Chapter 12

Question 1

In a simple Mendelian monohybrid cross, true-breeding tall plants are crossed with short plants, and the F1 plants, which are all tall, are allowed to self-pollinate. What fraction of the F2 generation are both tall and heterozygous?

A. 1/8
B. 1/4
C. 1/3
D. 2/3
E. 1/2

Answer 1

E

Question 2

The phenotype of an individual

A. depends at least in part on the genotype.
B. is either homozygous or heterozygous.
C. determines the genotype.
D. is the genetic constitution of the organism.
E. is either monohybrid or dihybrid.

Answer 2

A

Question 3

Which statement about an individual that is homozygous for an allele is not true?

A. Each of its cells possesses two copies of that allele.
B. Each of its gametes contains one copy of that allele.
C. It is true-breeding with respect to that allele.
D. Its parents were necessarily homozygous for that allele.
E. It can pass that allele to its offspring.

Answer 3

D

Question 4

Which statement about a test cross is not true?

A. It tests whether an unknown individual is homozygous or heterozygous.
B. The test individual is crossed with a homozygous recessive individual.
C. If the test individual is heterozygous, the progeny will have a 1:1 ratio.
D. If the test individual is homozygous, the progeny will have a 3:1 ratio.
E. Test cross results are consistent with Mendel’s model of inheritance for unlinked genes.

Answer 4

D

Question 5

In the F2 generation of a dihybrid cross

A. four phenotypes appear in the ratio 9:3:3:1 if the loci are linked.
B. four phenotypes appear in the ratio 9:3:3:1 if the loci are unlinked.
C. two phenotypes appear in the ratio 3:1 if the loci are unlinked.
D. three phenotypes appear in the ratio 1:2:1 if the loci are unlinked.
E. two phenotypes appear in the ratio 1:1 whether or not the loci are linked.

Answer 5

B

Question 6

The ABO blood groups in humans are determined by a multiple-allele system in which IA and IB are codominant and are both dominant to IO. A newborn infant is type A. The mother is type O. Possible phenotypes of the father are

A. A, B, or AB.
B. A, B, or O.
C. O only.
D. A or AB.
E. A or O.

Answer 6

D

Question 7

In epistasis

A. nothing changes from generation to generation.
B. one gene alters the effect of another.
C. a portion of a chromosome is deleted.
D. a portion of a chromosome is inverted.
E. the behavior of two genes is entirely independent.

Answer 7

B

Question 8

Linked genes

A. must be immediately adjacent to one another on a chromosome.
B. have alleles that assort independently of one another.
C. never show crossing over.
D. are on the same chromosome.
E. always have multiple alleles.

Answer 8

D

Question 9

The genetic sex of a human is determined by

A. ploidy, with the male being haploid.
B. the Y chromosome.
C. X and Y chromosomes, the male being XX.
D. the number of X chromosomes, the male being XO.
E. Z and W chromosomes, the male being ZZ.

Answer 9

B

Question 10

In humans, spotted teeth are caused by a dominant sex-linked gene. A man with spotted teeth whose father had normal teeth marries a woman with normal teeth. Therefore,

A. all of their daughters will have normal teeth.
B. all of their daughters will have spotted teeth.
C. all of their children will have spotted teeth.
D. half of their sons will have spotted teeth.
E. all of their sons will have spotted teeth.

Answer 10

B

Question 11

Which of the following is not a characteristic of pea plants (shown) that caused Mendel to choose them for his studies of inheritance?

A. Flower morphology that made controlled cross-pollination possible
B. Prior studies on meiosis in this species
C. Existence of true-breeding strains
D. Presence of many well-defined, contrasting traits
E. Ease of cultivation

Answer 11

B

Question 12

Which of the following statements about Mendel’s studies of monohybrid crosses (shown) is false?

A. Plants developing from seeds produced by crossing the two parent plants would be the F1 generation.
B. In studies of single characters, reciprocal crosses always gave the same results.
C. For each of the different monohybrid crosses, the trait that disappeared in the F1 generation reappeared in three-fourths of the F2 generation.
D. In monohybrid crosses, all F1 plants are heterozygous for the gene being studied.
E. In monohybrid crosses, approximately one-half of the F2 plants are homozygous for the gene being studied.

