Chapter 11

Question 1

homozygous

Answer 1

having two identical alleles for a given gene

Question 2

character

Answer 2

an observable heritable feature that may vary among individuals

Question 3

epistasis

Answer 3

a type of gene interaction in which the phenotypic expression of one gene alters that of another independently inherited gene

Question 4

true-breeding

Answer 4

referring to organisms that produce offspring of the same variety over many generations of self-pollination

Question 5

genotype

Answer 5

the genetic makeup, or set of alleles, of an organism

Question 6

homozygote

Answer 6

an organism that has a pair of identical alleles for a gene

Question 7

co-dominance

Answer 7

the situation which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways

Question 8

monohybrid cross

Answer 8

a cross between two organisms that are heterozygous for the character being followed

Question 9

law of segregation

Answer 9

Mendel’s first law, stating that the two alleles in a pair of segregate into different gametes during gamete formation

Question 10

dominant allele

Answer 10

an allele that is fully expressed in the phenotype of a heterozygote

Question 11

trait

Answer 11

one of two or more detachable variants in a genetic character

Question 12

alleles

Answer 12

any of the alternative versions of a gene that may produce distinguishable phenotypic effects

Question 13

incomplete dominance

Answer 13

the situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele

Question 14

complete dominance

Answer 14

the situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable

Question 15

hybridization

Answer 15

in genetics, the mating, or crossing, of two true breeding varieties

Question 16

dihybrids

Answer 16

an organism that is heterozygous with respect to two genes of interest

Question 17

carriers

Answer 17

an individual who is heterozygous at a given genetic locus for a recessively inherited disorder

Question 18

pleiotropy

Answer 18

the ability of a single gene to have multiple effects

Question 19

law of independent assortment

Answer 19

Mendel’s second law, stating that each pair of alleles segregates, or assorts, independently of each other pair during gamete formation

Question 20

F1 generation

Answer 20

the first filial, hybrid (heterozygous) offspring arising from a parental cross

Question 21

testcross

Answer 21

breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype

Question 22

quantitative characters

Answer 22

a heritable feature that varies continuously over a rate rather than in an either-or fashion

Question 23

heterozygous

Answer 23

having two different alleles for a given gene

Question 24

monohybrids

Answer 24

an organism that is heterozygous with respect to a single gene of that interest

Question 25

heterozygote

Answer 25

an organism that has two different alleles for a gene

Question 26

dihybrid cross

Answer 26

a cross between two organisms that are each heterozygous for both of the characters being followed

Question 27

phenotype

Answer 27

the observable physical and physiological traits of an organism, which are determined by its genetic makeup

Question 28

pedigree

Answer 28

a diagram of a family tree with conventional symbols, showing the occurrence of heritable characters in parents and offspring over multiple generations

Question 29

multifactorial

Answer 29

referring to a phenotype character that is influenced by multiple genes and environmental factors