Module 5

Based on the figure shown, which of the following statements is correct?

Animals are the only group within the Opisthokont clade whose members are all multicellular.

Which of the following statements about LUCA is NOT correct?

It refers to a single, ancestral organism.

Which of the following breaks up or removes linkage disequilibrium from a population?

Sexual reproduction

The apicoplast is an organelle found only in species in a phylum called Apicoplasta. This phylum includes a deadly human parasite, Plasmodium falciparum, which is responsible for malaria. Which of the following is FALSE regarding the apicoplast organelle?

There was only one endosymbiosis event, which probably involved a large cyanobacterium engulfed by a protozoan cell, and they both developed second membranes for protection.

In 1970, Lynn Margulis proposed that the origin of two eukaryotic organelles, mitochondria and chloroplasts, occurred through endosymbiosis. According to more recent phylogenetic analyses based on molecular genetic data, which of these prokaryotic lineages is a candidate for the ancestral source of mitochondria?

proteobacteria

Why did the role of horizontal gene transfer ultimately become diminished over evolutionary time?

As cells became more complicated, they also became more integrated, less modular and less likely to take up new genes by horizontal gene transfer.

In the cliff swallows studied by Charles and Mary Brown, it is common to find a blood-sucking parasite, an insect known as the swallow bug. This bug often clings to the feet of birds, can move from swallow to swallow within colonies, and is responsible for most of the nest failures and juvenile mortality in these birds (Brown and Brown 1996). The graph shows a correlation between the colony size and the number of bugs per nest. What conclusion(s) can we make based on this study?

As group size increases, the fitness cost of parasitism increases.

The human parasite Mycoplasma genitalium, with one of the smallest genomes of any organism that can be grown in a laboratory, as well as Chlamydia trachomatis, an obligate intracellular parasite, are examples of the types of organisms that functional genomics researchers have focused on. What is the main purpose of the study of such genomes?

By studying such genomes, researchers try to discover the basic and essential cellular functions of early life

Which of the following is FALSE regarding the evolution of chloroplasts?

Chloroplasts are derived from ancient free-living photosynthetic archaebacteria.

In light of recent achievements in the field of genomics, would it be reasonable to expect that the use of comparative genomics might shed light on the extinct genomes of early life?

Comparative genomics and studies of bacteria with very small genomes shed light on a common ancestor, and researchers can estimate the minimal characteristics that a cell would need to operate as a living organism.

Which of the following statements regarding the benefit of making the switch from an RNA- to a DNA-based genetic system during the evolution of life is correct?

DNA is a more stable molecule because deoxyribose is less reactive than is ribose.

A number of evolutionary studies show a strong phylogenetic link between prokaryotic and eukaryotic cells. Which of the following is the best statement about the evolutionary origins of eukaryotic cells?

Eukaryotic "informational" genes are most closely related to archaeal genes, while their "operational" genes are most closely related to bacterial genes.

An analysis by Maria Rivera and James Lake suggests that ancient eukaryotic cells emerged from the fusion of an archaeal cell (most likely from the phylum Eocyta) and a bacterium (Rivera and Lake 2004). Which of the following is correct regarding this working hypothesis?

Eukaryotic cells probably evolved through endosymbiosis, in which either the archaeal or bacterial cell was engulfed within the other.

Which of the following is FALSE regarding the evolution of group living?

Group living provides many benefits, but it does not improve foraging success (finding food).

Biologists have documented asexual reproduction in some animal lineages. Even in certain vertebrates, such as reptiles, a few species reproduce only with parthenogenesis (development from unfertilized eggs). However, parthenogenesis has never been documented in mammals. What is the current genetic explanation for this difference between mammals and other vertebrates?

Mammals evolved a process of genetic imprinting and therefore some genes from the father's genomes need to be expressed.

r=h2*s

R= Size of change between generations h2= narrow sense heritability Selection = (breeding mean - population mean)

Slime molds are unusual eukaryotes. They spend most of their life cycle as single-celled organisms, and yet under certain conditions, they form a slug-like multicellular stage and then a fruiting body composed of both somatic cells and reproductive spores. The best known species of slime mold is a soil dweller, Dictyostelium discoideum. Why is it important to study this and related species of slime molds?

Slime molds provide clues as to how multicellularity may have evolved.

Identify which of the given examples is the best match for the following statement. "Individuals give up the ability to reproduce independently, and they join together to form a larger grouping that shares reproduction."

Solitary individuals start living together in colonial groups, sometimes even giving up the possibility of independent replication, as we see in many species of social insects.

