genetics and evolution exam 3 review

Thyroid hormone (TH) has been identified as one of the factors promoting phenotype development in the Mexican salamander, or axolotl. All of the following statements regarding the impact of TH are true except:

Adding thyroid hormone (T4) to the water in which axolotl individuals were reared causes them to remain in a larval stage

Which of the following are/is considered a type of heterochrony (changes in the rate and timing of development)?

All of the above

Which of the following statements is true about Hox genes experiments?

All of the above

In order to understand the origin of life on Earth, evolutionary biologists collaborate with:

All of the above (Chemists, geologists, and atmospheric scientists)

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

All of the above (Chloroplasts are derived from once free-living photosynthetic cyanobacteria, Cyanobateria are related to algal plastids, and RNA shows that the chloroplasts of plants are closely related to cyanobacteria)

Miller and Urey developed and conducted some experimental tests for a "prebiotic soup" model of the origin of life, which had been proposed a few decades earlier by Oparin and Haldane. What did Miller and Urey show could be synthesized abiotically?

Amino acids

Young marsupials are born underdeveloped and with a number of adaptations to the life in mother's pouch. One adaption is particularly important for their survival, since it enables the jaw structures to suckling mother's milk at this early stage of development. What changes in the neural crest development are responsible for this?

Analysis of marsupial embryos found that neural crest cells begin their migration much earlier in marsupials than in other mammal groups and this promotes early jaw development

One of the first studied Hox gene mutations in Drosophila was a mutation in the Antennapedia (Ant) gene, which controls leg formation. This mutation is abbreviated as Antp. What is the phenotypic effect of this mutation?

Antennae are replaced by legs

In the cliff swallows 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 it is responsible for most of the nest failures and juvenile mortality. The following graph shows a correlation between the colony size and the number of bugs per nest. What conclusion(s) can you make, based on this study?

As group size increases, the cost of parasitism increases

One of the gene duplications in developmental genes in plants, OEP16 is also known to arise along with neofunctionalization. Which of the following statements is true regarding these genes?

Both A and B

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 shaped the evolution of nuclear genomes. Which of the following is a source of the eukaryotic nuclear genes?

Both mitochondria and chloroplasts

The human parasite Mycoplasma genitalium, with one of the smallest genomes of any organism that can be grown, 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

When we say that a cell is totipotent, we refer to a cell that:

Could differentiate into any of the cell types that makes up the adult organism

In a 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?

Cyclic adenosine monophosphate

Rivera and Lake's analysis (2004) suggests that ancient eukaryotic cells emerged from the fusion of an archaeal cell (most likely from the phylum Eocyta) and a bacterium. Which of the following is correct regarding this phylogenetic 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 molecules involved in membrane structure was likely favored by selection in the evolution of early cells?

Fatty acids

Karl Ernst von Baer (1792-1876), a German naturalist, biologist, and embryologist, rejected both the scala naturae and the Meckel-Serres law. Instead, von Baer's law states that the:

General characteristics of embryos in closely related species develop before specific characteristics, and embryos of higher taxa do not resemble the adult form of ancestral lower-taxa species

Which of the following is not true regarding the evolution of group living?

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

What do we know about horizontal gene transfer (HGT) in the evolution of early life?

HGT was probably a powerful force during early cell evolution, leading to complex cellular organisms

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

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

Which of the following statements regarding the complexity of living organisms is not correct?

Natural selection necessarily entails an increase of complexity over evolutionary time

The origin of cell structures might be hypothesized to have involved a hypercycle, based on mutualism at the molecular level. Which of the following is correct regarding the hypercycle model?

Natural selection will favor a hypercycle that is enclosed in a membrane

Douc langurs are primates that have a diet of leaves instead of insects and fruit. In order to digest such food, these langurs use symbiotic bacteria in their gut and digest some of them using an enzyme associated with a gene known as RNASE. Gene duplication and the subsequent divergence of this gene, seems to be the genetic basis for its evolution. We could say that this is an example of:

Neofunctionalization

Heterochrony is well studied in amphibians. One of the famous examples is in a species of salamanders (Mexican axolotl), where reproductively mature individuals still live in the water and have external gills and flat tails, as in the salamander embryos. This phenomenon is best defined as:

Neotony

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

O2

Which two scientists elaborated on Darwin's idea of the "warm little pond" and formulated the "prebiotic soup hypothesis" as the first hypothesis for the abiotic origin of life on earth?

Oparin and Haldene

When a reproductive trait appears earlier in development or when some somatic traits of an adult are retarded, we could define this type of development as:

Paedomorphosis

In 1970, Lynn Margulis proposed that the origin of two eukaryotic organelles, mitochondria and chloroplasts, occurred through endosymbiosis. Which prokaryotic lineage is a phylogenetic candidate as the source of mitochondria?