Answer 12

C

Question 13

Which of the following statements about the interpretation of Mendel’s monohybrid studies is false?

A. Mendel’s monohybrid crosses allowed him to study a single gene in isolation.
B. A plant’s phenotype depends largely on which alleles are present for the gene being studied.
C. For each gene, the alleles from the two parents blend together to form a new phenotype.
D. Although F2 plants show only two phenotypes, three genotypes were present in this generation.
E. The alleles for a gene segregate independently of each other during gamete formation.

Answer 13

C

Question 14

Which of the following statements about the dihybrid cross shown is false?

A. ssY- is a genotype that produces a recombinant phenotype.
B. The probability of obtaining the genotype ssYY in the F2 generation is 0.25 × 0.25 = 0.0625.
C. The physical basis for the law of independent assortment occurs during metaphase I of meiosis.
D. If the two genes shown in the cross were linked, you would expect mostly spherical green and wrinkled yellow F2 plants.
E. A test cross with F1 plants would produce one-fourth each of all four possible phenotypes.

Answer 14

D

Question 15

The cross shown here depicts the F1 progeny resulting from mating true-breeding white and red snapdragons, which display incomplete dominance with respect to flower color. Complete the following sentence about the expected results in the F2 generation: According to the blending theory of inheritance, you should observe _______; whereas if the mode of inheritance is particulate with incomplete dominance, the expected results are _______.

A. 100% pink; 50% pink and 50% white
B. 100% pink; 75 percent red and 25% white
C. 100% pink; 25% white, 50% pink, and 25% red
D. 100% red; 50% pink and 50% white
E. 100% red; 25% white, 50% pink, and 25% red

Answer 15

C

Question 16

The following figure shows clotting reactions for the ABO blood group system in humans. Select the following combination of terms that best describes the mode of inheritance illustrated by this system.

A. Codominance, pleiotropic
B. Codominance, multiple alleles
C. Codominance, multiple genes
D. Codominance, epistasis
E. Incomplete dominance, multiple alleles

Answer 16

B

Question 17

Which of the following statements regarding quantitative variation of phenotypes is false?

A. Quantitative variation is also referred to as continuous variation.
B. Multiple genes with multiple alleles contribute to quantitative variation.
C. The environment contributes to quantitative variation.
D. Human height is an example of quantitative variation.
E. Identifying quantitative trait loci is relatively straightforward.

Answer 17

E

Question 18

This figure shows gamete production in a wild-type female (left) and a black vestigial-winged male fruit fly (right) involved in a test cross. Which of the following genotypes are recombinant, and what would be the expected number of recombinants among 250 progeny if the map unit distance between these genes is 10 cM?

A. BbVgvg and bbvgvg; 10
B. BbVgvg and Bbvgvg; 25
C. bbvgvg and bbVgvg; 25
D. Bbvgvg and bbVgvg; 10
E. Bbvgvg and bbVgvg; 25

Answer 18

E

Question 19

Gene Mapping: Given the genetic map for Drosophila melanogaster shown here, if you were to cross a YyMm female with a yymm male, what would be the expected number of YyMm individuals among 200 offspring?

A. 35
B. 70
C. 65
D. 100
E. 130

Answer 19

C

Question 20

Which of the following statements about sex determination in humans (shown here) is false?

A. In both humans and Drosophila, the genetic constitution of sperm determines sex of the zygote.
B. XO individuals in both humans and Drosophila are female and sterile.
C. XXY individuals are female in Drosophila, but male in humans.
D. In humans, XX individuals with the SRY portion of the Y chromosome translocated onto another chromosome are male.
E. The Y chromosome plays no role in sex determination in Drosophila, whereas in humans it does.

Answer 20

B

Question 21

Sex is determined in different ways in different species. Which of the following statements about sex determination in animals is false?

