Chapter 4 Patterns of Inheritance

Chapter 4: Patterns of Inheritance ____ 1. Which factor allows inheritance patterns for a specific trait or health problem to be traced from one ____ 2. If there are 10 possible alleles for the single-gene trait of nose shape, how many alleles can a person ____ 3. An infant with type B blood is born to parents who both have type O blood. What genetic action or ____ 4. Is it possible for two parents with achondroplasia to have a child who is of normal stature? A. Yes, because the disorder is autosomal dominant, and if both parents are family generation to another? B. Allele segregation with euploid chromosomes inherit from his or her biological parents? B. 2 phenomenon is responsible for this unusual blood type expression? A. Decreased penetrance of a dominant trait heterozygous, the child could inherit two normal stature gene alleles. ____ 5. What is the risk for a person to inherit an autosomal-dominant genetic disease–causing allele from a ____ 6. Which statement reflects the criterion for autosomal-dominant transmission of single-gene traits? A. The risk for a person who is homozygous for the trait to transmit the trait to his or parent who is heterozygous if the disorder has a penetrance factor of 75%? C. 50% her children is 100% with each pregnancy. ____ 7. In which situation are phenotype and genotype always the same? C. Autosomal-recessive traits ____ 8. A girl of normal stature is born to two parents with achondroplasia who have very short stature, ____ 9. Which statement or factor is a criterion for autosomal-recessive transmission of single-gene traits? A. About 25% of the members of a large kindred with an autosomal-recessive trait especially disproportionately short arms and legs. What is the probability (by Punnett square analysis) that any pregnancy this girl eventually has will result in the birth of an infant with achondroplasia if her partner also has normal stature? D. Zero out of four (0%) will express the trait. ____ 10. Which person is an obligate carrier of an autosomal-recessive single-gene trait or disorder without expressing the trait or disorder? D. The daughter of a woman who expresses attached earlobes ____ 11. With which type of inheritance pattern does the trait or disorder usually first appear among siblings rather than in parents of affected children? B. Autosomal recessive ____ 12. Which type of genetic transmission promotes the continued existence of genetic mutations in single genes? B. Autosomal recessive ____ 13. On a five-generation pedigree, which feature distinguishes an X-linked-dominant disorder in which males and females are equally affected from an autosomal-recessive pattern of inheritance? C. There are no instances of an affected father transmitting the disorder to his son. ____ 14. A woman whose father does not have hemophilia gives birth to a son with classic hemophilia. This woman is found to have only 15% of the normal amount of clotting factor VIII (the clotting factor males with hemophilia are missing) and does have abnormal blood-clotting issues. Which phenomenon or factor is most likely responsible for her abnormal clotting factor expression? A. The X chromosome most commonly inactivated in her bone marrow is paternally derived. ____ 15. Which statement regarding inheritance of an autosomal-dominant gene allele with known variability in expressivity is true? C. The degree of expressivity of a given autosomal-dominant trait with known variability cannot be predicted by analyzing parental expression. ____ 16. A man whose parents both have brown hair claims that his red beard was inherited from his maternal uncle. Why is this claim incorrect? B. Genetic traits are transmitted in only a direct vertical direction. ____ 17. Mating of a yellow male parakeet with a blue female parakeet resulted in 18 offspring. Four (two males; two females) had blue feathers, and 14 (eight females and six males) had yellow feathers. What allelic combinations and mode of inheritance can you determine from the evidence of the feather colors expressed? A. Yellow allele dominant; blue allele recessive; autosomal ____ 18. Mating of a female rabbit with a long tongue with a male rabbit that had a short tongue resulted in 12 offspring. Two had long tongues, two had short tongues, and eight had medium-length tongues. Which allele combinations explains the tongue lengths of the offspring? C. Short tongue dominant; long tongue dominant ____ 19. Which trait or disorder has both an autosomal-dominant form and an autosomal-recessive form? C. Polycystic kidney disease ____ 20. What is the most likely explanation for the expression of responses related to pleiotropy? B. The protein coded for by the single gene is an important component of more than one tissue. ____ 21. Which statement is a criterion for an autosomal-dominant pattern of inheritance of a specific trait or characteristic that is highly penetrant? B. Unaffected family members do not transmit the trait to their children. ____ 22. Which statement or condition best reflects multifactorial inheritance? B. The susceptibility to a problem is an inherited trait, but development of the problem is related to environmental conditions. ____ 23. What is the expected outcome of any pregnancy or child produced by two parents who are each heterozygous for the Huntington disease allele? C. A child who is homozygous for the mutated alleles is not likely to transmit the disorder to his or her children. ____ 24. A baby boy is born with six toes (polydactyly) on his right foot, a trait that neither parent has but one that the paternal grandfather has. What is the best explanation for this occurrence? C. The father’s phenotype results from incomplete penetrance of a dominant allele. ____ 25. What can be inferred about a genetic disorder that, when it occurs in monozygotic twins, affects one twin 80% of the time and affects both twins only 20% of the time? B. Nongenetic factors can influence the expression of identical alleles. ____ 26. A woman (Adele) has three daughters (Barbara, Brenda, Beverly) with a man (Adam) who is color- blind. Barbara has a daughter (Carol) and a son (Cliff) who have normal color vision. Brenda has no children. Beverly has two sons (Carl, Charlie) who are both color-blind. To which genetic generation do Carl and Charlie belong? D. F2 ____ 27. What is the expected expression of a monogenic trait that has its locus on the Y chromosome? A. Females never inherit the trait. ____ 28. Which genetic disorder has both an autosomal-dominant and an autosomal-recessive form? D. Retinitis pigmentosa ____ 29. Which situation most closely represents an example of “regression to the mean”? C. The three children of a mother who has an intelligence quotient (IQ) of 170 all have IQs in the 110 to 120 range. ____ 30. Why are dizygotic twins less likely to show concordance for a monogenic trait than monozygotic twins? A. Dizygotic twins share fewer allele sequences in common than monozygotic twins. ____ 31. When calculating the recurrence risk for a complex, possibly polygenic disorder with a couple who already have one child with the disorder, which additional factor has the greatest impact on increasing this risk? D. The mother has a brother who also has the same disorder. ____ 32. Which common health problem has the highest heritability estimate? D. Schizophrenic behavior ____ 33. Which statement about the X chromosome is true? A. Most of the X chromosome genes encode proteins that have no role in female sexual development. ____ 34. If a man with classic hemophilia (X-linked recessive) has children with a woman who is a carrier for the disorder, what is the expected risk pattern? C. All sons have a 50% risk of the disorder; daughters will all either be affected or carriers. ____ 35. What is the significance of a shift to the left in the threshold value of liability in a threshold of liability model for the expression of a complex health problem with genetic influences? D. The threshold required for disease expression is lower. ____ 36. Which situation is an example of modifier gene action? B. Two children in the same family both have sickle cell disease, but one child has more severe symptoms than the other.