chapter 5

Question 1

Homozygous

Answer 1

Possessing two identical alleles of a gene

AA is a homozygous dominant genotype

aa is a homozygous recessive genotype

Question 2

Heterozygous

Answer 2

Possessing two different alleles ofa gene; dominant allele will be expressed

Aa is a heterozygous genotype

Question 3

Pure breed

Answer 3

Identical set of allele

Question 4

autosomal trait

Answer 4

-An autosomal trait is inherited on an autosome – a chromosome that is not a sex chromosome.
*A gene on an autosome is called autosomal

Question 5

sex linked trait

Answer 5

A sex-linked trait is inherited on a sex chromosome (X or Y). A gene on a sex chromosome is called sex-linked

Question 6

allele

Answer 6

One of various versions of the same gene (at the same locus) distinguished by small differences in its DNA sequence

Question 7

artificial selection

Answer 7

The breeding of plants and animals to produce desirable traits in successive generations; also known as selective breeding

Question 8

autosomal inheritance

Answer 8

The passing on of a trait through a gene located on an autosome, a chromosome that is not a sex chromosome

Question 9

autosomal trait

Answer 9

A trait coded for by a gene on an autosome, a chromosome that is not a sex chromosome; a gene of this kind is called autosomal

Question 10

carrier

Answer 10

n reference to a genetic disease, a carrier is a healthy, heterozygous organism carrying an allele for a recessive phenotype; the organism may transmit the recessive allele and its associated phenotype to its offspring

Question 11

codominance

Answer 11

A state in which both alleles of a heterozygous individual are fully expressed in the phenotype

Question 12

continuous variation

Answer 12

Variation in a phenotype characteristic that shows a smooth range; this occurs when a trait is controlled by many genes; when graphed, such variation forms a bell-shaped (normal) curve

Question 13

Dihybrid cross

Answer 13

A cross between two organisms that are heterozygous at two gene loci

Question 14

Discontinuous variation

Answer 14

Variation in a characteristic that shows two or just a few clearly distinct phenotypes

Question 15

dominant

Answer 15

A phenotype that requires only one copy of its allele for it to be expressed in an individual

Question 16

First filial generation (F1)

Answer 16

The first generation of offspring produced from a cross between two parents (P)

Question 17

gene

Answer 17

A set of instructions that specifies the structure of a protein

Question 18

genetics

Answer 18

The study of the mechanisms and patterns of inheritance associated with the transmission of coded chemical instructions from one generation to the next

Question 19

genotype

Answer 19

The specific combination of alleles for a particular gene locus belonging to an individual or cell

Question 20

heredity

Answer 20

The study of inheritance; the genetic transmission of characteristics from one generation to the next

Question 21

Heterozygous

Answer 21

A genotype with two different alleles for a single gene locus

Question 22

Homozygous

Answer 22

A genotype with two identical alleles for a single gene locus

Question 23

Incomplete dominance

Answer 23

The state in which a heterozygous individual has a phenotype that is intermediate between those of the corresponding homozygous individuals

Question 24

Independent assortment

Answer 24

Random orientation of maternal and paternal homologous chromosomes at the equator during metaphase I, resulting in random combinations of alleles in the gametes at the conclusion of meiosis

Question 25

Inheritance

Answer 25

The genetic acquisition of characteristics by offspring from their parents

Question 26

Linked genes

Answer 26

Genes or alleles that are inherited together more frequently because they are located near one another on the same chromosome

Question 27

Monohybrid

Answer 27

An organism that is heterozygous with respect to a single gene

Question 28

Monohybrid cross

Answer 28

A cross between two monohybrids (see monohybrid); only one gene is involved, and the cross is between two organisms that are heterozygous at one gene locus for a dominant and a recessive allele

Question 29

Multiple alleles

Answer 29

A type of inheritance when three or more alleles of a gene exist among members of a population, for one trait.

Question 30

Non-homologous chromosomes

Answer 30

Chromosomes that do not belong to the same pair; they contain different sets of genes

Question 31

Parental generation (P)

Answer 31

Two individuals or lines that represent the start of a breeding experiment; their offspring are the F1 generation

Question 32

Phenotype

Answer 32

The actual form taken by a specific feature in a particular individual, based on their genotype and influenced by the environment; it can be used in reference to particular traits or characteristics, or to the overall form of an individual

Question 33

Polygene

Answer 33

A gene whose alleles have a small, additive effect on a phenotype; many polygenes together contribute to continuous variation in a phenotype

Question 34

Polygenic inheritance

Answer 34

Transmission between generations of characteristics that are controlled by polygenes (see polygenes)

Question 35

Punnett square

Answer 35

A Punnett square is a table that displays all the possible offspring genotypes given the parent alleles that can pair up at fertilisation; it can be used to determine the likelihood of producing offspring with particular genotypes and phenotypes from known parental genotypes, and sometimes to deduce parental genotypes given offspring genotype and phenotype percentages

Question 36

Pure-breeding

Answer 36

A line of organisms that always produce offspring with the same phenotype when crossed with one another

Question 37

Recessive

Answer 37

A phenotype that requires two copies of its allele in an individual in order to be expressed

Question 38

Second filial generation (F2)

Answer 38

Offspring of the F1 generation; the second generation produced from a cross between two homozygous parents (P)

Question 39

Selective breeding

Answer 39

A process by which humans domesticate animals or plants by purposely choosing individuals with the most desirable characteristics as parents for each successive generation of breeding

Question 40

Sex-linked

Answer 40

Describes a gene located on a sex chromosome

Question 41

Sex-linked trait

Answer 41

A trait inherited on a sex chromosome (X or Y chromosome); the gene of interest on a sex chromosome is described as sex-linked

Question 42

Test cross

Answer 42

A technique used by geneticists in which an individual whose genotype is unknown for a dominant phenotype (it could be homozygous dominant or heterozygous dominant) is crossed with an individual that is homozygous recessive at the locus in question

Question 43

Trait

Answer 43

An inheritable characteristic; phenotype

Question 44

X-linked

Answer 44

Related to a gene located on the X chromosome

Question 45

X-linked recessive

Answer 45

When a phenotype is determined by a recessive allele on the X chromosome

Question 46

Y-linked

Answer 46

Related to a gene located on the Y chromosome