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BIOLOGY101 > EXAM 4 > Flashcards

EXAM 4 Flashcards

1
Q

In cellular communication, the first step of signaling pathway in which a signaling molecule is detected by a receptor molecule on or in the cell

A

Reception

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2
Q

In cell communication the conversion of a signal from outside the cell to a from that can bring about a specific cellular response

A

Transduction

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3
Q

In a cellular communication, the change in a specific cellular activity brought about by a transduced signal from outside the cell

A

Response

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4
Q

The signaling molecule that binds to a receptor

A

Ligand

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5
Q

Referring to a secreted molecule that acts on a neighboring cell

A

Paracrine signaling

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6
Q

Signals released from the end of a neuron, diffuse across a short space and bind to a target cell, triggering a response.

A

Synaptic signaling

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7
Q

Signaling by secreted chemicals that are formed in specialized endocrine cells, travels in body fluids, and act on specific target cells

A

Hormonal signaling

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8
Q

Signal Transduction Pathway diagram (pg216)

A 
A: Reception
B: Transduction
C: Response
D: Plasma membrane
E: Signaling molecule (Ligand)
F: receptor 
G: relay molecules
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9
Q

The enzymes that transfer phosphates from ATP to protein often activating the target protein, a process called phosphorylation

A

Protein kinases

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10
Q

The enzymes that remove the phosphates from proteins often deactivating the target protein, a process called dephosphorylation

A

Protein phosphatases

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11
Q

A series of chemical reactions during cell signaling mediated by kinases, in which each kinase in turn phosphorylates and activates another

A

Phosphorylation Cascade

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12
Q

Signal transduction enzyme cascades can increase the cell’s response by activating products much more than in the preceding step

A

amplification of the signal

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13
Q

Different kinds of cells have different collections of proteins and these different proteins allow cells to detect and respond to different signals

A

Specificity of the response

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14
Q

For an organism to remain capable of responding to incoming signals, each molecular change in its signaling pathways must last only a short time.

A

termination of the signal

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15
Q

Large relay proteins to which other relay proteins are attached that increase the signal transduction efficiency by grouping together different proteins

A

scaffolding proteins

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16
Q

A type of programmed cell death, which is brought about by activation of caspase enzymes

A

apoptosis

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17
Q

Which of the following best describes hormone signaling

A

Specialized endocrine cells release signal molecules into the circulatory system, permitting distant cells to be affected.

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18
Q

The three stages of signal transduction in a cell are

A

signal reception, signal transduction, and cellular response

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19
Q

One type of cell signaling is called paracrine signaling. This type of signaling

A

involves secreting cells acting on nearby target cells by discharging a local regulator into the extracellular fluid

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20
Q

Growth factors often bind to receptors called

A

receptor tyrosine kinases

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21
Q

Just after a receptor tyrosine kinase binds to a signal molecule

A

dimerization and phosphorylation occurs

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22
Q

A phosphorylation cascade uses ___ as the source of phosphate for signaling.

A

ATP

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23
Q

At the end of the Receptor Tyrosine Kinase signaling pathway a transcription factor is turned on. This will directly cause

A

the synthesis of mRNA

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24
Q

Signaling through elaborate phosphorylation cascades of several kinases is beneficial to a cell because

A

it amplifies the original signal manyfold

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25
Q

The type of protein that terminates signaling through a phosphorylation cascade by performing dephosphorylation is a(n)

A

phosphatase

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26
Q

Apoptosis involves all except which of the following?

A

lysis of the cell

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27
Q

The process of turning genes on and off that ensures the appropriate genes are expressed at the proper times. This process can also help an organism respond to its environment.

