chapter 19 study

c

A father is blood type B and a mother is blood type A. They have a child with blood type O. What are the genotypes of the father and mother? a. The father must be BB and the mother must be AA. b. The father must be BO and the mother must be AA. c. The father must be BO and the mother must be AO d. This isn't possible.

d

A female is diagnosed with hemophilia, a condition caused by an X-linked recessive gene. While checking her medical history, the doctor will most likely discover that ________. a. her mother had hemophilia and her father was normal b. both her parents were carriers of the hemophilia gene c. neither parent had hemophilia d. her father had hemophilia but her mother did not have the disorder

b

All of the following human traits are determined by the interaction of multiple genes and alleles, EXCEPT __________. a. eye color b. sickle cell anemia c. hair color d. height

a

Alterations in chromosome number can occur with any chromosome, but most alterations are not seen in human populations because a. they are lethal during fetal development b. most are corrected during the first mitotic event in the fertilized egg c. the genotype still represents a normal condition d. the phenotype is homozygous recessive

c *Testosterone stimulates the expression of the allele, causing men who are heterozygous to show some degree of baldness.

Baldness is a sex-influenced trait. Women must inherit both recessive alleles to be bald, while men need only inherit one recessive allele. This occurs because __________. a. the baldness allele is linked to the Y chromosome b. estrogen masks the effect of the baldness allele c. testosterone stimulates the expression of the baldness allele d. the presence of two X chromosomes in a woman suppresses expression of the baldness allele

One of her gametes might be AaDd.

Based on what you know about two-trait inheritance, what can you say about the gametes produced by a female with the genotype AaDd that could NOT be possible?

incomplete dominance

Caucasians people having the trait of straight, wavy or curly hair is an example of

human gene pool

Collectively, all the various genes and their alleles in the human population are known as the

a *All the children will express the trait because both parents have the recessive gene on all of their X chromosomes.

Consider the hypothetical X-linked recessive gene M. Suppose a woman expresses this gene. So does her husband. What are the chances that a child of theirs will NOT express this gene? a. All of the children will express the trait. b. All of the male children will express trait M, but none of the female children will express the trait. c. All of the female children will express trait M, but none of the male children will express the trait. d. Half the female children and a quarter of the male children will express the trait.

nonsister chromatids of homologous chromosomes

Crossing over, resulting in an increase in genetic variation, occurs between _____.

a recessive allele of a gene on chromosome 7

Cystic fibrosis (CF), the most common potentially fatal genetic disease in North America today, is caused by

50%

Cystic fibrosis is a genetic disorder that results from the inheritance of two recessive alleles. What is the chance that a child will inherit the disorder if one parent is heterozygous for this gene and one parent has cystic fibrosis?

nucleotides

DNA is composed of building blocks called _____.

c. *Heterozygous individuals will not show the trait of a recessive allele in completely dominant inheritance, but they will show the trait of a dominant allele.

Dominant alleles that cause disease are especially dangerous because __________. a. the severity of the disease is greater than that of diseases caused by recessive alleles b. dominant alleles are inherited more frequently than recessive alleles c. heterozygous individuals will develop the disease d. individuals must inherit two dominant alleles to show the disease

d

Examination of a karyotype reveals 23 pairs of chromosomes, with each homologous pair illustrating similar size and centromere location. Which of the following can be concluded from this karyotype? a. The individual has Down syndrome. b. The individual does not have cystic fibrosis. c. The individual does not have sickle-cell anemia d. The individual is a female.

codominance

Identify the mode of inheritance AB blood type

nondisjunction

Identify the mode of inheritance Down syndrome

inheritance of a dominant-lethal allele

Identify the mode of inheritance Huntington disease

sex-influenced trait

Identify the mode of inheritance baldness

polygenetic inheritance

Identify the mode of inheritance human eye color

X-linked inheritance

Identify the mode of inheritance red-green color blindness

incomplete dominance

Identify the mode of inheritance straight vs. curly vs.wavy hair in humans

b

If a piece of chromosome breaks off during mitosis or meiosis and does not reattach, the event is called a. translocation b. a deletion c. dysplasia d. nondisjunction

homozygous

If both alleles of a particular gene are identical, the person is said to be

codominance *Codominance expresses two alleles equally.