In the common bluegill sunfish, foraging in small groups increases success in finding food. They feed on small, aquatic insects that live in underwater vegetation, and when bluegills forage together, they are able to flush out many more insects. Which of the following is correct in this case of group foraging?

The bluegill example illustrates a "passive" benefit of group foraging.

Eugene Koonin and his colleagues used the distributions of genes in the minimal gene sets of Haemophilus influenza and Mycoplasma genitalium to predict the distribution of a minimal gene set for Bacillus subtilis (Koonin 2003). What did they conclude from their comparison?

The predicted distribution of genes in B. subtilis was a close fit to the minimal gene sets observed.

Which of the following is FALSE regarding the evolution of multicellularity?

The transition from unicellular to multicellular life occurred only once in evolutionary history, giving rise to all multicellular organisms today.

Many species of mammals and birds are known to live in close communities, while other species live solitary lives. What do we know about the benefits of sociality, such as that observed in cliff swallows?

There is often a significant positive correlation between group size (such as colony size in cliff swallows) and survival rate of the population.

V(p) = V(g) + V(e) + V(g) X V(e)

V(p) = variation in phenotype V(g) = variation in genetics V(e) = variation in environment V(g) X V(e) = variation in genotype depending on environment

Which of the following is FALSE regarding studies on volvocine algae to explore the evolution of individuality?

Which of the following is FALSE regarding studies on volvocine algae to explore the evolution of individuality?

In order to understand the origin of life on Earth, evolutionary biologists collaborate with__________.

atmospheric scientists, geologists, and chemists

One of the main features of a eukaryotic cell is the nucleus. Recent evidence suggests that the cell nucleus may have evolved from archaeal ancestors and that the organelles may have evolved from bacterial ancestors, but there is another important factor that has shaped the evolution of nuclear genomes. Which of the following is a source of some eukaryotic nuclear genes?

both mitochondrial and chloroplast genes

Which one of the following is NOT a major transition in the evolution of life, according to biologists John Maynard Smith and Eörs Szathmary?

formation of the solar system including Earth

Which of the following best represents the definition of an individual, as proposed by evolutionary biologist Rick Michod?

integrated and indivisible wholes that can reproduce and pass heritable variations on to their offspring

Which of the following lists four factors that can cause or create linkage disequilibrium in a population?

natural selection, migration, mutation, and genetic drift

Which gas was most likely the LEAST abundant in early Earth's atmosphere?

oxygen

All of the following are true regarding Sol Spiegelman's experiment on the origins of life, except that __________.

there was no selection for any of the variations in length

The figure describes the percent oil content in corn from different generations. In 1899, the mean oil content was 5.65% dry mass, the mean of the selected plants was 6.30% dry mass, and the mean of all plants in 1900 was 6.10% dry mass. What is the expected slope of a parent-offspring regression (narrow-sense heritability) for corn oil content?

0.692

For many years in the United Kingdom, people with urinary tract infections have been treated with sulfonamide antibiotics. These antibiotics used to be very effective against the common pathogen of the urinary tract, E. coli, but in the late 1990s, increased resistance among the E. coli strains was documented. In the meantime, worrisome side effects of these drugs were documented as well, so doctors curtailed their use. Which of the following statements is TRUE about the evolution of resistance to the sulfonamides in the last decade?

Despite the infrequent use of sulfonamides, there was little reduction in frequency of resistance among the bacteria.

Which of the following statements regarding the complexity of living organisms is FALSE?

Natural selection always results in an increase of complexity over evolutionary time.

V(g)

V(a) Additive effects = add to produce a phenotype, can be passed on to offspring. Narrow sense heritability (h2) V(d) Dominance genetic effects = not passed on V(i) = two or more loci that interact only accurate for population measured in

In mice that are homozygous for the dark-color Agouti allele (D), the effects of the Mc1R locus are entirely masked so that, irrespective of the genotype at Mc1R, the mice have fully dark coloration. However, if at least one copy of the light-color Agouti allele (L) is expressed, the different shades of brown Mc1R locus are revealed (with the particular shade depending on the number of copies of L). This is an example of __________.

epistatic effects of the two genes

In selection experiments on quantitative traits, we often measure a value of the response to selection (R). What is R equal to?

h2*S

In quantitative genetics theory, the value of a quantitative trait is sometimes given by the equation P = G + E. We could define P as the _________ of the continuous trait that we are studying.

phenotypic value

In the slime mold species Dictyostelium discoideum, single-celled individuals gather in the migratory slug stage of development, in response to environmental cues. Which molecule is associated with this signaling?

small rnas