Chapter 12.2: Monohybrid Crosses: The Principle of Segregation

Question 1

What is a monohybrid cross?

Answer 1

• A monohybrid cross is a cross that follows only two variations on a single trait

Question 2

Define first filial (F1) generation

Answer 2

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

Question 3

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

Answer 3

first filial (F1) generation

Question 4

Define dominant allele

Answer 4

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

Question 5

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

Answer 5

dominant allele

Question 6

Define recessive allele

Answer 6

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

Question 7

What is 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?

Answer 7

recessive allele

Question 8

Define Mendelian Ratio

Answer 8

the characteristic dominant-to-recessive phenotypic ratios that Mendel observed in his genetic experiments

Question 9

What is the characteristic dominant-to-recessive phenotypic ratios that Mendel observed in his genetic experiments?

Answer 9

Mendelian Ratio

Question 10

Define allele

Answer 10

one of two or more alternative states of a gene

Question 11

What is one of two or more alternative states of a gene?

Answer 11

allele

Question 12

Define homozygous

Answer 12

having two identical alleles of the same gene

Question 13

What is having two identical alleles of the same gene?

Answer 13

homozygous

Question 14

Define heterozygous

Answer 14

having two different alleles of the same gene

Question 15

What is having two different alleles of the same gene?

Answer 15

heterozygous

Question 16

Define genotype

Answer 16

the genetic constitution underlying a single trait or set of traits

Question 17

What is the genetic constitution underlying a single trait or set of traits?

Answer 17

genotype

Question 18

Define phenotype

Answer 18

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

Question 19

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

Answer 19

phenotype

Question 20

What does the Principle of Segregation state?

Answer 20

The two alleles for a gene segregate during gamete formation and are rejoined at random, one from each parent during fertilization

Question 21

Define punnet square

Answer 21

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

Question 22

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

Answer 22

punnet square

Question 23

Define pedigree

Answer 23

a consistent graphic representation of matings and offspring over multiple generations for a particular genetic trait

Question 24

What is a consistent graphic representation of matings and offspring over multiple generations for a particular genetic trait?

Answer 24

pedigree

Question 25

Is albinism a dominant or recessive trait?

Answer 25

recessive

Question 26

Is Alkaptonuria a dominant or recessive trait?

Answer 26

recessive

Question 27

Is Duchenne Muscular Dystrophy a dominant or recessive trait?

Answer 27

recessive

Question 28

Is Hemophilia a dominant or recessive trait?

Answer 28

recessive

Question 29

Is Sickle Cell Anemia a dominant or recessive trait?

Answer 29

recessive

Question 30

Is Middigital Hair a dominant or recessive trait?

Answer 30

dominant

Question 31

Is Brachydactyly a dominant or recessive trait?

Answer 31

dominant

Question 32

Is Huntington Disease a dominant or recessive trait?

Answer 32

dominant

Question 33

Is Phenylthiocarbamide (PTC) sensitivity a dominant or recessive trait?

Answer 33

dominant

Question 34

Is Camptodactyly a dominant or recessive trait?

Answer 34

dominant

Question 35

Is Hypercholesterolemia a dominant or recessive trait?

Answer 35

dominant

Question 36

Is Polydactyly a dominant or recessive trait?

Answer 36

dominant

Question 37

Is Red-green color blindness a dominant or recessive trait?

Answer 37

recessive

Question 38

What is the phenotype for albinism?

Answer 38

Lack of melanin pigmentation

Question 39

What is the phenotype for Middigital Hair?

Answer 39

Presence of hair on middle segment of fingers

Question 40

What is the phenotype for Alkaptonuria?

Answer 40

Inability to metabolize homogentisic acid

Question 41

What is the phenotype for Brachydactyly?

Answer 41

Short fingers

Question 42

What is the phenotype for Red-green color blindness?

Answer 42

Inability to distinguish red or green wavelengths of light

Question 43

What is the phenotype for Huntington Disease?

Answer 43

Degeneration of nervous system, starting in middle age

Question 44

What is the phenotype for Cystic Fibrosis?

Answer 44

Abnormal gland secretion, leading to liver degeneration and lung failure

Question 45

What is the phenotype for Phenylthiocarbamide (PTC) sensitivity?

Answer 45

Ability to taste PTC as bitter

Question 46

What is the phenotype for Duchenne Muscular Dystrophy?

Answer 46

Wasting away of muscles during childhood

Question 47

What is the phenotype for Camptodactyly?

Answer 47

Inability to straighten the little finger

Question 48

What is the phenotype for Hemophilia?

Answer 48

Inability of blood to clot properly, some clots form but the process is delayed

Question 49

What is the phenotype for Hypercholesterolemia ?

Answer 49

Elevated levels of blood cholesterol and risk of heart attack

Question 50

What is the phenotype for Sickle Cell Anemia?

Answer 50

Defective hemoglobin that causes red blood cells to curve and stick together

Question 51

What is the phenotype for Polydactyly?

Answer 51

Extra fingers and toes