In the human ABO blood-typing system, an individual with A and B alleles will express both A and B phenotypes on his or her red blood cells. This is an example of __________. A. incomplete dominance B. polygenic inheritance C. complete dominance D. codominance

true

In the human male, genotype and phenotype associated with the genes on the X chromosome are determined by the one X chromosome he inherits from his mother. true false

c, e, a, d, b

Match each of the following disorders to the genotype with which it is associated. 1. recessive allele on chromosome 15 2. one X chromosome; no Y or additional X chromosome 3. trisomy 21 4. XXY 5. trisomy 18 a. Down syndrome b. Edwards syndrome c. Tay-Sachs d. Klinefelter syndrome e. Turner syndrome

d *Homologous chromosomes align in the middle of the cell in meiosis I and fail to separate if nondisjunction occurs.

Nondisjunction in meiosis I results in failure of __________. a. meiosis I to continue to completion b. gametes to separate c. sister chromatids to separate d. homologous chromosomes to separate

homozygous

People with the same two alleles of a gene (either aa or AA) are

d. *The testes will develop in response to the Y chromosome, but the absence of testosterone will prevent further male development.

Testosterone is responsible for the development of the male reproductive system, and it is produced by the testes. The development of the testes depends on the presence of a Y chromosome. What might occur if the Y chromosome is present, but the testes are unable to produce testosterone? a. normal female development b. The testes and ovaries would be present. c. normal male development d. The testes would be present, but further male development would be arrested.

all pink.

The flower color in this plant is inherited by incomplete dominance. If a red flower that is homozygous dominant is crossed with a white flower that is homozygous recessive, the color of the offspring flowers will be expected to be A. 50% white and 50% pink. B. 50% white and 50% red. C. all red. D. all pink.

incomplete dominance

The offspring resulting from a cross between a nearly white horse (cc) and a chestnut-colored horse (CC) is of an intermediate color (between white and chestnut). Which one of the following patterns of inheritance best explains this? A. complete dominance B. codominance C. polygenic inheritance D. incomplete dominance

true *Females have two copies of the X chromosome, so if they have one allele for a recessive disorder and one normal allele, they will be normal; however, males have only one copy of the X chromosome, so they will have the disorder if they inherit one recessive allele.

True or false. X-linked recessive disorders are more commonly expressed in males than in females because males have only one copy of the X chromosome.

alleles

Variations of homologous genes that result in differences in structure and function are

b *Because recessive traits will be expressed in the absence of the dominant trait and because males have only one X chromosome, the X-linked recessive trait will be more common in males than in females.

What can we say about the frequency of X-linked recessive traits? a. It is not possible to determine whether an X-linked trait will occur more frequently in males or in females. b. X-linked recessive traits are more common in males than in females. c. X-linked recessive traits are expressed about equally in males and females. d. X-linked recessive traits are more common in females than in males.

a

What is the likelihood that a man with hemophilia mating with a woman who is homozygous for the normal form of the blood clotting factor gene will have a son with hemophilia? a. 0 % b. 25 % c. 50 % d. 100 %

A. 0 %

What is the likelihood that a parent with type AB blood would have a child with type O blood? A. 0 % B. 25 % C. 50 % D. This can't be determined without knowing the blood type of the other parent.

b *There is a 1/2 probability that this couple will have a child with normal color vision (either a son or a daughter) and a 1/2 probability that they will have a child who is color blind.

What is the probability that a woman who is a carrier for the red-green color-blindness allele and a man who is color blind will have a child who is NOT color blind? a. 100% (all of the offspring will be color blind) b. 50% c. 25% d. 0% (none of the offspring will be color blind)

d

When a piece of chromosome breaks off and reattaches at another site on the same or another chromosome, this is called a. nontranslation b. a deletion c. recombination d. translocation

D. incomplete dominance *In incomplete dominance, the offspring exhibits a phenotype intermediate between the phenotypes of the parents.

When a straight-haired parent and a curly-haired parent have a wavy-haired child, this is an example of __________. A. polygenic inheritance B. complete dominance C. codominance D. incomplete dominance

a

When continuous variation occurs in a phenotypic trait, the trait is likely due to __________. a. polygenic inheritance b. codominance c. incomplete dominance d. complete dominance

b

Which of the following events or processes can result in Down syndrome, Turner Syndrome, or Klinefelter syndrome? a. independent assortment b. nondisjunction c. deletion of part of a chromosome d. crossing-over

d

Which of the following statements is/are true? a. Phenotype determines genotype. b. Genotype determines phenotype. c. Environment can affect phenotype. d. Both that genotype determines phenotype and that environment can affect phenotype are true.

