Question 1

Which of the following is a primary reason why pedigree analysis is used in human genetics?

Accepted Answer

To study the inheritance of traits across multiple generations when experimental crosses are not possible

Question 2

A pedigree shows a trait that appears in every generation and affected individuals always have at least one affected parent. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 3

Why do deleterious recessive alleles persist in human populations?

Accepted Answer

Heterozygous individuals carry the allele without developing the phenotype and are not at a selective disadvantage

Question 4

Which of the following best describes a horizontal pattern of inheritance in a pedigree?

Accepted Answer

A trait appears among siblings but not in their parents, indicating a rare recessive trait

Question 5

A couple, both unaffected by a rare genetic disorder, have a child who is affected. What is the most likely explanation?

Accepted Answer

Both parents are heterozygous carriers for a recessive allele

Question 6

Which of the following statements about dominant alleles is correct?

Accepted Answer

A dominant allele usually determines a normally functioning protein

Question 7

In a pedigree, two affected parents have an unaffected child. What does this suggest about the genotype of the parents and the mode of inheritance?

Accepted Answer

Both parents are heterozygous for a dominant allele; the trait is dominant

Question 8

Which of the following is a limitation of pedigree analysis in humans?

Accepted Answer

Data collection often depends on recollection, which can be inaccurate

Question 9

A rare autosomal recessive disease is being studied in a pedigree. If both parents are heterozygous, what is the expected proportion of affected children?

Accepted Answer

$$\frac{1}{4}$$

Question 10

Which molecular principle explains why a recessive allele often leads to a disease phenotype?

Accepted Answer

A recessive allele usually does not encode a functional protein

Question 11

A pedigree shows that all children of two affected parents are also affected. What is the most likely mode of inheritance?

Accepted Answer

Autosomal recessive

Question 12

Which of the following best explains why Mendelian inheritance patterns can be difficult to determine in human pedigrees?

Accepted Answer

There are no pure-breeding lines and no controlled matings

Question 13

A pedigree for Huntington disease shows that every affected individual has an affected parent and the trait appears in every generation. What pattern of inheritance does this demonstrate?

Accepted Answer

Vertical pattern, typical of dominant traits

Question 14

If a rare recessive trait is extremely common in a population, what pattern might it show in a pedigree?

Accepted Answer

A vertical pattern, similar to dominant traits

Question 15

Which of the following is a correct statement about the CFTR protein in cystic fibrosis?

Accepted Answer

Heterozygous individuals produce enough CFTR for normal lung function

Question 16

A pedigree shows that a trait skips generations and appears only among siblings, not in their parents. What is the most likely explanation?

Accepted Answer

The trait is recessive

Question 17

In a family, a rare disease is present in a child whose parents are both unaffected. The parents are first cousins. What genetic principle does this illustrate?

Accepted Answer

Increased likelihood of recessive disorders due to consanguinity

Question 18

Which of the following is NOT a complication in human pedigree analysis?

Accepted Answer

Controlled matings are possible

Question 19

A pedigree shows that two unaffected parents have an affected child, and the trait is rare in the population. What is the most likely genotype of the parents if the trait is due to a single gene with alleles A (dominant) and a (recessive)?

Accepted Answer

Aa and Aa

Question 20

A geneticist is analyzing a pedigree for a rare disease. The trait appears in every generation, and two affected parents have an unaffected child. What is the most likely genotype of the parents if D is the dominant disease allele and d is the normal allele?

Accepted Answer

Dd and Dd

Pedigree Analysis and Mendelian Inheritance in Humans

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