Review questions, Nov 8

 

1. In a certain plant, the alleles A, B, and C are dominant to the alleles a, b, and c. A plant with the genotype AABbcc will have the same phenotype as the plant with the genotype _____.

a. AABBCC      b. AaBBcc     c. aaBbcc       d. AaBbCc     e. AAbbcc

 

2. It is far more common to find human genetic disease caused by __________ alleles than by __________ alleles because __________.

a. dominant ... recessive ... individuals with dominant alleles have an advantage over individuals with recessive alleles

b. dominant ... recessive ... dominant alleles became dominant because they aid the survival of the organism carrying them

c.  recessive ... dominant ... harmful recessive alleles can survive in the heterozygote without causing any adverse effects on the phenotype

d. recessive ... dominant ... even when homozygous, recessive alleles usually do not cause as much damage as dominant alleles

 

3. Several inherited disorders are much more common in close-knit religious communities, such as the Amish, than in the general population. This is at least partly due to the fact that _____.

a. they are more likely to marry relatives

b. they share environmental conditions which can increase mutation rate

c.  such disorders are contagious

d. they are more likely to have large families

 

4. Achondroplastic dwarfism is a dominant genetic disorder.  When two average-height parents give birth to a child exhibiting achondroplastic dwarfism, it is most likely due to a new mutation. This is because _____.

a. the frequency of achondroplasia is unknown

b. achondroplasia is a relatively rare disorder

c.  achondroplasia is caused by an allele that is always expressed, so the parents couldn't have the allele

d. such mutations are statistically predictable

 

5.  Huntington’s disease is a dominant trait.  One grandmother had Huntington’s disease but neither parents had Huntington’s disease.  What is the probability of the child having the disease?