A. Reciprocal crosses involving genes on the X chromosome do not give identical results.
B. Sex determination mechanisms are only seen in dioecious species.
C. Male birds are hemizygous for genes on the sex chromosomes.
D. Male honeybees have only one set of autosomes.
E. In both Drosophila and humans, males are XY and females are XX.

Answer 21

C

Question 22

In the following cross shown, the expected results are _______, whereas the reciprocal cross would produce _______.

A. all red-eyed flies; all white-eyed flies
B. all red-eyed flies; red-eyed females and white-eyed males
C. all red-eyed flies; red-eyed males and white-eyed females
D. red-eyed males and white-eyed females; red-eyed females and white-eyed males
E. red-eyed males and white-eyed females; all white-eyed flies

Answer 22

B

Question 23

Which of the following statements about the two crosses shown here is false?

A. In cross 1, half of the daughters will be carriers and half will be color-blind.
B. In cross 1, all sons will be normal.
C. In cross 2, half of the daughters will be normal and half will be carriers.
D. In cross 2, half of the sons will be normal and half will be color-blind.
E. The Y chromosome plays no role in the determination of red-green color blindness.

Answer 23

A

Question 24

Plants may show maternal inheritance of a trait because

A. the gene for the trait is present in plastid DNA.
B. the gene for the trait is present in mitochondrial DNA.
C. the gene for the trait is present on the Y chromosome.
D. plastids and mitochondria are often not present in sperm.
E. A, B, and D

Answer 24

E

Question 25

Which of the following statements about bacterial conjugation is false? A. There is transfer of DNA from the donor cell to the recipient cell and vice versa. B. The donor and recipient cells recognize each other by sex pili. C. DNA transfer occurs through a cytoplasmic bridge between the two cells. D. DNA must be cut before it is transferred. E. DNA from the donor may be integrated in the recipient's chromosome.

Answer 25

A

Question 26

Mendel concluded that each pea has two heritable units for each character, and each gamete receives one unit. Mendel's "unit" is new referred to as a(n) A. base pair of DNA. B. character. C. allele of a gene. D. chromosome. E. locus.

Answer 26

C

Question 27

If a trait not expressed in the F1 generation reappears in the F2 generation, the inheritance of the trait in question is an example of A. codominance. B. dominance and recessiveness. C. incomplete dominance. D. epistasis. E. a sex-linked trait.

Answer 27

B

Question 28

If two strains of true-breeding plants that have different alleles for a certain character are crossed, the F1 progeny A. are dihybrids. B. are heterozygous for that character. C. are also true-breeding. D. have an intermediate phenotype. E. have the same genotype as the dominant parent.

Answer 28

B

Question 29

In the ABO blood type system, A. A, B, and O are codominant. B. A, B, and O are incompletely dominant. C. A and B are codominant. D. O is incompletely dominant to A and B. E. A is dominant to B, and B is dominant to O.

Answer 29

C

Question 30

The cross AaBb x AaBb is an example of a ___ cross and the result of such crosses led Mendel to propose what we now call \_\_\_. A. dihybrid cross; law of independent assortment B. dihybrid cross; law of segregation of genes C. test cross; law of segregation of genes D. test cross; law of independent assortment E. selfcross; law of segregation of genes

Answer 30

A

Question 31

The 9:3:3:1 ratio is obtained A. through a dihybrid cross in which the genes are linked on the same chromosome. B. through a dihybrid cross in which the genes are on different chromosomes. C. when crossing over occurs. D. in a test cross. E. None of the above

Answer 31

B

Question 32

The site on the chromosome occupied by a gene is called a(n) A. allele. B. region. C. locus. D. type. E. phenotype.

Answer 32

C

Question 33

In Mendel's experiments, if the allele for tall (T) plants was incompletely dominant over the allele for short (t) plants, what offspring would have resulted from crossing two Tt plants? A. 1/4 tall; 1/2 intermediate height; 1/4 short B. 1/2 tall; 1/4 intermediate height; 1/4 short C. 1/4 tall; 1/4 intermediate height; 1/2 short D. All tall offspring E. All intermediate height offspring

Answer 33

A

Question 34

The physical appearance of a character is called A. the genotype. B. the phenotype. C. an allele. D. a chromosome. E. a gene.

