Makali and his parents recently emigrated from the highlands of Papua New Guinea. His family is part of the famous Fore tribe; after living in the tribe for most of their lives, they decided to give Makali a different life in the United States. His mother starts to cry as she recalls that both her parents died in the kuru epidemic that made the tribe famous, and she is terrified that Makali might be coming down with kuru. His father interjects to say that it is not possible and that he is far more concerned that Makali has some other infectious disease to which he had never previously been exposed. His father says that Makali had a severe allergic reaction to the tetanus/pertussis booster shot as a child and has been unable to be re-vaccinated due to the risk of anaphylactic shock. Therefore, Makali may be susceptible to whooping cough (pertussis). This would not have been a concern 10 years ago, but vaccination rates for whooping cough have plummeted in the United States, eliminating herd immunity and sparking a return of the disease in some regions. Ironically, vaccination rates in the Fore tribe are much higher than in the United States, so Makali's parents had concerns about coming to the United States, which is falling behind other countries in this area of basic medical care!

One of the doctors you are working with says that checking immunoglobulin (Ig) levels should reveal if there is a serious infection. He also points out that kuru does not cause immunoglobin levels to rise. If Makali does have kuru, a brain biopsy may be required to make a definitive diagnosis.

1. Select the next step or steps that would be appropriate to diagnose Makali?
a. Test immunoglobulin (IgG, IgA, and IgM) levels in the blood for signs of infection.
b. Perform a brain biopsy.
c. Interview one of Makali's friends to ask about the day he first became sick.

2. Which statement most accurately describes the citric acid cycle?
a. It is an unregulated process, like an intersection without signal lights.
b. It is the main center of ATP production during anaerobic metabolism.
c. It plays a central role in key metabolic processes in the cell, with many metabolic intermediates leaving and entering.
d. It serves a catabolic role only, which is to generate ATP and reducing equivalents for cellular energy needs.