Chapter 12 Patterns of Inheritance

universal blood receiver

AB

assuming independent assortment, which of the following are examples of gametes produced by an AaBb individual?

AB, ab

universal blood donor

O

punnett square

a diagrammatic way of showing the possible genotypes and phenotypes of genetic crosses

An organism's ____ is/are determined by its ______.

alleles; phenotype

phenylthiocarbamide (PTC) sensitivity

dominant; ability to taste PTC as bitter

mendel used the garden pea plant to study inheritance because the pea plants a) existed in one variety b) produced few offspring c) were edible d) have short generation times

have short generation times

heterozygous

having two different alleles of the same gene; the term is usually applied to the one or more specific loci, as in "heterozygous with respect to the W locus" (Ww)

if the offspring from a testcross contain homozygous and heterozygous, the genotype of the unknown parent must be ____

heterozygous

the potential outcomes of the offspring of a testcross include which of the following? a) heterozygous b) homozygous dominant c) homozygous recessive

heterozygous and homozygous recessive

If the offspring from a testcross contain only heterozygotes, the genotype of the unknown parent must be _____

homozygous

Which of the following is NOT a part of Mendel's five-element model? a) traits have alternative forms (what we now call alleles) b) parents transmit discrete to their offspring c) if an allele is present it will be expressed d) traits do not blend

if an allele is present it will be expressed

dominance is not always complete

in complete dominance the heterozygote is intermediate & in codominance no single allele is dominant, and the heterozygote shows some aspect of both homozygotes example: japanese four o'clocks, human blood groups

a 9:3:3:1 ratio represents the 16 potential combinations between gametes in an _____ assorting dihybrid cross

independently

alleles

one of two or more alternative states of a gene

cross-fertilization involves placing ____ from one plant onto the stigma of a flower on a different plant

pollen

reciprocal fertilization

pollen collected from anthers of a white flower placed onto the stigma of a purple flower with anthers removed

cross fertilization

pollen from a white-flowered plant is used to fertilize a purple-flowered plant, while pollen from a purple-flowered plants is used to fertilize a white-plant

human height is an example of a trait that has a continuous distribution of phenotypes. human height is therefore an example of _____ inheritance

polygenic

a trait that has multiple genes contributing to its expression is know as a

polygenic trait

cystic fibrosis

recessive; abnormal gland secretion, leading to liver degeneration and lung failure

sickle cell anemia

recessive; defective hemoglobin that causes red blood cells to curve and stick together

hemophilia

recessive; inability of blood to clot properly, some clots form but the process is delayed

red-green color blindness

recessive; inability to distinguish red or green wavelengths of lights

alkaptonuria

recessive; inability to metabolize homogentisic acid

albinism

recessive; lack of melanin pigmentation

duchenne muscular dystrophy

recessive; wasting away of muscles during childhood

true-breeding

said of a breed of variety of organism in which offspring are uniform and consistent from one generation to the next. this is due to the genotypes that determine relevant traits being homozygous

an individual with a dominant phenotype, may have a genotype of:

homozygous dominant and heterozygous

Which of the following are inherited as dominant traits? huntington disease brachydactyly albinism hemophilia

huntington disease, brachydactyly

the classical assumptions of heredity would eventually lead to all members within a species having

the same appearance

self-fertilization

the union of egg and sperm produced by a single hermaphroditic organism

in a heterozygous individual, the probability of a recessive allele being present in a gamete is

.5

in a homozygous recessive individual the probability of the dominant allele being present is:

0

how many potential phenotypes can results from a dihybrid cross when the traits assort independently from one another?

