John Carl Ross attended the Boys' High School at Sea Point, Cape Town, and passed the matriculation examination of the University of the Cape of Good Hope in 1908. Continuing his studies at the South African College, Cape Town, he received the college's gold medal in science in 1911 and that same year was awarded the Bachelor of Arts (BA) degree with honours in chemistry by the university. During 1912-1913 he was a lecturer in chemistry at the recently established Grootfontein Agricultural School at Middelburg, Eastern Cape. Thereafter he went to the United States and was awarded the degree Doctor of Philosophy (PhD) by the University of Illinois. In 1918 he was appointed as research chemist at the School of Agriculture at Elsenburg, near Stellenbosch. By 1921 he was a member of the Faculty of Agriculture of the Transvaal University College (from 1930 the University of Pretoria), where he remained until at least 1933. Later he became a member of the inspectorate in the Department of Education of the Cape Provincial Administration, a position he held until 1946.
Ross seems to have been interested mainly in the chemistry of nutrition. In 1917 he published a paper on 'The place of protein in nutrition' in the South African Journal of Science (Vol. 14, pp. 350-354). Later he and A.M. Bosman wrote 'Digestibility of teff hay for sheep' (Publications of the University of Pretoria, Series 1: Agriculture, 1927, No. 10). The same authors, with the addition of L.P. van Wyk, followed this up with 'Digestibility of teff hay, maize oil cake and lucerne hay for cattle' (Ibid, 1931, No. 20).
Ross became a member of the South African Association for the Advancement of Science in 1917 and of the South African Chemical Institute in 1918. He was still a member of the latter in 1958, living in Pretoria.