Chapter 12 - Patterns of Inheritance

Question 1

What evidence contradicted the idea that traits are directly passed from parent to offspring?

Answer 1

Crossing hybrids led to some offspring resembling original strains rather than the hybrid strains.

Question 2

Why did Gregor Mendel choose to study pea plants?

Answer 2

1. pea hybrids could be produced
2. many pea varieties available
3. peas are small and easy to grow
4. can self-fertilize or be cross-fertilized

Question 3

What were the 7 characters Mendel studied in his experiments?

Answer 3

• purple vs white flowers
• yellow seeds vs green seeds
• round seeds vs wrinkled seeds
• green pods vs yellow pods
• inflated pods vs constricted pods
• axial flowers vs terminal flowers
• tall plants vs dwarf plants

Question 4

Mendel’s experimental method:

Answer 4

1. produce true-breeding strains for each trait he was studying
2. cross-fertilize true-breeding strains having alternate forms of trait
   - perform reciprocal crosses as well
3. allow hybrid offspring to self-fertilize and count # of offspring showing each form of the trait

Question 5

Monohybrid cross:

Answer 5

a cross to study only 2 variations of a single trait

Question 6

F1 generation (1st filial generation):

Answer 6

offspring produced by crossing 2 true-breeding strains

Question 7

F2 generation:

Answer 7

offspring resulting from the self-fertilization of F1 plants

Question 8

Dominant:

Answer 8

the form of each trait expressed in the F1 plants

Question 9

Recessive:

Answer 9

the form of the trait not seen in the F1 plants

Question 10

Dominant to Recessive ratio in F2 plants (phenotype):

Answer 10

3:1

Question 11

Genotype ratio in F2 plants:

Answer 11

1 true-breeding dominant: 2 non-true-breeding dominant: 1 true-breeding recessive

Question 12

Gene:

Answer 12

information for a trait passed from parent to offspring

Question 13

Alleles:

Answer 13

alternate forms of a gene

Question 14

homozygous

Answer 14

having 2 of the same allele

Question 15

heterozygous

Answer 15

having 2 different alleles

Question 16

genotype

Answer 16

total set of alleles of an individual

Question 17

homozygous dominant

Answer 17

PP

Question 18

heterozygous

Answer 18

Pp

Question 19

homozygous recessive

Answer 19

pp

Question 20

phenotype

Answer 20

outward appearance of an individual

Question 21

Principle of Segregation

Answer 21

two alleles for a gene segregate during gamete formation and are joined at random, one from each parent, during fertilization

Question 22

The genotypes of potential offspring can be represented within a(n) ____________.

Answer 22

punnett square

Question 23

Dihybrid cross:

Answer 23

examination of 2 separate traits in a single cross

Question 24

Principle of Independent Assortment

Answer 24

(in a dihybrid cross) the alleles for each gene assort independently

Question 25

The probability of 2 mutually exclusive events occurring simultaneously

Answer 25

rule of addition

Question 26

The probability of 2 independent events occurring simultaneously

Answer 26

rule of multiplication

Question 27

test cross

Answer 27

a cross used to determine the genotype of an individual with dominant phenotype; cross individual w/ unknown genotype w/ a homozygous recessive

Question 28

polygenic inheritance

Answer 28

when multiple genes are involved in controlling the phenotype of a trait

Question 29

pleiotropy

Answer 29

an allele which has more than one effect on the phenotype ex. cystic fibrosis or sickle cell anemia

Question 30

incomplete dominance

Answer 30

the heterozygote is intermediate in phenotype between 2 homozygotes (blending)

Question 31

codominance

Answer 31

heterozygote shows some aspect of the phenotypes of both (equally shown)

Question 32

Sugars exhibited in type A blood:

Answer 32

galactosamine

Question 33

Sugars exhibited in type B blood:

Answer 33

galactose

Question 34

Sugars exhibited in type AB blood:

Answer 34

galactosamine and galactose

Question 35

Sugars exhibited in type O blood:

Answer 35

none

Question 36

epistasis

Answer 36

one gene can interfere with the expression of another gene (lab coat color)