A

Gene regulation

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28
Q

A cluster of functionally related genes can be under coordinated control by a single “on-off switch”

A

Operon

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29
Q

A regulatory “switch” that is a segment of DNA usually positioned within the promoter

A

Operator

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30
Q

A protein that can switch off the operon by binding to the operator and blocking RNA polymerase

A

Repressor (Lac Repressor)

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31
Q

A molecule that inactivates the repressor to turn an operon on

A

Inducer (allolactose)

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32
Q

A protein that can increase gene expression for an operon

A

Activator (CRP)

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33
Q

When glucose (a preferred food source of E. coli) is scarce, CRP is activated by this small molecule

A

Cyclic AMP (cAMP)

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34
Q

Lac Operon

A 
A: DNA
B: mRNA
C: Proteins
D: Inducer
E: Lacl Repressor
F: Lac Operon
G: Regulatory gene
H: RNA polymerase
I: Operator
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35
Q

Expression of different genes by cells with the same genome resulting in differences between cell types.

A

Differential Gene Expression

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36
Q

Distal gene regulation control elements in eukaryotic cells that may be far away from a gene or even located in an intron

A

Enhancers

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37
Q

The developmental process that irreversibly commits a cell to becoming a particular cell type

A

Determination

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38
Q

The process by which cells become specialized in structure and function

A

Cell Differentiation

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39
Q

Normal cellular genes that are responsible for normal cell growth and division that can be mutated to increase cell division and cause cancer

A

Proto-oncogenes

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40
Q

Cancer-causing mutated genes that promote excess cell division like mutated ras

A

Oncogenes

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41
Q

Genes that prevent uncontrolled cell growth that can be mutated to contribute to cancer like p53

A

tumor-suppressor gene

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42
Q

The idea that multiple mutations are generally needed to cause full-fledged cancer; thus the incidence increases with age

A

Multi step model of cancer

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43
Q

The type of gene that produces repressor and activator proteins

A

Regulatory gene (lacl)

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44
Q

In bacteria, a set of genes that is controlled as a single unit is called a(n)

A

operon

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45
Q

The LacI repressor protein blocks transcription of the lac operon by binding to which of these?

A

the operator

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46
Q

For the lac operon, the repressor protein is deactivated when the ___ is present inside the cell increasing the amount of lac operon transcription .

A

inducer

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47
Q

Which of these turns on a eukaryotic gene by binding to an enhancer?

A

Activator

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48
Q

In both prokaryotes and eukaryotes, which of the following is an important part of gene regulation?

A

controlling the attachment on RNA polymerase to the promoter

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49
Q

All of the different types of cells in a person come from the one cell created by fertilization; the fusion of an egg cell with a sperm cell. Amazingly, almost all of the cells in us have all of the DNA that was in that original cell but are cells become very different from one another. What process below makes our cells distinct even though they have the same genes?

A

differential gene expression

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50
Q

The process that makes cells become more specialized in structure and function like muscle cells is called

A

cell differentiation

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51
Q

As people get older their risk of cancer increases because

A

the longer we live, the more mutations accumulate

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52
Q

Cancer is caused by changes in specific types of genes. Which of the genetic changes below is most likely to cause cancer in a person?

A

mutations in proto-oncogenes and inactivation of a tumor suppressor gene

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53
Q

In breast cells the receptor tyrosine kinase HER2 is expressed and responds to growth factors causing cell division. A new therapeutic called Herceptin binds to HER2 and inhibits signaling. Herceptin should be used to treat breast cancer under which of these circumstances?

A

If patient’s cancer cells have high levels of HER2

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54
Q

The branch of biology concerned with classifying and naming organisms

A

Taxonomy

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55
Q

Remains or traces of organisms from the past, usually found in sedimentary rock

A

Fossils

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56
Q

The study of fossils, that was largely developed by French scientist Georges Cuvier

A

Paleontology

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57
Q

Favorable inherited traits for the environment a species live in

A

Adaptations

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58
Q

A process in which individuals with favorable inherited traits are more likely to survive and reproduce

A

Natural selection

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59
Q

The process in which humans have modified other species by selecting and breeding individuals with desired traits.