c

Which one of the following genetic disorders is caused by the inheritance of a dominant-lethal allele? a. muscular dystrophy b. Down syndrome c. Huntington's disease d. hemophilia

your genotype

Your complete set of alleles is called

human gene pool

all the various genes and their alleles in the human population are known as the

The X and Y chromosomes, also called the sex chromosomes,

carry the genes that determine the gender of the individual.

inheritance

characteristics or traits that are transmitted from parents to offspring via genes

only just before cell division

chromosomes are identifiable in cells

their size, centromere location, and characteristic banding patterns

chromosomes are identified and paired according to

characteristic size, centromere location, and distinct banding pattern

each chromosome can be identified by its

law of segregation

when gametes are formed in the parents, the alleles sperate from each other so that each gamete gets only one allele of each gene

100%

"In humans, the ability to roll the tongue is a dominant trait;the inability to roll the tongue is a recessive trait. If an individual homozygous dominant for this trait has a child with an individual who cannot roll their tongue, what is the chance that the child will have a heterozygous genotype?

25%

"In humans, the ability to roll the tongue is a dominant trait;the inability to roll the tongue is a recessive trait. If two individuals heterozygous for this trait have a child, what is the chance that the child will not be able to roll their tongue?

0%

"In humans, the ability to roll the tongue is a dominant trait;the inability to roll the tongue is a recessive trait. If two individuals homozygous dominant for this trait have a child, what is the chance that the child will not be able to roll their tongue?

mutation

A change in the DNA base pair sequence of a cell

karyotype

A composite display of all the chromosomes of an organism is called

punnett square

A grid used for predicting patterns of inheritance and the probability a particular genotype will be inherited

Punnett square

A grid used for predicting patterns of inheritance and the probability that a particular genotype will be inherited

C. either dominant or recessive *Homozygous means that both alleles are the same. These alleles may be dominant or recessive.

A homozygous trait can be ________. A. recessive only B. heterozygous under certain circumstances C. either dominant or recessive D. dominant only

incomplete dominance

A pattern of genetic inheritance in which the heterozygous genotype results in a phenotype that is intermediate between the two homozygous phenotypes

heterozygous

A person who has two different alleles of a gene is

both alleles present are recessive

A recessive phenotype will be expressed when __________.

when there is no dominant allele, that is, when both alleles are recessive

A trait expressed by a recessive allele will only be present

law of independent assortment

All alleles of different genes are distributed to egg and sperm cells independently of each other during meiosis

A. The alleles on homologous chromosomes are identical to each other.

All of the following statements about homologous chromosomes are true, EXCEPT that __________. A. The alleles on homologous chromosomes are identical to each other. B. One of each pair of homologous chromosomes comes from each parent. C. Homologous chromosomes physically pair up and may exchange parts during meiosis. D. They have genes for the same traits at the same loci.

recessive allele

An allele that does not manifest itself in the presence of a more dominant allele.

dominant allele

An allele that masks or suppresses the expression of its complementary allele

genotype

An individual's particular set of genes

genotype

An individuals particular set of genes

sickle-cell anemia

An inherited disorder in which the red blood cells assume a sickle shape when the oxygen concentration is low

They must all have the sickle-cell trait. *This statement is false. Because the parents are both heterozygous, there is a 25% chance that a child of theirs will have sickle-cell anemia and a 25% chance that a child of theirs will be homozygous for no sickle-cell gene.

An unaffected man whose mother had sickle-cell anemia marries an unaffected woman whose father had sickle-cell anemia. Which of the following statements about their offspring is NOT true? A. About 75% can be expected to have the sickle-cell allele. B. They must all have the sickle-cell trait. C. They may not have either sickle-cell trait or sickle-cell anemia. D. About 50% can be expected to be heterozygous for the sickle-cell allele.

genes

DNA sequences that code for one or more specific proteins are called

DNA and genes and their transmission from one generation to the next

Genetics is the study of

The chances are about 1 in 16 that their child will have no chin dimple and short eyelashes *No chin dimple and short eyelashes are independent recessive traits. The chance of a child inheriting two independent recessive alleles from heterozygous parents is 1 in 16.

