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Two-character genetic inheritance (problems solved). (Page 13)

Genetics problem 99

Albinism is produced by a recessive gene, compared to the normal brown-colored M gene. On the other hand, hemophilia is produced by a recessive gene linked to the X chromosome. If a healthy albino man and a dark-haired woman whose father was hemophiliac and whose mother was albino, indicate what genotypes and phenotypes this offspring will have and in what proportions.

Genetics problem 100

The white color of the hair in pigs is determined by a dominant allele (N) and the black by its recessive allele (n); its normal cleft leg character is due to the recessive homozygous condition while the dominant allele (H)
produces a mule leg condition. A male and a female are crossed, both with white hair and with mule feet.
Among the offspring were white pigs with cleft hoofs (paw); Negroes with mule feet; whites with mule feet and blacks with cloven hoofs.

a. Indicate the genotypes of the parents.
b. Indicate the genotypes of the offspring
c. Indicate how many descendants are homozygous for both characters.

Genetics problem 101

Marta's parents gave her a dog as a reward for her excellent results in the EVAU test. They chose a certain breed with white silky hair but which may have brown "dark circles" if its genotype is double recessive (bb). In this breed of dog, cardiac pathology due to the autosomal recessive "r" allele is relatively common.
Frodo, the specimen they chose for Marta, does not have dark circles or heart disease, although the breeder assured them that their father was a specimen with dark circles and the mother had to undergo heart surgery.

a. Determine, as far as possible, the genotypes of Frodo and his parents.
b. Marta wants to cross Frodo with Lula, a friend's dog, who has dark circles and no heart disease, although her father died from this anomaly. How likely are they to have a puppy with dark circles and no heart disease?

Genetics problem 102

A short-sighted, curly-haired man and a curly-haired woman with good vision had two children, one with short-sighted curly hair and the other with straight hair and good vision. Knowing that the characters curly hair (R) and myopia (M) are dominant, what will be the genotype of the parents? What about the children? If they had a third child, what would be the probability that it was a boy, with curly hair and normal vision? Give reasons for all answers.