A

Artificial selections

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60
Q

Argument for Natural selection:
Individuals in a population___ identical in their heritable characteristics
Organisms produce _____ offspring than the environment can support
Individuals that are more suited to their environment tend to leave ____ offspring than other individuals
Over time, ____ traits accumulate in the population

A

Vary
More
More
Favorable

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61
Q

Similarity between organisms resulting from common ancestry

A

Homology

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62
Q

Remnants of features that served important functions in the organisms ancestors

A

Vestigial traits

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63
Q

Is the evolution of similar, or analogous, features in distantly related groups

A

Convergent Evolution

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64
Q

Depiction of the hypothesis about the relationships among different groups and show that homolgies form nested patterns

A

Evolutionary trees

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65
Q

The history of life on earth written in the remains of organisms that is evidence of the extinction of species, and changes within groups over time

A

Fossil record

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66
Q

The geographic distribution of species, provides evidence of evolution

A

Bio geography

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67
Q

Layers of sedimentary rock that can contain fossils

A

Strata

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68
Q

Charles Darwin made important contributions to our understanding of how populations evolve but he did not discover everything. Of the statements below, which is correct about Darwin’s contributions?

A

He proposed natural selection as the mechanism of evolution

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69
Q

Which of the following people below was the first scientist to recognize that evolutionary change explains patterns in fossils and the match of organisms to their environments but incorrectly proposed that the mechanism for evolution was the use and disuse of traits.

A

Lamarck

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70
Q

Darwin incorporated which of these ideas from Malthus into his mechanism of natural selection?

A

populations tend to increase at a faster rate than their food supply normally allows

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71
Q

Before Darwin published On the Origin of Species most biologists thought that animals and plants never changed and each species was independent and unrelated to any other species. However, during the time that Darwin lived, observations of fossils and homologous structures in living organisms showing underlying similarities specifically suggested to biologists that ___ .

A

dissimilar organisms might have evolved from a distant, common ancestor

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72
Q

You can summarize the scientific theory of evolution as

A

an overarching explanation, supported by much evidence, for how populations change overtime

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73
Q

Darwin developed the mechanism of natural selection to explain how evolution happens. Which of the options below best describes the mechanism of natural selection?

A

Organisms better adapted to their immediate environment are most likely to survive and reproduce

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74
Q

The mechanism of natural selection relies on ___ to determine which traits will be successful.

A

the environment

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75
Q

Given a population that contains genetic variation, what is the correct sequence of the following events, under the influence of natural selection?

Genetic frequencies within the population change.
Poorly adapted individuals have decreased survivorship.
A change occurs in the environment.
Well-adapted individuals leave more offspring than do poorly adapted individuals.
A

3-2-4-1

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76
Q

On an island, a species of rabbit has two fur colors, tan and gray. One population of rabbits lives on the western side of the island where there are gray rocky beaches and another rabbit population lives on the eastern side of the island where there are tan sandy beaches. A species of falcon on the island is constantly hunting the rabbits. On this island, natural selection will cause which of the following to occur?

A

Since tan rabbits blend better with the sandy beaches and gray rabbits blend better with the rocky beaches, the amount of tan rabbits will increase on the east side of the island and the number of gray rabbits will increase on the west side of the island.

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77
Q

Mosquitoes transmit many diseases including malaria. The pesticide DDT has been used for decades to reduce the number of mosquitoes but now it is much less effective that it used to be because ___.

A

many mosquitoes today are descendants of mosquitoes with insecticide-resistant characteristics

78
Q

Homologous structures like the wings of an eagle and the wings of a hummingbird provide evidence for which of these?

A

common ancestry

79
Q

Which of the following pairs of traits is an example of convergent evolution?

A

the wings of a dragonfly and the wings of a hawk

80
Q

In dolphin flippers, the bones are homologous to the bones in the ___ of a cat.

A

front limbs

81
Q

Which of these is the strongest evidence that all life on Earth is related back to a single common ancestor?

