chapter 14

Question 1

What is a character?

Answer 1

distinct heritable features; genes

Question 2

What is a trait?

Answer 2

character variants; alleles

Question 3

Give an example of a character used by Mendel that has two traits.

Answer 3

Answer could be any of the following: Flower color, flower position, seed color, seed shape, pod shape, pod color, stem length

Question 4

What are characters and traits in modern terminology?

Answer 4

Characters are genes, traits are alleles

Question 5

Describe Mendel’s four-point hypothesis

Answer 5

1) Alternative versions of genes account for variations in inherited characters
2) For each character, an organism inherits two alleles, one from each parent
3) If the two alleles at a locus differ, then one (the dominant allele) determines the organism’s appearance, and the other (the recessive allele) has no noticeable effect on appearance
4) Law of Segregation: the two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes

Question 6

What is a monohybrid cross?

Answer 6

A cross between two individuals that are heterozygous for one gene

Question 7

What is a dihybrid cross?

Answer 7

A cross between two individuals that are heterozygous for two genes

Question 8

State the law of segregation.

Answer 8

The two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes

Question 9

State the law of independent assortment.

Answer 9

Each pair of alleles segregates independently of each other pair of alleles during gamete formation

Question 10

In Mendel’s experiment, what is meant by the P, F1, and F2 generations? Which generation is entirely homozygous? Which is entirely heterozygous? Which is both?

Answer 10

P = parent; F1 = first generation; F2 = second generation. P is homozygous. F1 is heterozygous. F2 is both.

Question 11

In which stage in meiosis do the alleles for character segregate during gamete formation?

Answer 11

Anaphase 1

Question 12

In what stage of meiosis does independent assortment of chromosomes occur?

Answer 12

Metaphase 1

Question 13

Complete dominance

Answer 13

when phenotypes of the heterozygous and dominant homozygote are identical

Question 14

Incomplete dominance

Answer 14

the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties

Question 15

Codominance

Answer 15

two dominant alleles affect the phenotype in separate, distinguishable ways

Question 16

Compare the inheritance pattern of dominant and recessive inherited disorders.

Answer 16

Recessively inherited disorders show up only in individuals homozygous for the allele whereas expression of dominant disorders only requires one copy of the allele

Question 17

What is a carrier?

Answer 17

heterozygous individuals who carry the recessive allele but are phenotypically normal

Question 18

true breeding

Answer 18

a homozygous individual

Question 19

hybrid

Answer 19

a heterozygous individual

Question 20

alleles

Answer 20

the alternative versions of a gene

Question 21

dominant

Answer 21

the allele that determines the organism’s appearance

Question 22

recessive

Answer 22

the allele that has no noticeable effect on appearance unless the organisms is homozygous

Question 23

homozygous

Answer 23

the two alleles at a particular locus are identical

Question 24

heterozygous

Answer 24

the two alleles at a locus differ

Question 25

phenotype

Answer 25

physical characteristics

Question 26

genotype

Answer 26

genetic makeup

Question 27

heritable feature

Answer 27

character that can be passed down to offspring

Question 28

locus

Answer 28

location of a gene on a chromosome