Question 1

What is characteristic of a congenital disorder?

Accepted Answer

A congenital disorder is present at birth and is usually manifested in the neonatal period or early childhood.

Question 2

Which of the following are common manifestations of Down syndrome?
1) Congenital heart defect
2) Cleft lip and palate
3) Large protruding tongue
4) Limited intellectual development

Accepted Answer

Congenital heart defect is a common manifestation of Down syndrome, with roughly 50% of individuals with Down syndrome having some form of heart abnormality. A large protruding tongue is also common, as individuals with Down syndrome typically have a smaller oral cavity in proportion to their tongue size. Limited intellectual development is another hallmark feature of Down syndrome, with individuals typically exhibiting mild to moderate intellectual disability. While cleft lip and palate can occur in those with Down syndrome, it is not as common as the other manifestations listed.

Question 3

Which of the following statements applies to Huntington's disease?

Accepted Answer

There is a genetic test available to determine if an individual carries the defective gene that causes Huntington's disease. The effects of Huntington's disease are not usually obvious at birth, but symptoms typically appear later in life. There is a 50% probability that a child of an affected parent will inherit the defective gene, but they do not need to inherit it from both parents in order to be affected.

Question 4

In the case of an X-linked recessive disorder, a carrier mother and unaffected father could produce a/an:

Accepted Answer

If the mother is a carrier of the X-linked recessive disorder and the father is unaffected, there is a 50% chance that the daughter will inherit the carrier X chromosome from the mother and a normal X chromosome from the father. This would result in a normal female offspring. The chances of an affected female or a male carrier being produced are much lower.

Question 5

Hemophilia A has been diagnosed in a young boy. He has inherited this defective gene from:

Accepted Answer

Hemophilia A is an X-linked recessive disorder, meaning that the defective gene is located on the X chromosome. Males inherit one X chromosome from their mother and one Y chromosome from their father. If the mother is a carrier of the defective gene, there is a 50% chance that her son will inherit it from her. Females who inherit the defective gene from one parent will be carriers, but typically do not show symptoms of the disorder.

Question 6

A spontaneous alteration in genetic material that may result from exposure to harmful substances is termed:

Accepted Answer

A mutation is a spontaneous alteration in genetic material that may result from exposure to harmful substances. Autosome refers to any chromosome that is not a sex chromosome, genotype refers to the genetic makeup of an individual or organism, and meiosis refers to the process of cell division that results in the production of gametes.

Question 7

Which of the following statements applies to the sex chromosomes?

Accepted Answer

The answer of Which of the following statements applies to...

Question 8

Which of the following statements regarding Down syndrome is TRUE?

Accepted Answer

The typical physical characteristics of Down syndrome are present at birth, including a flattened facial profile, upward-slanting eyes, a small nose and mouth, and a small head and ears.

Answer: B 
 Children with Down syndrome can have a range of organ defects and medical problems, but not all children will have the same issues. Common medical problems include heart defects, hearing loss, and vision problems.

Answer: C 
 The extent of cognitive impairment in individuals with Down syndrome cannot be accurately assessed at birth. It can vary greatly from person to person and may not become fully apparent until later in life.

Answer: D 
 While the risk of having a child with Down syndrome does increase with the mother's age, it is not limited to women over age 35. Women of any age can have a child with Down syndrome.

Question 9

What is the probability of two parents, both carriers of a defective recessive gene, producing a homozygous child (with each pregnancy)?

Accepted Answer

Both parents carry a recessive gene, meaning they each have one normal and one defective gene. When they reproduce, there is a 25% chance of each parent passing on the defective gene to the child. For the child to be homozygous (having two copies of the defective gene), they would need to receive the defective gene from both parents. This can only occur if both parents pass on their defective gene, which is a 25% chance for each parent. Therefore, the probability of both parents passing on the defective gene is 0.25 x 0.25 = 0.0625 or 6.25%. This means there is a 6.25% chance of the couple producing a homozygous child with each pregnancy.

Question 10

Down syndrome is an example of a/an:

Accepted Answer

Down syndrome is caused by an extra copy of chromosome 21, which is a chromosomal disorder. It is not caused by a single dominant gene (autosomal dominant disorder) or a combination of genetic and environmental factors (multifactorial disorder). It is also not a developmental defect, as it is caused by a genetic abnormality rather than a problem in the development process.

Question 11

A person with sickle cell trait that is heterozygous has:

Accepted Answer

The answer of A person with sickle cell trait that...