A

All organism use essentially the same genetic code

82
Q

The finches on the Galapagos islands are more similar to the finches of South America than to finches anywhere else in the world. This type of evidence for common ancestry comes from

A

bio geography

83
Q

Microevolution states which of the following?

A

populations are the units of evolution

84
Q

A natural population can be described as

A

a group of individuals of the same species occupying a given area that interbreed

85
Q

Which of the following is the only source for new gene variations in a population?

A

mutation

86
Q

What is the term for all copies of every type of allele at every locus in all members of the population?

A

gene pool

87
Q

When analyzing the population genetics of a single gene with 2 alleles the Hardy-Weinberg theorem states that p + q = 1. The 1 in this equations represents ___.

A

the sum of the frequencies of both alleles in a gene pool

88
Q

In the Hardy-Weinberg formula, 2pq represents _____.

A

the frequency of heterozygous individuals in the gene pool

89
Q

If the frequency of a dominant allele is 0.2, what is the frequency of the recessive allele?

A

0.80

90
Q

The presence of freckles is due to a dominant allele. 16% of the individuals in a particular population lack freckles. Use the Hardy-Weinberg formula to calculate the percentage of individuals in this population who are homozygous dominant for freckles

A

36%

91
Q

Which of the following conditions not required for Hardy-Weinberg equilibrium?

A

non-random mating

92
Q

The mechanism of evolution called genetic drift is caused by

A

chance events

93
Q

Of the options below, which describes gene flow the best?

A

Wind blows pollen from one population of plants to another, and cross-fertilization occurs.

94
Q

Genetic drift has the greatest impact on the allele frequencies of a population when _____

A

the population size is small

95
Q

A small number of birds of the same species migrate from an island to found a population on a newly formed volcanic island. The population grows to the point where it consists of as many individuals as the population on the original island. Which of the following statements is most likely to apply to this population of birds on the newly formed volcanic island?

A

The new island population exhibits less genetic variation than the old island population.

96
Q

Which of the following allows for gene flow between populations?

A

migration

97
Q

A sudden change in the environment, such as a fire or flood, that drastically reduces the size of a population leading to changes in allele frequencies is called __

A

the bottleneck effect

98
Q

Students that are new to the theory of evolution by natural selection are often surprised that the process can produce an organism with greater relative fitness because mutations are random changes. Which statement explains how greater relative fitness evolves even though mutations are random?

A

mutation is random but natural selection causes adaptive mutations to accumulate over time

99
Q

Relative fitness is best described as

A

reproductive success

100
Q

Birds with longer and shorter wings survive in a region that has many severe storms more successfully than other birds in the same population with average-sized wings. This illustrates _

A

disruptive selection

101
Q

A population of squirrels is preyed on by small hawks. Only the smallest squirrels can escape into burrows. After several generations, the squirrels in the area tend to be very small. What process is responsible for this outcome?

A

directional selection

102
Q

Adult male peacocks have colored feathers and compete for female mates. The coloration of the male feathers is best explained as the result of ________, and specifically of ________.

A

sexual selection; intrasexual selection

103
Q

Which of the following represents evolutionary change above the species level like the origin of a new group of organisms through a series of speciation events and the impact of mass extinctions on the diversity of life and its subsequent recovery?

A

macroevolution

104
Q

According to the Biological Species Concept, two individuals would be considered part of separate species if they

A

cannot interbreed

105
Q

Unfortunately, the biological species concept is not useful for all organisms. It cannot be applied to which of the organisms below?

A

bacteria that only reproduce asexually

106
Q

We can use the morphological species concept to describe a fossil species based on

A

its body shape

107
Q

Reproductive isolation that happens before mating is called ___.

A

a prezygotic barrier

108
Q

Two species of frogs in the same pond mate but do not produce viable fertile offspring because the sperm of each species cannot fertilize the eggs of the other species. The reproductive barrier between them is an example of

A

gametic isolation

109
Q

Which of the following best describes sympatric speciation?