Proteobacteria

The first genetic material was most likely?

RNA

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 hints as to how multicellularity may have evolved

Which of the following examples would be the best match for the statement? "Individuals give up the ability to reproduce independently, and they join together to form a larger grouping that shares reproduction."

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

Deep homology of homeotic genes is also seen in plants. For example, the MADS-box genes have been used to work out phylogenetic relationships within flowering species of plants. What was also documented in these studies across many plant lineages?

The MADS-box genes are also instrumental in nonflowering plant species, where they are involved in developmental pathways in leaf and root systems

Which of the following is true for the ancient Greek view of ontogeny (the development of an individual over its lifetime), which was later developed as the concept of "scala naturae" (or the "great chain of being") in the European natural sciences?

The ancient Greeks argued that the ontogeny of an individual was built up from simple traits in early development to more complex traits later in the developmental process

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

Ernst Haeckel (1834-1919), a German biologist and naturalist, disagreed with von Baer and further expanded on the Meckel-Serres law with his biogenetic law. What does the biogenic law claim?

The developmental progress of an organism (its ontogeny) recapitulates its evolutionary history (its phylogeny).

In some species of fruit flies, males have black spots on the edge of their wings, which they use for visual displays during courtship dances with females, while in other species, these spots are completely absent. A gene called "yellow" plays a role in the development of these visual features in all of the species. The key to the differences in the amount and spatial distribution of the yellow protein is due to?

The effects of regulatory enhancers on the yellow gene

If a gene is affected by many regulatory enhancers, what would be an important evolutionary implication?

The enhancers can increase morphological variation and hence the amount of variation that natural selection has to act on.

Which one of the following is not a major transition in the evolution of life, based on Maynard Smith and Szathmary (1997)?

The formation of the solar system including Earth

Define a regulatory enhancer of a gene.

The regulatory enhancer is a section of DNA that lies outside of that gene but is involved in regulating the timing and level of that gene's expression.

Which of the following statements about the Lincoln and Joyce experiment on self-replicating ribozymes is most likely correct?

The self-replicating ribozymes that had more efficient catalytic activities would soon began to dominate their populations

Which of the following is not true 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 alike are known to live in close communities, while other species live solitary lives. What do we know about the benefits of sociality?

There is often a significant positive correlation between group size, such as, for instance, colony size in birds and survival rate of the population

All of the following is true regarding Spiegelman's experiment on the origins of life except that:

There was no selection for any of the variations in length

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 not true regarding the apicoplast organelle?

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

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 closely related to Archaea, while their "operational" genes are closely related to Bacteria

In 1977 Sidney Fox tried a different approach to testing the prebiotic synthesis of biological molecules. He mixed a number of different amino acids together at a high temperature (120°C) in an environment lacking water. When he subsequently placed the mixture into water to investigate what the amino acids would form, he:

Found some peptide-like structures, but the bonds between the amino acids were weak and unstable

Among the oldest fossils on Earth are the microfossils from the Agnes gold mine of South Africa, which are __________ years old.

3.2 billion

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 the bacteria with very small genomes do shed light on a common ancestor and researchers can estimate the minimal characteristics that a cell would need to operate as a living organism

What is the most relevant hypothesis for the benefit of making the switch from the RNA- to a DNA-based genetic system during the evolution of life?

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

Neural crest cells in vertebrates are cells that are initially positioned near the neural tube during early development and then migrate to new locations. The development and positioning of these cells is controlled by a set of:

Homeotic genes

Define homeotic genes.

Homeotic genes are "master-switch" genes that control other genes in a set sequence and thereby affect cell size, shape, division, and the positioning of the cells within the organism.

What would be an appropriate evolutionary explanation of the fact that the ordering of some homeotic genes (e.g., Hox genes) on vertebrate chromosomes parallels the ordering of homeotic genes on fruit fly chromosomes?

Homeotic genes display ancient homologies

In the late 1800s William Bateson documented, both in insects and in vertebrates, many cases where one body part had replaced another, producing unusual forms. Bateson believed that his studies could teach us something about evolutionary changes. He named these changes:

Homeotic transformation

In the early 1980s, studies in fruit flies led to discovery of the master-switch genes involved in animal development. Which of these genes are essential for the development of different body segments of fruit flies?

Hox genes

Which of the following statements about LUCA is NOT correct?

It is meant to be a single organism

Biologists have documented asexual reproduction in some animal lineages. Even in some vertebrates, such as reptiles, some 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 father's genomes need to be expressed