Question 1

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

Accepted Answer

C

Question 2

Exposure to cocaine during pregnancy leads to increased risk of:

Accepted Answer

Exposure to cocaine during pregnancy leads to an increased risk of premature birth and respiratory problems in the infant. Additionally, there is evidence that suggests an increased risk of sudden infant death syndrome (SIDS) in infants exposed to cocaine in utero. Therefore, option E that includes all three choices is the correct answer.

Question 3

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

Accepted Answer

If both parents carry a defective recessive gene, they each have a 50% chance of passing that gene on to their offspring. To produce a homozygous child (meaning they have two copies of the defective gene), both parents must pass on their copy. The chance of this happening is 25% (0.5 x 0.5 = 0.25). Therefore, the probability of two carriers producing a homozygous child is 25%.

Question 4

What is an example of a multifactorial congenital disorder?

Accepted Answer

Cleft lip and palate is an example of a multifactorial congenital disorder, meaning that it is caused by a combination of genetic and environmental factors. Factors such as maternal smoking, alcohol consumption, and certain medications have been linked to an increased risk of cleft lip and palate, but there is also a genetic component involved. Type AB blood is not a congenital disorder, but rather a blood type determined by genetics. Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21. Color blindness can be genetic, but it is not considered a congenital disorder as it does not typically cause physical deformities or developmental abnormalities.

Question 5

What is an arrangement of the chromosomes from an individual's cell,organized in pairs in descending order of size,called?

Accepted Answer

An arrangement of chromosomes from an individual's cell, organized in pairs in descending order of size, is called a karyotype. A pedigree is a diagram showing the inheritance of a trait in a family. Punnett squares are used to predict the possible genotypes of offspring based on the genotypes of the parents. The genotype is the genetic makeup of an individual.

Question 6

What is characteristic of a congenital disorder?

Accepted Answer

The answer of What is characteristic of a congenital disorder?
...

Question 7

Ultrasonography during pregnancy would be helpful in detecting fetal:

Accepted Answer

Ultrasonography during pregnancy is used to detect structural anomalies in the fetus, such as neural tube defects, heart defects, and abnormalities in other organs. It is not useful in detecting enzyme deficits, chromosomal defects, or hormonal abnormalities.

Question 8

Which of the following statements apply to the sex chromosomes?

Accepted Answer

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

Question 9

The laboratory practice of changing DNA sequences in microorganisms is called:

Accepted Answer

The practice of changing DNA sequences in microorganisms is a form of genetic engineering. This process involves artificially manipulating genes to produce desired traits in an organism. Gene mutation refers to a spontaneous change in the DNA sequence and is not done intentionally in a laboratory setting. Gene therapy is a medical treatment approach that involves altering or adding genes to treat or prevent disease in humans, and not specific to microorganisms. The genotype refers to an organism's genetic makeup, which can be influenced by genetic engineering, but is not the specific practice itself.

Question 10

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

Accepted Answer

In an X-linked recessive disorder, the affected gene is located on the X chromosome. Males only have one X chromosome, so if they inherit the affected gene from their mother, they will be affected by the disorder. Females have two X chromosomes, so they can be either homozygous (both X chromosomes carry the affected gene) or heterozygous (only one X chromosome carries the affected gene) carriers of the disorder.

In this case, the mother is a carrier, meaning she has one normal X chromosome and one X chromosome with the affected gene. The father is unaffected, meaning he has two normal X chromosomes.

There are a few possible outcomes for their children:

- Normal female: If the mother passes on her normal X chromosome, the daughter will not be affected by the disorder.
- Heterozygous carrier female: If the mother passes on her X chromosome with the affected gene, the daughter will be a carrier like her mother.
- Normal male: If the mother passes on her normal X chromosome, the son will not be affected by the disorder.
- Affected male: If the mother passes on her X chromosome with the affected gene, the son will be affected by the disorder.

Since the prompt does not include any information about the gender of the child, we can only guarantee that a normal female could be produced.

