What would Mendel have observed if he had inadvertently chosen characters controlled by genes that were found on the same chromosome?
The correct answer and explanation is:
If Mendel had inadvertently chosen characters controlled by genes located on the same chromosome, he would have observed results that differed from what he actually observed in his experiments. Specifically, he would not have seen the expected 9:3:3:1 ratio of phenotypes in the F2 generation for dihybrid crosses. Instead, he would have observed a modified ratio that would be closer to the parental phenotype combinations. This is due to the fact that genes located on the same chromosome tend to be inherited together, a phenomenon known as genetic linkage.
Genetic linkage occurs because genes that are physically close to one another on the same chromosome are less likely to be separated by recombination during meiosis. When Mendel crossed pea plants with different traits, he observed independent assortment of traits. This observation was based on the assumption that the genes were located on different chromosomes or far apart on the same chromosome, so they could assort independently.
However, when genes are located on the same chromosome and close to each other, the likelihood of recombination (and thus the separation of alleles) is reduced. As a result, the offspring tend to inherit the parental combination of traits more often than recombinant combinations. For instance, if a gene for seed color and a gene for seed shape were located on the same chromosome, Mendel would have seen mostly seeds that were either round and yellow or wrinkled and green, depending on the parental combinations, instead of a mix of all four possible combinations of traits.
In conclusion, Mendel would have noticed that the offspring’s phenotypes were not distributed according to the expected independent assortment, but rather in a way that reflected the genetic linkage of the traits. This deviation from Mendel’s predicted ratios would have pointed to the underlying mechanism of genetic linkage.