4

reciprocal crosses

a genetic cross involving a single trait in which the sex of the parents is reversed; for example, if pollen from a white-flowered plant is used to fertilize a purple-flowered plant, the reciprocal cross would be pollen from a purple-flowered plant used to fertilize a white-flowered plant

a mismatched blood transfusion may lead to ____ in the blood due to the reaction between blood cells antigens and antibodies

agglutination

homozygous

being a homozygote, having two identical alleles of the same gene; the term is usually applied to one or more specific loci, as in "homozygous with respect to the W locus" (WW or ww)

the concept of inheritance which suggested that parents make equal contributions to their offspring and that their genetic material blends together is called

blending inheritance

an individual with two identical alleles of a gene of a particular trait has a(n) ______ genotype with respect to that gene

homozygous

codominant

describes a case in which two or more alleles of a gene are each dominant to other alleles but not to each other. the phenotype of a heterozygote for codominant alleles exhibit characteristics of each of the homozygous forms. for example, in human blood types, a cross between an AA individual and a BB individual yields AB individuals

the result of a testcross indicate that all of the offspring have a dominant phenotype. the genotype of the parent in question must be: a) homozygous recessive b) heterozygous c) homozygous dominant

homozygous dominant

incomplete dominance

describes a case in which two or more alleles of a gene do not display clear dominance. the phenotype of a heterozygote is intermediate between the homozygous forms. for example, crossing red-flowered with white-flowered four o'clocks yields pink heterozygous

what type of cross follows the simultaneously inheritance of two different traits?

dihybrid cross

which of the following genotypes are true-breeding? a) tt b) Tt c) TT d) tT

tt, TT

In a cross of Aa Bb cc x Aa Bb Cc, what is the probability of obtaining an individual with the genotype AA Bb Cc? a) 1/16 b) 3/16 c) 1/64 d) 3/64

1/16

What is the probability of obtaining an individual with the genotype bb from a cross between two individuals with the genotype Bb?

1/4

match these percentages based on the 3:1 ratio in the F2 generation of a monohybrid cross: 1/2 1/4 1/4 & not true-breeding true-breeding dominant true-breeding recessive

1/4 = true-breeding dominant 1/4 = not true-breeding 1/2 = true-breeding recessive

how many possible allele combinations (consider all possible combinations even those that are identical) are produced in the offspring of heterozygous parents in a dihybrid cross?

16

a 3:1 phenotypic ratio in the F2 generation of a monohybrid cross represents this genotypic ration:

1:2:1

in incomplete dominance, the genotypic ratio in the F2 generation is which of the following? a) 1:2:1 b) 9:3:3:1 c) 3:1

1:2:1

if a particular gene in a population has multiple alleles, how many alleles can an individual inherit?

2

a punnett square for a single trait should be set up as a _____ square

2x2

The F1 plants from the previous question (monohybrid cross purple (PP) x white (pp) flower pea plants) are allowed to self-fertilize. The phenotypic ration for the F2 should be: a) all purple b) 1 purple: 1 white c) 3 purple: 1 white d) 3 white: 1 purple

3 purple: 1 white

Japanese four o'clocks that are red and tall are crossed to white short ones, producing an F1 that is pink and tall. If these genes assort independently, and the F1 is self-crossed, what would you predict for the ration of F2 phenotypes? a) 3 red tall: 1 white short b) 1 red tall: 2 pink short: 1 white short c) 3 pink tall: 6 red tall: 3 white tall: 1 pink short: 2 red short: 1 white short d) 3 red tall: 6 pink tall: 3 white tall: 1 red short: 2 pink short: 1 white short

3 red tall: 6 pink tall: 3 white tall: 1 red short: 2 pink short: 1 white short

in a dihybrid testcross, a homozygous recessive individual would be crossed with which of the following potential individuals: a) aabb b) AaBB c) AaBb d) Aabb e) AABB

AaBB, AaBb, AABB

which of the following is an example of a testcross? a) AaBb x AABB b) AaBb x aabb c) aabb x aabb d) AaBb x AaBb

AaBb x aabb (in a testcross, one of the individuals has be to homozygous recessive)

in a dihybrid testcross, a homozygous recessive individuals would be crossed with which of the following potential individuals: AaBb AaBB aabb Aabb AABB

AaBb, AaBB, AABB

this generation is produced when the F1 monohybrids self fertilize

F2

When you cross true-breeding tall and short tobacco plants you get an F1 that is intermediate in height. When this F1 is self-crossed, it yields an F2 with a continuous distribution of heights. What is the best explanation of these data?

