Biology Quiz 1

Hardy-Weinberg equilibrium conditions

no mutations, random mating, no natural selection, extremely large population size, no gene flow

Domain

A taxonomic category above the kingdom level. The three domains are Archaea, Bacteria, and Eukarya.

Adaptation

A trait that helps an organism survive and reproduce

Beetles represent an extraordinarily diverse group of organisms, comprising nearly 25% of all described animal species. The figure above examines the distribution of beetle species. Which of the following statements are TRUE? (Select all that apply.) A. B is a shared common ancestor of groups H, I, J and K. B. Groups of beetles that feed on angiosperms (G,I,K) have lower rates of diversification than those that do not. C. The availability of diverse habitats is one factor that drives differentiation of species. D. Our understanding of phylogenetic relationships has remained relatively static over time. E. Beetles that currently feed on angiosperms all descended from a single common ancestor that switched to feed on angiosperms.

A,C

Archaea

Domain of unicellular prokaryotes that have cell walls that do not contain peptidoglycan; halophiles, do not cause disease

random fertilization

source of genetic variation caused by the unlimited number of possible sperm & egg combinations

frequency-dependent selection

the fitness of a phenotype depends on how common it is in the population

null hypothesis

the hypothesis that there is no significant difference between specified populations, any observed difference being due to sampling or experimental error, no change in frequency, no evolution, no selection

law of independent assortment

the law that states that genes separate independently of one another in meiosis

root of a phylogenetic tree

the most ancestral branch in the tree

Transduction

viruses transfer genes between prokaryotes

Key outcomes of evolution

1. Accumulation of favored trait in population 2. Adaptation to environment 3. Change in populations

Requirements for natural selection

1. Certain traits must be selected for because they provide an advantage 2. Those traits must be passed down. 3. Those traits must be passed down at greater frequencies than others

Critical features of hydrothermal vents

1. Create stream that gives rise to hydrogen ions 2. Mold for the formation of pockets for cells

LUCA and people share

1. DNA 2. Enzymes for DNA replication and repair 3. Proteins produced through an RNA intermediate + ribosomes 4. Uses H+ gradients to generate ATP 5. Lipid bilayer with ion pumps

Abiogenesis

1. Must work to avoid decay and disorder 2. Must be made of cells (closed system) 3. Must have molecule to carry information 4. Information must evolve by natural selection

Requirements for Evolution

1. Variation in population 2. Variation must be heritable 3. Limited resources to create competition (or selective pressure exists) 4. Variation must influence reproductive success

Transformation

A change in genotype and phenotype due to the assimilation of external DNA by a cell.

genetic drift

A change in the allele frequency of a population as a result of chance events rather than natural selection.

phylogenetic tree

A family tree that shows the evolutionary relationships thought to exist among groups of organisms

population bottleneck

A period during which only a few individuals of a normally large population survive.

relative fitness

the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

Which of the following statements regarding LUCA are TRUE? (Select all that apply.) A. The branches in the tree of life before LUCA do not have any current living descendants. B. LUCA is the ancestor of Archaea and Eukarya, but not Bacteria. C. LUCA likely used RNA rather than DNA as its genetic material. D. LUCA did not have a lipid bilayer membrane. E. LUCA was able to fix carbon, or in other words was autotrophic.

A,E

A single population of dung beetles was subdivided into four separate populations when irrigation canals were constructed within the region. No migration was possible. Ten years later each of the four populations were assessed for the % alleles at Hu locus, which has two alleles. The table below shows these results. Table 1. Allele frequencies at the Hu gene loci. Hu-A Hu-B Population 1 70% 30 % Population 2 24 % 76% Population 3 48 % 53% Population 4 95 % 5% Which major genetic mechanism acted to generate the differences in the allele frequencies in each of the derived populations? A. Genetic drift B. New mutations C. Gene flow D. Selection

A. Genetic drift

Which of the following statements about heterozygote advantage is true? A. Heterozygote advantage tends to maintain genetic variation from a population. B. Heterozygote advantage is an example of directional selection. C. Heterozygote advantage would result in fewer heterozygotes in a population than would be predicted by the Hardy-Weinberg equation. D. A locus with heterozygote advantage would be in Hardy-Weinberg equilibrium.

A. Heterozygote advantage tends to maintain genetic variation from a population.

Choose all of the following statements about meiosis and genetic variation that are TRUE: A. Recombination occurs during the formation of egg and sperm cells. B. Both recombination and independent assortment contribute to variation within a population of organisms. C. During recombination, chromosomes can cross-over and exchange segments of DNA so that chromosomes in the gametes are different from the chromosomes of the parents. D. During meiosis the chromosomes inherited from one parent are all pulled to one of the cell, and chromosomes from the other parent are pulled to the other end of the cell.

A. Recombination occurs during the formation of egg and sperm cells. B. Both recombination and independent assortment contribute to variation within a population of organisms. C. During recombination, chromosomes can cross-over and exchange segments of DNA so that chromosomes in the gametes are different from the chromosomes of the parents.

Select all of the following statements about genetic drift that are TRUE. A. The effect of genetic drift is most pronounced in small populations. B. Genetic drift can result in the loss of an allele from a population. C. Because the direction of genetic drift is random, it is not considered an evolutionary force. D. If an allele is beneficial or has a selective advantage, the allele cannot be lost by genetic drift. E. Genetic drift can result in a loss of genetic diversity when a population experiences a bottleneck.

A. The effect of genetic drift is most pronounced in small populations. B. Genetic drift can result in the loss of an allele from a population. E. Genetic drift can result in a loss of genetic diversity when a population experiences a bottleneck.

Choose all of the following statements regarding "the modern synthesis" that are TRUE: A. The modern synthesis filled a gap in Darwin's theory of evolution by natural selection. B. The modern synthesis completely explains everything about how evolution works. C. The modern synthesis established that there is an inherent linkage between genetics and evolution.

A. The modern synthesis filled a gap in Darwin's theory of evolution by natural selection. C. The modern synthesis established that there is an inherent linkage between genetics and evolution.

A new commercial development within the region will result in the transfer of a large amount of soil from the area containing population 1 to the area containing population 2. The soil contains a large number of dung beetles. How do you think this manipulation will effect the % of Hu alleles within population 2? A. The percent of Hu-A allele will increase. B. The percent of Hu-A allele will decrease.

A. The percent of Hu-A allele will increase.

In the 1950's in an attempt to reduce the spread of malaria by mosquitoes, the World Health Organization began a program of spraying with the pesticide DDT. Although initially effective, within a few years mosquitoes in many populations were resistant to the effects of DDT. The figure below shows the percentage of mosquitoes from a population that were killed by DDT treatment at 0, 10, and 16 months. Assume that DDT treatment in the area began at time = 0 months. A. The proportion of individuals resistant to DDT treatment increased over time. Feedback: Notice that the y-axis is % mortality, so decreased mortality = increased resistance. B. Resistance to DDT had a genetic basis that could be passed onto offspring. C. DDT resistant individuals produced fewer offspring than those not resistant to DDT. D. Resistant mosquitoes were present in the population prior to use of DDT. E. If DDT application were stopped, the % of resistant individuals in population would likely continue to increase. F. Following the application of DDT, individual mosquitoes became more resistant to DDT.

A. The proportion of individuals resistant to DDT treatment increased over time. C. DDT resistant individuals produced fewer offspring than those not resistant to DDT. D. Resistant mosquitoes were present in the population prior to use of DDT.

Which of the following mechanisms of evolutionary change are NON-adaptive (i.e. do not necessarily increase fitness). Select all that apply: A. gene flow B. genetic drift C. selection D. mutation

A. gene flow B. genetic drift D. mutation

The ultimate source of genetic variation is: A. mutation B. independent assortment C. crossing-over/recombination D. the environment

A. mutation

The figure above represents two different hypotheses regarding the relationships of the domains of living organisms. Which of the following statements about the relationship of Archaea, Eukarya, and Bacteria are TRUE? (Select all that apply.) A. Figure B is consistent with a 3 domain structure of living organisms. B. In both A and B, Eukarya are more closely related to Archaea than to Bacteria. C. Eukarya likely arose when an Archaean was engulfed by a bacterium. D. In Figure B, in order for the domain Archaea to be considered a "monophyletic" group, Eukarya would need to be reclassified as A

B,D

Given that a population contains genetic variation, what is the correct sequence of the following events, under the influence of natural selection? 1) Well adapted individuals leave more offspring than do poorly adapted individuals. 2) A change occurs in the environment. 3) Genetic frequencies within the population change. 4) Poorly adapted individuals have decreased survivorship. A. 2 → 4 → 1 → 3 B. 2 → 3 → 4 → 1 C. 4 → 1 → 2 → 3 D. 4 → 2 → 3 → 1

B. 2 → 3 → 4 → 1

Which of the following statements are implications of the Hardy-Weinberg equation? Select all that are TRUE. A. Dominant traits will tend to be more common in a population than recessive traits. B. When the 5 conditions for equilibrium are met, the frequency of an allele in a population will not change over time. C. The Hardy-Weinberg equation describes a population that is not evolving for a particular locus. D. The frequency of a particular phenotype in a population is a product of the frequency of alleles in the gene pool. (For example, the number of homozygous individuals in a population can be predicted by either p^2 or q^2. ) E. The Hardy-Weinberg equation can be applied to the whole genome of an organism (all of the genes) at once.

B. When the 5 conditions for equilibrium are met, the frequency of an allele in a population will not change over time. C. The Hardy-Weinberg equation describes a population that is not evolving for a particular locus. D. The frequency of a particular phenotype in a population is a product of the frequency of alleles in the gene pool. (For example, the number of homozygous individuals in a population can be predicted by either p^2 or q^2. )

Choose all of the following statements regarding particulate and blending inheritance that are TRUE: A. Particulate inheritance supports natural selection because particulate inheritance results in a loss of variation over generations. B. Darwin's theory of natural selection did not require that traits be heritable. C. At the time of Darwin, most people thought that inheritance followed a blending model. D. Particulate inheritance can only be applied to simple traits controlled by one or two genes.

C. At the time of Darwin, most people thought that inheritance followed a blending model.

crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

Choose all of the following statements regarding mutation that are TRUE: A. Most mutations are mildly advantageous. B. A mutation that occurs in a somatic cell can be passed onto offspring. C. Mutations occur randomly without respect to the need of the organism. D. In some cases, a mutation can beneficial to an organism. E. If the environment changes, the relative benefit or cost of a mutation can change.

C. Mutations occur randomly without respect to the need of the organism. D. In some cases, a mutation can beneficial to an organism. E. If the environment changes, the relative benefit or cost of a mutation can change.

Consider the flatwing allele found in Hawaiian crickets of Kaua'i in the years just following the introduction of flies to the island. Select all of the following statements that are TRUE. (NOTE: You can watch a short video here for a reminder https://youtu.be/gugY9C6aIlI). A. Just following the introduction of the parasitic flies, the cricket population would be in Hardy Weinberg equilibrium for the locus/gene that determines wing structure. B. The observed increase in the frequency of flatwing allele and the silent phenotype is the result of genetic drift. C. The mutation that created the flatwing allele likely arose as a result of exposure to the parasitic flies. D. In this population of Kaua'i, the relative fitness of crickets with the flatwing allele/silent phenotype is higher than crickets without the flatwing allele. E. The cricket population is evolving at the wing structure locus/gene. F. The silent wing allele would remain at high frequencies if the parasitic flies are removed from the island.

D. In this population of Kaua'i, the relative fitness of crickets with the flatwing allele/silent phenotype is higher than crickets without the flatwing allele. E. The cricket population is evolving at the wing structure locus/gene.

directional selection

Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve

sister taxa

Groups of organisms that share an immediate common ancestor and hence are each other's closest relatives.

Conjugation

In bacteria, the direct transfer of DNA between two cells that are temporarily joined.

Law of Segregation

Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete

stabilizing selection

Natural selection that favors intermediate variants by acting against extreme phenotypes

horizontal gene transfer

The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms.

Particulate Inheritance Hypothesis

Traits are passed in discrete heritable units. Genes are passed down.

continuous variation

Variation measured on a continuum rather than in discrete units or categories (eg height in human beings)

outgroup (phylogenetic tree)

a taxon that diverged prior to the taxa that are the focus of the study

Blending Theory of Inheritance

hypothetical inheritance pattern in which parental traits are blended together in the offspring to produce an intermediate physical appearance

founder effect

change in allele frequencies as a result of the migration of a small subgroup of a population

node of phylogenetic tree

common ancestor

disruptive selection

form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle

monophyletic group

group that consists of a single ancestral species and all its descendants and excludes any organisms that are not descended from that common ancestor

gene flow

movement of alleles from one population to another

balancing selection

natural selection that maintains two or more phenotypic forms in a population

descent with modification

principle that each living species has descended, with changes, from other species over time

Woese's discovery

prokaryotes were genetically different in their cell wall chemistry; archaea are more closely related to eukarya than bacteria