Answer 34

B

Question 35

PTC tasting is a dominant trait. Finn and Maggie both can taste PTC but their daughter, Celia, cannot. If Finn and Maggie have a second child, what is the probability that this child also will not taste PTC? A. 1/2 B. 0 C. 1 D. 3/4 E. 1/4

Answer 35

E

Question 36

Segregation of alleles occurs A. during gamete formation. B. at fertilization. C. during mitosis. D. during the random combination of gametes to produce the F2 generation. E. only in monohybrid crosses.

Answer 36

A

Question 37

Which of the following statements about Mendelian genetics is false? A. Alternative forms of genes are called alleles. B. A locus is a gene's location on its chromosome. C. Only two alleles can exist for a given gene. D. A genotype is a description of the alleles that represent an individual's genes. E. Individuals with the same phenotype can have different genotypes.

Answer 37

C

Question 38

In a test cross, round peas of an unknown genotype were crossed with wrinkled peas of a known genotype (rr). If half of the offspring from that cross are round and half are wrinkled, what is the genotype of the unknown plant? A. Heterozygous: Rr B. Dominant: R C. Homozygous recessive: rr D. The genotype cannot be determined from the information given. E. Homozygous dominant: RR

Answer 38

A

Question 39

\_\_\_ is the term for an allele that has more than one distinguishable phenotypic effect. A. Epistasis B. Multiple alleles C. Codominance D. Pleiotropy E. Incomplete dominance

Answer 39

D

Question 40

The genetic sex of a human is determined by A. the number of X chromosomes, with XX and XXY being female. B. the SRY gene located on the Y chromosome. C. the number of copies of the HER gene, with two copies resulting in female development. D. the number of Y chromosomes with YY being male and XY being female. E. the ratio of autosomes to sex chromosomes.

Answer 40

B

Question 41

It is predictable that half ot eh human babies born will be male and half will be female because A. of the segregation of the X and Y chromosomes during male meiosis. B. of the segregation of the X chromosomes during female meiosis. C. all eggs contain an X chromosome D. Both a and b E. Both a and c

Question 42

When reciprocal crosses rpoduce identical results, the trait is A. sex-linked. B. not sex-linked. C. not autosomally inherited. D. Both a and c E. Both b and c

Answer 42

B

Question 43

Suppose that a dihybrid cross produces a F2 generation with a phenotypic ratio close to 11:1:1:3 rather than 9:3:3:1. This ratio is indicative of: A. independent assortment. B. complete dominance. C. non-disjunction. D. gene linkage. E. mutation of alleles.

Answer 43

D

Question 44

Sex determination in birds and mammals is similar except that in birds, females are ___ while in mammals, females are \_\_\_. A. heterogametic; homogametic B. homogametic; heterogametic C. haploid; heterogametic D. diploid; heterogametic E. None of the above

Answer 44

A

Question 45

When a given trait is the result of multigene action, one of the genes may mask the expression of one or all other genes. this phenomenon is termed A. epistasis. B. epigenesis. C. dominance. D. incomplete dominance. E. pleitropy.

Answer 45

A

Question 46

White eyes is a recessive sex-linked (X-linked) trait in fruit flies. If a white-eyed female fruit fly is mated to a red-eyed male, their offspring should be A. 50% red-eyed and 50% white-eyed for both sexes B. all white-eyed for both sexes C. all white-eyed males and all red-eyed females. D. all white-eyed females and all red-eyed males. E. 50% red-eyed males and 50% white-eyed males and all red-eyed females.

Answer 46

C

Question 47

A human male carrying an allele for a trait on the X chromosome is A. heterozygous. B. homozygous. C. hemizygous. D. monozygous. E. holozygous.

