Chapter 14

Question 1

character

Answer 1

A heritable feature that varies among individuals (such as flower color)

Question 2

trait

Answer 2

Each variant for a character (ex. purple or white color for flowers)

Question 3

advantages of using peas

Answer 3

Short generation time
Large numbers of offspring
Mating could be controlled
to self-pollinate or 
cross pollinated

Question 4

true breeding

Answer 4

plants that produce offspring of the same variety when they self-pollinate

Question 5

hybridization

Answer 5

He mated two contrasting, true-breeding varieties

Question 6

P generation

Answer 6

The true-breeding parents

Question 7

F1 generation

Answer 7

The hybrid offspring of the P generation

Question 8

F2 generation

Answer 8

When F1 individuals self-pollinate or cross- pollinate with other F1 hybrids

Question 9

alleles

Answer 9

alternative versions of a gene
account for variation in inherited characteristics
reside at a specific locus on a specific chromosome

Question 10

where do alleles for each character come from?

Answer 10

one from each parent

Question 11

law of segregation

Answer 11

the two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes

Egg or a sperm get only one of the two alleles that are present in the organism

Question 12

law of independent assortment

Answer 12

It states that each pair of alleles segregates independently of each other pair of alleles during gamete formation
This law applies only to genes on different, nonhomologous chromosomes or those far apart on the same chromosome
Genes located near each other on the same chromosome tend to be inherited together

Question 13

complete dominance

Answer 13

occurs when phenotypes of the heterozygote and dominant homozygote are identical

Question 14

incomplete dominance

Answer 14

the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties

Question 15

codominance

Answer 15

two dominant alleles affect the phenotype in separate, distinguishable ways

Question 16

types of blood

Answer 16

IAIA or IAi=A
IBIB or IBi=B
IAIB=AB
ii=O

Question 17

pleiotropy

Answer 17

Most genes have multiple phenotypic effects

Question 18

epistasis

Answer 18

a gene at one locus alters the phenotypic expression of a gene at a second locus

Question 19

example of epistasis

Answer 19

For example, in Labrador retrievers and manyother mammals, coat color depends on two genes
One gene determines the pigment color (with alleles B for black and b for brown)
The other gene (with alleles E for color and e forno color) determines whether the pigment will be deposited in the hair

Question 20

quantitative characters

Answer 20

are those that vary in the population along a continuum

Question 21

polygenic inheritance

Answer 21

additive effect of two or more genes on a single phenotype

skin color

Question 22

multifactorial

Answer 22

Traits that depend on multiple genes combined with environmental influences

Question 23

what does phenotype include?

Answer 23

An organism’s phenotype includes its physical appearance, internal anatomy, physiology, and behavior
An organism’s phenotype reflects its overall genotype and unique environmental history

Question 24

why are humans bad subjects for genetic research?

Answer 24

Generation time is too long
Parents produce relatively few offspring
Breeding experiments are unacceptable

Question 25

pedigree

Answer 25

pedigree is a family tree that describes the interrelationships of parents and children across generations

Question 26

Consanguineous matings

Answer 26

(i.e., matings between close relatives) increase the chance of mating between two carriers of the same rare allele

Question 27

Cystic fibrosis

Answer 27

is the most common lethal genetic disease in the United States, striking one out of every 2,500 people of European descent

Question 28

Sickle-cell disease

Answer 28

affects one out of 400 African-Americans

Question 29

dominantly inherited disorders

Answer 29

dominant alleles that cause a lethal disease are rare and result from mutation

Question 30

amniocentesis

Answer 30

the liquid that bathes the fetus is removed and tested

Question 31

chorionic villus sampling (CVS)

Answer 31

a sample of the placenta is removed and tested