Unit 7

Question 1

Alleles

Answer 1

Alternative versions of a gene that produce distinguishable phenotypic events

Question 2

Carrier

Answer 2

In genetics, an individual who is heterozygous at a given genetic locus, with one normal allele and one potentially harmless recessive allele. The heterozygote is phenotypically normal for the character determined by the gene but can pass on the harmful allele to offspring

Question 3

Character

Answer 3

An observable heritable feature

Question 4

Codominance

Answer 4

The situation in which the phenotypes of both alleles are exhibited in the heterozygote

Question 5

Complete dominance

Answer 5

The situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable

Question 6

Dihybrid

Answer 6

An organism that is heterozygous with respect to two genes of interest. All the offspring from a cross between parents doubly homozygous for different alleles are dihybrids. For example, parents of AABB and aabb produce a dihybrid of AaBb

Question 7

Dominant allele

Answer 7

An allele that is fully expressed in the phenotype of a heterozygote

Question 8

Epistasis

Answer 8

A type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited

Question 9

F1 generation

Answer 9

The first filial, or hybrid, offspring in a series of genetic crosses

Question 10

F2 generation

Answer 10

Offspring resulting from interbreeding of the hybrid F1 generation

Question 11

Genotype

Answer 11

The genetic makeup, or set of alleles, of an organism

Question 12

Heterozygous

Answer 12

Having two different alleles for a given gene

Question 13

Homozygous

Answer 13

Having two identical alleles for a given gene

Question 14

Hybridization

Answer 14

In genetics, the mating, or crossing, of two true-breeding varieties

Question 15

Incomplete dominance

Answer 15

The situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele

Question 16

Law of Independent Assortment

Answer 16

Mendel’s second law, stating that each pair of alleles segregates independently during gamete formation; applies when genes for two characters are located on different pairs of homologous chromosomes

Question 17

Law of segregation

Answer 17

Mendel’s first law, stating that each allele in a pair separates into a different gamete during gamete formation

Question 18

Monohybrid

Answer 18

An organism that is heterozygous with respect to a single gene of interest. All the offspring from a cross between parents homozygous for different alleles are monohybrids. For example, parents of genotype AA and aa produce a monohybrid of genotype Aa.

Question 19

P generation

Answer 19

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

Question 20

Phenotype

Answer 20

The physical and physiological traits of an organism, which are determined by its genetic makeup

Question 21

Pleiotropy

Answer 21

The ability of a single gene to have multiple effects

Question 22

Polygenic inheritance

Answer 22

An additive effect of two or more gene loci on a single phenotypic character

Question 23

Recessive allele

Answer 23

An allele whose phenotypic effect is not observed in a heterozygote

Question 24

Trait

Answer 24

An detectable variation in genetic character

Question 25

True-breeding

Answer 25

Referring to plants that produce offspring of the same variety when they self-pollinate