1.
A change in a gene is called
Correct Answer
B. A mutation
Explanation
A change in a gene is called a mutation because a mutation refers to any alteration or change that occurs in the DNA sequence of a gene. These changes can range from small substitutions of a single nucleotide to larger deletions, insertions, or rearrangements of genetic material. Mutations can lead to variations in traits and can be inherited or occur spontaneously.
2.
Hemophilia is a sex-linked genetic disorder. Which statement best describes its inheritance pattern?
Correct Answer
A. It is recessive in both males and females
Explanation
Hemophilia is a sex-linked genetic disorder that is caused by a recessive gene located on the X chromosome. Since males have only one X chromosome, they are more likely to express the disorder if they inherit the recessive gene. Females, on the other hand, have two X chromosomes, so they need to inherit the recessive gene from both parents to express the disorder. Therefore, the inheritance pattern of hemophilia is recessive in both males and females.
3.
Male pattern baldness is a sex-linked trait. That means that it is most commonly passed from:
Correct Answer
B. Mother to son
Explanation
This is the most common way for males to inherit X-linked traits such as male pattern baldness. Since the son's X chromosome comes from his mother, any recessive traits on this chromosome (including those related to baldness) are more likely to be expressed.
4.
The presence of more than 2 chromosomes to a set. This occurs when a germ cell containing more than 23 chromosomes is involved in conception.
Correct Answer
B. Polysomy
Explanation
Polysomy is the correct answer because it refers to the presence of more than 2 chromosomes in a set. This can happen when a germ cell with more than 23 chromosomes is involved in conception. Nondisjunction, fetal alcohol syndrome, and TORCH are not relevant to the given explanation.
5.
The chromosomes of the same quantity and type in both sexes (44 in humans).
Correct Answer
C. Autosomes
Explanation
Autosomes refer to the chromosomes that are not involved in determining an individual's sex. In humans, there are 22 pairs of autosomes, making a total of 44 autosomes. This is the same quantity and type of chromosomes in both sexes. The remaining pair of chromosomes, known as the sex chromosomes, differs between males (XY) and females (XX). Therefore, the statement correctly identifies autosomes as the chromosomes of the same quantity and type in both sexes.
6.
Down syndrome is an example of a/an?
Correct Answer
D. Chromosomal disorder
Explanation
Down syndrome is caused by the presence of an extra copy of chromosome 21, which is known as trisomy 21. This extra chromosome occurs during the formation of the sperm or egg and results in individuals with Down syndrome having 47 chromosomes instead of the usual 46. This extra genetic material affects the development and functioning of the body and brain, leading to characteristic physical features and intellectual disabilities. Therefore, Down syndrome is classified as a chromosomal disorder.
7.
Agents that cause damage during embryonic or fetal development are called:
Correct Answer
A. Teratogeneic
Explanation
Teratogenic agents are substances or factors that can cause abnormalities or malformations in the developing embryo or fetus. These agents can include drugs, chemicals, infections, radiation, or maternal factors such as poor nutrition or certain diseases. They can disrupt the normal development of the embryo or fetus, leading to structural or functional abnormalities in various organs or body systems. Teratogenic agents are a significant concern during pregnancy, and avoiding exposure to known teratogens is important for the health and well-being of the developing baby.
8.
What is an example of multifactorial congenital disorder?
Correct Answer
D. Cleft lip and palate
Explanation
Cleft lip and palate is an example of a multifactorial congenital disorder. It is caused by a combination of genetic and environmental factors. While there may be a genetic predisposition, environmental factors such as maternal smoking, alcohol consumption, and certain medications can also contribute to the development of this disorder.
9.
Ultrasonography during pregnancy would be helpful in detecting fetal.
Correct Answer
B. Structural anamolies
Explanation
Ultrasonography during pregnancy is a useful diagnostic tool for detecting structural anomalies in the fetus. This imaging technique uses high-frequency sound waves to create detailed images of the developing baby in the womb. It can help identify any abnormalities or malformations in the baby's organs, limbs, or other structures. By detecting structural anomalies early on, healthcare providers can provide appropriate medical interventions or counseling to ensure the best possible outcome for both the mother and the baby.
