Nicotiana glutinosa (2 n = 24) and N. tabacum (2 n = 48) are two closely related plants that can be intercrossed, but the F1 hybrid plants that result are usually sterile. In 1925, Roy Clausen and Thomas Goodspeed crossed N. glutinosa and N. tabacum and obtained one fertile F1 plant (R. E. Clausen and T. H. Goodspeed. 1925 Genetics 10:278– 284). They were able to self-pollinate the flowers of this plant to produce an F2 generation. Surprisingly, the F2 plants were fully fertile and produced viable seeds. When Clausen and Goodspeed examined the chromosomes of the F2 plants, they observed 36 pairs of chromosomes in metaphase I and 36 individual chromosomes in metaphase II. Explain the origin of the F2 plants obtained by Clausen and Goodspeed and the numbers of chromosomes observed.

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Inheritance and Mendelian Genetics

Inheritance means the passing of traits to offspring from parents. These traits could be passed either through asexual reproduction or sexual reproduction. The offspring receives the genetic material from the parents. Mendelian inheritance is a certain biological inheritance that follows the rules and principles laid down by Gregor Mendel in 1865. The initial hypothesis was considered wrong, but other inheritance theories modified the concept of inheritance and thus genetics.