Bio Chapter 7

Your father's mother was a heterozygous carrier of a X-linked trait. If you are a male, what are the chances of you inheriting this X-linked trait by direct descent from your paternal grandmother? 0% 37.5% 12.5% 25% 50%

0%A son inherits the Y chromosome and cannot inherit an X-linked disease from his father.

If two giraffes were crossed, where one is heterozygous for albinism (a) and the other has a homozygous dominant genotype, what would be the expected genotypic and phenotypic ratios? 1 AA: 2 Aa: 1 aa; 3 pigmented: 2 albino 2 AA: 2 Aa: 0 aa; 4 pigmented: 2 albino 0 AA: 0 Aa: 1 aa; all albino 2 AA: 0 Aa: 0 aa; all pigmented 2 AA: 2 Aa: 0 aa; all pigmented

2 AA: 2 Aa: 0 aa; all pigmented

The chance of two separate events occurring together is equal to the product of their separate chances. Two people who are carriers of the recessive Tay-Sachs gene decide to have children. What are the chances this couple will give birth to three children with Tay-Sachs? None. They can't produce any Tay-Sachs children. 1/64, or 1.56% 1/16, or 12.5% 1/8, or 50% 1/4, or 25%

1/64, or 1.56%

If humans have 23 pairs of chromosomes (46 individual chromosomes), then how many copies do they have of each gene?

2

he woman's father had normal color vision but her mother was color-blind. Color-blindness is an X-linked recessive disorder. What are the chances that this man and woman will give birth to a color-blind girl (restated: of all the possible children, how many would be female and color-blind)? None 25% 50% 75% 100%

25%

Pea flowers may be purple (P) or white (p). Pea seeds may be round (R) or wrinkled (r). What proportion of the offspring from a cross between purple-flowered, round-seeded individuals (heterozygous for both traits) will have both white flowers and round seeds? b. 1/2 c. 3/16 a. 1/16 e. 9/16 d. 3/4

3/16

A male with an X-linked recessive disorder mates with a female who is a carrier for this same X-linked recessive disorder. Which of the following is the correct expected frequency of this disorder in their children? 50-percent frequency in the sons 100-percent frequency in the sons 100-percent frequency in the daughters 50-percent frequency in the daughters 50-percent frequency in both the sons and the daughters

50-percent frequency in the sons

In peas, yellow seeds (Y) are dominant to green seeds (y). A homozygous dominant and a homozygous recessive plant are crossed and have two offspring. These two offspring are now crossed with each other. What are the chances that the second generation of offspring (the offspring of the first offspring) will have yellow seeds? 25% 50% 75% zero 100%

75%

Dihybrid Cross

A cross between two individuals that are heterozygous for the same two genetic loci.

Punnett Square

A diagram showing the possible outcomes of a cross between two individuals; the possible crosses are shown in the manner of a multiplication table.

Test-Cross

A mating in which a homozygous recessive individual is bred with individuals of unknown genotype that have the dominant phenotype; this type of cross can reveal the unknown genotype by the observed characteristics, or phenotypes, of the offspring.

Pleiotropy

A phenomenon in which an individual gene influences multiple traits.

What is the purpose of a test-cross? A test-cross can reveal an unknown genotype. A test-cross can demonstrate the efficiency of breeding. A test-cross can reveal an unknown internal phenotype. A test-cross is just another term for an experimental cross between two unknown organisms. A test-cross allows a breeder to see how quickly it takes to go from generation to generation for a particular organism.

A test-cross can reveal an unknown genotype.

Sex-linked trait

A trait controlled by a gene on a sex chromosome.

Single-gene trait

A trait that is determined by instructions on only one gene; examples are a cleft chin, a widow's peak, and unattached earlobes.

A woman with type B blood and a man with type A blood could have children with which of the following phenotypes?

A, B, AB, or O

Which of the following statements about the Rh marker allele is most accurate? The Rh marker results from a single gene with two alleles. An individual's red blood cells carry the Rh cell surface marker if they have one or two copies of the dominant Rh marker allele. If a person has one or two copies of the dominant Rh marker allele then their blood type is noted as "positive," that is, B+ or B positive. If an individual has two copies of the recessive allele for the gene, they do not have any Rh markers, and are therefore are described as "negative," that is, B- or B negative. All of the above.

All of the above.

Alleles

Alternate versions of a gene

Dihybrid

An individual that is heterozygous at two genetic loci.