Question 11

The purpose of the Human Genome Project was to:

Accepted Answer

The Human Genome Project was a scientific research project with the goal of mapping the nucleotide sequence and identifying the genes on each human chromosome. This would provide a comprehensive understanding of the human genome and aid in the study of genetic disorders, among other applications. Manipulating DNA sequences in microorganisms and animals and identifying spontaneous alterations caused by teratogens are not specific objectives of the Human Genome Project. While the study of inheritance patterns was relevant, it was not the primary purpose of the project.

Question 12

Which term refers to prenatal diagnosis through examination of amniotic fluid?

Accepted Answer

The term for prenatal diagnosis through examination of amniotic fluid is amniocentesis. Chorionic villus testing (A) is a prenatal diagnosis through examination of cells taken from the placenta. Preparing a family pedigree (B) is a tool used to help identify patterns of inheritance in genetic disorders. The triple-screen test (D) is a blood test done during pregnancy to screen for specific birth defects.

Question 13

During which of these time periods do teratogens have the most serious effects on fetal development?

Accepted Answer

The period of organogenesis, which occurs during the first 8 weeks of pregnancy, is when the major organs and structures are formed. It is during this time that exposure to teratogens can lead to the most serious and permanent effects on fetal development.

Question 14

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

Accepted Answer

A mutation is a change in the DNA sequence that can result from exposure to harmful substances like chemicals or radiation. This can alter the genetic material of an organism and potentially cause changes in its phenotype or health. Autosome, genotype, meiosis, and allele are not related to this phenomenon.

Question 15

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 the mutated gene is located on the X chromosome. Since males only inherit one X chromosome from their mother, a boy with hemophilia A can only inherit the mutated gene from his mother. His father may carry the gene but would not have the disorder unless he inherits two copies of the mutated gene.

Question 16

A person with sickle cell trait that is heterozygous has:

Accepted Answer

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

Question 17

Which of the following statements regarding Down syndrome is TRUE?

Accepted Answer

The typical physical characteristics of Down syndrome are present at birth, including almond-shaped eyes, a small nose and mouth, and a single crease in the palm of the hand.

Answer: B 
 Children with Down syndrome may have organ defects and medical problems, but these vary in type and severity from individual to individual.

Answer: C 
 The extent of cognitive impairment in individuals with Down syndrome cannot be fully assessed at birth and may vary greatly.

Answer: D 
 The risk of giving birth to a child with Down syndrome increases with the mother's age, but it can occur in mothers of any age.

Question 18

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

Duchenne muscular dystrophy is an X-linked recessive genetic disorder. Since the mother is a carrier, she has one normal X chromosome and one with the mutated gene. The father, on the other hand, has one normal X chromosome. When they have a son, there is a 50% chance that the son inherits the mother's X chromosome with the mutated gene and develops muscular dystrophy. When they have another son, there is a 50% chance that he inherits the mother's mutated X chromosome and also develops muscular dystrophy. Therefore, the probability of the second son having muscular dystrophy is 50%.

Question 19

Down syndrome is an example of a/an:

Accepted Answer

Down syndrome is caused by the presence of an extra copy of chromosome 21 (trisomy 21) and is therefore an example of a chromosomal disorder. Option A is incorrect because autosomal dominant disorders are caused by a mutation in a single dominant gene. Option B is incorrect because multifactorial disorders are caused by a combination of genetic and environmental factors. Option C is incorrect because developmental defects refer to abnormalities that occur during embryonic or fetal development.

Question 20

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

Accepted Answer

There is a known genetic test for Huntington's disease, which can determine whether or not an individual carries the defective gene that causes the disorder. Choices A, C, and D are all incorrect statements. The symptoms of Huntington's disease typically do not appear until mid-adulthood, and the child of an affected parent has a 50% chance of inheriting the defective gene, but does not necessarily become a carrier. Additionally, inheriting the defective gene from only one parent is enough to cause the disease.

Quiz 7: Congenital and Genetic Disorders