Darwin explored the Galapagos Islands and observed variations of certain species. For example, he saw that the mockingbirds on three different islands were distinct but still similar to the mockingbirds found on the mainland. The level of diversity in an ecosystem can be determined by the frequency of speciation and extinction. Describe speciation and identify two possible prezygotic barriers of the mockingbirds that contribute to speciation. If the mockingbirds became extinct, explain how this could lead to adaptive radiation.

Explain nonnuclear inheritance. ~ ap biology

Match the following terms describing electrical events with the correct phases of the cardiac cycle. the ventricular muscle cells depolarize at the start of this phase. during this phase, na+ entry through the funny channels causes the pacemaker potential of sa nodal cells to gradually become less negative until it reaches threshold. the ventricular muscle cells repolarize right before this phase. the cytosolic concentration of calcium in the contractile cells of the ventricle is highest during this phase. a. isovolumetric relaxation b. ventricular ejection c. isovolumetric contraction d. ventricular filling

As a small change in a person's dna can cause a genetic disorder