(BIO240) GENETICS HW PROBLEM SETS: EXAM 2

Multiple sclerosis (MS) is being studied in twins. In one study, 50 monozygotic twin pairs were identified in which at least one member of the pair had MS. In 15 of these twin pairs, the other member of the pair also had MS. What is the concordance rate for MS in monozygotic twins? A. 30% B. 15% C. 100% D. 50%

A. 30%

According to genetic evidence from studies of mitochondrial DNA, which of the following continents was first inhabited by modern-day humans most recently? A. Africa B. Europe C. South America D. North America E. Asia

C. South America (inhabited most recently) (Africa was inhabited 1st- "out of Africa hypothesis) (South Am. & Africa would be the most dissimilar)

Heart attack in males is being studied using twins. For monozygotic twins, the concordance rate is 39%, and for dizygotic twins the concordance rate is 26%. This means that: A. genetic factors are involved in determining male heart attacks B. environmental factors are involved in determining male heart attacks C. a and b D. it is impossible to tell

C. a and b

Which of the following genetic tests could not be used on its own to detect the presence of an abnormal number of chromosomes in the fetus of a pregnant woman? A. preimplantation genetic diagnosis B. chorionic villus sampling C. the quad screen D. amniocentesis

C. the quad screen

Which of the following (real or imaginary) would not have the same mitochondrial DNA as you? A. your brother B. your mother's brother C. your mother's father D. your mother's sister's son E. d and e

C. your mother's father

Some human mitochondrial diseases have neuromuscular disease symptoms; these are called mitochondrial myopathy. These diseases are caused by a mutation in mitochondrial DNA. In a cross between a woman with mitochondrial myopathy and a normal man, which of the following is true? A. all their sons would be expected to get the disease B. all their daughters would be expected to get the disease C. an affected daughter would be expected to pass this disease on to her children D. an affected son would not be expected to pass this disease on to his children E. all of the above

E. all of the above

Eye color in fruit flies is determined by a gene on the X-chromosome. The dominant wild-type allele causes red color and the recessive white allele causes white color. A new recessive X-linked mutation that causes green eye color has been identified. In a cross between a male with green eyes and a female with white eyes, all the male offspring have white eyes and all the females have green eyes. Which of the following is/are most likely true? A.) the green and white alleles do not show complementation (i.e., are mutations in two different genes) B.) the green and white alleles show complementation (i.e., are in the same gene) C.) the green allele is dominant to the white allele D.) a and b E.) a and c F.) b and c

F.) b and c

(True/False): You would expect your mitochondrial DNA to be identical to the mitochondrial DNA of your father's mother.

FALSE

(True/False?) If the concordance value for a trait is 80% in monozygotic twins and 80% in dizygotic twins, this indicates that the trait is influenced by both genes and the environment.

False

(True/False): The mitochondrial DNA present in the skeleton of Richard III would be expected to be identical to the mitochondrial DNA of his sister, and all ancestors descended from that sister.

TRUE

In an adoption study, the role of genetic factors in obesity is being examined. Body-mass index (BMI) is being used as a measure of obesity. The research shows that adoptees with a higher BMI generally have biological parents with higher BMI, but the adoptees do not consistently have adoptive parents with higher BMI. (True/False?) This study shows that genetic factors influence BMI.

TRUE

Alec is color-blind. Both his mother and father have normal vision, but his mother's father is color-blind. All Alec's other grandparents have normal vision. Alec has four sisters, all with normal color vision. One of Alec's sisters is married to a man with normal color vision, and they have two boys - one with normal vision and one who is color-blind. If Alec marries a woman who has no family history of color-blindness, what is the probability that their first child will be a color-blind boy? a. 0 b. 1/4 c. 1/2 d. 1

a. 0

Look at Pedigree 3. What is the most likely genotype for individual III-2? Assume that a dominant allele is "A" and the recessive allele is "a" a. AA b. Aa c. aa d. XaXa

b. Aa

Look at Pedigree 3. Which of the following individuals rules out the possibility that this trait is due to an X-linked recessive mutation? a. IV-1 b. IV-2 c. IV-3 d. IV-4

b. IV-2

The next four questions use the pedigrees in the word document titled "Pedigrees for Homework Problem Set 5" located in the "Assessments" folder. Look at the two families in Pedigree 1. Which of the following modes of inheritance is/are possible in this family? a. X-linked dominant b. X-linked recessive c. autosomal dominant d. autosomal recessive e. a and c

c. autosomal dominant

Look at Pedigree 2. At a glance, this pedigree might be due to either an autosomal dominant or an X-linked dominant mutation. Which of the following individuals rules out the possibility that the disease shown in this pedigree is due to an X-linked dominant mutation? a. II-2 b. II-6 c. III-2 d. III-3 e. III-4 and III-5

e. III-4 and III-5