ch 12
Which of the following populations would be most likely to demonstrate genetic drift? Someone takes an extended course of antibiotics, leaving a relatively small number of surviving bacteria. A researcher transfers bacteria into fresh medium but accidentally collects only a very small quantity of bacteria in the process. A large population of bacteria is grown over an extended period in a continuous culture system. A researcher performs a Gram stain to separate gram-positive and gram-negative bacteria. He places the gram-positive bacteria in one test tube and the gram-negative bacteria in the other.
A researcher transfers bacteria into fresh medium but accidentally collects only a very small quantity of bacteria in the process
Why would it be highly advantageous to a cell to form a mutualism with a prokaryote capable of aerobic cellular respiration? Having a symbiotic prokaryote increases the genetic diversity of the cell. A prokaryote capable of aerobic cellular respiration is capable of producing organic materials, such as sugars, using light energy. A symbiotic prokaryote increases the nutritional diversity of the organism, greatly increasing possible food sources. Aerobic cellular respiration involves an electron transport chain with oxygen as the terminal electron acceptor. This produces large amounts of ATP as the electron transport chain produces the greatest amount of ATP in cellular respiration.
Aerobic cellular respiration involves an electron transport chain with oxygen as the terminal electron acceptor. This produces large amounts of ATP as the electron transport chain produces the greatest amount of ATP in cellular respiration.
Scientists believe life may have begun as an RNA world because __________. RNA can bind small molecules RNA is essential to processes found in all cells RNA can have catalytic activity All of the listed responses are correct.
All of the listed responses are correct.
The major source of carbon was _________ for early cells and the major fuel for energy was __________ for early cells. CO2 ; H2 CO2 ; N2 N2 ; H2 O2 ; CO2
CO2 ; H2
All unicellular organisms belong to the same domain of life. True False
False
At present there are four phyla in the domain Bacteria. True False
False
Sequencing technology and molecular phylogenetic analyses have had very little impact on our understanding of the evolution and diversity of life on Earth. True False
False
The 16S rRNA sequence is an approximately 1,500 bp linear strand of single stranded RNA. True False
False
The earliest nucleic acid was probably a simple DNA molecule. True False
False
Which of the following best explains the endosymbiont hypothesis? Prokaryotes capable of cellular respiration and prokaryotes capable of photosynthesis took up residence in larger prokaryotes, forming obligate mutualisms. The prokaryotes capable of cellular respiration evolved into mitochondria and the prokaryotes capable of photosynthesis evolved into chloroplasts. Prokaryotes capable of cellular respiration and prokaryotes capable of photosynthesis took up residence in larger prokaryotes, forming obligate mutualisms. The prokaryotes capable of cellular respiration evolved into chloroplasts and the prokaryotes capable of photosynthesis evolved into mitochondria. Prokaryotes capable of cellular respiration began to associate with prokaryotes capable of photosynthesis. They fused together to form eukaryotic cells. Prokaryotes capable of digestion took up residence in larger prokaryotes, forming obligate mutualisms. The prokaryotes capable of digestion evolved into lysosomes.
Prokaryotes capable of cellular respiration and prokaryotes capable of photosynthesis took up residence in larger prokaryotes, forming obligate mutualisms. The prokaryotes capable of cellular respiration evolved into mitochondria and the prokaryotes capable of photosynthesis evolved into chloroplasts.
Molecular sequencing suggests that mitochondria arose from a group of prokaryotic organisms within the iron-oxidizing bacteria. cyanobacteria. Proteobacteria. Crenarchaeota.
Proteobacteria.
Chemical reactions involving ________ have been proposed as energy-yielding reactions for primitive organisms. S, and H2 S, O2, and H2 Fe, O2, and H2 S, and O2
S, and H2
The most widely used molecule in sequence-based evolutionary analyses are ________ genes. electron transport ATPase SSU rRNA tRNA
SSU rRNA
Which statement most closely expresses our present understanding? The chloroplast arose from the incorporation of a cyanobacterial-like organism. The chloroplast and the cyanobacteria are not closely (or specifically) related. The chloroplast is an ancestor of the cyanobacteria. The cyanobacteria are descendents of the chloroplast.