Having a chin dimple (cleft chin) is dominant over having no chin dimple. Having long eyelashes is dominant over having short eyelashes. Jack and Jill are both heterozygous for a chin dimple and long eyelashes. What are the chances that their baby will have no chin dimple and short eyelashes? A. There is about a 25% chance that the child of Jack and Jill will have no chin dimple and short eyelashes. B. The chances are about 1 in 16 that their child will have no chin dimple and short eyelashes. C. Because Jack and Jill are both heterozygous for both traits, all of their children will have a 100% chance of having no chin dimple and short eyelashes. D. The chances are about 9 in 16 that their child will have no chin dimple and short eyelashes.

heterozygous

Having different alleles at the same location (on a pair of homologous chromosomes)

homozygous

Having identical alleles at the same location (on a pair of homologous chromosomes)

metaphase I

Homologous pairs of chromosomes are lined up independently of other such pairs during _____.

heterozygous for both genes (EeWw), and will have a widow's peak and free earlobs

If a person with a widow's peak and free earlobes who is homozygous dominant for both genes (EEWW) mates with a person with a straight hairline and attached earlobes who is homozygous recessive for both genes (eeww), all of their children will be

homozygous

If an individual possesses two identical alleles of a particular gene, the person is said to be

A and B *The type AB individual must pass on either the gene for the A polysaccharide or the gene for the B polysaccharide. It would not be possible for this person to have a type O child. The type O individual cannot pass on either an A or a B allele. All children would be either type A or type B and could not be type AB or type O.

If an individual with type O blood marries an individual with type AB blood, what are the possible blood types of their children? A. A, B, and O B. A and B C. AB, A, B, and O D. AB and O

double helix

In eukaryotic cells DNA has the appearance of a _____.

2-3

In human gamete production there is an average of _____ crossover events per chromosome pair.

C. All offspring will have a straight hairline.

In humans, the allele for a widow's peak (W) is dominant and the allele for a straight hairline (w) is recessive. This trait shows complete dominance. Which of the following represents the possible phenotypes in the offspring of two parents, both with a straight hairline? A. Most of the offspring will have a straight hairline, but it is possible for an offspring to have a widow's peak. B. Each offspring will show both phenotypes. C. All offspring will have a straight hairline. D. All offspring will have a widow's peak.

polygenetic inheritance

Inheritance of phenotypic traits that depend on many genes is called

Females have two X chromosomes and males have an X and a Y chromosome.

Male and females have which chromosomes?

false

Mendel's law of independent assortment states that genes separate from each other during gamete formation so that each sperm or egg gets only one unit of each pair TRUE FALSE

the two alleles of each gene separate from each other so that each sperm or egg receives only one allele of each gene.

Mendel's law of segregation holds that when sperm and eggs form

nucleotide, gene, chromosome, genome

Place the following in order from smallest, simplest, least complex, to largest and most inclusive: A. gene, nucleotide, genome, chromosome B. nucleotide, gene, genome, chromosome C. genome, chromosome, gene, nucleotide D. nucleotide, gene, chromosome, genome

predict the outcomes of a particular combination of parental alleles

Punnett squares are used to

carry the genes that determine the gender of the individual. Females have two X chromosomes and males have an X and a Y chromosome

The X and Y chromosomes, also called the sex chromosomes

Gregor Mendel

The basic laws of genetic inheritance were described by ________. A. Barbara McClintock B. Gregor Mendel C. Watson and Crick D. Charles Darwin

karyotype

The diploid chromosomal complement in any species. The human _____ typically is shown as a composite display of the 22 pairs of autosomes arranged from longest to shortest, plus the sex chromosomes X and Y

in the formation of gametes, alleles separate from each other so that each gamete receives only one allele

The law of segregation states that __________.

phenotype

The observable physical and functional traits of an organism

true *In both types of inheritance, the heterozygote shows a phenotype that is distinct from either homozygote.

True or false. In codominance, both phenotypes are expressed in heterozygotes; but in incomplete dominance, the heterozygotes exhibit a phenotype that is intermediate between the two homozygotes.

D. all of these choices

What is the basis for the tremendous genetic diversity resulting from sexual reproduction? A. crossing-over and shuffling of linked genes during meiosis B. independent assortment during gamete production C. random fertilization D. all of these choices

Tyrosinase is an enzyme that facilitates the conversion of tyrosine to melanin.

