Comprehension Questions

Section 6.1

Question 6.1

What three factors complicate the task of studying the inheritance of human characteristics?

Section 6.2

Question 6.2

Who is the proband in a pedigree? Is the proband always found in the last generation of the pedigree? Why or why not?

Question 6.3

For each of the following modes of inheritance, describe the features that will be exhibited in a pedigree in which the trait is present: autosomal recessive, autosomal dominant, X-linked recessive, X-linked dominant, and Y-linked inheritance.

Question 6.4

How does the pedigree of an autosomal recessive trait differ from the pedigree of an X-linked recessive trait?

Question 6.5

Other than the fact that a Y-linked trait appears only in males, how does the pedigree of a Y-linked trait differ from the pedigree of an autosomal dominant trait?

Section 6.3

Question 6.6

What are the two types of twins and how do they arise?

Question 6.7

Explain how a comparison of concordance in monozygotic and dizygotic twins can be used to determine the extent to which the expression of a trait is influenced by genes or by environmental factors.

Question 6.8

How are adoption studies used to separate the effects of genes and environment in the study of human characteristics?

Section 6.4

Question 6.9

What is genetic counseling?

Question 6.10

Give at least four different reasons for seeking genetic counseling.

Question 6.11

Briefly define newborn screening, heterozygote screening, presymptomatic testing, and prenatal diagnosis.

Question 6.12

Compare the advantages and disadvantages of aminocentesis versus chorionic villus sampling for prenatal diagnosis.

Question 6.13

What is preimplantation genetic diagnosis?

Question 6.14

How does heterozygote screening differ from presymptomatic genetic testing?

Question 6.15

What are direct-to-consumer genetic tests? What are some of the concerns about these tests?

Question 6.16

What activities do the Genetic Information Nondiscrimination Act prohibit?

Question 6.17

How might genetic testing lead to genetic discrimination?

For more questions that test your comprehension of the key chapter concepts, go to for this chapter.