Exam 1 PPTs - 4

Question 1

The simplest model of selection is for … at …

Answer 1

one favored allele;

one locus

Question 2

The simplest model of selection is for one favored allele at one locus:
Genotype: AA, Aa - chance of survival is 1
Genotype aa, chance of survival is 1 - s
s = …
chance of survival = … or simply …

Answer 2

selection coefficient;
relative fitness;
fitness

Question 3

industrial melanism in moths evolved by natural selection:

• the species was historically … color
• a … form was first recorded in 1848 near Manchester
• high frequency of the … form in polluted areas in the mid twentieth century
• in unpolluted areas, the … form remained common

Answer 3

peppered (light);
dark (melanic);
melanic;
light

Question 4

industrial melanism in moths evolved by natural selection:
- peppered form: homozygotes - …
- melanic form: homozygote …
- … allele is dominant
what happens with the fitness of the genotypes in polluted areas?

Answer 4

cc;
CC;
C

Question 5

industrial melanism in moths evolved by natural selection:

• Fitness of CC, Cc: …
• Fitness of cc: …

Answer 5

1;

1-s

Question 6

industrial melanism in moths evolved by natural selection:

• The melanic C gene had a frequency of … in 1848
• By 1898, the frequency increased to …

Answer 6

• 10^-5;

0. 8

Question 7

industrial melanism in moths evolved by natural selection:
- what happens with the fitness of the genotypes in unpolluted areas:
Fitness for CC, Cc:
Fitness for cc:

Answer 7

1 - s;

1

Question 8

selection can maintain a polymorphism when the … is fitter than …

Answer 8

heterozygote;

either homozygote

Question 9

when the heterozygote is fitter than either homozygotes:

• fitness of AA: …
• fitness of Aa: …
• fitness of aa: …

Answer 9

1 - s;
1;
1 - t

Question 10

Sickle cell disease:

• it is a nearly … condition in humans, responsible for about 100,000 deaths a year
• it is caused by a genetic variant of …

Answer 10

lethal;

alpha-hb

Question 11

Sickle cell disease: 
- A allele: normal hb
- S allele: sickle shaped hb 
- AA: normal individual 
- SS: sickle cell disease
About 80% of SS individuals ...

Answer 11

die before reproducing

Question 12

Sickle cell disease:

• attacks of …
• …
• … in the hands and feet
• …
• …

Answer 12

pain; 
anemia; 
swelling; 
bacterial infections; 
stroke

Question 13

sickle cell anemia is a polymorphism with … in malarial zones

Answer 13

heterozygous advantage

Question 14

The frequency of alleles can change at random through time in a process called …

Answer 14

genetic drift

Question 15

a small founder population may have a … sample of the ancestral population’s genes

Founder effect: the establishment of a new population by a few original founders (in an extreme case, by a …) which carry only a … of the total genetic variation of the parental population

Answer 15

non-representative;
single fertilized female;
small fraction

Question 16

founder effect:

chance of homozygosity =

Answer 16

[(p^2)^N + (q^2)^N]

Question 17

Founder events can have important consequences:

• The Afrikaner population of South Africa descended from one shipload of immigrants who landed in 1652
• The early colonists included individuals with a number of rare genes like the gene for …, a lethal … disease
• Most cases of the disease in the modern Afrikaner population can be traced back to …

Answer 17

Huntington’s disease;
autosomal dominant;
a Dutch man

Question 18

One gene can be … for another by random drift:

• the frequency of a gene is as likely to … as to … by random drift
• it is therefore possible for a gene to be carried up to a much … frequency. In the extreme case, its frequency could be carried up to …

Answer 18

substituted;
decrease; 
increase; 
higher; 
1

Question 19

neutral drift over time increases … and reduces …

Answer 19

homozygosity;

heterozygosity

Question 20

heterozygosity equation:

H =

Answer 20

1 - (p^2 + q^2)