Genetics Test 1

Front 1

What does the term recombination mean?

Back 1

Generation of new combinations of alleles that are different from the parental combinations.

Front 2

Honeybees have haplodiploid sex determination: females are diploid, developing from fertilized eggs, whereas males are haploid, developing from unfertilized eggs. Otto Mackensen studied linkage relations among eight mutations in honeybees (O. Mackensen, 1958, Journal of Heredity 49:99–102). The following table gives the results of two of Mackensen's crosses, including three recessive mutations: cd (cordovan body color), h (hairless), and ch (chartreuse eye color).



Determine the nonrecombinant and recombinant progeny for each cross and calculate the map distances between cd, h, and ch. In a linkage map illustrating the linkage arrangements among the three genes, the distance between cd and h is

Back 2

They are unlinked.

Front 3

A geneticist studies a series of characteristics in monozygotic twins and dizygotic twins, obtaining the following concordances.



Based on the data, variation in which characteristic appears to be controlled almost exclusively by genetic variation and not by environmental variation?

Back 3

Eye color

Front 4

The following pedigree illustrates the inheritance of ringed hair, a rare condition in which each hair is differentiated into light and dark zones. What mode of inheritance is most likely for the ringed-hair trait in this family?

Back 4

Autosomal dominant

Front 5

Consider the pedigree shown in Figure 6.3. If individuals IV-4 and IV-5 mated and produced a child, what is the probability that the child would have Waardenburg syndrome?

Back 5

Zero

Front 6

Which feature(s) would allow you to distinguish between X-linked recessive inheritance and autosomal recessive inheritance in a pedigree?

A. Normally, more females than males are affected by an X-linked recessive trait.

B. Normally, more males than females are affected by an X-linked recessive trait.

C. The trait tends to skip generations in a pedigree showing autosomal recessive inheritance but not X-linked inheritance.

D. The trait tends to skip generations in a pedigree showing X-linked recessive inheritance but not autosomal recessive inheritance.

E. More than one of the above

Back 6

Normally, more males than females are affected by an X-linked recessive trait.