Answer 47

C

Question 48

Red-green colorblindness is a recessive X-linked trait in humans. A woman with normal color vision marries a man who also has normal color vision. They have three children: a daughter with normal color vision, a son with normal color vision, and a son with colorblindness. Which of the following statements is true concerning this family? A. The woman (mother) is a carrier of the colorblindness allele. B. The woman (mother) had a mutation occur in the color vision gene in one of her eggs. C. The man (gather) is a carrier of the colorblindness allele. D. The man (father) must have a Y chromosome with the colorblindness allele. E. The son with colorblindness much have two copies of the recessive colorblindness allele.

Answer 48

A

Question 49

Which of the following observations support the idea that the gene controlling maleness is lcoated on the Y chromosome? A. XO individuals are usually sterile, normal intelligence, female, with slight physical abnormalities. B. XXY individuals are sterile males with long limbs. C. XXX individuals are normal females. D. Some men are XX but have a small piece of the Y attached to another chromosome. E. All of the above are observations suggesting that the gene controlling maleness is on the Y chromosome.

Answer 49

E

Question 50

A dramatic departure from expected phenotypic ratios may be the result of A. environmental influences. B. linkage. C. epistasis. D. gene interactions. E. All of the above

Answer 50

E

Question 51

segregation

Answer 51

separation of alleles during mitosis or homologous chromosomes during meiosis

Question 52

epistasis

Answer 52

presence of an allele or gene determines whether another gene will be expressed

Question 53

gene

Answer 53

unit of heredity

Question 54

allele

Answer 54

alternate form(s) of a genetic character; found at same loci on homologous chromosomes

Question 55

heterozygous

Answer 55

having different alleles of a given gene, e.g. Aa

Question 56

expressivity

Answer 56

degree to which a genotype is expressed in the phenotype can be affected by the environment

Question 57

particulate theory

Answer 57

genes are hpysical entities that retain identities after fertilization

Question 58

genotype

Answer 58

exact description of genetic constitution, wrt single trait or a larger set of traits

Question 59

Punnett wquare

Answer 59

method of predicting results of a genetic cross based on parental genotypes

Question 60

heritable trait

Answer 60

trait that is at least partially determined by genes

Question 61

quantitative trait loci

Answer 61

set of genes that determines a complex character that exhibits quantitative variation

Question 62

secondary sex determination

Answer 62

formation of secondary sex characteristics

Question 63

dihybrid cross

Answer 63

cross between parents wrt alleles of two loci of interest e.g. AABB, AaBb, aabb

Question 64

true-breeding

Answer 64

genetic cross in which same result occurs every time wrt traits of interest due to homozygous parents

Question 65

pleiotropy

Answer 65

determination of more than one character by a single gene

Question 66

haploid

Answer 66

having chromosomal complement consisting of just one copy of each chromosome 1*n* or *n*

Question 67

homozygous

Answer 67

having identical alleles of a given gene on both homologous chromosomes e.g. AA or aa

Question 68

polymorphic

Answer 68

coexistence in a population of 2+ distinct traits

Question 69

genome

Answer 69

complete set of DNA in an organism or individual

Question 70

penetrance

Answer 70

proportion of individuals with a particular genotype that show expected phenotype

Question 71

wild-type

Answer 71

standard or reference type

Question 72

inbreeding

Answer 72

breeding among close relatives

Question 73

primary sex determination

Answer 73

genetic determination of gametic sex (male, female)

Question 74

recessive

Answer 74

allele that doesn't determine phenotype in presence of dominant allele

Question 75

dominance

Answer 75

ability of one form of a gene to determine the phenotype of a heterozygous individual

Question 76

sex pilus

Answer 76

cellular structure on cell wall that allows bacterial organisms to adere to each other prior to conjugation

Question 77

parental generation | (designation)

Answer 77

P generation

Question 78

parental (P) generation

Answer 78

individuals that mate in a genetic cross give rise to F1 generation

Question 79

phenotype

Answer 79

physically observable properties resulting from genetic and environmental factors

