BIOL ch. 4 & 19
Select all that apply What was typical of ideas about the origin and diversity of species before the 1700s?
-People thought that each individual form of life was created and then remained the same. -Life-forms were regarded as fixed and unchanging.
Match each type of selection with the phenotype(s) it favors.
-directional selection: favors one extreme phenotype -stabilizing selection: favors the intermediate phenotype -diversifying selection: favors both extreme phenotypes but selects against intermediate phenotypes -balancing selection: favors heterozygosity, or can favor the uncommon allele
Match the shapes of Galápagos finches to the feeding habits noted by Darwin.
-tree finches: grasping or probing beaks for picking insects -Ground finches: crushing beaks for eating seedings -cactus finches: probing beaks for opening up fruits
A particular gene segregates two alleles, and the dominant allele has a frequency of 0.9. What is the frequency of the recessive allele?
0.1
A student proposes that left-handedness is a recessive trait. A survey of a class of 36 students finds that 27 (0.75) are right-handed and 9 (0.25) are left-handed. If this population is in Hardy-Weinberg equilibrium, what are the genotypic and allele frequencies?
0.25 homozygous dominant, 0.50 heterozygous, and 0.25 homozygous recessive, and a 0.5 allele frequency for each allele
In four-o'clock plants, flowers with the genotype CRCR are red, flowers with the genotype CRCW are pink, and flowers with the genotype CWCW are white. A population of four-o'clocks consists of 30 plants with red flowers, 10 plants with pink flowers, and 60 plants with white flowers. What is the frequency of the CR allele in this population?
0.35
The MN blood group in humans is determined by two alleles of a single gene. In a population containing 90 individuals with genotype MM and blood group M, 80 individuals with genotype MN and blood group MN, and 30 individuals with genotype NN and blood group N, what is the frequency of the genotype MN?
0.40
In radishes, genotype RR is red, genotype Rr is purple, and genotype rr is white. In a population of radishes consisting of 100 red radishes, 100 purple radishes, and 300 white radishes, what is the frequency of the genotype rr?
0.6
Consider a population of 100 four o'clock flowers, where 55 flowers are red and have the genotype CRCR, 20 flowers are pink and have the genotype CRCW, and 25 flowers are white with the genotype CWCW. The frequency of the CR allele in this population is _______.
0.65
In a diploid species, how many copies of a given allele are present in an individual who is heterozygous for the gene?
1
Click and drag on elements in order List the stages of the origin of life in the proper order from first (at the top of the list) to last (at the bottom of the list).
1. nucleotides and amino acids were produced prior to the existence of cells 2. nucleotides became polymerized to form RNA and/or DNA and amino acids became polymerized to form proteins 3. polymers became enclosed in membranes 4. polymers enclosed in membranes acquired cellular properties
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.4. What is the percentage of the population that is homozygous for this allele?
16
A diploid homozygous individual has ______ copies of the given allele.
2
Using the letters p and q, the genotype frequency of heterozygotes in a Hardy-Weinberg population is designated by the term
2pq
Which of the following statements is true of a gene subject to diversifying selection?
A genotype that has high fitness in one environment has low fitness in a different environment.
What is a gene pool?
All of the alleles for every gene in a population
Which of the following is an example of directional selection?
An increase in the number of mice with brown fur compared to the number of mice with white fur.
What type of selection tends to keep two or more alleles in stable equilibrium in a population over many generations?
Balancing selection
Which type of selection tends to maintain genetic diversity within a population?
Balancing selection
Select all that apply Select the types of selection that tend to increase or maintain genetic diversity within a population.
Balancing selection Disruptive selection
Which of the following best describes the third stage in the origin of life?
Cell-like structures may have originated when polymers were enclosed by a boundary
Which of the following processes caused RNA molecules to develop into more complex molecules with cell-like characteristics?
Chemical selection
Consider two species from different lineages that have independently evolved comparable traits because they occupy similar environments. This similarity is the result of:
Convergent evolution
In the process of reverse transcription,
DNA is synthesized from RNA.
___________ stores genetic information, _________ acts as an intermediary in protein synthesis, and proteins form the foundation for the structure and activities of living cells.