Carrier

An individual who carries one allele for a recessive trait and does not exhibit the trait; if two carriers mate, they may produce offspring that do exhibit the trait.

Inheriting two copies of a defective gene can cause someone to smell like a rotten fish. Which of the following best supports this statement? If a child does not have a parent with fish odor syndrome, then they automatically cannot acquire the syndrome. There is no particular gene that can cause a person to smell like a rotten fish; personal hygiene is not inherited. As long as a person has at least one normal version of the FMO3 gene, he/she will not suffer from fish odor syndrome. A person with fish odor syndrome will always have at least one child with fish odor syndrome. If a person who is a carrier of the fish odor allele has a child with someone who is not a carrier, the child will only smell slightly of rotten fish.

As long as a person has at least one normal version of the FMO3 gene, he/she will not suffer from fish odor syndrome.

Little Johnny's father is incredibly organized, but his mother tends to be messy. When Little Johnny's aunt notices that all of his binders are labeled and his room is spotless, she claims "you obviously didn't inherit your mother's 'messy' genes!". What is wrong with this statement? This statement is incorrect because the son may actually have some of his mother's "messy" genes, too. The gene for organization is recessive. Nothing is wrong with this statement. Our behaviors, just as much as our physical characteristics, are inherited from our parents. The organizational-skill gene is an X-linked gene; therefore, since Johnny is a boy, he only took after his mother. Characteristics, such as organizational skills, are behavioral and environmentally influenced. Therefore, they are not specifically inherited. The organizational-skill gene is Y-linked; therefore, that is why he is organized, like his father.

Characteristics, such as organizational skills, are behavioral and environmentally influenced. Therefore, they are not specifically inherited.

True-breeding

Describes a population of organisms in which, for a given trait, the offspring of crosses of individuals within the population always show the same trait; for example, the offspring of pea plants that are true-breeding for round peas always have round peas.

Polygenic

Describes a trait that is influenced by many different genes.

Dominant

Describes an allele that masks the phenotypic effect of the other, recessive allele for a trait; the phenotype shows the effect of the dominant allele in both homozygous and heterozygous genotypes

Recessive

Describes an allele whose phenotypic effect is masked by a dominant allele for that trait

Homozygous

Describes the genotype of a trait for which the two alleles an individual carries are the same.

Heterozygous

Describes the genotype of a trait for which the two alleles an individual carries differ from each other.

Additive Effects

Effects from alleles of multiple genes that all contribute to the ultimate phenotype for a given characteristic.

Linked Genes

Genes that are close to each other on a chromosome and so are more likely than others to be inherited together.

Which of the following results of a test-cross between a pigmented alligator (M_) and an albino alligator (mm) would indicate that the pigmented parent is heterozygous? Getting three offspring that are pigmented Getting six offspring that are pigmented Getting even a single albino offspring Both choices A and B are true. None of the above

Getting even a single albino offspring

Pedigree

In genetics, a type of family tree that maps the occurrence of a trait in a family, often over many generations.

How can an individual carry a defective gene but not exhibit the defective phenotype? An individual may not have that defective gene in every cell, and so he/she appears normal. Individuals carry two copies of gene instructions, and one dominant allele could mask the presence of a recessive defective allele. Individuals are always homozygous. Both the first and third choices are true. None of the above.

Individuals carry two copies of gene instructions, and one dominant allele could mask the presence of a recessive defective allele.

Which of the following is INCORRECTLY matched regarding the Punnett square and a one-factor cross (e.g. BB x Bb)? Top of the square: lists the two alleles that one of the parents produces Inside the square: genotypes of potential offspring Inside the square: genotypes of actual offspring There are no rules to setting up a Punnett square; just do it in a way that you understand. Left side of the square: lists the two alleles that the other parent produces

Inside the square: genotypes of actual offspring

Which phenomenon accounts for the fact that most people with red hair have freckles? linked genes pleiotropy additive effects codominance incomplete dominance

Linked Genes

Which of the following is NOT true about Mendel's genetics experiments? Mendel controlled which plant was "crossed" with another by using "pollen dusting." Mendel used relatively unsophisticated methods and good experimental design to learn about inheritance. Mendel believed that a tiny, pre-formed pea plant was passed via pollen to a pea plant egg. True-breeding, to Mendel, meant that certain plants always produced the same version of traits as their parents. Mendel studied only seven traits found in pea plants.

