1) Slime molds are unusual eukaryotes. They spend most of their life cycle as si

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Question

1) 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 first appeared about 1 billion years ago.

Dictyostelium discoideum is an important human pathogen.

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

none of the above

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

The body size of the largest living organisms has increased over evolutionary time.

The complexity of multicellular organisms, as measured by the number of cell types, has increased over evolutionary time.

Natural selection necessarily entails an increase of complexity over evolutionary time.

Modern bacteria and archaea are not more complex than their ancestors that lived before the origin of multicellular life.

3) 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

the origin of self-replicating molecules capable of heredity

the evolution of sexual reproduction

the evolution of multicellular organisms from single-celled ancestors

4) 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.

Single-stranded RNA with low replication fidelity was replaced as an informational molecule by double-stranded DNA with high replication fidelity.

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.

Within a single multicellular body, different cells may specialize in generating movement, digesting food, processing information, or other tasks.

all of the above

5) 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 fathers genomes need to be expressed.

Mammals are the only class of vertebrates with evolutionary benefits of recombination.

The number of offspring produced sexually exceeds the number of offspring in asexual reproduction.

all of the above

6) 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?

Eukaryotes probably evolved from a lost prokaryotic lineage, which could not be placed among either the Archaea or Bacteria domains.

Eukaryotes shared a common ancestor with species in the domain Archaea.

Eukaryotes shared a common ancestor with species in the domain Bacteria.

Eukaryotic informational genes are closely related to Archaea, while their operational genes are closely related to Bacteria.

7) Rivera and Lakes 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 when a parasitic species of bacteria residing in some other prokaryotic cell became less harmful.

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

The origin of eukaryotic lineage probably began when an archaeal cell became integrated into abacterial cell.

None of the above is a working hypothesis on the origin of eukaryotic cells.

8) 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

archaea

cyanobacteria

ancient protozoa

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

Chloroplasts are derived from once free-living photosynthetic cyanobacteria.

Cyanobacteria are related to algal plastids.

RNA shows that the chloroplasts of plants are closely related to cyanobacteria.

all of the above

10) 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?

mitochondria

chloroplasts

both mitochondria and chloroplasts

promiscuous genes from nonrelated species of eukaryotes

11) 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?

Apicoplasts are unique organelles with a quadruple membrane.

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

The primary endosymbiosis occurred when one prokaryotic host engulfed a cyanobacterium, giving rise to the initial eukaryote, which was subsequently engulfed in a secondary endosymbiosis.

Apicoplasts in Plasmodium falciparum and related species are involved in the production of at least 500 different gene products.