Pattern baldness is a sexinfluenced trait the alleles for th

Pattern baldness is a sex-influenced trait (the alleles for this gene are B^+ and B^B). A young woman suffering from pattern baldness is married to a man who has a full head of hair. What is the chance that this couple will have a child that will not be affected with pattern baldness in adulthood? a. 0 b. 1/4 c. 1/3 d. 1/2 e. 3/4 Imagine that you are studying coat color in a newly discovered animal call the tribble. You have learned that one gene determines this trait, and that the two alleles of the gene have a simple relationship - the dominant allele results in a brown coat, while the recessive allele results in a white coat. In the F1 generation of a large number of monohybrid crosses you notice tribbles that have dark brown coats, medium brown coats, butterscotch colored coats, tan coats and white coats. Based on the information given, which of the following genetic phenomena best describes this trait? a. anticipation b. incomplete dominance c. incomplete penetrance d. overdominance e. variable expressivity f. variable expressivity and anticipation g. incomplete penetrance and variable expressivity

Solution

2. 1/2

3. incomplete penetrance and variable expressivity

Some genes in homozygous as well as in heterozygous conditions fail to provide complete phenotypic expression of them. Such genes exhibit incomplete penetrance. A trait though penetrant, may be quite variable in its phenotypic expressions. The degree of effect produced by a penetrant phenotype is called expressivity.