Height is determined by the additive effect of many genes

What property distinguished Mendel's investigation from previous studies? a) Medel used true-breeding pea plants b) Mendel quantified his results c) Mendel examined many different traits d) Mendel examined the segregation of traits

Mendel quantified his results

in terms of probabilities, the cross of a tall yellow seeded pea plants (TTYy) with a tall green seeded pea plant (Ttyy) is equivalent to which two monohybrid crosses? a) TT x Tt and Yy x yy b) TT x Yy and Tt x yy c) TT x yy and Tt x Yy

TT x yy and Tt x Yy

an individual with genotype Aa can produce which gamete(s)?

Two: A and a

pedigree

a consistent graphic representation of matings and offspring over multiple generations for a particular genetic trait, such as albinism or hemophilia

pea plants are self-fertilizing which means that a female gamete is fertilized by which of the following?

a male gamete from the same plant

testcross

a mating between a phenotypically dominant individual of unknown genotype and a homozygous "tester", done to determine whether the phenotypically dominant individual is homozygous or heterozygous for the relevant gene

ABO blood groups

a set of four phenotypes produced by different combinations of three alleles at a single locus; blood types are A, B, AB, and O, depending on which alleles are expressed as antigens on the red blood cell surface

pleiotropic

a single gene can affect more than one trait example: a pleiotropic allele dominant for yellow fur in mice is recessive for a lethal developmental defect; cystic fibrosis; sickle cell anemia

Mendel's model assumes that each trait is determined by a single factor with alternate forms. We now know that this is too simplistic and that

a single gene can affect more than one trait, and traits may be affected by more than one gene

quantitative traits

a trait that is determined by the effects of more than one gene; such a trait usually exhibits continuous variation rather than discrete either-or values

in a cross between two individuals who are both heterozygous Tt, if you want to determine the probability that the offspring will have either the genotype TT or the genotype Tt, you would need to use the ____ rule

addition

a nonfunctional allele for tyrosinase is characteristic of the genetic condition called _____

albinism

The F1 generation of the monohybrid cross purple (PP) x white (pp) flower pea plants should: a) all have white flowers b) all have purple flowers c) all have a light purple or blended appearance d) have 3/4 purple flowers and 1/4 white flowers

all have purple flowers

dominant

an allele that is expressed when present in either the heterozygous or the homozygous condition

recessive

an allele that is only expressed when present in the homozygous condition, but being "hidden" by the expression of a dominant allele in the heterozygous condition

dihybrid cross

an individual heterozygous cross involving two different traits, such as flower color and plant height

the law of independent assortment is related to which of the following activities in meiosis?

chromosome alignment

huntington disease

dominant; degeneration of nervous system, starting in middle age

hypercholesterolemia

dominant; elated levels of blood cholesterol and risk of heart attack

polydactyly

dominant; extra fingers and toes

camptodactylly

dominant; inability to straighten little finger

middigital hair

dominant; presence of hair on middle segment of fingers

brachydactyly

dominant; short fingers

the law of independent assortment states that alleles of different genes assort independently of each other during ____ formation

gamete

in his studies, mendel referred to unit factors that are passed intact from one generation to the next. we now know that these factors are actually ____

genes

environmental factors

genes may be affected by the environment example: siamese cats

multiple alleles for one gene

genes may have more than two alleles example: ABO blood type in humans

the results of a testcross indicate that all of the offspring have a dominant phenotype. the genotype of the parent in question must be

homozygous dominant

a true-breeding line can be which of the following? a) homologous b) homozygous dominant c) homozygous recessive d) heterozygous

homozygous dominant and homozygous recessive

epistasis

interaction between two nonallelic genes in which one of them modifies the phenotypic expression of the other

the physical basis for allele segregation is the behavior of chromosomes during the process of ______

meiosis

Mendel's Principle of Segregation

mendel's first law of heredity, stating that alternative alleles for the same gene segregate from each other in production of gametes

principle of independent assortment

mendel's second law of heredity, stating that genes located on nonhomologous chromosomes assort independently of one assortment

mendel observed a 3:1 ratio in _____ crosses between dominant and recessive in the F2 offspring

monohybrid

the inheritance pattern of many traits (more or less) complex than simple Mendelian patterns