10.
Inactivated and highly condensed X chromosomes in females.
Correct Answer
D. Barr bodies
Explanation
Barr bodies are the condensed and inactivated X chromosomes found in the cells of females. During embryonic development, one of the two X chromosomes in each cell of a female is randomly inactivated to ensure dosage compensation between males and females. The inactivated X chromosome becomes highly condensed and forms a Barr body. This process helps to equalize the gene expression between males and females. Therefore, the presence of Barr bodies is a characteristic feature of female cells.
11.
The tendency of genes located on the same chomosome to be transmitted together in inheritance; can be disrupted by crossing over.
Correct Answer
A. Linkage
Explanation
Linkage refers to the tendency of genes located on the same chromosome to be inherited together. This means that these genes are less likely to be separated and shuffled during the process of genetic recombination. However, crossing over can disrupt this linkage by breaking the physical connection between genes on the same chromosome, leading to the exchange of genetic material between homologous chromosomes. This process can result in the recombination of genes and the creation of new genetic combinations.
12.
A disease that most affected children have normal parents, heterozygotes have a normal phenotype, two affected parents will always have affected children, both males and females are affected with equal frequency. Examples: albinism, sickle-cell anemia
Correct Answer
B. Autosomal recessive inheritance
Explanation
Autosomal recessive inheritance is the correct answer because the given information suggests that the disease is most likely inherited in an autosomal recessive manner. This means that the disease is caused by two copies of the recessive allele, one from each parent. Normal parents can carry one copy of the recessive allele without showing any symptoms, but when both parents are carriers, there is a 25% chance that their children will inherit two copies of the recessive allele and therefore be affected by the disease. Additionally, the fact that both males and females are affected with equal frequency supports the idea of autosomal inheritance rather than X-linked inheritance.
13.
A disease that affected children usually have an affected parent, homozygous dominant are rarely observed, unaffected persons do not transmit the characteristic, both males and females are affected with equal frequency. Examples:Huntington's disorder, achondroplasia, polydactyly, progeria
Correct Answer
B. Autosomal dominance inheritance
Explanation
Autosomal dominance inheritance is the correct answer because the given information states that a disease that affects children usually has an affected parent, which suggests that the disease is inherited. Additionally, the information mentions that homozygous dominant individuals are rarely observed, indicating that the disease is caused by a dominant allele. This type of inheritance pattern is known as autosomal dominance, where the presence of a single copy of the dominant allele is sufficient to cause the disease.
14.
A disease that is more males than females are affected, in order for a female to have the characteristic, her father must also have it, Her mother must have it or be a carrier, the characteristic often skips a generation from the grandfather to the grandson, If a woman has the characteristic (is affected), all of her sons will have it. Examples: color blindness, hemophilia
Correct Answer
A. X-linked recessive inheritance
Explanation
X-linked recessive inheritance is the correct answer because it aligns with the given information. X-linked recessive inheritance refers to the inheritance pattern of genes located on the X chromosome. In this pattern, the disease affects more males than females because males have only one X chromosome, while females have two. For a female to have the characteristic, her father must have it because he passes the X chromosome to his daughter. The characteristic often skips a generation from the grandfather to the grandson because the gene can be passed from carrier females to their sons. This pattern fits with examples of X-linked diseases like color blindness and hemophilia.
15.
Which of the following statements applies to Huntington’s disease?
Correct Answer
B. There is a test for the defective gene
Explanation
The statement "There is a test for the defective gene" is correct because there is indeed a test available to identify the presence of the defective gene associated with Huntington's disease. This test can be performed to determine whether an individual has inherited the gene mutation that causes the disease.
16.
