What was the most important scientific advance gained from gregor mendel's experiments with pea plants? a. we learned that chromosomes are composed of dna. b. we learned that recessive alleles occur more frequently in the f2 generation than do dominant ones. c. we learned that many traits are inherited in discrete units, and are not the result of blending. d. we learned that there is considerable genetic variation in garden peas. e. darwin's theory of evolution by natural selection was confirmed?