HUMANBIOLOGY_CHAPTERTEN

A(n) ______ is a portion of DNA that encodes a protein.

gene

Who discovered the basic principles of inheritance using traits of pea plants?

Gregor Mendel

A(n) ______ organism always produces offspring that are identical to the parent when self-fertilized.

true-breeding

The genetic makeup of an individual is called the

genotype

What is a sequence of DNA nucleotides that encodes the instructions to make a protein?

gene

In a genetic cross, what does the P generation represent?

parental generation

The gametes of humans are called ______.

eggs and sperm

An example of a(n) ______ cross is the mating of two rats that both contain the alleles Ff for fur color. This cross is made to examine which of two fur colors their offspring will have.

monohybrid

Gregor Mendel formulated key principles of ______ before DNA, genes, and chromosomes were discovered.

genetics

Mendel deduced the law of ______ , which states alleles of a gene move apart from each other during gamete formation.

segregation

A(n) ______ organism produces mixed offspring: some that are identical to the parent plant and some that are different.

hybrid

What type of cross is a mating between two individuals that are both heterozygous for the same two genes?

dihybrid cross

An individual's allele combination for a particular gene is called the ______.

genotype

Although Mendel did not know that the random orientation of homologous chromosome pairs during metaphase I leads to random allele combinations of different genes in gametes, he created the law of ______ _______, which deduced this phenomenon.

independent assortment

What is the first set of individuals mated in a particular cross?

P generation

A ______ cross is a mating between two individuals that are both heterozygous for the same, single gene.

monohybrid

After Mendel's work, biologists determined that a single chromosome carries ______. 

many genes

Mendel's law of ______ states that alternative versions of genes are packaged into separate gametes.

segregation

Which of the following is a dihybrid cross?

RrYy x RrYy

Genes that are located on the same chromosome and inherited together are called _____ genes.

linked

The picture of gamete production with two genes uninfluenced by each other as they are divided in meiosis I and II supports Mendel's ______. 

law of independent assortment

In a gene expression pattern called ______, the heterozygote has an intermediate phenotype between the homozygotes.

incomplete dominance

If a couple that are both heterozygous carriers of the cystic fibrosis allele have children, the chance that both their first and their second child are carriers is 0.5 x 0.5, or 25%, as determined by the ______. 

product rule

In ______, one gene encodes a protein that is important in many biochemical pathways or that affects many parts of the body.

pleiotropy

Select the true statement about genes and chromosomes.

The number of genes in a cell exceeds the number of chromosomes.

Genes that are located on the X or Y chromosome are said to be ______ and often are expressed in one sex more than the other.

sex-linked

Mendel deduced the law of ______ , which states alleles of a gene move apart from each other during gamete formation.

segregation

A woman who is heterozygous for the X-linked, recessive hemophilia allele has children with a man who does not have hemophilia. Which of the possible offspring will have hemophilia?

Son: one X chromosome carrying the recessive hemophilia allele and one Y chromosome

Genes that are carried on the same chromosome are called ______ genes and are inherited together.

linked

X inactivation occurs early in ______ embryonic development and prevents ______ of every gene on the X chromosome.

female; a double dose

The pink snapdragon flowers in the picture are an example of

incomplete dominance

A chart showing the presence and absence of phenotypes in multiple generations of a family is called a

pedigree

A type of gene expression called pleiotropy occurs when

one gene has multiple effects on the phenotype.

Siamese cats and Himalayan rabbits have light-colored bodies but darker-colored paws, ears, and tail due to an enzyme whose activity varies with temperature. This is an example of ______.

environmental effects

Red-green color blindness and hemophilia are examples of ______, which are controlled by alleles on the sex chromosomes.

sex-linked genes

If the phenotype reflects the activities of more than one gene, it is called a ______ trait.

polygenic

X-linked recessive disorders can affect more human males than females because ______ always express the disorder when they inherit the recessive allele from ______.

males; the mother

What describes X inactivation in humans?

One X chromosome in each cell is turned off in XX females.

What diagram that tracks traits within a family is shown in the picture?

pedigree