Mendel believed that a tiny, pre-formed pea plant was passed via pollen to a pea plant egg.

Mendel's Law of Independent Assortment

Mendel's law of independent assortment The principle that allele pairs for different genes separate independently in meiosis, so the inheritance of one trait generally does not influence the inheritance of another trait (the exception, unknown to Mendel, occurs with linked genes).

Which of the following best explains Mendel's law of segregation? Of the two copies of each gene everyone carries, only one of the two alleles gets put into each gamete. Both alleles are put into a gamete, and during development, the two gametes segregate by chance. Both gametes and fertilized eggs have two copies of each gene. If someone is heterozygous, they exemplify Mendel's law of segregation. Organisms have one copy of a gene, and they place that copy into each gamete during the process of meiosis.

Of the two copies of each gene everyone carries, only one of the two alleles gets put into each gamete.

How can two pea plants that have different genotypes for seed color be identical in phenotype? Genotype has no relation to phenotype. One of the two plants could be homozygous for the dominant allele, while the other could be heterozygous. Seed color in pea plants is not genetically determined. One of the two plants could be homozygous for the dominant allele, while the other could be homozygous for the recessive allele. One of the two plants could be homozygous for the recessive allele, while the other could be heterozygous.

One of the two plants could be homozygous for the dominant allele, while the other could be heterozygous.

Cross

The breeding of organisms that differ in one or more traits.

Mutiple Allelism

The case in which a single gene has more than two possible alleles.

Incomplete Dominance

The case in which the heterozygote has a phenotype intermediate between those of the two homozygotes; an example is pink snapdragons, with an appearance intermediate between homozygous for white flowers and homozygous for red flowers.

Which of the following is an example of pleiotropy? Sickle-cell allele: This allele can disrupt red blood cell oxygen delivery and cause blood cells to be inhospitable to malarial parasites. SRY gene: This gene causes fetal gonads to develop as testes shortly after fertilization and is responsible for numerous behavioral characteristics. PKU disease: A mutation in the gene for a particular enzyme leads to mental retardation and reduced hair and skin pigmentation. Height: The gene for height can result in various degrees/levels of height, that is, some people are taller than others. The first three choices are examples of pleiotropy.

The first three choices are examples of pleiotropy.

Genotype

The genes that an organism carries for a particular trait; also, collectively, an organism's genetic composition

Hereditiy

The greater resemblance of offspring to parents than to other individuals in the population, a consequence of the passing of characteristics from parents to offspring through their genes.

If a male with color-blindness (sex-related variety) and a female with normal vision have a color-blind son, what can you infer about the parents? The son inherited the gene for color-blindness from his father. The mother was a carrier for color-blindness. The son inherited a gene for color-blindness from his mother and one from his father. The mother was homozygous for color-blindness. The mother's father was color-blind.

The mother was a carrier for color-blindness.

Mendel's Law of Segregation

The principle that during the formation of gametes, the two alleles for a gene separate, so that half the gametes carry one allele, and half the gametes carry the other

What is a linked gene? An abnormality where two chromosomes are connected due to some sort of mutation The situation where two different genes are found on the same chromosome A gene that suppresses the effects of another gene Any gene that exhibits an outward effect; in fact, all genes are linked. A gene that causes mutations, such as trisomy 21

The situation where two different genes are found on the same chromosome

What is the percent chance of a child inheriting Tay-Sachs disease from parents who are heterozygous (Tt) and homozygous (tt) for Tay-Sachs? (Enter the percentage as a number. Do not enter a % symbol.)

There is a 50% chance that the gamete produced by the heterozygous parent (Tt) will carry the recessive t allele. Whereas there is a 100% chance that a gamete produced by the homozygous parent (tt) will carry the recessive t allele. Multiplying 1.0 x 0.5 = 0.5 or 50% chance that the child will be homozygous for Tay-Sachs.

Which of the following statements is true regarding a cross between a homozygous albino female giraffe (aa) and a heterozygous pigmented male giraffe (Aa)? Under normal conditions, there is a 99% chance that the mother's egg will carry the recessive allele. There is a 50% chance that the offspring will be albino. There is a 100% chance that the sperm will carry the dominant A allele. There is a 12.5% chance that the offspring will be an albino female giraffe. In the event that a homozygous dominant offspring results, it will most likely die due to excessive pigment production.

