C. I and II only
The question is asking for the acidic salt(s). The conjugate acid of a weak base will lower the pH, while the conjugate base of a weak acid will raise it. Conjugates of strong acids or bases have no effect on pH. NH4+, the conjugate of the weak base NH3, is acidic. Cl-, the conjugate of the strong acid HCl, will not affect pH. Thus, Item I is an acidic salt (eliminate choice B). K+ and HSO4- are conjugates of a strong base and strong acid, respectively. Generally this would indicate a neutral salt. However, the HSO4- ion is acidic in its own right and will lower the pH, so Item II is also true (eliminate choice A). Na+ is the conjugate of a strong base and HCO3- is the conjugate of a weak acid, so Item III is a basic salt and will raise the pH of the solution (eliminate choice D).
Ribose-5-phosphate, a product of the PPP, is used in the formation of nucleotides. Which of the following is true regarding the structure of nucleotides?
A. The purines, adenine and guanine, are double-ring structures.
B. The pyrimidines, cytosine and thymine, are double-ring structures.
C. The purines, adenine and guanine, are single-ring structures.
D. The pyrimidines, guanine and thymine, are single-ring structures.
Suppose that an SAH patient presents with the following sequelae: problems initiating speech, mild depressive symptoms, and subtle personality changes, such as increased anger and impulsivity. Based on these symptoms, which of the following brain regions have most likely been affected by the SAH?
A. The amygdala, Broca's area, and the hypothalamus
B. The amygdala, Wernicke's area, and the hypothalamus
C. Portions of the frontal lobe, Broca's area, and the hypothalamic-pituitary axis
D. The prefrontal cortex, Wernicke's area, and the hypothalamic-pituitary axis