Question 12

Which statement applies to the effects of exposure to harmful substances during embryonic life?
1) During the first two weeks, exposure will usually cause death of the embryo.
2) Organs or body structures may be altered by exposure during the first two months.
3) The effects of exposure depend on the stage of development at the time of exposure.
4) Metabolic abnormalities usually follow exposure to teratogens.

Accepted Answer

1) During the first two weeks, the embryo is in the process of implanting into the uterine wall and has not yet formed vital organs. Exposure to harmful substances during this time may result in death of the embryo.
2) During the first two months, major organs and body structures are formed. Exposure to harmful substances during this time may alter the structure or function of these organs or structures.
3) The effects of exposure during embryonic life depend on the stage of development at the time of exposure. Different organs and body structures form at different times during embryonic development, and exposure during those critical periods can have different effects.
4) Metabolic abnormalities are one possible outcome of exposure to teratogens (harmful substances that cause birth defects), but this is not always the case. Other types of birth defects or developmental delays may also result from exposure to teratogens.

Question 13

A mother is a carrier of Duchenne muscular dystrophy; the father is unaffected. They have one son with muscular dystrophy. Another male child is expected. The probability of the second son having muscular dystrophy is:

Accepted Answer

The mother is a carrier of Duchenne muscular dystrophy, meaning she has one normal and one mutated copy of the gene that controls the production of dystrophin (a protein needed for healthy muscle function). The father is unaffected, meaning he has two normal copies of the gene. 
When they have a son, there is a 50% chance of him inheriting the mother's mutated copy of the gene, which would result in the development of muscular dystrophy. There is also a 50% chance of him inheriting the father's normal copy of the gene, which would result in him not having the condition. 
For the second son, since the parents have already had one affected son and the mother is a carrier, there is still a 50% chance of him inheriting the mutated copy of the gene and developing muscular dystrophy. However, there is also a 50% chance of him inheriting the father's normal copy of the gene and not having the condition. Therefore, the probability of the second son having muscular dystrophy is 50%.

Question 14

Exposure to cocaine during pregnancy leads to increased risk of:

Accepted Answer

Exposure to cocaine during pregnancy can lead to a number of negative outcomes for the baby, including premature birth, respiratory problems, and an increased risk of sudden infant death syndrome (SIDS). Therefore, option D - A, B, and C - is the best choice.

Question 15

What is the term for an arrangement of the chromosomes from an individual's cell, organized in pairs based on size and shape?

Accepted Answer

A karyotype is a visual representation of an individual's chromosomes arranged in pairs based on size and shape. Pedigrees are used to track the inheritance of genetic traits within a family. Punnett squares are used to predict the outcomes of genetic crosses between two individuals. Genotype refers to the genetic makeup of an individual.

Question 16

TORCH is an acronym for routine prenatal screening tests for high-risk maternal infections; TORCH stands for:

Accepted Answer

TORCH is an acronym for the following infections: toxoplasmosis, other (hepatitis B, mumps, rubeola, varicella, gonorrhea, syphilis), rubella, cytomegalovirus, and herpes. These are routine prenatal screening tests for high-risk maternal infections. Option B and C have incorrect infections listed, and option D has tuberculosis and rabies which are not part of the TORCH screening.

Question 17

A father affected with hemophilia A, whose wife is unaffected, will pass on the defective gene to:

Accepted Answer

The answer of A father affected with hemophilia A, whose...

Question 18

What is an example of a multifactorial congenital disorder?

Accepted Answer

Cleft lip and palate is an example of a multifactorial congenital disorder as it is caused by a combination of genetic and environmental factors such as maternal smoking, alcohol consumption, and certain medications. Type AB blood is determined by a single gene and is not a congenital disorder. Down syndrome is a chromosomal disorder caused by an extra copy of chromosome 21. Color blindness is also a genetic disorder caused by mutations in genes on the X chromosome.

Question 19

Agents that cause damage during embryonic or fetal development are called:

Accepted Answer

Teratogenic agents are those that cause structural or functional abnormalities in the developing embryo or fetus. Examples of teratogenic agents include alcohol, certain medications, and viruses like Rubella. Mutagenic agents cause changes in DNA and may lead to mutations, but they may not necessarily cause damage during embryonic or fetal development. Multifactorial agents and polygenic agents are not terms used in this context.

Question 20

Ultrasonography during pregnancy would be helpful in detecting fetal:

Accepted Answer

Ultrasonography during pregnancy is commonly used to detect any structural anomalies in the fetus, such as heart defects or spinal cord abnormalities, which can help in early diagnosis and treatment planning. Enzyme deficits, chromosomal defects, and hormonal abnormalities are not typically detected through ultrasonography.

Quiz 21: Congenital and Genetic Disorders