There is a 50% chance that the offspring will be albino.

Sickle-cell anemia is a genetic disease caused by the presence of a faulty hemoglobin gene (HbS). The normal version of this gene is HbA. Which of the following is TRUE about HbS and HbA? A person with two HbS genes would be a silent carrier. They're both alleles for the same trait. It is impossible for a person to carry two HbS genes. People carrying two HbS genes smell like rotten fish. Hemoglobin genes are always inherited from one's mother.

They're both alleles for the same trait.

Heart disease is thought to be a polygenic disorder in humans. Knowing this, what would you expect to see if you screened a large number of people for heart disease? Those with heart disease should carry two of three or four different alleles for a single heart disease gene. Those heterozygous for heart disease should be normal. They should either have no heart disease or suffer full, debilitating effects from the disease. Those with heart disease should exhibit three levels of disease: mild, intermediate, and intense. Those with heart disease should show a continuous range of symptoms, from very mild to very intense.

Those with heart disease should show a continuous range of symptoms, from very mild to very intense.

Which of the following statements is FALSE? Type A blood cells produce A antigens and B antibodies. Type B blood cells produce B antigens and A antibodies. Type AB blood cells produce A and B antigens but neither A nor B antibodies. Type O blood cells produce neither A nor B antigens and produce both A and B antibodies. Type AB blood cells produce A and B antigens and A and B antibodies.

Type AB blood cells produce A and B antigens and A and B antibodies.

Given the information that type O is the universal donor blood type and type AB is the universal recipient, which of the following is FALSE? Type A can donate to type A and AB and can receive from type A and type O. Type B can donate to type B and AB and can receive from type B and type O. Type AB can donate to AB, A, and B and can receive from type A, B, AB, and O. Type O can donate to A, B, AB, and O and can receive from type O. All of the above are true.

Type AB can donate to AB, A, and B and can receive from type A, B, AB, and O.

Which of the following blood types is incorrectly matched with its potential recipient? Type AB can only receive from type A, B, or AB. Type A can only receive from type A or type O. Type B can only receive from type B or type O. Type O can only receive from type O. None of the above is incorrectly matched.

Type AB can only receive from type A, B, or AB.

If an individual carries only two alleles, is it possible for a single gene to have more than two alleles? Yes, but the alleles that the individual carries then would no longer be inherited as one from the mother and one from the father. The law of segregation does not apply to genes with multiple alleles. Yes, but it results in diseases such as trisomy 21. No. If a gene had more than two alleles, it would be too variable to be identified as one gene. Yes. More than two possible alleles for a single gene type is called multiple allelism. The alleles for the ABO blood types are an example. No. If a gene had more than two alleles, it would not be dominant or recessive.

Yes. More than two possible alleles for a single gene type is called multiple allelism. The alleles for the ABO blood types are an example.

In pea plants, purple flower color is dominant to white flower color. If two pea plants that are true-breeding for white flowers are crossed, in the offspring all of the flowers will be white. three-quarters of the flowers will be purple and one-quarter will be white. one-quarter of the flowers will be purple and three-quarters will be white. half of the flowers will be purple and half will be white. all of the flowers will be purple.

all of the flowers will be purple.

Most genes come in alternative forms called: traits. alleles. chromosomes. dominants. recessives.

alleles

Traits that are determined by a single gene: are common in humans. can have only two alleles. occur in single-celled organisms, but not in humans. must occur on the X chromosome because males have only a single X, so the gene must be able to function in the absence of its homologous allele. include eye color and skin color.

are common in humans

What was the MOST important scientific advance gained from Gregor Mendel's experiments with pea plants? a. We learned that chromosomes are composed of DNA. b. We learned that recessive alleles occur more frequently in the F2 generation than do dominant ones. c. We learned that many traits are inherited in discrete units, and are not the result of blending. d. We learned that there is considerable genetic variation in garden peas. e. Darwin's theory of evolution by natural selection was confirmed.

c. We learned that many traits are inherited in discrete units, and are not the result of blending.

A cross between homozygous red-eyed flies and homozygous white-eyed flies results in progeny that all have red-eyes. This result demonstrates the norm of reaction. the blending model of genetics. dominance. a dihybrid cross. the law of independent assortment.

dominance

The law of segregation states that an allele on one chromosome will always segregate from an allele on a different chromosome. the transmission of genetic diseases within families is always recessive. the number of chromosomes in a cell is always divisible by 2. each of two alleles for a given trait segregate into different gametes. gametes cannot be separate and equal.

each of two alleles for a given trait segregate into different gametes.

