5-3 Vocab

Question 1

Complete Dominance

Answer 1

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

Question 2

Epistasis

Answer 2

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

Question 3

Law of Independent Assortment

Answer 3

Mendel’s second law, stating that each pair of alleles segregates, or assorts, independently of each other pair during gamete formation; applies when genes for two characters are located on different pairs of homologous chromosomes or when they are far enough apart on the same chromosome to behave as though they are on different chromosomes

Question 4

F1 Generation

Answer 4

The first filial, hybrid (heterozygous)
offspring arising from a parental
(P generation) cross

Question 5

Testcross

Answer 5

Breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype. The ratio of phenotypes in the offspring reveals the unknown genotype

Question 6

Quantitative Characters

Answer 6

A heritable feature that varies continuously over a range rather than in an either-or fashion

Question 7

Heterozygous

Answer 7

Having two different alleles for a given gene

Question 8

Monohybrids

Answer 8

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 genotypes AA and aa produce a monohybrid of genotype Aa

Question 9

Homozygous

Answer 9

Having two identical alleles for a given gene

Question 10

Codominance

Answer 10

The situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways

Question 11

Genotype

Answer 11

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

Question 12

Addition Rule

Answer 12

A rule of probability stating that the probability of any one of two or more mutually exclusive events occurring can be determined by adding their individual probabilities

Question 13

Heterozygote

Answer 13

An organism that has two different alleles for a gene (encoding a character)

Question 14

F2 Generation

Answer 14

The offspring resulting from interbreeding (or self-pollination) of the hybrid F1 generation

Question 15

Recessive Allele

Answer 15

An allele whose phenotypic effect is not observed in a heterozygote

Question 16

Dihybrid Cross

Answer 16

A cross between two organisms that are each heterozygous for both of the characters being followed (or the self-pollination of a plant that is heterozygous for both characters)

Question 17

Tay-Sachs Disease

Answer 17

A human genetic disease caused by a recessive allele for a dysfunctional enzyme, leading to accumulation of certain lipids in the brain. Seizures, blindness, and degeneration of motor and mental performance usually become manifest a few months after birth, followed by death within a few years

Question 18

Phenotype

Answer 18

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

Question 19

Law of Segregation

Answer 19

Mendel’s first law, stating that the two alleles in a pair segregate (separate from each other) into different gametes during gamete formation

Question 20

Homozygote

Answer 20

An organism that has a pair of identical alleles for a gene (encoding a character)