Ch. 9 - Patterns of Inheritance

Question 1

ABO blood groups

Answer 1

Genetically determined classes of human blood that are based on the presence or absence of carbohydrates A and B on the surface of red blood cells. The ABO blood group phenotypes, also called blood types, are A, B, AB, and O.

Question 2

achondroplasia

Answer 2

A form of human dwarfism caused by a single dominant allele. The homozygous condition is lethal.

Question 3

alleles

Answer 3

An alternative version of a gene.

Question 4

Carrier

Answer 4

An individual who is heterozygous for a recessively inherited disorder and who therefore does not show symptoms of that disorder.

Question 5

character

Answer 5

A heritable feature that varies among individuals within a population, such as flower color in pea plants.

Question 6

chromosome theory of inheritance

Answer 6

A basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.

Question 7

codominance

Answer 7

The expression of two different alleles of a gene in a heterozygote.

Question 8

dihybrid cross

Answer 8

A mating of individuals differing at two genetic loci.

Question 9

dominant allele

Answer 9

In a heterozygote, the allele that determines the phenotype with respect to a particular gene.

Question 10

F1 generation

Answer 10

The offspring of two parental (P. generation) individuals. F1 stands for first filial.

Question 11

F2 generation

Answer 11

The offspring of the F1 generation. F2 stands for second filial.

Question 12

Genetics

Answer 12

The scientific study of heredity (inheritance).

Question 13

Hemophilia

Answer 13

A human genetic disease caused by a sex-linked recessive allele and characterized by excessive bleeding following injury.

Question 14

Heredity

Answer 14

The transmission of traits from one generation to the next.

Question 15

heterozygous

Answer 15

Having two different alleles for a given gene.

Question 16

homozygous

Answer 16

Having two identical alleles for a given gene.

Question 17

Huntington’s disease

Answer 17

A human genetic disease caused by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms.

Question 18

hybrids

Answer 18

The offspring of parents of two different species or of two different varieties of one species; the offspring of two parents that differ in one or more inherited traits; an individual that is heterozygous for one or more pairs of genes.

Question 19

hypercholesterolemia

Answer 19

An inherited human disease characterized by an excessively high level of cholesterol in the blood.

Question 20

inbreeding

Answer 20

The mating of close relatives.

Question 21

incomplete dominance

Answer 21

A type of inheritance in which the phenotype of a heterozygote (Aa) is intermediate between the phenotypes of the two types of homozygotes (AA and aa).

Question 22

law of independent assortment

Answer 22

A general rule of inheritance, first proposed by Gregor Mendel, that states that when gametes form during meiosis, each pair of alleles for a particular character segregate (separate) independently of each other pair.

Question 23

law of segregation

Answer 23

A general rule of inheritance, first proposed by Gregor Mendel, that states that the two alleles in a pair segregate (separate) into different gametes during meiosis.

Question 24

linkage map

Answer 24

A map of a chromosome showing the relative positions of genes.

Question 25

linked genes

Answer 25

Genes located close enough together on a chromosome that they are usually inherited together.

Question 26

locus

Answer 26

(plural, loci) The particular site where a gene is found on a chromosome. Homologous chromosomes have corresponding gene loci.

Question 27

monohybrid cross

Answer 27

A mating of individuals differing at one genetic locus.

Question 28

P generation

Answer 28

The parent individuals from which offspring are derived in studies of inheritance. P stands for parental.

Question 29

pedigree

Answer 29

A family tree representing the occurrence of heritable traits in parents and offspring across a number of generations.

Question 30

phenotype

Answer 30

The expressed traits of an organism.

Question 31

pleiotropy

Answer 31

The control of more than one phenotypic character by a single gene.

Question 32

polygenic inheritance

Answer 32

The additive effect of two or more genes on a single phenotypic characteristic.

Question 33

Punnett square

Answer 33

A diagram used in the study of inheritance to show the results of random fertilization.

Question 34

recessive allele

Answer 34

In heterozygotes, the allele that has no noticeable effect on the phenotype.

Question 35

recombination frequency

Answer 35

With respect to two given genes, the number of recombinant progeny from a mating divided by the total number of progeny. Recombinant progeny carry combinations of alleles different from that seen in either of the parents as a result of independent assortment of chromosomes and crossing over.

Question 36

Red-green colorblindness

Answer 36

A category of common sex-linked human disorders involving several genes on the X chromosome and characterized by a malfunction of light-sensitive cells in the eyes; affects mostly males but also homozygous females.

Question 37

rule of multiplication

Answer 37

A rule stating that the probability of a compound event is the product of the separate probabilities of the independent events.

Question 38

sex-linked gene

Answer 38

A gene located on a sex chromosome.

Question 39

sickle-cell disease

Answer 39

A genetic disorder in which the red blood cells have abnormal hemoglobin molecules and take on an abnormal shape.

Question 40

testcross

Answer 40

The mating between an individual of unknown genotype for a particular character and an individual that is homozygous recessive for that same character.

Question 41

trait

Answer 41

A variant of a character found within a population, such as purple flowers in pea plants.

Question 42

true-breeding

Answer 42

Referring to organisms for which sexual reproduction produces offspring with inherited traits identical to those of the parents. The organisms are homozygous for the characteristics under consideration.

Question 43

wild-type trait

Answer 43

The trait most commonly found in nature.