Chapter 17

Question 1

What does inheritance mean?

Answer 1

The transmission of characteristics from parent to offspring.

Question 2

particulate inheritance:

Answer 2

The idea that the determinants of hereditary traits are transmitted in discrete units, or particles, from one generation to the next.

Question 3

hybridization:

Answer 3

The process in which two individuals of the same species with different characteristics are bred or crossed to each other; the offspring are referred to as hybrids.

Question 4

What is a character in relation to Mendel’s experiments?

Answer 4

A characteristic of an organism, such as the appearance of seeds, pods, flowers, or stems in the garden pea.

Question 5

What is a trait?

Answer 5

An identifiable characteristic; usually refers to a variant.

flower color is character, purple flowers is trait

Question 6

What is a monohybrid?

Answer 6

The F1 offspring, also called single-trait hybrids, of true-breeding parents that differ with regard to a single character.

Question 7

What is an allele?

Answer 7

A variant form of a gene.

Question 8

What is a dominant trait?

Answer 8

Refers to the trait that is displayed in a heterozygote.

Question 9

What is a recessive trait?

Answer 9

Refers to a trait that is masked by the presence of a dominant trait in a heterozygote.

Question 10

What is a gene?

Answer 10

A unit of heredity. At the molecular level, a gene is an organized unit of base sequences in a DNA strand that can transcribed into RNA and ultimately results in the formation of a functional product.

Question 11

What is Mendel’s law of segregation?

Answer 11

The two alleles of a gene separate (segregate) from each other during the process that gives rise to gametes, so every gamete receives only one allele.

Question 12

What does genotype mean?

Answer 12

The genetic composition of an individual.

Question 13

What does it mean for an individual to be homozygous?

Answer 13

An individual with two identical copies of an allele.

Question 14

What does it mean for an individual to be heterozygous?

Answer 14

An individual with two different alleles of the same gene.

Question 15

What does phenotype mean?

Answer 15

The characteristics of an organism that are the result of the expression of its genes.

Question 16

Steps of creating a Punnett square?

Answer 16

Step 1: Write down the genotypes of both parents
Step 2: Write down the possible gametes that each parent can make
Step 3: Create an empty Punnett square
Step 4: Combine the alleles of the gametes in the empty boxes
Step 5: Determine ratios

Question 17

What is a testcross?

Answer 17

A cross to determine if an individual with a dominant phenotype is a homozygote or a heterozygote.

Question 18

dihybrid:

Answer 18

Refers to an offspring that is a hybrid with respect to two traits.

Question 19

Mendel’s law of independent assortment:

Answer 19

The alleles of different genes assort independently of each other during the process that gives rise to gametes.

Question 20

What is an X-linked gene?

Answer 20

A gene found on the X chromosome but not on the Y.

Question 21

What are sex-linked genes?

Answer 21

A gene that is found on one sex chromosome but not on the other.

Question 22

hemizygous:

Answer 22

Having only one copy of a particular gene; a male mammal is hemizygous for an X-linked gene.

Question 23

wild-type allele:

Answer 23

A prevalent allele in a population.

Question 24

mutant allele:

Answer 24

An allele that has been altered by mutation.

Question 25

pleiotropy:

Answer 25

The phenomenon in which a mutation in a single gene can have multiple effects on an individual’s phenotype.

Question 26

incomplete dominance:

Answer 26

The phenomenon in which a heterozygote that carries two different alleles exhibits a phenotype that is intermediate between the phenotypes of the corresponding homozygous individuals.

Question 27

What does multiple alleles mean?

Answer 27

The phenomenon in which a gene has three or more alleles in a natural population.

Question 28

codominance:

Answer 28

The phenomenon in which a single individual expresses two alleles.

Question 29

norm of reaction:

Answer 29

The phenotype range that individuals with a particular genotype exhibit under differing environmental conditions.

Question 30

gene interaction:

Answer 30

The phenomenon in which a single trait is controlled by two or more genes, each of which has two or more alleles.