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:
Correct Answer
B. 50%
Explanation
Since the mother is a carrier of Duchenne muscular dystrophy, she has one X chromosome with the mutated gene and one X chromosome without the mutation. The father is unaffected, meaning he has one X chromosome without the mutation. In order for a male child to have muscular dystrophy, he must inherit the mutated gene from his mother. Therefore, there is a 50% chance that the second son will have muscular dystrophy, as he has a 50% chance of inheriting the mutated gene from his carrier mother.
17.
The loss of a chromosome segment, changes in chromosome structure:"point mutations":
Correct Answer
B. Deletion
Explanation
Deletion refers to the loss of a chromosome segment, resulting in a change in chromosome structure. This is a type of chromosomal mutation, where a portion of the chromosome is missing. Unlike other types of chromosomal mutations such as inversion or duplication, deletion specifically involves the loss of genetic material.
18.
A lab preparation which makes chromosomes visual.
Correct Answer
A. Karyotype
Explanation
A karyotype is a lab preparation that allows for the visualization of chromosomes. It involves arranging and pairing chromosomes according to their size, shape, and banding patterns. This technique is commonly used in genetic testing and diagnosis of chromosomal abnormalities. It helps in identifying any structural or numerical abnormalities in the chromosomes, such as deletions, duplications, translocations, or aneuploidies. By examining the karyotype, scientists and medical professionals can gain valuable insights into an individual's genetic makeup and potential genetic disorders.
19.
Changes in chromosome number or arrangement.
Correct Answer
B. Chromosomal mutations
Explanation
Chromosomal mutations refer to changes in the structure or number of chromosomes. This can include translocation, which is the exchange of genetic material between non-homologous chromosomes, inversion, which is the reversal of a chromosome segment, and duplication, which is the replication of a chromosome segment. These mutations can lead to alterations in the arrangement or number of genes, potentially resulting in genetic disorders or other phenotypic changes.
20.
Occurs when a part of one chromosome is transferred to a nonhomologous chromosome. Changes in chromosome structure: "point mutations"
Correct Answer
A. Translocation
Explanation
Translocation refers to a chromosomal abnormality where a part of one chromosome breaks off and attaches to a nonhomologous chromosome. This can result in changes in the structure of the chromosome, such as point mutations. Monosomy refers to the condition where there is a loss of one copy of a chromosome, while aneuploidy refers to an abnormal number of chromosomes in a cell. Trisomy, on the other hand, refers to the condition where there is an extra copy of a chromosome. Therefore, translocation is the correct answer as it specifically describes the transfer of a part of one chromosome to a nonhomologous chromosome.
21.
A condition in which the gametes or cells of an affected individual end up with one extra or one less chromosome than is normal due to nondisjunction (failure of homologous chromosomes or chromatids to separate during meiosis. changes in chromosome number.
Correct Answer
A. Aneuploidy
Explanation
Aneuploidy is the correct answer because it refers to a condition where there is an abnormal number of chromosomes in the gametes or cells of an affected individual. This can occur when there is a failure of homologous chromosomes or chromatids to separate during meiosis, leading to one extra or one less chromosome than is normal. Aneuploidy can result in various disorders, such as Down syndrome, which is a specific example of trisomy, where there is an extra copy of chromosome 21. Monosomy, on the other hand, refers to the condition of having only one copy of a particular chromosome.
22.
The fusion of a gamete with an extra chromosome (n + 1) with a normal gamete resulting in a 2n+1 condition. changes in chromosome number.
Correct Answer
A. Trisomy
Explanation
Trisomy is the correct answer because it refers to the condition where there is an extra chromosome (n + 1) in the fusion of a gamete with a normal gamete, resulting in a 2n+1 condition. This leads to an abnormal chromosome number, specifically an extra chromosome in the cells of the individual. Trisomy can occur in various chromosomes, and examples of trisomy disorders include Down syndrome (trisomy 21) and Edwards syndrome (trisomy 18).
23.
The fusion of a gamete with a missing chromosome (n - 1) with a normal gamete resulting in a 2n-1 condition. changes in chromosome number.