more

polygenic inheritance

more than one gene can affect a single trait example: four genes are involved in determining eye color; human height

the rule of addition is applied to events with _________ outcomes

mutually exclusive

juvenile glaucoma is a hereditary disease that causes blindness due to the degeneration of nerves in which of the following? optic nerve cornea retina blind spot

optic nerve

in snapdragons, alleles resulting in red pigment and white pigment exhibit incomplete dominance. if red snapdragons are crossed with pure white snapdragons the offspring of the F1 generation will be: a) red b) white c) purple d) pink

pink

sickle cell anemia is caused by a ____ allele because this mutation has more than on effect on the phenotype

pleiotropic

this allele is one that has more than one effect on a phenotype

pleiotropic

gene interaction

products of genes can interact to alter genetic ratios example: the production of a purple pigment in corn, coat color in mammals

a ____ trait is one that that is not expressed in a heterozygous individual

recessive

those who are homozygous ______ will exhibit the symptoms of cystic fibrosis, including abnormalities of the pancreas, intestine, sweat glands, and lungs

recessive

an example of a _____ cross is using pollen from a green-seeded pea plant to fertilize a yellow-seeded pea plant and then using pollen from a yellow-seeded pea plant to fertilize a green-seeded pea plant

reciprocal

this rule is applied to events with mutually exclusive outcomes:

sum

self fertilization

takes place within an individual flower if it is not disturbed

the cross of an individual who has a dominant phenotype with an individual who is homozygous recessive for that gene is known as a ______

testcross

Phenotypes like height in humans, which show a continuous distribution, are usually the result of: a) an alteration of dominance for multiple alleles of a single gene b) the presence of multiple alleles for a single gene c) the action of one gene on multiple phenotypes d) the action of multiple genes on a single phenotype

the action of multiple genes on a single phenotype

Mendelian ratio

the characteristic dominant-to-recessive phenotypic ratios that Mendel observed in his genetics experiments. For example, the F2 generation in a monohybrid cross shows a ratio of 3:1, the F2 generation in a dihybrid cross shows a ratio 9:3:3:1

genotype

the genetic constitution underlying a single trait or set of traits

hybridization

the mating of unlike parents

Mendel's work involved quantitative experiments are careful analysis of the offspring carrying specific traits. he paid the most attention to which of the following? a) the total number of offspring, regardless of what type they were b) the numbers of every different type of offspring c) the numbers of the offspring that were of a specific gender

the numbers of every different type of offspring

first filial generation

the offspring resulting from a cross between a parental generation ( P ); in experimental crosses, these parents usually have different phenotypes

second filial generation

the offspring resulting from a cross between members of the F1 generation

segregation

the process by which alternative forms of traits are expressed in offspring rather than blending each trait of the parents in the offspring

phenotype

the realized expression of the genotype; the physical appearance or functional expression of a trait

rule of multiplication

the rule stating that for two independent events, the probability of both events occurring is the product of the individual probabilities

rule of addition

the rule stating that for two independent events, the probability of either event occurring is the the sum of the individual probabilities

prior 20th century, the two main ideas that provided the basis for most thinking about hereditary were: a) traits are transmitted directly from parents to offspring b) traits in offspring are different from parents c) heredity occurs within species

traits are transmitted directly from parents to offspring and heredity occurs within species

true or false: crossing pure breed white flowered pea plants with pure breed purple flowered pea plants produced hybrid pea plants with purple flowers

true

an individual can acquire only ____ allele(s) per trait, even if multiple alleles are present in the population

two

the probability of genotypes in an independently assorted dihybrid cross is based on a probabilities of: a) the parent's genotypes b) two monohybrid crosses c) mutually exclusive events

two monohybrid crosses

a temperature-sensitive enzyme, ______, is responsible for the pattern of fur color in Siamese cats

tyrosinase

continuous variation

variation in a trait that occurs along a continuum, such as the trait of height of human beings; often occurs when a trait is determined by more than one gene

a punnett square has rows and columns which represent gametes made by males and females. at the intersection of each row and column we combine the corresponding gametes to produce the genotype of a potential ____

zygote