The distinctive fur color of a Siamese cat is an example of: environmental effects. albinism. pleiotropy. sex-linkage. codominance.

environmental effects.

Phenotype

he manifested structure, function, and behaviors of an individual; the expression of the genotype of an organism.

Prior to Mendel: humans had no ideas about heredity. humans knew that heredity was controlled by genes, but didn't know the DNA structure. humans observed and manipulated heredity, but did not understand how it worked. humans observed, manipulated, and understood heredity and how it worked. humans observed heredity, but could not understand or manipulate it.

humans observed and manipulated heredity, but did not understand how it worked.

A situation in which the heterozygote offspring of two homozygotes show a phenotype intermediate between those of the parents is called incomplete dominance. a testcross. heterozygote superiority. a single-gene trait. multiple allelism.

incomplete dominance.

Individuals carrying two non-functioning alleles for the gene producing the enzyme that converts phenylalanine into tyrosine: will develop both PKU and Tay-Sachs disease because one pleiotropic gene influences both traits. may or may not develop phenylketonuria because the environment (diet, in this case) also plays a role in determining their phenotype. will develop phenylketonuria (PKU). don't need to limit their phenylalanine consumption because PKU depends on both genes and the environment. will develop both PKU and Tay-Sachs disease because the genes causing the two traits are on the same chromosome.

may or may not develop phenylketonuria because the environment (diet, in this case) also plays a role in determining their phenotype.

Sex-linked traits are coded for by genes on the Y chromosome only. often are expressed in different frequencies in males and females. occur in females but not males. occur in males but not females. are coded for by genes on the autosomes.

often are expressed in different frequencies in males and females. OR are coded for by genes on the autosomes.

In snapdragons, flower color is inherited as a trait with incomplete dominance. There is an allele, CW, that produces no pigment, and an allele, CR, that produces red pigment. A plant with the CWCR genotype will produce _________________ flowers. red white no petals of alternating color pink

pink

The impact of a single gene on more than one characteristic is called: polygenic inheritance. codominance. homozygosity. pleiotropy. epistasis.

pleiotropy.

Which term refers to the genetic control of continuously varying traits such as height? multi-allelic codominant pleiotropic polygenic incomplete dominance

polygenic

A particular trait is analyzed using a pedigree diagram. More males than females appear to be affected. This trait is probably: autosomal dominant. autosomal recessive. sex-linked dominant. sex-linked recessive. None of the above Need help on this question? ebookRead the ebook page on this topic (no penalty) Get a hint (fewer points)

sex-linked recessive.

The fact that freckles tend to be inherited with red hair is counter to which of Mendel's assertions? that two copies of genetic instructions are carried per cell for a given characteristic that there are only two alleles possible for a trait that one allele is always fully dominant over another that genes for different traits sort independently of each other that a single phenotype is dictated by two genes carried in each cell

that genes for different traits sort independently of each other

According to Mendel's law of independent assortment: individuals with red hair are more likely to have freckles. skin color and hair texture tend to be inherited together. we can deduce that genes cannot exist as free-floating entities within a cell but must be carried on chromosomes. the alleles coding for one trait do not usually influence the inheritance pattern for another trait. Both the first and second answers are correct.

the alleles coding for one trait do not usually influence the inheritance pattern for another trait.

If a baby has "his father's nose," it's because: the father's nose is not a heritable trait, it is just a chance event that the baby has a similar nose. the baby has not inherited the "suppress father's nose allele" from his mother. the baby has inherited the "father's nose" allele from his father. the baby has inherited the "father's nose" allele from his mother. the baby has inherited many alleles from his father that work together to shape the baby's nose.

the baby has inherited many alleles from his father that work together to shape the baby's nose.

Mendel's law of independent assortment states that the alleles at one locus separate independently of those at other loci. This law does not apply to genes located close together on the same chromosome. if recombination between the two loci occurs. to identical twins. to genes that influence the same character. to autosomal genes.

to genes located close together on the same chromosome.

Virtually everyone __________________ has a parent that exhibits the same trait. over six feet tall under five feet tall with Tay-Sachs disease with unattached earlobes with albinism

with unattached earlobes