Passage I

The figure below is a pedigree that shows the inheritance of a trait, Trait G, in a family. The presence of Trait G in an individual is determined entirely by Gene G. Gene G has 2 alleles: G, which is dominant, and g, which is recessive.

Each individual represented in the pedigree was assigned a number (shown below the symbol for the individual) for reference. Scientists determined that the Gene G genotype of Individual 20 is gg and that the Gene G genotype of Individual 21 is Gg. Based on this information, the scientists concluded that Trait G is a recessive trait.

5. Based on the figure, is it likely that Trait G is a sex-linked trait?

Answer and Explanation

Your Answer is

Correct Answer is D

Explanation

If it is a sex-linked trait, then you will definitely see the obvious uneven ratio of male to female in Trait G. However, it can be seen from the figure that there are 5 females and 6 males with Trait G. The ratio of male to female is almost equal, so it should not be a sex-linked trait, choose no;

According to the picture, it can be seen that the son of female No. 4, No. 11, did not inherit the trait G of the mother, so choose D