CH 3 Basic Principles of Heredity

Question 1

an inherited factor that determines a characteristic

Answer 1

gene

Question 2

one of two or more alternative forms of a gene

Answer 2

allele

Question 3

a specific place on a chromosome occupied by an allele

Answer 3

locus

Question 4

a set of alleles possessed by an individual organism

Answer 4

genotype

Question 5

an individual organism possessing two of the same alleles at a locus

Answer 5

homozygote

Question 6

an individual organism possessing two different alleles at a locus

Answer 6

heterozygote

Question 7

an attribute or feature possessed by an organism

Answer 7

characteristic/character

Question 8

the appearance or manifestation of a characteristic

Answer 8

phenotype/trait

Question 9

crosses between parents that differed in a single characteristic

Answer 9

monohybrid crosses

Question 10

first generation of a cross

Answer 10

P (parental) generation

Question 11

offspring of the parents in the P generation

Answer 11

F1 generation

Question 12

second generation of offspring from crosses in F1 generation

Answer 12

F2 generation

Question 13

what are dominant traits

Answer 13

traits that appear unchanged in heterozygous offspring

Question 14

what are recessive traits

Answer 14

traits that disappear in heterozygous offspring

Question 15

what is Mendel’s first law? his second law?

Answer 15

First –> Law of segregation
Second –> Law of independent assortment

Question 16

describe Mendel’s law of segregation (first law)

Answer 16

1. each individual possesses two alleles encoding a trait
2. alleles separate when gametes are formed
3. alleles separate in equal proportions

Question 17

describe Mendel’s law of independent assortment (second law)

Answer 17

alleles at different loci separate independently

Question 18

cross between an F1 genotype and either of the parental genotypes

Answer 18

backcross

Question 19

what does it mean when events are independent? what rule is used to calculate the probability of independent events?

Answer 19

the outcome of one event doesn’t influence the other event
multiplication rule

Question 20

what does it mean when events are mutually exclusive?
what rule is used to calculate the probability of mutually exclusive events?

Answer 20

one event excludes the possibility of the other
addition rule

Question 21

what is a testcross?

Answer 21

an individual with an unknown genotype is crossed with another individual that is homozygous recessive for that trait

Question 22

in a testcross, if all the progeny displays the dominant phenotype, what does that reveal about the genotype of the unknown individual?

Answer 22

they were homozygous

Question 23

in a testcross, if half the progeny displays the dominant phenotype and half displays the recessive phenotype, what does that reveal about the genotype of the unknown individual?

Answer 23

they were heterozygous

Question 24

what is a dihybrid cross?

Answer 24

a cross between two organisms that differ in two characteristics

Question 25

what ratio results from a dihybrid cross between two heterozygous individuals?

Answer 25

9:3:3:1

Question 26

what ratio results from a dihybrid testcross between a heterozygote individual and homozygous recessive individual?

Answer 26

1:1:1:1 (1/4 each)

Question 27

in a chi-square goodness-of-fit test, what does a high probability mean?

Answer 27

assumes chance alone produced the deviation between observed and expected values

Question 28

in a chi-square goodness-of-fit test, what does a low probability mean?

Answer 28

assumes some other significant factor produced the deviation between observed and expected values