2 AAMC 8 Questions ; Please Help

[MedicalMan14]

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Both of these are Bio Section questions from AAMC 8
For question 16 it says enhanced activity of which of the following basic muscle types would be most likely to cause hypertension. I said cardiac muscle, because enhancing the activity of cardiac muscle would increase CARDIAC OUTPUT and thus CO and thus P from P=CO X VR. Where am I going wrong with my thinking?

My second question is for #23. The answer is apparently "affecting an allosteric site of PRPP synthetase. And the answer explanation says that it is because the levels in VIVO of activity are higher then in Vitro. Where does it mention in Vitro in the paragraph? It says that the enzyme activity was three times normal levels in cultured cells, but nothing about their levels in Vitro environments. Can anyone clarify?

 

[Geekchick921]

For the first one, they're asking you about what is presented in Hypothesis A. "Vascular resistance is predominantly a function of blood vessel radius. Therefore, and increase in systemic vascular resistance caused by factors such as blood vessel disease or enhanced muscle tone in the vessel walls (vasoconstriction) may be the major cause of systemic hypertension."

Major blood vessels are lined with smooth muscle, not cardiac muscle.

For the second question, I believe the next to last sentence in the last paragraph, "The pH optimum and the enzyme activity of the purified enzyme were normal." suggests a laboratory setting.