Correct Answer
C. Monosomy
Explanation
Monosomy is the correct answer because it is the condition described in the explanation. Monosomy refers to the presence of only one copy of a particular chromosome in an individual's cells, instead of the usual two copies. In the given explanation, it is stated that the fusion of a gamete with a missing chromosome (n - 1) with a normal gamete results in a 2n-1 condition, which is characteristic of monosomy. This condition can lead to various genetic disorders, including Turner syndrome, which is specifically mentioned in the other answer choices.
24.
Results from trisomy 21; results in mental retardation; chances increase with age (trisomy). a chromosomal disorder involving aneuploidy.
Correct Answer
C. Down syndrome
Explanation
Down syndrome is a chromosomal disorder that results from trisomy 21, which means there is an extra copy of chromosome 21. This condition leads to mental retardation and the chances of having a child with Down syndrome increase with the age of the mother. Therefore, the given answer, Down syndrome, aligns with the information provided in the question.
25.
Involves females whose cells have only one X chromosome (designated XO); affected individuals are sterile and have other phenotypic problems such as premature aging and shorter life expectancy (monosomy). chromosomal disorder involving aneuploidy.
Correct Answer
A. Turner syndrome
Explanation
Turner syndrome is a chromosomal disorder that affects females who have only one X chromosome (XO). This condition leads to various phenotypic problems such as infertility, premature aging, and a shorter life expectancy. It is considered a monosomy, which is a type of chromosomal disorder involving aneuploidy.
26.
Nondisjunction results in an extra X chromosome in the cells (XXY) of these affected males; mental retardation and sterility are symptoms (trisomy). a chromosomal disorder involving aneuploidy.
Correct Answer
C. Klinefelter syndrome
Explanation
Nondisjunction is a chromosomal disorder that occurs when chromosomes fail to separate properly during cell division. In the case of Klinefelter syndrome, this results in an extra X chromosome (XXY) in the cells of affected males. This condition leads to symptoms such as mental retardation and sterility, which are characteristic of trisomy. Therefore, Klinefelter syndrome is the correct answer as it matches the given description.
27.
Any substance that can cause developmental abnormalities in the embryo or fetus.
Correct Answer
D. Teratogen
Explanation
The term "teratogen" refers to any substance or factor that can cause developmental abnormalities in the embryo or fetus. In this context, the substances mentioned in the question, such as Accutane, tetracycline, coumadin, and antidepressants, are known teratogens. Additionally, other factors like placenta previa, placental abruption, low birthweight/prematurity, pharmaceuticals, alcohol/smoking/drugs, infection, radiation, and maternal disease can also act as teratogens. These teratogens can interfere with normal fetal development and increase the risk of birth defects or other adverse outcomes.
28.
Illness causing damage (TORCH):
Correct Answer
C. Toxoplasmosis, rubella, cytomegalovirus, herpes, others
Explanation
Exposure to high levels of ionizing radiation, such as gamma rays, can be extremely harmful to the fetus and newborn, potentially causing death. Lower doses of radiation can lead to congenital abnormalities, growth retardation, and an increased risk of cancer. The timing of exposure is also important, as early or late exposure is less harmful. The answer refers to TORCH infections, which include toxoplasmosis, rubella, cytomegalovirus, herpes, and others. These infections can cause illness and damage to the fetus and newborn if contracted during pregnancy.
29.
Normal number of chromosomes:
Correct Answer
D. 46
Explanation
The normal number of chromosomes in a human body is 46. This is because humans have 23 pairs of chromosomes, with each pair consisting of two chromosomes (one from each parent), resulting in a total of 46 chromosomes.
30.
Chromosome number stays the same except for:
Correct Answer
B. In the S-pHase of cell division; number doubles in prep for mitosis
Explanation
During the S-phase of cell division, the chromosome number doubles in preparation for mitosis. This is because DNA replication occurs during the S-phase, where each chromosome duplicates itself to form two identical sister chromatids. These sister chromatids are held together by a centromere. When mitosis occurs, the sister chromatids separate and are distributed equally to each daughter cell, ensuring that each cell receives the same number of chromosomes as the parent cell. Therefore, the chromosome number stays the same except during the S-phase when it temporarily doubles.
