Chapter 14: Mendel And The Gene Idea

Question 1

Character

Answer 1

An observable heritable feature that may vary among indiviudals such as flower color

Question 2

Trait

Answer 2

One of two or more detectable variants in a genetic character such as a purple or white flower

Question 3

Allele

Answer 3

Any of the alternative versions of a gene that may produce distinguishable phenotypic effects

Question 4

Dominant allele

Answer 4

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

Question 5

Recessive Allele

Answer 5

An allele whose phenotypic effect is not observed in a heterozygote

Question 6

Homozygote

Answer 6

An organism that has a pair of identical alleles for a gene

Question 7

Heterozygote

Answer 7

An organism that has two different alleles for a gene

Question 8

Heterozygous

Answer 8

Having two different alleles for a given gene

Question 9

The law of Segregation

Answer 9

The two alleles in a pair separate from each other into different gametes during gamete formation

Question 10

Phenotype

Answer 10

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

Question 11

Genotype

Answer 11

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

Question 12

Test Cross

Answer 12

Breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype

Question 13

Monohybrids

Answer 13

An organism that is heterozygous with respect to a single gene of interest

All of the offspring between parents that are homozygous for different alleles are monohybrids
AA + aa = Aa

Question 14

Monohybrids cross

Answer 14

A cross between two organisms that are heterozygous for the character being followed

Question 15

Dihybrids

Answer 15

An organism that is heterozygous with respect to two genes of interest.

All of the offspring from a cross between parents doubly homozygous for different alleles are dihybrids
AABB + aabb = AaBb

Question 16

The law of independent assortment

Answer 16

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

Question 17

Multiplication rule

Answer 17

A rule of probability stating that the probability of two or more independent events occurring together can be determined by multiplying their individual probabilities

One event and another

Question 18

Addition rule

Answer 18

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.

One event or another

Question 19

Complete dominance

Answer 19

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

Question 20

Incomplete dominance

Answer 20

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

Question 21

Codominance

Answer 21

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 22

Tay-Sachs Disease

Answer 22

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 performances usually become manifest a few months after birth, followed by death within a few years

Question 23

Pleiotropy

Answer 23

The ability of a single gene to have multiple effects

Question 24

Epistasis

Answer 24

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

Question 25

Polygenetic Inheritance

Answer 25

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

Question 26

Quantitative character

Answer 26

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

Question 27

Multi factorial

Answer 27

Referring to a phenotypic character that is influenced by multiple genes and environmental factors

Question 28

Pedigree

Answer 28

A diagram of a family read with conventional symbols, showing the occurrence of heritable characters in parents and offspring over multiple generations.