Biology Chapter 12: Genetics and Evolution

Question 1

Chromosomes

Answer 1

contain genes in a linear sequence

Question 2

Alleles

Answer 2

Alternate forms of a gene

Question 3

dominant allele

Answer 3

masks recessive allele and requires only one copy to be expressed.

Question 4

Recessive allele

Answer 4

Requires two copies to be expressed - masked by a dominant allele

Question 5

genotpe

Answer 5

combination of alleles one has at a given genetic locus.

Question 6

phenotype

Answer 6

observable manifestation of a genotype

Question 7

Penetrance

Answer 7

the proportion of a population with a given genotype.

Question 8

Medel’s first law of segregation

Answer 8

an organism has two alleles for each gene, which segregates during meiosis, resulting in gametes carrying only one allele for a trait.

Question 9

Mendel’s second law of independent assortment

Answer 9

state that the inheritance of one allele does not influence the probability of inheriting a given allele for a different trait.

Question 10

Griffith experiment

Answer 10

demonstrated the transforming principle, converting non-virulent bacteria to virulent bacteria by exposure to heat-killed virulent bacteria.

Question 11

Avery-MacLeod-McCarthy experiment

Answer 11

demonstrated that DNA is the genetic material because degradation of DNA led to a cessation of bacterial transformation

Question 12

Hershey-Chase

Answer 12

confirmed that DNA is the genetic material because only radiolabeled DNA could be found in bacteriophage-infected bacteria.

Question 13

Gene pool

Answer 13

All of the alleles in a given population.

Question 14

Point mutations

Answer 14

substitute one nucleotide for another

Question 15

Frameshift mutation

Answer 15

moving the three letter transcriptional reading frame

Question 16

Silent mutation

Answer 16

no effect on the protein

Question 17

Missense mutation

Answer 17

results in the substitution of one amino acid for another.

Question 18

Nonsense mutation

Answer 18

results in the substitution of a stop codon for an amino acid.

Question 19

Frame shift

Answer 19

caused by insertions and deletions

Question 20

Translocation

Answer 20

a segment of DNA is swapped with a segment of DNA from another chromosome

Question 21

Genetic leakage

Answer 21

a flow of genes between species through hybrid offspring

Question 22

Genetic drift

Answer 22

occurs when the composition of the gene pool changes as a result of change

Question 23

Founder effect

Answer 23

results from bottlenecks that suddenly isolate a small population, leading to inbreeding and increased prevalence of certain homozygous genotypes.

Question 24

Monohybrid cross

Answer 24

Accounts for one gene

Question 25

Dihybrid corss

Answer 25

Accounts for two genes

Question 26

Recombination frequency

Answer 26

the likelihood of the two alleles being separated during crossing over in meiosis. Genetic maps can be makde using recombination frequency as the scale in centimorgans.

Question 27

Hardy-Weinberg principle

Answer 27

states that if a population meets certain criteria (aimed at a lack of evolution), then the allele frequencies will remain constant

Question 28

Natural selection

Answer 28

States that chance variations exist between individuals and that advantageous variations - those that increase an individuals fitness for the environment - afford the most opportunity for reproductive success

Question 29

Modern synthesis model

Answer 29

accounts for mutation and recombination as mechanisms of variation and considers differential reproduction to be the mechanism of reproductive success.

Question 30

Inclusive fitness

Answer 30

considers an organism's success to be based on the number of offspring, success in supporting offspring or relatives ensures continuation of genes in subsequent generations

Question 31

Punctuated equilibrium

Answer 31

considers evolution to be a very slow process with intermittent rapid bursts of evolutionary activity.

Question 32

Stabilizing selection

Answer 32

keeps phenotypes in a narrow range, excluding extremes

Question 33

Directional selection

Answer 33

moves the average phenotype toward one extreme

Question 34

Disruptive selection

Answer 34

moves toward two different phenotypes at the extremes and can lead to speciation

Question 35

Adaptive radiation

Answer 35

the rapid emergence of multiple species from a common ancestor, each of which occupies its own ecological niche.

Question 36

Species

Answer 36

largest group of organisms capable of breeding to form fertile offspring. Species are reproductively isolated from each other by pre- or postzygotic mechanisms.

Question 37

Divergent evolution

Answer 37

occurs when two species sharing a common ancestor become more different

Question 38

Parallel evolution

Answer 38

occurs when two species sharing a common ancestor evolve in similar ways due to analogous selection pressures.

Question 39

Convergent evolution

Answer 39

occurs when two species not sharing a recent ancestor evolve to become more similar due to analogous selection pressures.

Question 40

Molecular clock model

Answer 40

the degree of difference in the genome between two species is related to the amount of time since the two species broke off from a common ancestor.