Question

In Pisum sativum, the axial (A) flower position is dominant and the terminal flower position (a) is recessive. Two pea plants were crossed, producing seeds that yielded 165 plants with axial flowers and 54 plants with terminal 165. The genotypes of the parent plants were most likely
A. Aa and AA
B. Aa and Aa
C. aa and Aa
D. AA and aa

Answer 1

Hint: The process of how an offspring receives genetic information from the parent is called inheritance. The heredity is dependent upon the inheritance of traits or characters from the parents.

Complete answer: The members of the same family possess similar characteristics due to inheritance. Gregor John Mendel derived the principles of Mendelian inheritance by performing experiments using the Pisum sativum plant. He considered 7 traits for conducting the experiments in which one of the traits was the position of the flower that is axial (A) position which is considered as dominant and the terminal position (a)is considered as recessive. In the above-given question, the crossing of two seeds produced 165 plants with axial flowers and 54 plants with terminal flowers. So, let ‘A’ be the dominant allele and ‘a’ be the recessive allele. The product obtained is in the ratio of 165:54 that is 3:1. This product can be obtained by crossing the parents with genotype Aa and Aa. So, crossing these genotypes produces 75% axial flowers and 25% terminal flowers.
Thus, option B is the correct answer.

Additional information: Gregor Mendel proposed three laws of inheritance after successfully conducting the experiments. The law of dominance states that an organism with at least one dominant allele will have the phenotype appearance of the dominant allele. Law of segregation states that the alleles for each gene segregate from each other during gamete formation. So that each gamete carries only one allele for each gene Law of independent assortment states that during the formation of gametes Genes of different traits can segregate independently.

Note: The phenotype of progeny F1 produced in monohybrid cross is always in the ratio of 3:1. The phenotype of progeny F1 produced in the dihybrid cross is always in the ratio of 9:3:3:1. The phenotype refers to the external appearance of an organism depending upon the genotype.