Uranium-235, with a half-life of 713,000,000 years, decays to lead-207. If a rock sample is determined to have one-quarter of the uranium-235 content it had when it formed, the age of the rock sample can be estimated to be approximately ______ years old.

The trees below are members of this major group: [1], which are characterized by this major evolutionary innovation: [2].

Refer to the following figure. If there were an additional trophic level that consisted of organisms that prey on snakes, about how much energy would be available to organisms at that trophic level?

Flamingos get their color by eating certain types of crustaceans.  Some flamingos aren’t very good at finding food and are white, and some have adaptations that make finding food easy and they are red.  Pink males find an intermediate amount of food and have lots of time to court females, so they are deemed most attractive by females. Which graph most closely matches the population distribution after selection?  Note: the solid graph denotes distribution before selection, the red dashed graph denotes distribution after selection.

______ are the dominant herbivores of tropical grassland ecosystems.

A contralateral ICA occlusion may cause the ipsilateral ICA velocities to be which one of the followings?

A normal ultrasound characteristic of the internal carotid artery (ICA) includes which one of the following?

The Brachiocephalic (innominate) artery divides into the ___________ and ___________ arteries.

Which of the following maneuvers will identify that the Doppler signal is coming from the external carotid artery?

The most utilized of the Doppler criteria for estimation of percentage diameter stenosis is