A

It is the appearance of a new species in the same area as the parent population.

110
Q

Speciation that occurs when a population is divided into geographically isolated subpopulations preventing gene flow is called

A

allopatric speciation

111
Q

Although very rare, some plants species have been documented to arise in a single generation

A

if a polyploidy event creates a reproductive barrier.

112
Q

If a new species of plant is to be produced by means of allopolyploidy from two parental species that are 2n = 10 and 2n = 14, how many chromosomes would you expect in the somatic cells of the new species?

A

24

113
Q

Which of the following is the best definition of a hybrid zone?

A

an area where mating occurs between members of two closely related species, producing viable offspring

114
Q

Which of these describes the way that speciation between two populations is slowed down by hybrid zones

A

incomplete reproduction isolation

115
Q

A pattern of evolution in which species diverge from one another more slowly and steadily over time fits the ______ model of speciation

A

gradualistic

116
Q

You are examining the fossil record and notice that through time there are abrupt changes resulting in speciation followed by long periods of no change. The model for the tempo of speciation that best fits this description is

A

punctuated equilibrium

117
Q

The Hardy-Weinberg equation can be used to test whether evolution is occurring in a population. Let’s use the Hardy-Weinberg equation to investigate the evolution of the population below. In particular, the Hardy-Weinberg equation makes it possible to predict the genetic make up of the next generation of a population like Mendelian genetics is used to predict the genetics of children for two parents.

An example population has 700 individuals: 85 of genotype AA, 320 of genotype Aa, and 295 of genotype aa. The first step in this process is to determine the gene pool of our population by counting up the number of each allele, A and a.

A

Total # of A alleles 85(2)+1(320)= 490
total # of a alleles: 910
total #: 490+910=1400

what is the frequency of A:490/1400= 0.35
frequency of a: 0.65

p^2+2pq+q^2
predicted AA genotype frequency p^2: 0.1225
Aa 2pq: 0.455
aa q^2: 0.4255

Next gen 10000 : 500AA; 4500 Aa, 5000 aa
(multiply 10000 with frequency)
AA: 1225
Aa: 4550
aa: 4225

Evolution?
Yes the number of AA individuals is lower and the number of aa individuals higher than predicted

118
Q

The Hardy-Weinberg equation ( p2 + 2pq + q2 = 1) can be used in several ways to investigate population genetics. In the problem below we will use the Hardy-Weinberg equation in a slightly different way to investigate the frequency of a human disease and the allele that causes it.

Phenylketonuria (PKU) is a recessive human metabolic disease. We will use the Hardy-Weinberg equation to investigate the why this disease continues to occur in humans.

The occurrence of PKU is the United States population is 1 child born with PKU per 10,000 births.

A
  1. 0001
  2. 01
  3. 9
  4. 18
119
Q

A change in allele frequencies (evolution) in a population over generations

A

Microevolution

120
Q

A localized group of individuals capable of interbreeding and producing fertile offspring

A

Population

121
Q

All the alleles for all loci in a population

A

Gene pool

122
Q

The proportion of each allele in a population

A

Allele frequency

123
Q

Hardy-Weinberg equilibrium equation for population genetics

A

p^2+2pq+q^2

124
Q

The frequency of the homozygous genotypes

A

p^2 and q^2

125
Q

The frequency of the heterozygous genotypes

A

2pq

126
Q

How allele frequencies generally fluctuate unpredictably from one generation to the next

A

Genetic drift

127
Q

Genetic drift that occurs when a few individuals become isolated from a larger population

A

Founder effect

128
Q

Genetic drift that occurs when there is a sudden reduction in population size due to a change in the environment

A

Bottleneck effect

129
Q

The movement of alleles among populations

A

gene flow

130
Q

The mechanism of evolution that consistently results in adaptive evolution

A

natural selection

131
Q

Mechanisms of evolutionary change

Gen 1

A 
14
6
20
0.7
0.3
132
Q

Mechanisms of evolutionary change

Gen 2

A 
10
10
20
0.5
0.5
133
Q

Comparing the allele frequencies in Generation 1 and Generation 2, is evolution occurring in this population?

