In tissues deriving energy anaerobically (such as rapidly exercising skeletal muscle), lactate, rather than pyruvate, serves as the end product of glycolysis.
which of the following statements best explains why pyruvate is converted to lactate under these circumstances?
a. the mitochondrion is more permeable to lactate than to pyruvate.
b. lactate, but not pyruvate, serves as a substrate for gluconeogenesis.
c. the conversion of pyruvate to lactate is accompanied by the production of atp.
d. nad+ necessary for the glyceraldehyde phosphate dehydrogenase reaction is regenerated

Mr. j, age 42, is a construction worker in las vegas. he recently noticed that a mole on his face seemed to be getting larger and darker. at first he did not worry because he was in the sun a lot and assumed the change may have been caused by sunburn. after a month, not only was the mole larger and darker, but it appeared to be “bumpy.” his doctor diagnosed a malignant melanoma skin cancer following biopsy of the nevus. mr. j reports pain in his right shin that does not go away when he puts his feet up or sleeps. discussion questions 1. relate mr. j’s skin changes to the warning signs for malignant melanoma. (see malignant melanoma.) 2. discuss the normal progression of this malignancy. what is the significance of the bone pain that mr. j is experiencing? (see malignant melanoma.) 3. discuss the treatment available for this patient and the prognosis for recovery. (see malignant melanoma.)