31.
Marfan syndrome:
Correct Answer
B. Autosomal dominant; variable expressivity; allelic heterogeneity
Explanation
This answer suggests that Marfan syndrome is inherited in an autosomal dominant manner, meaning that a person only needs to inherit one copy of the mutated gene from one parent to develop the condition. It also indicates that the syndrome exhibits variable expressivity, meaning that the severity of symptoms can vary among affected individuals. Additionally, it mentions allelic heterogeneity, which suggests that there can be different mutations in the same gene that can cause the syndrome.
32.
Huntington disease:
Correct Answer
B. Autosomal dominant; late age of onset
Explanation
Huntington's disease is a neurodegenerative disorder characterized by the progressive loss of muscle control, cognitive decline, and psychiatric symptoms. It is caused by a mutation in the huntingtin gene, which is inherited in an autosomal dominant manner. This means that only one copy of the mutated gene is needed to develop the disease. The late age of onset refers to the fact that symptoms typically appear in adulthood, usually between the ages of 30 and 50. Therefore, individuals with the disease have a 50% chance of passing it on to each of their children.
33.
A father affected with hemophilia A, whose wife is unaffected, will pass on the defective gene to:
Correct Answer
C. All of his daughters, who will be carriers
Explanation
Hemophilia A is an X-linked recessive disorder, which means it is caused by a defective gene on the X chromosome. Since the father is affected with hemophilia A, he will pass on the defective gene to all of his daughters. However, since the mother is unaffected, the daughters will only be carriers of the disorder, meaning they will have one copy of the defective gene but will not be affected by the disorder themselves. Sons, on the other hand, inherit their X chromosome from their mother, so they have a 50% chance of inheriting the defective gene and being affected by hemophilia A.
34.
Exposure to cocaine during pregnancy leads to increased risk of:
Correct Answer
D. All of the choices are correct
Explanation
Exposure to cocaine during pregnancy can have detrimental effects on both the mother and the developing fetus. It increases the risk of premature birth, which can lead to various health complications for the baby. Additionally, cocaine use during pregnancy can cause respiratory problems in the newborn, as the drug can affect the development and functioning of the respiratory system. Furthermore, there is an increased risk of sudden infant death syndrome (SIDS) in babies born to mothers who used cocaine during pregnancy. Therefore, all of the choices listed - premature birth, respiratory problems, and SIDS - are correct risks associated with cocaine exposure during pregnancy.
35.
Which of the following can be detected using amniotic fluid?
Correct Answer
A. Chromosomal abnormalities
Explanation
Amniotic fluid can be used to detect chromosomal abnormalities. This is because the fluid contains fetal cells that can be analyzed for genetic abnormalities, such as Down syndrome or Turner syndrome. By examining the chromosomes in these cells, doctors can identify any abnormalities and provide appropriate counseling and treatment options for the parents. Amniotic fluid, however, is not typically used to detect metabolic disorders or certain structural abnormalities.
36.
The laboratory practice of changing DNA sequences in microorganisms is called:
Correct Answer
C. Genetic engineering
Explanation
Genetic engineering refers to the laboratory practice of altering DNA sequences in microorganisms. This process involves manipulating the genetic material of an organism to introduce new traits or modify existing ones. It can be used to develop new medicines, improve crop yields, and create genetically modified organisms (GMOs). Gene therapy, on the other hand, involves the treatment of genetic disorders by introducing functional genes into a patient's cells. The other options, genotype and gene mutation, do not accurately describe the practice of changing DNA sequences in microorganisms.
37.
How are X-linked diseases expressed in women?
Correct Answer
B. While X-linked are normally recessive, females also have X-inactivation. So variable proportion of disease is expressed
Explanation
X-linked diseases are typically recessive, meaning that both copies of the gene must be mutated for the disease to be expressed. However, in females, one of the X chromosomes is randomly inactivated in each cell, leading to a variable proportion of cells expressing the mutated gene. This can result in a range of disease expression in females, from no symptoms to mild or severe symptoms, depending on the proportion of cells with the active mutated gene.