The chloroplast arose from the incorporation of a cyanobacterial-like organism.
Oxygen was a driving factor in the formation of eukaryotic cells. True False
True
The establishment of DNA as the genome of the cell may have resulted from the need to store genetic information in a more stable form than RNA. True False
True
Phylogenetic trees for bacteria are constructed by which of the following? examining the amount of horizontal gene transfer; those organisms that exchange the largest amounts of genetic material in this manner are the most closely related analyzing molecular similarities and then using computer algorithms or optimality criteria to construct phylogenetic trees showing hypothesized evolutionary relationships examining morphological, nutritional, and biochemical similarities to determine which individuals appear to be the most similar placing organisms with the most similar characteristics together; these organisms show convergent evolution and therefore belong together in the phylogeny
analyzing molecular similarities and then using computer algorithms or optimality criteria to construct phylogenetic trees showing hypothesized evolutionary relationships
The earliest RNA probably functioned in catalysis. neither catalysis nor self-replication. both catalysis and self-replication. self-replication
both catalysis and self-replication.
You are studying 12 new isolates from the human skin. The isolates have 16S rRNA sequences that are 97% similar and share important phenotypic traits. Their genomes have 55% of their genes in common. The isolates would most likely be classified as individual species of the same genus. classified as individual strains of the same species. split into different families. classified as the same species if they can mate via conjugation
classified as individual species of the same genus.
Horizontal gene transfer only affects the evolution of plasmids. is so rare over evolutionary history that it is not considered when examining microbial evolution. complicates the construction of phylogenetic trees and the interpretation of specific traits in relation to evolution. occurs within bacterial species
complicates the construction of phylogenetic trees and the interpretation of specific traits in relation to evolution.
What has occurred when organisms share a trait that was NOT inherited from a common ancestor? convergent evolution divergent evolution perpendicular evolution parallel evolution
convergent evolution
A change in allele frequencies in a set of organisms over time is called __________. evolution selection mutation fitness
evolution
Oxygen did not accumulate in the early atmosphere until it reacted with reduced materials, especially ________, in the oceans. ferrous iron nitrate hydrogen elemental sulfur
ferrous iron
What characteristics make a gene a good candidate for determining the evolutionary relationships between organisms? highly conserved and universally distributed universally distributed transferred horizontally between species highly conserved
highly conserved and universally distributed
The pan genome of a microbial species is constantly changing because of horizontal gene transfer. bottleneck events. substitutions. substitution and bottleneck events.
horizontal gene transfer.
Both deletions and insertions occur during the evolution of microbial genomes. Insertions bring in new genes that may be useful for the cell, but deletions are uncommon because they are usually lethal. always result in a severe loss of fitness but keep microbial genomes compact. may increase fitness of a microorganism by eliminating unneeded genes. always result in a severe loss of fitness for the microorganism.
may increase fitness of a microorganism by eliminating unneeded genes.
Which taxonomic tool would scientists use if they wanted to determine if an outbreak of food poisoning was caused by a particular strain of a pathogen? fatty acid methyl ester analysis DNA:DNA hybridization fluorescence in situ hybridization multilocus sequence typing
multilocus sequence typing
The evolutionary history of a group of organisms is called its ________ and it is inferred from ________. phylogeny / phenotype taxonomy / phenotype phylogeny / nucleotide sequence data taxonomy / morphology
phylogeny / nucleotide sequence data
A key concept in evolution is that all mutations are deleterious. neutral. either deleterious or beneficial. random.
random.
Evolution is driven by random mutation. selection pressure applied to random mutation. selection pressure. novel metabolic pathways.
selection pressure applied to random mutation.
Microorganisms were probably restricted to the oceans and subsurface environments until phototrophy evolved. chemoorganotrophy developed. aquatic life brought them onto land. the ozone layer was made.
the ozone layer was made.
The genes for 16S rRNA are used to determine genetic relatedness because __________. these genes have changed a great deal over time these genes have different functions in different cells these genes are of adequate length to show deep relationships these genes are only found in eukaryotes
these genes are of adequate length to show deep relationships
Systematic analysis now commonly includes ________ to identify, characterize, and determine relationships between new strains of bacterial species. whole genome analysis staining microscopy pigments
whole genome analysis