Several features of Gregor Mendel's experiments on plant breeding and patterns of inheritance distinguished his work from that of his contemporaries. Which of the following was a critical experimental innovation employed by Mendel that distinguished his experiments from those of his contemporaries? A. Mendel used self-fertilizing wild strains in his experiments. B. Mendel restricted his observations to the first-generation progeny from his crosses. C. Mendel performed controlled crosses with pure-breeding strains. D. Mendel used strains that displayed a broad range of phenotypes for each trait.

The correct answer is: C.

Explanation:

Gregor Mendel identified the manner in which different traits are transferred from the parents to their offspring. He explained the three Laws which determines the pattern of inheritance by examining the some traits of pea plant in the parental and offspring generation. The traits includes, seed colour seed shape, pod colour, etc. The parent pea plants which Mendel experimented with belonged to the pure-breeding strains. This means that the parent pea plants were homozygous (either dominant or recessive) and not heterozygous for the different traits which Mendel observed. This is why Mendel could determine the pattern of inheritance of the traits in different generations of the offspring. The three laws of inheritance as explained by Mendel were, The Law of Dominance. It states that in a diploid organism, each trait is controlled by two contrasting variants of the same gene called Alleles. Among the two variants one can express itself even in the presence of the other variant (heterozygous condition) and is called the Dominant allele. The other variant gets suppressed in the presence of the dominant allele and can express itself only in the homozygous condition. This is the Recessive allele. The Law of Segregation. It states that different pair of alleles segregate during the formation of gametes and during the process of fertilization they associate with the corresponding allele, obtained from the other parent, randomly. The Law of Independent Assortment. It states that during gamete formation, alleles of two different genes get randomly sorted in the gametes independent of each other.