Biochemistry
From Memory Alpha, the free Star Trek reference
Biochemistry is one of the science courses offered at Starfleet Academy. This course can lead to a medical position. Biochemistry can be taken for more than two semesters. (VOY: "Parallax")
After sodium pentathol was having no effect on Quark in 1947 Earth, Jeff Carlson noted that Ferengi biochemistry was nothing like that of Humans. (DS9: "Little Green Men")
Cardassian biochemistry was all but unknown to Federation doctors, including Julian Bashir, in 2370. (DS9: "The Wire")
Tom Paris took two semesters of biochemistry in the Academy. This qualified him to be a field medic on board the USS Voyager. The biochemistry course Paris enrolled in did not teach how to perform a respiratory series. (VOY: "Parallax", "Phage")
In 2372, the Doctor found that Tom Paris' entire biochemistry was changing after being admitted to sickbay for having an allergic reaction to the water in his coffee. (VOY: "Threshold")
In 2377, the Doctor told B'Elanna Torres that it was not unusual for a pregnancy to cause biochemical changes in the mother. (VOY: "Lineage")
