Question 1

Which of the following best explains why males are more frequently affected by X-linked recessive disorders than females?

Accepted Answer

Males inherit only one X chromosome, so a single recessive allele will cause the disorder.

Question 2

A woman who is a carrier for red-green color blindness (XNXn) has a child with a man who is color-blind (XnY). What is the probability that their son will be color-blind?

Accepted Answer

50%

Question 3

Which chromosomal abnormality is characterized by an individual having only one X chromosome and no second sex chromosome?

Accepted Answer

Turner syndrome

Question 4

Morgan’s experiments with fruit flies demonstrated that genes located close together on the same chromosome tend to be inherited together. What is the term for these genes?

Accepted Answer

Linked genes

Question 5

Which of the following best describes the mechanism that produces recombinant chromosomes during meiosis?

Accepted Answer

Crossing over between homologous chromosomes

Question 6

A genetic map based on recombination frequencies is called a linkage map. If two genes are 10 map units apart, what is their expected recombination frequency?

Accepted Answer

$$10\%$$

Question 7

Which chromosomal alteration involves a segment of a chromosome being repeated, resulting in more than two alleles for certain traits?

Accepted Answer

Duplication

Question 8

A child is born with three copies of chromosome 21. Which syndrome does this child have, and what is the chromosomal notation?

Accepted Answer

Down syndrome; 47 chromosomes

Question 9

Which of the following is TRUE regarding the inheritance of mitochondrial genes?

Accepted Answer

They are inherited maternally, because the zygote’s cytoplasm comes from the egg.

Question 10

A plant species is found to have four complete sets of chromosomes in each cell. What is the term for this condition, and what is the formula for the chromosome number?

Accepted Answer

Tetraploidy; $$4n$$

Question 11

Which chromosomal alteration is most likely to result from exposure to radiation and involves the loss of an end piece of a chromosome?

Accepted Answer

Deletion

Question 12

If nondisjunction occurs during meiosis II in a human female, what is the possible chromosome number in the resulting egg?

Accepted Answer

$$24$$

Question 13

Which syndrome is associated with males who have an extra Y chromosome, and what are some of its characteristics?

Accepted Answer

Jacobs syndrome; taller than average, persistent acne, speech and reading problems

Question 14

Which of the following best describes the effect of random fertilization on genetic variation?

Accepted Answer

It increases genetic variation by combining alleles from two parents in unique ways.

Question 15

A male with genotype XnY for the color blindness gene has children with a female who is a carrier (XNXn). What percentage of their daughters will be color-blind?

Accepted Answer

50%

Question 16

Which chromosomal alteration involves the exchange of segments between two nonhomologous chromosomes?

Accepted Answer

Translocation

Question 17

Which syndrome is the only known monosomy in humans, and what is its chromosomal notation?

Accepted Answer

Turner syndrome; $$45$$ chromosomes

Question 18

Which of the following statements about polyploidy is correct?

Accepted Answer

Polyploidy is common in plants but rare in animals.

Question 19

Which chromosomal alteration is most likely to result in a child with poor muscle tone, intellectual disability, seizures, and autistic qualities due to a segment joining in the opposite direction?

Accepted Answer

Inversion

Question 20

Which of the following best explains why plants tolerate large-scale chromosomal alterations better than animals?

Accepted Answer

Plants can survive and reproduce with altered chromosome numbers, while animals often experience developmental disorders or miscarriages.

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