Question 1

When one gene causes multiple effects, the condition is called ________.
A) incomplete dominance
B) multiple alleles
C) codominance
D) pleiotropy

Accepted Answer

Pleiotropy is a genetic phenomenon where a single gene affects multiple traits or has multiple effects on an individual's phenotype. This can happen because the gene product (usually a protein) is involved in multiple biochemical pathways or developmental processes.

Question 2

In which condition are both alleles expressed in the heterozygous phenotype?
A) pleiotropy
B) codominance
C) epistasis
D) complete dominance

Accepted Answer

In codominance, both alleles are expressed equally in the phenotype of the heterozygous individual. This means that both traits appear separately and distinctly in the organism. For example, in humans, the AB blood type is an example of codominance, where both the A and B alleles are equally expressed in the phenotype.

Question 3

Carol has tested positive for phenylketonuria, or PKU, so let's help plan her diet when she gets to school. Which of the following foods should she be most careful about?
A) beans
B) tomatoes
C) meat
D) potatoes

Accepted Answer

PKU is a genetic disorder that prevents the body from breaking down an essential amino acid called phenylalanine. Foods containing high levels of protein, such as meat, should be avoided or eaten in very limited quantities to prevent build-up of phenylalanine in the body. Beans, tomatoes, and potatoes do not have significantly high levels of protein and can be included in Carol's diet in moderation.

Question 4

Albinism is an example of ________.
A) a dominant disease
B) an autosomal recessive disease
C) a sex-linked disease
D) a polygenic disease

Accepted Answer

Albinism is caused by a recessive allele on an autosomal chromosome, meaning an individual needs to inherit two copies of the allele to express the phenotype.

Question 5

Which genetic condition can be described as the inheritance of the heterozygous phenotype, which is expressed as an intermediate between the dominant and recessive alleles?
A) dominance
B) codominance
C) incomplete dominance
D) epistasis

Accepted Answer

Incomplete dominance is a genetic condition where neither of the two alleles is dominant, and thus a heterozygous individual will express a phenotype that is an intermediate between the two homozygous phenotypes. For example, in a flower with incomplete dominance for the color gene, a homozygous red flower crossed with a homozygous white flower will produce offspring with pink flowers, which express an intermediate phenotype.

Question 6

If two chromosomes have the same genes for the same trait, they are said to be ________.
A) autosomal
B) polypeptides
C) homologues
D) traits

Accepted Answer

Chromosomes that have the same genes for the same trait are called homologous chromosomes. Autosomal refers to any chromosome that is not a sex chromosome, polypeptides are chains of amino acids that make up proteins, and traits are characteristics that can be passed down through generations.

Question 7

Specific segments of DNA that are the functional units of inheritance are called ________.
A) chromosomes
B) genes
C) chromatids
D) telomeres

Accepted Answer

Genes are specific segments of DNA that are the functional units of inheritance. Chromosomes are the packaging structures that contain genes, chromatids are duplicated copies of chromosomes, and telomeres are protective caps at the end of chromosomes.

Question 8

If your parents are heterozygous for a gene, what is the chance that you will have at least one copy of it?
A) 0%
B) 25%
C) 50%
D) 75%

Accepted Answer

If both parents are heterozygous for a gene, each has one copy of the allele and one copy of the alternative allele. The possible combinations for their offspring are: one allele from each (heterozygous like the parents), both alleles from both parents, or the alternative allele from both parents. This results in a 75% chance of inheriting at least one copy of the gene in question.

Question 9

A pedigree is useful because it ________.
A) shows the genotype of a particular individual
B) can help predict the chances of an offspring displaying a particular trait
C) shows the phenotype of one individual
D) can look at multiple traits at one time

Accepted Answer

A pedigree can help predict the chances of an offspring displaying a particular trait by following the inheritance pattern of that trait through a family. It allows for the analysis of relationships between individuals and the presence or absence of a specific trait, providing insight into the genotype and potential phenotype of offspring. However, a pedigree does not provide the genotype or phenotype of a single individual (choice A and C) or allow for the examination of multiple traits at one time (choice D).

Question 10

Which of the following is a condition caused by a sex-linked inheritance in which a male child will bleed extensively because he lacks the physiological properties to form a blood clot?
A) color blindness
B) male-pattern baldness
C) hemophilia
D) sickle-cell disease

Accepted Answer

Hemophilia is a sex-linked inherited condition in which a male child lacks the physiological properties to form a blood clot, causing them to bleed extensively. It is caused by a mutation in the gene that is responsible for producing clotting factor VIII or IX. Females can also be carriers of the gene, but usually do not suffer from the condition themselves.

Question 11

Thalassemia is a very serious disorder that affects hemoglobin. It is caused by an autosomal recessive gene. If both a woman and a man are carriers, then what is the chance that they will have a child with the disease?
A) 100%
B) 75%
C) 50%
D) 25%

Accepted Answer

The chance of both carriers passing on the recessive gene to their child is 25%.

Question 12

If the two parents are each heterozygous for widow's peak and having freckles, what is the chance that any of their children will have the same phenotype?
A) 9/16
B) 3/16
C) 1/2
D) 1/16

Accepted Answer

Widow's peak and having freckles are both dominant traits. Each parent being heterozygous means they have one dominant and one recessive allele for each trait. When crossing two heterozygotes for each trait, the probability that a child will exhibit both dominant phenotypes (widow's peak and freckles) is 3/4 (for widow's peak) * 3/4 (for freckles) = 9/16.

