R r
R RR Rr
r Rr rr
In a classic experiment using pea shape, Mendel conducted two separate genetic crosses. In the first cross the parent plants were “true breeding” for pea shape; one had round peas ( R )and the other had wrinkled (r). The first cross produced a filial 1 generation of all round peas. In the second cross, Mendel bred plants from the filial 1 generation. This cross produced different results. Out of approximately 1000 plants, about 75% were round and 25% were wrinkled. From these experiments, Mendel developed four hypotheses. They include all BUT A) one heritable factor may be dominant and mask the other factor. B) any organism that "shows" a heritable factor must be homozygous. C) an organism has two "heritable factors", now called genes, one from each parent. D) a sperm or egg carries only one heritable factor for each trait in the offspring.
