Question 1

A researcher performs a cross between two pea plants and expects a 3:1 ratio of tasty to gross peas. The observed numbers are 2500 tasty and 1500 gross peas. The expected numbers are 3000 tasty and 1000 gross. Calculate the chi-square statistic ($$\$$chi^2$$) and determine whether to reject the null hypothesis at p=0.05$ with 1 degree of freedom.

Accepted Answer

Reject the null hypothesis because $$\$$chi^2$$ = 333.3 is $$much greater than the critical value.

Question 2

Which of the following human diseases is inherited in a Mendelian fashion as an autosomal recessive trait?

Accepted Answer

Cystic fibrosis

Question 3

A patient with oculocutaneous albinism has a mutation in the OCA2 gene. Which of the following best explains the inheritance pattern of this disorder?

Accepted Answer

It is inherited in an autosomal recessive manner, requiring two mutant alleles for the phenotype to be expressed.

Question 4

In a pedigree, a trait appears in children of unaffected parents and affects both sexes equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal recessive

Question 5

If a pea plant with genotype $$YyRRssaa is $$considered, how many different types of gametes can it produce?

Accepted Answer

4

Question 6

A test cross is performed with a pea plant of genotype $$GgRr. $$What is the expected genotypic ratio among the progeny?

Accepted Answer

1:1:1:1

Question 7

In peas, round seeds (R) and purple flowers (P) are dominant. If a plant with wrinkled seeds (rr) and white flowers (pp) is crossed with a plant that is homozygous for round seeds (RR) and heterozygous for purple flowers (Pp), what fraction of the offspring will have wrinkled seeds and purple flowers?

Accepted Answer

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

Question 8

A pedigree shows a trait that appears in every generation and affects both sexes equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 9

Which of the following statements about meiosis is TRUE?

Accepted Answer

Meiosis increases genetic variability through independent assortment and crossing over.

Question 10

Which genes will always assort independently according to Mendel's law of independent assortment?

Accepted Answer

Genes located on different chromosomes

Question 11

A pedigree for cystic fibrosis (autosomal recessive) shows a child with the disease and a sibling who is unaffected. What is the probability that the unaffected sibling is a carrier?

Accepted Answer

$$\frac{2}{3}$$

Question 12

Which of the following is FALSE regarding mitosis?

Accepted Answer

Mitosis produces four genetically unique haploid cells.

Question 13

A woman who is heterozygous for an X-linked recessive disorder has children with a man who is unaffected. What is the probability that their son will be affected?

Accepted Answer

$$\frac{1}{2}$$

Question 14

Which of the following best describes the phenomenon of X-inactivation in females?

Accepted Answer

It leads to mosaicism, where different cells express different X-linked alleles.

Question 15

Which of the following scenarios would most likely result in a violation of Mendel's law of independent assortment?

Accepted Answer

Two genes located close together on the same chromosome

Question 16

A genetic counselor is analyzing a pedigree for a rare autosomal dominant disorder. If an affected individual mates with an unaffected individual, what is the probability that their child will be affected?

Accepted Answer

$$\frac{1}{2}$$

Question 17

Which of the following is a real-world example of a disease caused by a mutation in a single gene, following Mendelian inheritance?

Accepted Answer

Sickle cell anemia

Question 18

During meiosis, which event is responsible for increasing genetic diversity among gametes?

Accepted Answer

Crossing over between homologous chromosomes

Question 19

A man with an X-linked dominant disorder has children with a woman who does not have the disorder. What is the expected outcome for their children?

Accepted Answer

All daughters will be affected, but none of the sons will be affected.

Question 20

Which of the following best explains why children with oculocutaneous albinism can be born to unaffected parents?

Accepted Answer

Both parents are carriers of a recessive allele.

Genetics Problems, Mendelian Inheritance, Pedigree Analysis, and Cell Division

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