Exam IV

Question 1

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

Answer 1

Character

Question 2

Each variant for a character, such as purple or white color for flowers is called a

Answer 2

trait

Question 3

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

Answer 3

true-breeding

Question 4

In a typical experiment, Mendel mated two contrasting, true-breeding varieties, a process called

Answer 4

hybridization

Question 5

The true-breeding parents are called the

Answer 5

P generation

Question 6

The hybrid offspring of the P generation are called the

Answer 6

F1 generation

Question 7

When F1individuals self-pollinate or cross-pollinate with other F1hybrids, the ___ is produced

Answer 7

F2 generation

Question 8

alternative versions of a gene are called

Answer 8

alleles

Question 9

Each gene resides at a specific ___ on a specific chromosome

Answer 9

locus

Question 10

if the two alleles at a locus differ, then one, the _______, determines the organism’s appearance

Answer 10

dominant allele

Question 11

the ____, has no noticeable effect on appearance

Answer 11

recessive allele

Question 12

the law of segregation:

Answer 12

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

Question 13

Possible combinations of sperm and egg can be shown using a ______

Answer 13

Punnett square

Question 14

An organism with two identical alleles for a gene is called a

Answer 14

homozygote (PP, or pp).

Question 15

An organism with two different alleles for a gene is a ____

Answer 15

heterozygote (Pp)

Question 16

we distinguish between an organism’s ___, or physical appearance, and its ___, or genetic makeup

Answer 16

phenotype, genotype

Question 17

To determine the genotype we can carry out a _____: breeding the mystery individual with a homozygous recessive individual

Answer 17

testcross

Question 18

The F1offspring produced in this cross were ____, meaning that they were heterozygous for one character

Answer 18

monohybrids

Question 19

A cross between such heterozygotes is called a

Answer 19

monohybrid cross

Question 20

Crossing two true-breeding parents differing in two characters produces ___ in the F1 generation

Answer 20

dihybrids

Question 21

a ____, a cross between F1 dihybrids, can determine whether two characters are transmitted to offspring together as a unit or independently

Answer 21

dihybrid cross

Question 22

each pair of alleles segregates independently of any other pair of alleles during gamete formation

Answer 22

Law of Independent Assortment

Question 23

The _____ states that the probability that two or more independent events will occur together is the product of their individual probabilities

Answer 23

multiplication rule

Question 24

The ______ states that the probability that any one of two or more mutually exclusive events will occur is calculated by adding together their individual probabilities

Answer 24

addition rule

Question 25

occurs when phenotypes of the heterozygote and dominant homozygote are identical

Answer 25

Complete dominance

Question 26

the phenotype of F1hybrids is somewhere between the phenotypes of the two parental varieties

Answer 26

Incomplete dominance

Question 27

two dominant alleles affect the phenotype in separate, distinguishable ways

Answer 27

Codominance

Question 28

Tay-Sachs disease

Answer 28

a fatal inherited disorder; a dysfunctional enzyme causes an accumulation of lipids in the brain

Question 29

Most genes have multiple phenotypic effects, a property called ____

Answer 29

pleiotropy

Question 30

In ____, expression of a gene at one locus alters the phenotypic expression of a gene at a second locus

Answer 30

epistasis

Question 31

Quantitative characters

Answer 31

those that vary in the population along a continuum

Question 32

Quantitative variation usually indicates ____, an additive effect of two or more genes on a single phenotype

Answer 32

polygenic inheritance

Question 33

Traits that depend on multiple genes combined with environmental influences are called

Answer 33

multifactorial

Question 34

a family tree that describes the inheritance of a trait across generations

Answer 34

pedigree

Question 35

____ are heterozygous individuals who carry the recessive allele but are phenotypically normal

Answer 35

carriers

Question 36

Cystic fibrosis

Answer 36

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

Question 37

Sickle-cell disease

Answer 37

* It is caused by the substitution of a single amino acid in the hemoglobin protein in red blood cells * In homozygous individuals, all hemoglobin is abnormal (sickle-cell)

Question 38

Huntington’s disease

Answer 38

- a degenerative disease of the nervous system | - The disease has no obvious phenotypic effects until the individual is about 35 to 40 years of age

Question 39

In _____, the liquid that bathes the fetus is removed and tested for certain genetic disorders

Answer 39

amniocentesis

Question 40

In ______, a sample of the placenta is removed and tested

Answer 40

chorionic villus sampling (CVS)

Question 41

Around 1902, Sutton and Boveri and others independently noted these parallels and began to develop the

Answer 41

chromosome theory of inheritance

Question 42

Traits alternative to the wild type are called

Answer 42

mutant phenotypes

Question 43

A gene that is located on either sex chromosome is called a

Answer 43

sex-linked gene

Question 44

Genes on the X chromosome are called _____; the human X chromosome contains about 1,100 genes

Answer 44

X-linked genes

Question 45

Some disorders caused by recessive alleles on the X chromosome in humans:

Answer 45

–Color blindness (mostly X-linked) –Duchennemuscular dystrophy –Hemophilia

Question 46

The inactive X condenses into a

Answer 46

Barr body

Question 47

Genes that are located on the same chromosome tend to be inherited together and are called

Answer 47

linked genes

Question 48

the production of offspring with combinations of traits differing from either parent

Answer 48

genetic recombination

Question 49

Offspring with a phenotype matching one of the parental (P) phenotypes are called

Answer 49

parental types

Question 50

Offspring with non-parental phenotypes (new combinations of traits) are called

Answer 50

recombinant types, or recombinants

Question 51

an ordered list of the genetic loci along a particular chromosome

Answer 51

genetic map

Question 52

a genetic map of a chromosome based on recombination frequencies

Answer 52

linkage map

Question 53

Distances between genes can be expressed as _____; one map unit represents a 1% recombination frequency

Answer 53

map units

Question 54

In _______, pairs of homologous chromosomes do not separate normally during meiosis

Answer 54

nondisjunction

Question 55

____ results from the fertilization of gametes in which nondisjunction occurred

Answer 55

Aneuploidy

Question 56

A _____ zygote has only one copy of a particular chromosome

Answer 56

monosomic

Question 57

A____ zygote has three copies of a particular chromosome

Answer 57

trisomic

Question 58

_____ is a condition in which an organism has more than two complete sets of chromosomes

Answer 58

Polyploidy •Polyploidy is common in plants, but not animals •Polyploids are more normal in appearance than aneuploids

Question 59

removes a chromosomal fragment

Answer 59

deletion

Question 60

repeats a segment

Answer 60

duplication

Question 61

reverses orientation of a segment within a chromosome

Answer 61

inversion

Question 62

moves a segment from one chromosome to another

Answer 62

Translocation

Question 63

is an aneuploid condition that results from three copies of chromosome 21

Answer 63

Down syndrome

Question 64

For a few mammalian traits, the phenotype depends on which parent passed along the alleles for those traits. Such variation in phenotype is called ______

Answer 64

genomic imprinting