Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Bio 4 Midterm 4 > Chapter 23 > Flashcards

Chapter 23 Flashcards

1
Q

What does natural selection act on and what evolves?

A

natural selection acts on individuals, but only populations evolve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is genetic variation?

A

genetic variation among individuals is caused by differences in genes or other DNA segments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how can new genes and alleles arise?

A

new genes and alleles can arise by mutation or gene duplication, but sexual reproduction can result in genetic variation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how does sexual reproduction act with alleles?

A

sexual reproduction can shuffle existing alleles into new combinations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the most important in producing genetic differences?

A

sexual reproduction in organisms that produce sexually, more important than mutations; make adaptation possible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what does the hardy-weinberg equation test?

A

the hardy-weinberg equation can be used to test whether a population is evolving

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is a population?

A

a population is a localized group of individuals capable of interbreeding and producing fertile offspring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what does a gene pool consist of?

A

a gene pool consists of all the alleles for all loci in a population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

when is a locus fixed?

A

a locus is fixed if all individuals in a population are homozygous for the same allele

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is a community?

A

a community is an assemblage of populations of various species living close enough for potential interaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the total number of alleles for a diploid organism?

A

the number of individuals x 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the total number of dominant alleles at a locus?

A

two alleles for each homozygous dominant, plus one allele for each heterozygous individual (also applies to recessive)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

if there are two alleles at a locus, what is used to represent their frequencies?

A

p + q = 1
- frequency of alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

if there are 320 red flowers and 160 pink flowers and 20 white flowers, how many copies of each allele, and what is the frequency?

A

dominant: (320 x 2) + 160 = 800
recessive: (20 x 2) + 160 = 200
P: 800/ (800+200) = .8
Q: 200/ (800+200) = .2
.8 + .2 = 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how does hardy-weinberg suggest that a population may be evolving?

A

if the observed genetic makeup of the population differs from expectations under hardy-weinberg, it suggest that the population may be evolving

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is Hardy-Weinberg equilibrium?

A

in a population where gametes contribute to the next generation randomly and Mendelian inheritance occurs, allele and genotype frequencies remain constant from generation to generation
- describes the constant frequency of alleles in such a gene pool

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what does p^2 represent?

A

p^2 represents homozygous dominant

18
Q

what does 2pq represent?

A

2pq represents heterozygous

19
Q

what does q^2 represent?

A

q^2 represents homozygous recessive

20
Q

what is the quadratic and what is it used to represent?

A

p^2 + 2pq + q^2 = 1
- if p and q represent the relative frequencies of the only two possible alleles in a population at a particular loces
- used for frequency of genotypes

21
Q

what are the five assumptions for non-evolving populations?

A

no mutations, random mating, no natural selection, extremely large population size (avoid genetic drift), no gene flow

22
Q

what three major factors alter allele frequencies and bring about most evolutionary change?

A

natural selection, genetic drift, and gene flow

23
Q

does random or nonrandom mating cause evolution?

A

nonrandom mating causes evolution, but random mating is whoever you bump into that you mate with

24
Q

what can natural selection cause?

A

natural selection can cause adaptive evolution, which is an improvement in the match between organisms and their environment

25
Q

what is genetic drift?

A

genetic drift describes how allele frequencies fluctuate unpredictably from one generation to the next, tends to reduce genetic variation through loss of alleles
- the smaller a sample, the greater chance of random deviation

26
Q

what are the two types of genetic drift?

A

the founder and bottleneck effects

27
Q

what is the founder effect?

A

occurs when a few individuals become isolated from a larger population, and the small population starts their own with their own allele frequencies

28
Q

what is the bottleneck effect?

A

a sudden reduction in population size due to a change in the environment, the gene pool is not the original gene pool and population can become small
ex: natural disasters, earthquake,

29
Q

what is gene flow?

A

gene flow consists of the movement of alleles among populations (fancy way of saying members between two populations mate and transfer alleles)

30
Q

does gene flow reduce or increase genetic variation?

A

gene flow reduces genetic variation between two populations because they are ultimately sharing alleles and reducing differences

31
Q

what is directional selection? what moves?

A

directional selection: favors individuals at one extreme end of phenotypic range
- moves either left or right

32
Q

what is disruptive selection? what moves?

A

disruptive selection: favors individuals at both extremes of phenotypic range
- original is not favored anymore so there are 2 peaks
- the top gets pushed in and looks like an M

33
Q

what is stabilizing selection? what moves?

A

stabilizing selection: favors intermediate variants and acts against extreme phenotypes
- reinforces the regular mean so the peak gets higher

34
Q

what is sexual selection?

A

sexual selection is natural selection for mating success

35
Q

what can sexual selection result in?

A

dimorphism: marked differences between the sexes in secondary sexual characteristics, males need to impress but females need to choose

36
Q

what has a bigger impact, gene duplications or point mutations?

A

gene duplications because it brings more DNA, worst thing is insertion or deletion

37
Q

intrasexual selection vs intersexual selection

A

intrasexual is when males compete for women
intersexual is when females are picky with their mates
intra: between one group
inter: between two groups

38
Q

what does diploidy do?

A

diploidy maintains genetic variation in the form of recessive alleles hidden from selection in heterozygotes

39
Q

when does balancing selection occur?

A

balancing selection occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population
- includes heterozygote advantage and frequency dependent selection

40
Q

what is heterozygote advantage?

A

heterozygote advantage occurs when heterozygotes have a higher fitness than do both homozygotes

41
Q

how does heterozygote advantage work with sickle cell?

A

homozygote recessive have sickle cell, homozygote dominant have no resistance, but heterozygotes can’t get malaria

Bio 4 Midterm 4 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions