Sex linked Problems

A form of hemophilia called hemophilia a is caused by a recessive mutant gene found on the X chromosome. There is no similar allele on the Y chromosome. The normal gene is dominant and is also found on the X chromosomes. The normal gene is dominant and is also found on the X chromosome. The normal gene codes for a protein necessary for blood clotting (factor 8). People with the mutant gene have problems with clotting. Nicholas was the last czar of Russia and was normal for this characteristics as was his wife, Alexandra. However, their only son, Alex was a hemophiliac. What were the genotypes of Nicholas, Alexandra, and their son Alex? (Use X^H to indicate a normal X chromosome with the hemophiliacs gene linked to it; Y= the Y chromosomes with no gene linked to it

A man and his wife both have normal color vision, but a daughter has red-green color blindness, a sex-linked recessive trait. The man sues his wife for divorce on grounds of infidelity. Can genetics prove evidence supporting his case? Explain dihybrid crosses

In watermelons the genes for green color and for short shape are dominant over the alleles for striped color and long shape. Suppose a plant with long striped fruit is crossed with a plant heterozygous for both these characters. What phenotypes would this cross produce and in what ratios?

"In peas, an allele for tall plants (T) is dominant over the allele for short plants (t). The gene for smooth peas (S) is dominant over its allele for wronged peas (s). List all possible phenotypes and calculate the phenotype ratios for a cross between plants with the genotypes TtSs X TtSs

In guinea pigs, rough coat (R) is dominant over smooth coat (r). and black coat (B) is dominate over white (b). A rough, black guinea pig bread to a smooth, white one gave 28 rough, black offspring; 32 rough white; 31 smooth, black 29 smooth, white. What were the genotypes of the parents? How do you know?

The presence of a black coat to orange coat in cats is due to an X-linked gene. These alleles are codominant to each other, such that a heterozygote ends up having a tiger-striped coat. Additionally, a different autosomal gene can lead to the presence of with fur sports. The allele that cases white spots is dominant over the allele for no spots. A calcio cat has orange- trigger fur with spots of white. Give the two possible genotypes for a female calico cat. Calico cats are usually female. Why?