What causes exhalation?
a. a signal from the medulla to the mouth and nose
b. a signal from the alveoli to the medulla
c. a signal from the diaphragm to the medulla
d. a signal from the medulla to the lungs

Which of the following represents the results of a review of well-controlled studies of vitamin c supplementation on the resistance to, and recovery from, colds? there was a reduction in the duration of colds by 50% on the average. there was a slight effect on reducing the duration and severity of colds for people taking vitamin c supplements. there was a significant reduction in the duration of colds in people who consumed at least one gram a day. there was a significant reduction in the number of colds only in people who consumed > three grams per day.

Which of the following is not a symptom of chronic fatigue syndrome a) pain in joints with swelling b) low-grade fever c) unexplainable muscle weakness or pain d) forgetfulness, irritability, and confusion

Which of the following supports the argument that viruses are nonliving? a) they are not cellular.b) their dna does not encode proteins.c) they have rna rather than dna.d) they do not evolve.