Question 1

Which of the following best describes the difference between chromatin and chromosomes in terms of gene activity?

Accepted Answer

Chromatin is the open, strand-like form of DNA where genes are active, while chromosomes are the compact form where genes are generally inactive.

Question 2

A child is born with cystic fibrosis, a recessive autosomal disorder. If both parents are carriers, what is the probability that their next child will also have cystic fibrosis? Use a Punnett square to justify your answer.

Accepted Answer

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

Question 3

Which of the following is an example of a sex-linked recessive disorder?

Accepted Answer

Hemophilia

Question 4

A male inherits an X-linked recessive allele from his mother. What is the likelihood that he will express the trait?

Accepted Answer

He will express the trait because males have only one X chromosome.

Question 5

Which chromosomal abnormality is most commonly associated with Down syndrome?

Accepted Answer

Trisomy of chromosome 21

Question 6

Which process increases genetic variation by exchanging segments between homologous chromosomes during meiosis?

Accepted Answer

Crossing-over

Question 7

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

Accepted Answer

Autosomal dominant

Question 8

Which of the following best describes the principle of independent assortment?

Accepted Answer

Different genes independently separate from one another when reproductive cells are forming.

Question 9

Which genetic mechanism explains why some people with a disease-causing gene do not develop the disease or have a milder version?

Accepted Answer

Polygenic inheritance

Question 10

A woman is a carrier for hemophilia (an X-linked recessive disorder) and her partner is unaffected. What is the probability that their son will have hemophilia?

Accepted Answer

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

Question 11

Which of the following is a tool used to detect chromosomal abnormalities such as trisomies and monosomies?

Accepted Answer

Karyotype

Question 12

Which syndrome is characterized by the presence of a single X chromosome (XO) and features such as short stature and webbed neck?

Accepted Answer

Turner syndrome

Question 13

Which of the following best describes the role of epigenetics in genetic disease?

Accepted Answer

Epigenetics describes how environmental factors can turn genes on or off without changing the DNA sequence.

Question 14

Which of the following is a real-world example of gene therapy in humans?

Accepted Answer

Treating cystic fibrosis by inserting therapeutic genes into the respiratory tract using plasmids or viruses.

Question 15

A child is diagnosed with Tay-Sachs disease. Which of the following statements is true regarding the inheritance of this disorder?

Accepted Answer

Both parents must be carriers of the recessive allele.

Question 16

Which of the following best explains why males are more likely to express X-linked recessive disorders?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will be expressed.

Question 17

Which of the following is NOT a likely cause of genetic mutation?

Accepted Answer

Crossing-over during meiosis

Question 18

Which of the following best describes codominance?

Accepted Answer

Both alleles are expressed equally in the phenotype.

Question 19

A karyotype reveals a male with two X chromosomes and one Y chromosome (XXY). Which syndrome does this individual most likely have?

Accepted Answer

Klinefelter syndrome

Question 20

Which of the following statements about the Human Genome Project is correct?

Accepted Answer

It revealed that less than 2% of human DNA codes for proteins.

Genetics and Genetic Disease: Foundations for Nutrition Science

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