DNA, RNA
In seedcracker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds, respectively. If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population?
Directional selection
What type of selection can cause a favored allele to predominate in a population?
Directional selection
Select all that apply Prior to the development of tools to analyze DNA and protein sequences, which of the following provided evidence of biological evolution?
Distribution of related species The fossil record Comparative anatomy Selective breeding experiments
What type of selection favors the survival of two or more different genotypes that produce different phenotypes?
Diversifying selection
How does stabilizing selection affect genetic diversity within a population?
It tends to decrease genetic diversity.
What French naturalist proposed the idea of inheritance of acquired characteristics?
Jean-Baptiste Lamarck
Select all that apply What are possible outcomes of genetic drift?
Loss of an allele Fixation of an allele
Which two scientists demonstrated that prebiotic synthesis of organic molecules is possible?
Miller Urey
If directional selection favors a homozygous genotype, then what long-term result can occur?
Monomorphic gene
What types of genotypes are favored by diversifying selection?
Multiple different genotypes that produce different phenotypes
Which of the following is an example of stabilizing selection?
Newborn babies of intermediate weight are most likely to survive; both high and low birthweights are associated with increased infant mortality.
Remembering the concept of chemical selection, which of the following protobionts is most likely to proliferate?
One that can self-replicate and can also synthesize ribonucleotides
It is hypothesized that an ancestral ______ molecule that the ability to make DNA using RNA as template.
RNA
The macromolecule ______ can self-replicate, store information, and perform catalytic functions and may likely have been the first macromolecule to evolve.
RNA
In the concept of the ___________ _______, scientists envision that RNA served to both carry the genetic information and perform catalytic functions needed for life.
RNA world
What is genetic drift?
Random changes in the allele frequencies of a population over time
In which of the following patterns of natural selection are the extremes of a phenotypic distribution selected against?
Stabilizing selection
Select all that apply Which of the following can lead to genetic drift within a population?
The founder effect The bottleneck effect
What is the main difference between genetic drift due to the founder effect and genetic drift due to the bottleneck effect?
The founder effect occurs in a new location.
What is fitness?
The relative likelihood that a genotype will contribute to the gene pool of the next generation
What type of traits does sexual selection tend to favor?
Traits that increase an individual's ability to find a mate and mate successfully
Chemical evolution occurs when:
a population of molecules changes over time to have different chemical composition
An allele frequency describes the frequency at which a particular _______ occurs within a population.
allele
The term microevolution describes changes in
allele frequencies from generation to generation.
The number of copies of an allele in a population divided by the total number of all alleles for that gene in a population is the
allele frequency
The allele frequency is calculated by dividing the number of copies of a specific ______ in a population by the ______ for that gene in that population.
allele; total number of all alleles
Darwin's observation that there were Patagonian hares but no rabbits in South America would be considered ______ evidence of evolution.
biogeographical
It is during the third stage in the origin of life that an outer ______ formed to separate the internal polymers from the environment.
boundary
When a population of chemicals changes its composition over time, ________ evolution has occurred.
chemical
The concept of ______ explains how a protobiont that can both self-replicate and synthesize ribonucleotides has an advantage over a protobiont that can only self-replicate.
chemical selection
In negative frequency-dependent selection, the fitness of a genotype ______ when its frequency becomes higher.
decreases
Darwin expressed his concept of evolution as "the theory of ______ with _______ through variation and natural selection."
descent; modification
In selective breeding programs, artificial selection modifies domesticated species to produce traits that are
desirable from a human perspective.
Among a population of finches, beak size is either very small or very large; intermediate beak sizes are rarely observed. This is best explained by ______ selection.
diversifying
The black bellied seed cracker, Pyrenestes, is a West African finch. Within the same geographic region, two subspecies of the finch are found. One subspecies has a large beak, which is efficient at cracking the hard seeds of the sedge, Scleria verrucosa. The other subspecies has a small beak, which is more efficient at eating the soft seeds of the sedge, Scleria goossensii. What type of selection occurred to produce this situation?
diversifying selection
A prolonged change in the ______ can initiate directional selection because the new conditions may favor one genotype and promote elimination of the others.
environment
Select all that apply The RNA world is a hypothetical period on Earth when RNA molecules performed what functions?
enzymatic catalysis genetic information
The term _______ refers to changes in heritable characteristics of a population over time.
evolution
True or false: Due to genetic drift, alleles with high fitness tend to become fixed in populations, and alleles with lower fitness tend to become lost.
false
A variation in ______ occurs when some genotypes result in greater reproductive success than other genotypes.
fitness
Genetic drift can lead to the _______ or ________ of alleles in a population.
fixation; removal
As the size or location of a population changes, often the ______ composition changes, which can lead to ______ that make some individuals more likely to survive and reproduce.
genetic; adaptations
The frequency at which homozygotes and heterozygotes occur within a population can be described by:
genotype frequency
The number of individuals with a particular genotype in a population divided by the total number of individuals in a population is the:
genotype frequency
The genotype frequency is calculated by dividing the number of individuals in a population who have a particular ______ by the total number of ______ in that population.
genotype; individuals
A(n) _______ is a similarity in an anatomical, developmental, or molecular feature that occurs due to descent from a common ancestor.
homology
Similarity that occurs due to a common ancestor is called a(n)
homology.
Chemical selection occurs when a chemical within a mixture has special properties that cause it to _______ in number compared to other chemicals in the mixture.
increase
For a trait subject to stabilizing selection, individuals with ______ have the highest fitness.
intermediate phenotypes
Stabilizing selection tends to decrease genetic diversity because
it eliminates alleles that cause extreme phenotypes.
Select all that apply Which of the following may have formed spontaneously on early Earth?
macromolecules organic molecules
Balancing selection tends to ______ by favoring maintenance of two or more alleles, even if one of the alleles results in lower fitness.
maintain genetic diversity
To understand how life originated on Earth, it is important to realize that after RNA or DNA was formed, these polymers were enclosed in
membranes
Changes in the gene pool of a population from generation to generation are called
microevolution
Recently, what type of evidence has allowed biologists more insight into how genetic changes relate to the evolution of new species?
molecular
If individuals with rare phenotypic variants tend to have the highest fitness for a particular trait, the trait is likely subject to
negative frequency-dependent selection.
Conditions on early Earth may have been more conducive to the spontaneous formation of _____
organic molecules
Conditions on early Earth may have been more conducive to the spontaneous formation of
organic molecules.
For a gene with two alleles, if the frequency of one allele in a population that is not evolving is symbolized p and the frequency of the other allele in the population is symbolized q, then
p + q = 1
For a gene with two alleles whose frequencies are given by p and q, the Hardy-Weinberg equation states that:
p2 + 2pq + q2 = 1
Balancing selection results in a condition called balanced ______, in which two or more alleles are kept in balance over many generations.
polymorphism
A(n) _________ is a group of individuals of the same species that occupy the same environment and can interbreed with one another.
population
A collection of prebiotically produced molecules and macromolecules possessing a boundary which separates its internal and external environments is a:
protobiont
A(n) _______ is an aggregate of prebiotically produced molecules and macromolecules with a boundary to separate its internal chemical environment from its surroundings.
protobiont
Consider a gene that segregates two alleles, A and a, with allele frequencies given by p and q, respectively. The frequency of the aa genotype will be ______ if the population is in Hardy-Weinberg equilibrium.
q2
All of the following can provide evidence of biological evolution EXCEPT:
reproduction
The likelihood that an individual will contribute fertile offspring to the next generation is called _______ success.
reproductive
Simple organic molecules polymerized to form complex organic polymers during the ______ stage in the origin of life.
second
Procedures in which matings or crosses are designed to modify traits in domesticated species are referred to as
selective breeding
Birds that lay intermediate numbers of eggs have greater fitness than birds that lay either too many or too few eggs. This is an example of
stabilizing selection.
Select all that apply What functions exhibited by RNA may have led to it being the first macromolecule?
store information self-replicate function as ribozymes
Biogeography is the study of
the geographic distribution of modern and extinct species.
Environmental changes can lead to directional selection because they cause changes in
the relative fitness of various genotypes.
Early thinkers about the diversity of life on Earth were strongly influenced by philosophy and religion and regarded life-forms as
unchanging
