Question 1

Which chromosomal abnormality is depicted in the karyotype with three copies of chromosome 21, and what syndrome does it cause?

Accepted Answer

Trisomy 21, causing Down syndrome

Question 2

A child presents with overlapping fingers, low-set ears, heart/lung abnormalities, and clubfeet. Which chromosomal disorder is most likely responsible for these symptoms?

Accepted Answer

Trisomy 18 (Edwards syndrome)

Question 3

Which of the following best describes the process shown in the first image, where homologous chromosomes exchange segments?

Accepted Answer

Crossing over during meiosis

Question 4

A karyotype analysis reveals a person with 47 chromosomes, including an extra X chromosome. Which syndrome does this individual most likely have?

Accepted Answer

Klinefelter syndrome

Question 5

Which chromosomal structural alteration is illustrated when a segment of chromosome 9 is exchanged with a segment of chromosome 22, resulting in the Philadelphia chromosome?

Accepted Answer

Translocation

Question 6

What is the primary purpose of fetal testing methods such as amniocentesis and chorionic villus sampling (CVS)?

Accepted Answer

To detect chromosomal abnormalities and genetic disorders

Question 7

Which syndrome is characterized by a female with only one X chromosome (45,X), resulting in sterility and lack of secondary sexual characteristics without hormone treatment?

Accepted Answer

Turner syndrome

Question 8

In the context of X inactivation in female mammals, what is the condensed, inactive X chromosome called?

Accepted Answer

Barr body

Question 9

Which chromosomal structural change involves the removal of a segment from a chromosome?

Accepted Answer

Deletion

Question 10

A karyotype shows 47 chromosomes with an extra Y chromosome. What is the most likely phenotype of this individual?

Accepted Answer

Taller than average male with few symptoms

Question 11

Which equation represents the chromosomal number for a person with Down syndrome?

Accepted Answer

$$2n + 1$$

Question 12

Which fetal testing method is noninvasive and analyzes cell-free fetal DNA from maternal blood?

Accepted Answer

Noninvasive prenatal testing (NIPT)

Question 13

Which chromosomal abnormality is most likely to result in a viable individual with normal intelligence but sterility and lack of secondary sexual characteristics?

Accepted Answer

Turner syndrome (X0)

Question 14

Which chromosomal structural change is illustrated when a segment is reversed within the same chromosome?

Accepted Answer

Inversion

Question 15

Which syndrome is associated with the karyotype 47,XXY and is characterized by sterility, breast development, and long limbs?

Accepted Answer

Klinefelter syndrome

Question 16

Which chromosomal abnormality is most likely to result in profound developmental delays, heart defects, and brain abnormalities, with most affected individuals not surviving past the first year?

Accepted Answer

Trisomy 13 (Patau syndrome)

Question 17

Which of the following is NOT a purpose for preparing a karyotype?

Accepted Answer

To measure fetal heart rate

Question 18

Which equation best represents the chromosomal number for a person with Turner syndrome?

Accepted Answer

$$2n - 1$$

Question 19

Which chromosomal structural change is illustrated when a segment is repeated within the same chromosome?

Accepted Answer

Duplication

Question 20

Which syndrome is associated with a karyotype showing three X chromosomes (47,XXX) and is characterized by healthy, fertile females?

Accepted Answer

Triple X syndrome

Chromosomal Abnormalities and Genetic Disorders: Structure, Number, and Detection

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