Q: Which equation correctly calculates the recombination frequency between two genes?

$$\text{Recombination frequency} = \frac{\text{Number of recombinant offspring}}{\text{Total number of offspring}} \times 100$$

Question 1

Which of the following best explains why Morgan chose Drosophila melanogaster (fruit flies) for his genetic experiments?

Accepted Answer

They have only four pairs of chromosomes, breed quickly, and produce many offspring.

Question 2

A woman who is heterozygous for the X-linked gene for color blindness (XNXn) marries a man with normal vision (XNY). What is the probability that their son will be color blind?

Accepted Answer

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

Question 3

Which chromosomal alteration is most likely responsible for the Philadelphia chromosome associated with chronic myelogenous leukemia (CML)?

Accepted Answer

Translocation

Question 4

If a diploid plant species undergoes polyploidy and becomes tetraploid, how many sets of chromosomes does it have?

Accepted Answer

$$4n$$

Question 5

A geneticist observes a cat with patches of black and orange fur. Which genetic phenomenon best explains this pattern?

Accepted Answer

X chromosome inactivation

Question 6

Which of the following is true about linked genes?

Accepted Answer

They are located on the same chromosome and tend to be inherited together.

Question 7

A child is born with three copies of chromosome 21. What is the most likely diagnosis?

Accepted Answer

Down syndrome

Question 8

Which equation correctly calculates the recombination frequency between two genes?

Accepted Answer

$$	ext{Recombination frequency} = \frac{	ext{Number of recombinant offspring}}{	ext{Total number of offspring}} 	imes 100$$

Question 9

Which of the following best describes the Law of Independent Assortment?

Accepted Answer

Alleles of genes on nonhomologous chromosomes assort independently during gamete formation.

Question 10

A male with an extra X chromosome (XXY) is diagnosed with which syndrome?

Accepted Answer

Klinefelter syndrome

Question 11

Which of the following is a possible result of nondisjunction during meiosis II?

Accepted Answer

Two normal gametes, one with $$n+1$$ chromosomes, and one with $$n-1$$ chromosomes.

Question 12

Which of the following human genetic disorders is caused by a deletion of part of chromosome 5?

Accepted Answer

Cri du chat syndrome

Question 13

Which gene on the Y chromosome is responsible for the development of testes in human embryos?

Accepted Answer

SRY gene

Question 14

A woman with genotype XNXn for an X-linked recessive disorder has children with a man who is XnY. What is the probability that their daughter will be affected by the disorder?

Accepted Answer

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

Question 15

Which of the following best describes an inversion mutation?

Accepted Answer

A segment of a chromosome is reversed within the chromosome.

Question 16

Which of the following statements about aneuploidy is correct?

Accepted Answer

Aneuploidy results from the fertilization of gametes in which nondisjunction occurred.

Question 17

Which of the following is NOT a disorder caused by a recessive allele on the X chromosome?

Accepted Answer

Sickle cell anemia

Question 18

If a gene is located on the Y chromosome, what is the probability that a father will pass it to his son?

Accepted Answer

$$1$$

Question 19

Which of the following best explains why polyploidy is more common in plants than in animals?

Accepted Answer

Plants can tolerate extra sets of chromosomes better than animals.

Question 20

Which of the following is the best example of a real-world application of the Law of Segregation?

Accepted Answer

A child inherits one allele for blood type from each parent, resulting in their own blood type.

The Chromosomal Basis of Inheritance

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