What is tyrosinase?

aaBb x Aabb

Which of the following parental genotypes would produce offspring in a 1:1:1:1 phenotypic ratio? A. aaBb x Aabb B. AaBb x AaBb C. aaBb x aabb D. AaBb x Aabb

A. crossing-over during meiosis I

Which of the following results in the separation (or unlinking) of linked genes? A. crossing-over during meiosis I B. separation of sister chromatids during mitosis C. independent assortment during mitosis D. segregation during meiosis

D. A dominant allele masks the expression of a recessive allele in a heterozygote.

Which of the following statements correctly expresses the relationship between dominant and recessive alleles? A. A dominant allele is always the most numerous allele in the population. B. A dominant allele is always the preferred or most beneficial allele. C. A dominant allele is expressed only when it is homozygous. D. A dominant allele masks the expression of a recessive allele in a heterozygote.

A. A person who is heterozygous for sickle cell tends to die at a younger age than a person with sickle-cell anemia does.

Which of the following statements is NOT true for a person who is heterozygous for sickle cell? A. A person who is heterozygous for sickle cell tends to die at a younger age than a person with sickle-cell anemia does. B. Cells generally sickle when oxygen is low. C. The red blood cells of the heterozygous person generally have both normal and abnormal hemoglobin. D. The heterozygous person is generally healthy under normal circumstances. E. The heterozygous person has a greater tendency for hemoglobin polymerization than does a person without the HbS allele.

adjacent genes on the same chromosome

Which of the following would provide an EXCEPTION to Mendel's law of independent assortment?

phenotype

Your genotype has a profound influence on your

by environmental factors and lifestyle choices such as how much you are exposed to the sun, whether you exercise, and how much and what you eat.

Your phenotype is determined not only by the alleles you inherit from your parents (your genotype), but also

gene

a segment of DNA that carries the code for making one or more proteins.

A Punnett square

a useful method for predicting the ratios of possible offspring genotypes from a particular mating.

alleles

genes coding for the same trait and found at the same locus on homologous chromosomes

phenotypic traits

hair, eye, and skin color; your height and body shape; and your ability (or inability) to curl your tongue are what kinds of traits?

genetics

is the study of DNA and genes and their transmission from one generation to the next.

autosomes

of the 23 pairs of human chromosomes, 22 are always matched pairs called

polygenetic inheritance

pattern of inheritance in which a phenotypic trait depends on many genes. An example is eye color, controlled by three or more genes

codominance

pattern of inheritance in which both alleles of a gene are equally expressed even though the phenotypes they specify are different

heterozygous

people with different alleles (Aa) are

Punnett square

provides a simple way to represent patterns of inheritance of alleles and to predict the probability that a particular genotype will be inherited

dominant allele

refers only to how an allele behaves in combination with a recessive allele in a heterozygote

alleles

sequence differences may occur within genes, and when they do, they produce alternative versions of genes called

polydactyly

some people possess a dominant allele (Pp or PP), and the presence of this allele causes them to have extra fingers and toes on each hand and foot a condition known as

homologous chromosomes

the 22 pairs of autosomes are called

karyotype

the diploid chromosomal complement in any species. Typically is shown as a composite display of the 22 pairs of autosomes arranged from longest to shortest, plus the sex chromosomes X and Y.

phenotype

the observable physical and functional traits of an organism (such as hair, eyes, skin color, height and body shape) (or traits less observable like blood type and susceptibility to disease)

codominance

the products of both alleles are expressed equally.

chromosomes

the structures that contain most of an organism's DNA

sex chromosomes, X and Y

the two chromosomes of the 23rd pair are the

gene

the unit of heredity. Most genes encode for specific polypeptides, and each gene has a specific location on a particular chromosome.

Alleles

two identical or nearly identical copies of a gene

a mating between two heterozygotes for both genes can indeed produce children with both dominant traits and children with both recessive traits, but other combinations are also possible. Some offspring may have the dominant widow's peak and the recessive attached earlobe phenotypes, and others may have the recessive straight hairline and the dominant free earlobe phenotypes

what happens if two people heterozygous for both genes mate? (for example with widows peak and free earlobes)

law of segregation

when gametes are formed in the parents, the alleles separate from each other so that each gamete gets only one allele of each gene

usually one is dominant and the other is recessive

when two alleles in an individual are different

most likely, resulted from millions of years of mutations or random changes to the DNA sequence, of cells destined to become sperm or eggs

where did these different alleles come from?

genotype

your complete set of alleles is called your

phenotype or the observable physical and functional traits that characterize you

your genotype has a profound influence on your

your particular physical and functional traits, and even your susceptibility to certain diseases

your genotype, determines

by the alleles you inherit from your parents (your genotype), environmental factors, lifestyle choices (such as exposure to sunlight, whether you exercise, and how much and what you eat)

your phenotype is determined by?