#4541S- (44¢) American Scientists - Set of 4

Melvin Calvin was the first scientist to trace in detail the process of photosynthesis, and he conducted pioneering research on using plants as an alternative energy source. He won the Nobel Prize in chemistry in 1961.Asa Gray, one of the first professional botanists in the United States, advanced the specialized field of plant geography and became the principal American advocate of evolutionary theory in the mid-nineteenth century.Maria Goeppert Mayer developed a theoretical model that helped explain the structure of the atomic nucleus; for this work she became one of only two women, the other Marie Curie, to win a Nobel Prize in physics.Severo Ochoa, a biochemist, was the first scientist to synthesize ribonucleic acid, and he competed in the race to decipher the genetic code. Ochoa won the Nobel Prize in physiology or medicine in 1959. Scott 4541-44 American Scientists