If evolution is occurring, what mechanism of evolution is causing the change in allele frequency?

A

Yes p and q change from gen 1 to gen 2

Genetic drift

134
Q

Modes of natural selection

A 
original pop
evolved pop
directional selection
disruptive selection
stabilizing selection
135
Q

The pattern of natural selection that favors individuals at one end of the phenotypic range

A

directional selection

136
Q

The pattern of natural selection that favors individuals at both extremes of the phenotypic range

A

disruptive selection

137
Q

The pattern of natural selection that favors intermediate variants and acts against extreme phenotypes

A

stabilizing selection

138
Q

Natural selection that selects for mating success traits

A

sexual selection

139
Q

Marked differences between the sexes in secondary sexual characteristics that results from sexual selection

A

sexual dimorphism

140
Q

Competition among individuals of one sex (often males) for mates of the opposite sex

A

intrasexual selection

141
Q

Often called mate choice, a selection that occurs when individuals of one sex (usually females) are choosy in selecting their mates

A

intersexual selection

142
Q

Microevolution states which of the following?

A

populations are the units of evolution

143
Q

a natural population can be described as:

A

a group of individuals of the same species occupying a given area that interbreed

144
Q

Which of the following is the only source for new gene variations in a population

A

mutation

145
Q

What is the term for all copies of every type of allele at every locus in all members of the population

A

gene pool

146
Q

When analyzing the population genetics of a single gene w (2) alleles the H-W theorem states that p+q=1 the 1 in this equation represents?

A

the sum of the frequencies of both alleles in a gene pool

147
Q

In the H-W formula 2pq represents

A

the frequency of heterozygous individuals in a gene pool

148
Q

if the frequency of a dominant allele is 0.2 what is the frequency of the recessive allele

A

0.80

149
Q

the presence of freckles is due to a dominant allele 16% of the individuals in a particular population lack freckles. use the H-W formula to calculate the % of individuals in this population who are homozygous dominant for freckles

A

36%

150
Q

Which of the following conditions not required for H-W equilibrium

A

non-random mating

151
Q

The mechanism of evolution called genetic drift is caused by

A

chance events

152
Q

of the options below, which describes gene flow the best

A

wind blows pollen from one population of plants to another, and cross fertilization occurs

153
Q

genetic drift has the greatest impact on the allele frequencies of a population when

A

the population size is small

154
Q

a small # of birds of the same species migrate from an island to found a population on a newly formed volcanic island. the population grows to the point where it consists of as many individuals as the population on the original island. which of the following statements is most likely to apply to this population of birds on the newly formed volcanic island?

A

the new island population exhibits less genetic variation than the old island population

155
Q

which of the following allows for gene flow btwn populations

A

migration

156
Q

a sudden change in environment that drastically reduces the size of a population leading to changed in allele frequencies is called

A

the bottleneck effect

157
Q

Students that are new to the theory of evolution by natural selection are often surprised that the process can produce an organism with greater relative fitness because mutations are random changes. Which statement explains how greater relative fitness evolves even though mutations are random?

A

mutation is random but natural selection causes adaptive mutations to accumulate overtime

158
Q

Relative fitness is best described as

A

reproductive success

159
Q

birds with longer and shorter wings survive in a region that has many severe storms more successfully than other birds in the same population with average-sized wings. this illustrates

A

disruptive selection

160
Q

A population of squirrels is preyed on by small hawks. Only the smallest squirrels can escape into burrows. After several generations, the squirrels in the area tend to be very small. What process is responsible for this outcome?

A

directional selection

161
Q

Adult male peacocks have colored feathers and compete for female mates. The coloration of the male feathers is best explained as the result of ________, and specifically of ________.

