1.
A normal human diploid zygote contains a full set of
Correct Answer
C. 46 chromosomes
Explanation
A normal human diploid zygote contains a full set of 46 chromosomes. This is because a diploid cell contains two sets of chromosomes, one set inherited from the mother and one set inherited from the father. In humans, each set consists of 23 chromosomes, resulting in a total of 46 chromosomes in a diploid zygote.
2.
A chart that traces the inheritance of a trait in the family is called a (an)
Correct Answer
A. Pedigree
Explanation
A chart that traces the inheritance of a trait in the family is called a pedigree. This term is commonly used in genetics to represent the family tree and show the pattern of inheritance of a particular trait or condition. It helps to identify if the trait is dominant or recessive and to understand the likelihood of it being passed on to future generations. Pedigrees are important tools in genetic counseling and research to study the inheritance patterns of various genetic disorders.
3.
Traits that are caused by the interaction of many genes are said to be
Correct Answer
C. Polygenic
Explanation
Polygenic traits are those that are influenced by the interaction of multiple genes. Unlike traits that are controlled by a single gene, polygenic traits result from the combined effects of several genes. These traits often display a wide range of variation, as each gene contributes a small effect to the overall phenotype. Examples of polygenic traits include height, skin color, and intelligence.
4.
An example of a trait that is caused by multiple alleles
Correct Answer
B. ABO blood groups
Explanation
ABO blood groups are an example of a trait that is caused by multiple alleles. The ABO blood group system is determined by three alleles: A, B, and O. Each person inherits two alleles, one from each parent, which determine their blood type. The A and B alleles are codominant, meaning that if an individual has both alleles, they will express both A and B antigens on their red blood cells, resulting in blood type AB. The O allele is recessive, so individuals with two O alleles will have blood type O. This multiple allele system allows for the existence of four blood types: A, B, AB, and O.
5.
Most sex-linked genes are found on the
Correct Answer
D. X chromosome
Explanation
Sex-linked genes are genes that are located on the sex chromosomes, which determine the sex of an individual. In humans, males have one X and one Y chromosome, while females have two X chromosomes. Since the question asks about "most" sex-linked genes, the correct answer is the X chromosome, as it carries a larger number of genes compared to the Y chromosome. The Y chromosome, on the other hand, carries fewer genes and is primarily responsible for male-specific traits.
6.
Hemophilia is a genetic disorder that is
Correct Answer
A. Sex-linked
Explanation
Hemophilia is a genetic disorder that is sex-linked, meaning it is caused by a gene located on the sex chromosomes. In this case, the gene responsible for hemophilia is located on the X chromosome. Since males have one X and one Y chromosome, and females have two X chromosomes, males are more likely to be affected by hemophilia because if their single X chromosome carries the gene, they will have the disorder. Females, on the other hand, need both X chromosomes to carry the gene in order to be affected. Therefore, hemophilia is more common in men than women.
7.
Which parental pair could produce females with colorblindness
Correct Answer
D. Heterozygous normal-vision mother, father with colorblindness
Explanation
A heterozygous normal-vision mother carries one normal-vision allele and one colorblindness allele. A father with colorblindness has two colorblindness alleles. When they reproduce, there is a 50% chance that the mother will pass on her colorblindness allele to a female offspring. Therefore, this parental pair could produce females with colorblindness.
8.
A common genetic disorder characterized by bent and twisted red blood cells is
Correct Answer
C. Sickle cell disease
Explanation
Sickle cell disease is a common genetic disorder characterized by the presence of abnormally shaped red blood cells that are bent and twisted, resembling a sickle or crescent shape. This abnormal shape affects the ability of the red blood cells to carry oxygen efficiently, leading to various complications such as anemia, pain crises, and organ damage. Cystic fibrosis is a genetic disorder that primarily affects the respiratory and digestive systems, hemophilia is a blood clotting disorder, and muscular dystrophy is a group of genetic disorders that cause progressive muscle weakness and degeneration.
9.
A student traced a widow's peak hairline in her family. Having a widow's peak is dominant to not having a widow's peak. What is the genotype of a mother who is heterozygous for having a widow's peak and a father who has a widow's peak?
Correct Answer
A. Mother - Ww, Father - WW
Explanation
The correct answer is Mother - Ww, Father - WW. In this scenario, the mother is heterozygous for having a widow's peak (Ww) while the father has a widow's peak (WW). Since having a widow's peak is dominant, the presence of the dominant allele (W) from the father would result in the child inheriting a widow's peak. The child would inherit one dominant allele (W) from the father and one recessive allele (w) from the mother, resulting in the genotype Ww for the child.
10.
What is the difference between a dominant genetic disorder and a recessive genetic disorder?
Correct Answer
D. A recessive genetic disorder is expressed only if the individual has two recessive forms of the allele.
Explanation
A recessive genetic disorder is expressed only if the individual has two recessive forms of the allele. This means that both copies of the gene must be recessive in order for the disorder to be expressed. If an individual has one dominant allele and one recessive allele, they will not have the disorder. A dominant genetic disorder, on the other hand, is expressed if the individual has just one copy of the gene, regardless of whether it is dominant or recessive.