Question 80

pedigree

Answer 80

pattern of transmission of a genetic trait within a family

Question 81

sex linkage

Answer 81

pattern of inhertiance characteristic of genes that are located on sex chromosomes (only in organisms having chromosomal mechanism of sex determination)

Question 82

sex chromosomes

Answer 82

one of the chromosomes involved in sex determination

Question 83

carrier

Answer 83

person heterozygous for a recessive trait

Question 84

recombinant frequency

Answer 84

proportion of progeny that have phenotypes different from parental phenotypes due to crossing over during gamete formation

Question 85

mutation

Answer 85

change in genetic material not due to recombination; usually random

Question 86

trait

Answer 86

specific form of a character

Question 87

recombinant

Answer 87

individual, meiotic product, or chromosome in which (linked) genes originally in two individuals ends up in the same haploid complement

Question 88

F2

Answer 88

progeny of mating cross between members of the F1 generation

Question 89

conjugation tube

Answer 89

cytoplasmic connection between two bacterial cells in the passage of DNA

Question 90

reciprocal crosses

Answer 90

female A, male B v.s. female B, male A

Question 91

test cross

Answer 91

mating of dominant phenotype with homozygous recessive individual generally to determine genotype of dominant individual

Question 92

monohybrid cross

Answer 92

mating in which only 1 allele is of interest

Question 93

locus

Answer 93

spot on a chromosome/in the genetic sequence

Question 94

incomplete dominance

Answer 94

heterozygous phenotype is an intermediate between the two homozyous phenotypes

Question 95

map unit

Answer 95

distance between two genes as calculated from recombination frequency

Question 96

heterosis

Answer 96

superior fitness of heterozygous offspring as compared to dissimilar homozygous parents e.g. hybrid vigor

Question 97

genetic map

Answer 97

positions of genes along a chromosome; determined using recombination frequencies

Question 98

centimorgan (cM)

Answer 98

map unit equal to 1% or 0.01 recombination frequency

Question 99

F1

Answer 99

progeny of mating P generation

Question 100

diploid

Answer 100

having chromosome complement consisting of two copies/homologs of each chromosome 2*n*

Question 101

plasmid

Answer 101

extrachromosomal DNA molecule found in bacteria may replicate independent of chromosomes

Question 102

codominance

Answer 102

condition in which two alleles at a locus produce different phenotypes, but both are expressed in heterozygotes

Question 103

independent assortment

Answer 103

random separation of genes carried on nonhomologous chromosomes only in non-linked genes

Question 104

autosome

Answer 104

chromosomes that are not sex chromosomes

Question 105

character

Answer 105

observable feature e.g. eye color

Question 106

hemizygous

Answer 106

having only one allele for a given trait

Question 107

separation of alleles during mitosis or homologous chromosomes during meiosis

Answer 107

segregation

Question 108

presence of an allele or gene determines whether another gene will be expressed

Answer 108

epistasis

Question 109

unit of heredity

Answer 109

gene

Question 110

alternate form(s) of a genetic character; found at same loci on homologous chromosomes

Answer 110

allele

Question 111

having different alleles of a given gene, e.g. Aa

Answer 111

heterozygous

Question 112

degree to which a genotype is expressed in the phenotype can be affected by the environment

Answer 112

expressivity

Question 113

genes are hpysical entities that retain identities after fertilization

Answer 113

particulate theory

Question 114

exact description of genetic constitution, wrt single trait or a larger set of traits

Answer 114

genotype

Question 115

method of predicting results of a genetic cross based on parental genotypes

Answer 115

Punnett wquare

Question 116

trait that is at least partially determined by genes

Answer 116

heritable trait

Question 117

set of genes that determines a complex character that exhibits quantitative variation

Answer 117

quantitative trait loci

Question 118

formation of secondary sex characteristics

Answer 118

secondary sex determination

Question 119

cross between parents wrt alleles of two loci of interest e.g. AABB, AaBb, aabb

Answer 119

dihybrid cross

Question 120

genetic cross in which same result occurs every time wrt traits of interest due to homozygous parents

