Biology 192 ch. 14

Question 1

Law of Dominance

Answer 1

When 2 different genes code for different forms of a trait, one gene can be expressed while the other is not. Seen in interphase.

Question 2

Law of Segregation

Answer 2

Genes from each parent remain distinct and do not blend together. Seen in anaphase 1. Applies to many traits.

Question 3

Law of Independent Assortment

Answer 3

Pairs of factors for one trait assort themselves independently of pairs of factors for other traits. Seen in metaphase 1. Applies when you’re looking at 2 traits.

Question 4

Why Mendel chose the garden pea

Answer 4

Natural self-pollinators. Many inherited traits seen in one of two forms. Short reproductive cycle. Manageable size. Easy availability of many varieties.

Question 5

Self-pollination

Answer 5

Purebred offspring. Homozygous. Can show dominant or recessive forms.

Question 6

Cross-pollination

Answer 6

Hybrid offspring. Heterozygous. Only shows dominant forms.

Question 7

Trait

Answer 7

Any characteristic that can be passed genetically from parent to offspring

Question 8

Genotype

Answer 8

The description of the genes (alleles) controlling a specific trait

Question 9

Phenotype

Answer 9

The appearance of a trait governed by the controlling pair of genes (alleles)

Question 10

Gametes

Answer 10

Haploid cells containing 50% of an organism’s genotype

Question 11

Zygote

Answer 11

Diploid cell that combines the genes from each parent

Question 12

Hybrid

Answer 12

Organism that has alleles for 2 different forms of a trait (= heterozygous)

Question 13

Monohybrid

Answer 13

A hybrid for one trait. Phenotypic ratio in F2 generation of a monohybrid cross is 3:1.

Question 14

Dihybrid

Answer 14

A hybrid for two traits. Phenotypic ratio in F2 generation of a dihybrid cross is 9:3:3:1.

Question 15

Mendelian Traits

Answer 15

Only 2 forms of a trait exist. One form is dominant and one is recessive.

Question 16

Affected state

Answer 16

Allele for disease present and causes disease

Question 17

Carrier state

Answer 17

Allele for disease present but not seen (only possible for a recessive disease)

Question 18

Unaffected state

Answer 18

Alleles both code for normality

Question 19

Codominance

Answer 19

Alleles for a trait are both fully expressed in a heterozygote

Question 20

Multiple alleles

Answer 20

More than two forms of alleles exist for a trait (each person can only have two of these alleles)

Question 21

Incomplete dominance

Answer 21

One form is expressed fully but the other form is expressed partially in a heterozygote

Question 22

Polygenic traits

Answer 22

A trait is coded for by many different pairs of alleles

Question 23

Alleles

Answer 23

Pairs of genes on homologous chromosomes that control the same trait. Alleles may or may not code in the same way.