38.
Nondisjunction:
Correct Answer
C. The failure of chromosome pairs to separate properly during cell division. Failure of homologous chromosomes to separate in meiosis I or the failure of sister chromatids to separate during meiosis II or mitosisCauses aneuploidy
Explanation
Nondisjunction refers to the failure of chromosome pairs to separate properly during cell division. This can occur either during meiosis I when homologous chromosomes fail to separate or during meiosis II or mitosis when sister chromatids fail to separate. This failure in chromosome separation leads to aneuploidy, which is the presence of an abnormal number of chromosomes in a cell. Aneuploidy can result in various genetic disorders and abnormalities.
39.
Down syndrome
Correct Answer
A. Trisomy 21 Increase risk in older mothers. Results in mental retardation, heart defects, and distinctive pHysical features like extra folds in upper eyelids and shore stature
Explanation
Trisomy 21, also known as Down syndrome, is caused by the presence of an extra copy of chromosome 21. This condition is more likely to occur in older mothers due to errors in chromosome separation during egg formation. Trisomy 21 leads to various developmental and physical abnormalities, including mental retardation, heart defects, and distinct physical features such as extra folds in the upper eyelids and shorter stature.
40.
Is a rare inherited disorder in which the blood does not clot normally.
Correct Answer
A. HemopHilia
Explanation
Hemophilia is a rare inherited disorder in which the blood does not clot normally. This means that individuals with hemophilia experience prolonged bleeding and are at a higher risk of excessive bleeding even from minor injuries. The condition is caused by a deficiency or absence of certain clotting factors in the blood. Hemophilia is typically inherited from parents who carry the faulty gene. Treatment for hemophilia involves replacing the missing clotting factors through injections or infusions to prevent or control bleeding episodes.
41.
Down syndrome
Correct Answer
A. Non-disjunction of 21st chromosome
Explanation
Down syndrome is a genetic disorder caused by the non-disjunction of the 21st chromosome during the formation of reproductive cells. This results in an individual having three copies of chromosome 21 instead of the usual two. This extra genetic material leads to various physical and intellectual disabilities commonly associated with Down syndrome, such as developmental delays, characteristic facial features, and increased risk of certain health conditions.
42.
Autosomes
Correct Answer
B. First 22 paris of chromosomes
Explanation
The correct answer is "First 22 pairs of chromosomes." This is because autosomes are the chromosomes that are not involved in determining the sex of an individual. In humans, the first 22 pairs of chromosomes are autosomes, while the 23rd pair determines the gender. Therefore, the first 22 pairs of chromosomes are considered autosomes.
43.
Sex chromosome
Correct Answer
D. 23rd pair, father determines gender
Explanation
The answer "23rd pair, father determines gender" is correct because the 23rd pair of chromosomes, known as the sex chromosomes, determines the gender of an individual. In humans, females have two X chromosomes (XX) while males have one X and one Y chromosome (XY). The presence of a Y chromosome determines the development of male characteristics. Therefore, the father determines the gender of the child by contributing either an X or a Y chromosome during fertilization.
44.
Genotype
Correct Answer
A. Combination of genes inherited for a particular trait
Explanation
Genotype refers to the combination of genes that an individual inherits for a specific trait. It is the genetic makeup of an organism, representing the genes that are present in its DNA. This combination of genes determines the characteristics and traits that an individual will have. For example, the genotype for eye color may include genes for blue, green, or brown eyes. The physical expression of these genes, such as having blue eyes, is known as the phenotype.
45.
Phenotype
Correct Answer
B. pHysical expression of genes
Explanation
The correct answer is "Physical expression of genes." This is because the term "phenotype" refers to the observable characteristics or traits of an organism, which are determined by the interaction of genes (genotype) with the environment. The physical expression of genes refers to how these genes are manifested in the physical appearance or traits of an individual. In the given context, it is mentioned that a phenotype is the physical expression of genes, which aligns with the definition of phenotype.