Chapter 18

Question 1

Incomplete dominance

Answer 1

Definition: Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely expressed over its paired allele. This results in a third phenotype in which the expressed physical trait is a combination of the phenotypes of both alleles.

Question 2

C O dominance

Answer 2

Alleles that are masked or hidden by dominant alleles are known as recessive alleles. In some situations both alleles are expressed equally. A genetic scenario where neither allele is dominant or recessive and both get expressed is known as codominance.

Question 3

Epistasis

Answer 3

the interaction of genes that are not alleles, in particular the suppression of the effect of one such gene by another.

Question 4

Polygenic

Answer 4

Polygenic inheritance occurs when one characteristic is controlled by two or more genes. Often the genes are large in quantity but small in effect. Examples of human polygenic inheritance are height, skin color, eye color and weight.

Question 5

Stabilizing Selection

Answer 5

Natural selection in which individuals expressing intermediate phenotypes have the best fitness

Question 6

Disruptive Selection

Answer 6

A type of natural selection in which individuals that have extreme phenotype characteristics have better fitness than intermediate characteristics

Question 7

Directional Selection

Answer 7

A type of selection in which individuals near one end of the phenotypic spectrum have the highest relative fitness