Question 13

A cardiac researcher is trying to determine whether a pattern of very high blood cholesterol is genetic in a group of Pennsylvania Dutch. Therefore, the scientist looks through years of medical records plus patterns of marriage through several generations. The investigator is doing a type of hereditary research called ________.
A) back crossing
B) pedigree analysis
C) linkage mapping
D) title searching

Accepted Answer

Pedigree analysis involves reviewing family trees and medical records to track the inheritance pattern of a particular trait or disease, which is exactly what the researcher is doing in this scenario. Back crossing refers to crossing an individual with its parent or ancestor, which is not relevant to this situation. Linkage mapping involves identifying the location of genes on a chromosome, which is not the focus of this study. Title searching refers to a process for finding legal documents related to property ownership, and is not relevant to this study.

Question 14

Adel has freckles, autosomal dominant. What is her genotype? A) FF B) Ff C) ff D) Can't say for certain; it could be FF or Ff.

Accepted Answer

Since freckles are autosomal dominant, having them means you have at least one dominant allele. Adel could have two dominant alleles (FF) or one dominant and one recessive allele (Ff). Without more information, we cannot determine which one specifically.

Question 15

Albinism is due to the inability to make ________.
A) tyrosine
B) melanin
C) hair
D) collagen

Accepted Answer

Albinism is a genetic condition where individuals are unable to produce enough or any melanin, the pigment responsible for skin, hair, and eye color.

Question 16

Emery had no freckles. His wife, Marguerite, was clearly freckled but known to be heterozygous for the gene. Predict the chance that any one of their children will have freckles.
A) 100%
B) 25%
C) 50%
D) 75%

Accepted Answer

Since Marguerite is heterozygous for the freckle gene (Ff) and Emery has no freckles (ff), their children have a 50% chance of inheriting the freckle gene (F) from Marguerite and a 50% chance of being freckle-free (f) from both parents.

Question 17

Someone who is heterozygous for a recessive genetic illness is said to be ________.
A) a carrier
B) pleiotropic
C) epistatic
D) allelic

Accepted Answer

A heterozygous individual has one dominant allele and one recessive allele. Although they do not show symptoms of the recessive genetic illness, they can pass on the recessive allele to their offspring. Therefore, they are carriers of the illness.

Question 18

Mary died suddenly of an aortic aneurysm (the sudden bursting of one of the body's largest blood vessels). Which of the following conditions should her children worry most about?
A) hemophilia
B) Turner syndrome
C) Marfan syndrome
D) albinism

Accepted Answer

Marfan syndrome is a genetic disorder that affects connective tissue, including the aorta. Individuals with Marfan syndrome have a higher risk of developing aortic aneurysms, which can lead to sudden death if not caught and treated early. Hemophilia, Turner syndrome, and albinism are not associated with an increased risk of aortic aneurysms.

Question 19

Diabetes mellitus type 2 (DM2) is partly hereditary and, if uncontrolled, can lead to kidney disease and heart failure and an increased risk of stroke and blindness. From this information alone, you could say that DM2 is an example of ________.
A) pleiotropy
B) epistasis
C) codominance
D) polygenes

Accepted Answer

Pleiotropy occurs when one gene influences multiple, seemingly unrelated phenotypic traits, such as DM2 affecting various organs and systems (kidney, heart, eyes, etc.).

Question 20

Paul was an orphan found wandering a city street when he was 2 years old. At age 52, he began to experience muscle spasms and was having difficulty walking. Which of the following genetic disorders is most probable?
A) PKU
B) CF
C) Huntington's disease
D) Marfan syndrome

Accepted Answer

Huntington's disease is a genetic disorder that typically affects individuals in midlife (around age 40) and is characterized by muscle spasms, difficulty walking, and eventually leads to cognitive and psychiatric symptoms. It is an autosomal dominant disorder, meaning that a person only needs to inherit one copy of the mutated Huntington gene to develop the disease. Since Paul was an orphan with unknown family history, it's possible that he inherited the disease from one of his biological parents.

Quiz 29: Genetics and Human Inheritance

When one gene causes multiple effects, the condition is called ________.

In which condition are both alleles expressed in the heterozygous phenotype?

Carol has tested positive for phenylketonuria, or PKU, so let's help plan her diet when she gets to school. Which of the following foods should she be most careful about?

Albinism is an example of ________.

Which genetic condition can be described as the inheritance of the heterozygous phenotype, which is expressed as an intermediate between the dominant and recessive alleles?

If two chromosomes have the same genes for the same trait, they are said to be ________.

Specific segments of DNA that are the functional units of inheritance are called ________.

If your parents are heterozygous for a gene, what is the chance that you will have at least one copy of it?

A pedigree is useful because it ________.

Which of the following is a condition caused by a sex-linked inheritance in which a male child will bleed extensively because he lacks the physiological properties to form a blood clot?

Thalassemia is a very serious disorder that affects hemoglobin. It is caused by an autosomal recessive gene. If both a woman and a man are carriers, then what is the chance that they will have a child with the disease?

If the two parents are each heterozygous for widow's peak and having freckles, what is the chance that any of their children will have the same phenotype?

Adel has freckles, autosomal dominant. What is her genotype?

Albinism is due to the inability to make ________.

Emery had no freckles. His wife, Marguerite, was clearly freckled but known to be heterozygous for the gene. Predict the chance that any one of their children will have freckles.

Someone who is heterozygous for a recessive genetic illness is said to be ________.

Mary died suddenly of an aortic aneurysm (the sudden bursting of one of the body's largest blood vessels) . Which of the following conditions should her children worry most about?

Diabetes mellitus type 2 (DM2) is partly hereditary and, if uncontrolled, can lead to kidney disease and heart failure and an increased risk of stroke and blindness. From this information alone, you could say that DM2 is an example of ________.

Paul was an orphan found wandering a city street when he was 2 years old. At age 52, he began to experience muscle spasms and was having difficulty walking. Which of the following genetic disorders is most probable?