Answer 120

true-breeding

Question 121

determination of more than one character by a single gene

Answer 121

pleiotropy

Question 122

having chromosomal complement consisting of just one copy of each chromosome 1*n* or *n*

Answer 122

haploid

Question 123

having identical alleles of a given gene on both homologous chromosomes e.g. AA or aa

Answer 123

homozygous

Question 124

coexistence in a population of 2+ distinct traits

Answer 124

polymorphic

Question 125

complete set of DNA in an organism or individual

Answer 125

genome

Question 126

proportion of individuals with a particular genotype that show expected phenotype

Answer 126

penetrance

Question 127

standard or reference type

Answer 127

wild-type

Question 128

breeding among close relatives

Answer 128

inbreeding

Question 129

genetic determination of gametic sex (male, female)

Answer 129

primary sex determination

Question 130

allele that doesn't determine phenotype in presence of dominant allele

Answer 130

recessive

Question 131

ability of one form of a gene to determine the phenotype of a heterozygous individual

Answer 131

dominance

Question 132

cellular structure on cell wall that allows bacterial organisms to adere to each other prior to conjugation

Answer 132

sex pilus

Question 133

P generation

Answer 133

parental generation | (designation)

Question 134

individuals that mate in a genetic cross give rise to F1 generation

Answer 134

parental (P) generation

Question 135

physically observable properties resulting from genetic and environmental factors

Answer 135

phenotype

Question 136

pattern of transmission of a genetic trait within a family

Answer 136

pedigree

Question 137

pattern of inhertiance characteristic of genes that are located on sex chromosomes (only in organisms having chromosomal mechanism of sex determination)

Answer 137

sex linkage

Question 138

one of the chromosomes involved in sex determination

Answer 138

sex chromosomes

Question 139

person heterozygous for a recessive trait

Answer 139

carrier

Question 140

proportion of progeny that have phenotypes different from parental phenotypes due to crossing over during gamete formation

Answer 140

recombinant frequency

Question 141

change in genetic material not due to recombination; usually random

Answer 141

mutation

Question 142

specific form of a character

Answer 142

trait

Question 143

individual, meiotic product, or chromosome in which (linked) genes originally in two individuals ends up in the same haploid complement

Answer 143

recombinant

Question 144

progeny of mating cross between members of the F1 generation

Answer 144

F2

Question 145

cytoplasmic connection between two bacterial cells in the passage of DNA

Answer 145

conjugation tube

Question 146

female A, male B v.s. female B, male A

Answer 146

reciprocal crosses

Question 147

mating of dominant phenotype with homozygous recessive individual generally to determine genotype of dominant individual

Answer 147

test cross

Question 148

mating in which only 1 allele is of interest

Answer 148

monohybrid cross

Question 149

spot on a chromosome/in the genetic sequence

Answer 149

locus

Question 150

heterozygous phenotype is an intermediate between the two homozyous phenotypes

Answer 150

incomplete dominance

Question 151

distance between two genes as calculated from recombination frequency

Answer 151

map unit

Question 152

superior fitness of heterozygous offspring as compared to dissimilar homozygous parents e.g. hybrid vigor

Answer 152

heterosis

Question 153

positions of genes along a chromosome; determined using recombination frequencies

Answer 153

genetic map

Question 154

map unit equal to 1% or 0.01 recombination frequency

Answer 154

centimorgan (cM)

Question 155

progeny of mating P generation

Answer 155

F1

Question 156

having chromosome complement consisting of two copies/homologs of each chromosome 2*n*

Answer 156

diploid

Question 157

extrachromosomal DNA molecule found in bacteria may replicate independent of chromosomes

Answer 157

plasmid

Question 158

condition in which two alleles at a locus produce different phenotypes, but both are expressed in heterozygotes

Answer 158

codominance

Question 159

random separation of genes carried on nonhomologous chromosomes only in non-linked genes

Answer 159

independent assortment

Question 160

chromosomes that are not sex chromosomes

Answer 160

autosome

Question 161

observable feature e.g. eye color

Answer 161

character

Question 162

having only one allele for a given trait

Answer 162

hemizygous