A

sexual selection; intrasexual selection

162
Q

The origin of new species also know as “the mystery of mysteries”.

A

Speciation

163
Q

Broad patterns of evolutionary change above the species level that is the cumulative effect of many speciation and extinction events

A

Macroevolution

164
Q

The general term for the existence of biological factors (barriers) that impede two species from reproducing

A

Reproductive Isolation

165
Q

The offspring of crosses between two different species

A

Hybrids

166
Q

The type of reproductive barrier that blocks fertilization from occurring

A

Prezygotic barrier

167
Q

The type of reproductive barrier that prevents the hybrid zygote from developing into a viable, fertile adult. This type of barrier sometimes results in hybrids.

A

postzygotic barrier

168
Q

A species model that states that a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring and they do not breed successfully with other populations

A

The biological species concept

169
Q

Reproductive barriers

A 
Presygotic barriers
mating attempt
fertilization
postzygotic barriers
fertilization
viable and fertile offspring
170
Q

Speciation that occurs when gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations

A

allopatric speciation

171
Q

Speciation that takes place in geographically overlapping populations through genetic changes (polyploidy), habitat differentiation, or sexual selection

A

sympatric speciation

172
Q

The general term for the presence of extra sets of chromosomes due to accidents during cell division

A

polyploidy

173
Q

A species with more than two chromosome sets, derived from one species

A

autopolyploid

174
Q

A species with multiple sets of chromosomes derived from different species

A

allopolyploid

175
Q

A model of evolution with periods of apparent stasis punctuated by sudden change during the evolutionary history of species

A

punctuated equilibrium

176
Q

A model of evolution which theorizes that most speciation is slow, uniform and gradual during the evolutionary history of species

A

gradualism

177
Q

Which of the following represents evolutionary change above the species level like the origin of a new group of organisms through a series of speciation events and the impact of mass extinctions on the diversity of life and its subsequent recovery?

A

macroevolution

178
Q

According to the Biological Species Concept, two individuals would be considered part of separate species if they

A

cannot interbreed

179
Q

Unfortunately, the biological species concept is not useful for all organisms. It cannot be applied to which of the organisms below?

A

bacteria that only reproduce asexually

180
Q

We can use the morphological species concept to describe a fossil species based on

A

its body shape

181
Q

Reproductive isolation that happens before mating is called ___.

A

prezygotic barrier

182
Q

Of the options below, which one is a postzygotic barrier?

A

the production of sterile hybrids

183
Q

Two species of frogs in the same pond mate but do not produce viable fertile offspring because the sperm of each species cannot fertilize the eggs of the other species. The reproductive barrier between them is an example of _____.

A

gametic isolation

184
Q

Which of the following best describes sympatric speciation?

A

it is the appearance of a new species in the same area as the parent population

185
Q

Speciation that occurs when a population is divided into geographically isolated subpopulations preventing gene flow is called ___.

A

allopatric speciation

186
Q

Although very rare, some plants species have been documented to arise in a single generation

A

if a polyploidy event creates a reproductive barrier

187
Q

If a new species of plant is to be produced by means of allopolyploidy from two parental species that are 2n = 10 and 2n = 14, how many chromosomes would you expect in the somatic cells of the new species?

A

24

188
Q

Which of the following is the best definition of a hybrid zone?

A

an area where mating occurs between members of two closely related species, producing viable offspring

189
Q

Which of these describes the way that speciation between two populations is slowed down by hybrid zones?

A

incomplete reproductive isolation

190
Q

A pattern of evolution in which species diverge from one another more slowly and steadily over time fits the ______ model of speciation.

A

gradualistic

191
Q

You are examining the fossil record and notice that through time there are abrupt changes resulting in speciation followed by long periods of no change. The model for the tempo of speciation that best fits this description is ___.

A

punctuated equilibrium

BIOLOGY101 (3 decks)

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