Like this study set? Create a free account to save it.

Sign up for an account

Already have a Quizlet account? .

Create an account

In the mid-19th century, the study of inheritance as a modern branch of science began with the work of..

Gregor Mendel

Offspring from the P generation are heterozygous; they are called the F1 or ________ generation

first filial

Offspring from the F1 cross are called the _______________ generation

second Filial

A ______________ gene may mask the expression of a _______________________ gene.

Dominant; Recessive

During meiosis, members of paired genes at each allele _______________ so that each gamete contains only one allele of each pair.


The site of a gene on a chromosome is called its _________


The two chromosomes that make up a pair are called _______________________ chromosomes


An individual is said to ____________ for a particular feature when the two alleles it carries for that feature are different


A ______________ predicts the ratios of genotypes and phenotypes of the offspring of a cross

punnett square

The phenotype of an individual does not always reveal its _________


A test cross is a cross between an individual of unknown genetic composition and a ______________________ individual.

homozygous recessive

A dihybrid cross is a cross between individuals that differ with respect to their alleles at _____________

two loci

The mechanics of _______ are the basis for independent assortment


The chromosome theory of inheritance can be explained by assuming that genes are ___________________ in specific locations along the chromosomes

linearly arranged

Genes in the same chromosome are said to be ________ and do not assort independently


The sex or gender of many animals is determined by the X and Y sex chromosomes. The other chromosomes in a given organism's genome are called ____________


When a Y-bearing sperm fertilizes an ovum, the result is a _________________ and fertilization by an X-bearing sperm produces a ________________

XY zygote; XX zygote

A dense, metabolically inactive X chromosome at the edge of the nucleus in female mammalian cells is known as the ________________

Barr body

In genetic crosses involving _________, the genotypic and phenotypic ratios are identical

Incomplete dominance

Multiple alleles are _____ different alleles that can occupy the same ___________

3 or more; locus

_____________ refers to the many different effects that can often result from a given gene


________________ is when one allele of a gene pair detemines whether alleles of other gene pairs are expressed


It is called ____________ when two or more independent pairs of genes have similar and additive effects on a phenotype

polygenic inheritance

The range of phenotypic possibilities that can develop from a single genotype under different environmental conditions is known as the ________________

norm of reaction

Two or more pair of genes that affect the same trait in an additive fashion


Having the same (identical) members of a gene pair


Having dissimilar (different) members of a gene pair


Pertaining to the mating of individuals differing in two specific pairs of genes


Pertaining to the mating of individuals differing in one pair of genes


Having only half (one) of a given pair of genes


Condition in which certain alleles at one locus can alter the expression of alleles at a different locus


An alternative form of a gene


The physical or chemical expression of an organism's genes


Condition in which a single gene produces two or more phenotypic effects


A condensed and inactivated X-chromosome appearing as a distinctive dense spot in the nucleus of certain cells of female mammals

Barr body

the allele that is not expressed in the heterozygous state

recessive allele

The place on a chromosome at which the gene for a given trait occurs


condition in which both alleles of a locus are expressed in a heterozygote

Incomplete dominance

The allele that is always expressed when it is present

Dominant allele

The transmission of genetic information from parent to offspring


the science of heredity


The differences between parents and offspring or among individuals of a population

genetic variation

A monk who bred pea plants

Gregor Mendel

First scientist to effectively apply quantitative methods to the study of inheritance

Gregor Mendel

The offspring of two genetically dissimilar parents


All hybrids that are the offspring of genetically pure

true breeding (pure breeding)

Refer to the physical appearance of an organism


The attributes for which heritable differences


members of two different true-breeding lines that are crossed to produce the F1 generation; parental generation

P generation

the first generation of hybrid offspring resulting from a cross between parents from two different true-breeding lines; first filial generation

F1 generation

The offspring of the F1 generation; second filial generation

F2 generation

the factors expressed


the factors that are present but not expressed


Part of DNA that serves as a unit of hereditary information


refers to the alternative forms of a gene


States that before sexual reproduction occurs, the two alleles carried by an individual parent must become separated

Principle of segregation

originally designated the location of a particular gene on the chromosome


When two alleles an organism carries for the locus are identical


an organism carry two different alleles for the locus


the possible combinations of eggs and sperm at fertilization can be represented in the form of this grid

punnett square

the inheritance of two different alleles of a single locus

monohybrid cross

the genetic constitution of that organism


an individual of unknown genotype is crossed with a homozygous recessive individual

test cross

a mating between individuals with different alleles at two love

dihybrid cross

states that members of any gene pair segregate from one another independently of the members of the other gene pairs

principle of independent assortment

when alleles do not assort independently and tend to be inherited together

linked genes

the tendency for a group of genes on the same chromosome to be inherited together in successive generations


the observation of linkage in the results of a test cross and because alleles of two love are involved

two-point cross

any process that leads to new gene combinations


a chromosome that plays a role in sex determination

sex chromosomes

what the cells of females of many animal species contain

X chromosome

What the cells of males contain

Y chromosomes

Chromosomes other than the sex chromosomes


A hormone which causes other male characteristics to develop


genes located in the X chromosome

sex linked genes

has only one copy of each X-linked gene


a condition in which neither member of a pair of contrasting alleles is completely expressed when the other is present

incomplete dominance

condition in which two alleles of a locus are expressed in a heterozygote


the four blood types

ABO blood groups

the condition which three or more alleles for a given locus exist within the population

multiple alleles

the ability of a single gene to have multiple effects


a common type of gene interaction in which the presence of certain alleles of one locus can prevent or mask the expression of alleles of a different locus and express their own phenotype instead


when multiple independent pairs of genes have similar and additive effects on the same character

polygenic inheritance

A person with one X but no Y chromosome has the overall appearance of a female but has defects such as short statue and undeveloped ovaries

turner syndrome

A person with an XXY constitution is a nearly normal male in external appearance, although his testes are underdeveloped

klinefelter syndrome

the sex reversal on Y gene. the major male-determined gene on the Y chromosome, acts as a "genetic switch" that causes testes to develop in the fetus

SRY gene

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

Voice Recording