SCIENCE PHOTO LIBRARY SCIENCE PHOTO LIBRARY
Mendelian genetics, Punnett square. Diagram showing the genetics of seed colour in peas, as discovered by Gregor Mendel in the 1850s and 1860s. The genes controlling seed colour are Y and y, with Y dominant over y. The combinations YY and Yy produce yellow seeds. The combination yy produces a green seed. The pure parent lines (top) combine gametes (pollen and eggs) to produce a first generation (F1) of yellow seeds (Yy). This self-fertilises to produce the second generation (F2). The colour proportions of the F2 generation of seeds are shown in the form of a Punnett square, with a quarter of the seeds being green (yy, bottom) and three-quarters yellow.
Model release not required. Property release not required.