of the following requires the least amount of energy? a. gaining an electron b. losing two electrons c. losing four electrons d. losing an electron

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.

Which of the following is caused by reproductive isolation within a species? a. a decrease in gene flow b. an increase in genetic flow c. a decrease in genetic drift d. an increase in gene flow

If t=tall and t=short what will be the physical appearance of the offspring the cross below? a. some will be tall and some will be short b. they will all be tall c. they will all be short d. they will be medium height