Question 1

Which statement best describes the Chromosome Theory of Inheritance?

Accepted Answer

Genes are found on chromosomes at specific locations, and each chromosome can carry dozens to thousands of genes.

Question 2

In humans, which chromosome combination determines a male offspring?

Accepted Answer

XY

Question 3

What is the function of the SRY gene (also called TDF) located on the Y chromosome?

Accepted Answer

It initiates male development.

Question 4

Why are X-linked recessive traits, such as red/green color blindness, more commonly observed in males?

Accepted Answer

Males are hemizygous for the X chromosome, so a single recessive allele will be expressed.

Question 5

A female cat is heterozygous for fur color genes located on the X chromosome. What phenomenon explains her tortoiseshell appearance?

Accepted Answer

X chromosome inactivation

Question 6

Which chromosomal mutation involves a section of DNA being moved to another chromosome?

Accepted Answer

Translocation

Question 7

What is the most likely outcome of meiotic non-disjunction during gamete formation?

Accepted Answer

Some gametes will have an extra chromosome, and some will have one less.

Question 8

Down syndrome is caused by which chromosomal abnormality?

Accepted Answer

Trisomy 21

Question 9

Which equation represents the chromosome number in a human zygote?

Accepted Answer

$$46$$

Question 10

If a female is heterozygous for an X-linked gene, what is the expected outcome in her cells due to X inactivation?

Accepted Answer

Different cells will express different alleles, leading to a mosaic phenotype.

Question 11

Which chromosomal mutation is most likely to result from exposure to radiation or carcinogens?

Accepted Answer

Structural mutations such as translocation, inversion, duplication, or deletion

Question 12

What is the term for DNA segments that can move within the genome and promote unequal crossover events?

Accepted Answer

Transposable elements

Question 13

Which of the following is NOT a structural chromosomal mutation?

Accepted Answer

Aneuploidy

Question 14

A pedigree shows a trait that appears only in males and is passed from father to son. What type of inheritance is this?

Accepted Answer

Y-linked inheritance

Question 15

Which equation best represents the possible gametes produced by a male with genotype $$X^A Y$$ for an X-linked gene?

Accepted Answer

$$X^A$$ and $$Y$$

Question 16

A child is diagnosed with Turner syndrome. Which karyotype is most likely observed?

Accepted Answer

$$45, XO$$

Question 17

Which chromosomal abnormality is most likely to cause spontaneous abortion or stillbirth in mammals?

Accepted Answer

Aneuploidy

Question 18

If a male inherits a recessive allele for an X-linked trait from his mother, what is the probability he will express the trait?

Accepted Answer

100%

Question 19

Which chromosomal mutation would most likely result in a genetic disorder such as Cri-du-chat syndrome?

Accepted Answer

Deletion

Question 20

A karyotype shows three copies of chromosome 13. What disorder does this indicate?

Accepted Answer

Patau syndrome

Chapter 15 Lecture Notes

Study Guide - Practice Questions