More than 20 species of Hawaiian honeycreepers are descended from a goldfinch-like ancestor that arrived on one of the islands about 5 million years ago from Asia or North America. The birds of the various species are similar in body size and shape, but differ in color and beak shape. How could so many species have evolved from a single ancestral species?

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

The organelle pictured is found in cells of and is theorized to have once been an independent organism.

The green colored pigment in chloroplasts is? a. nitrogen b. chlorophyll c. chlorophorm d. chlorofloromethane