MICR 271 Midterm Exam with All
Complete Answers.
3 Domains - Answer 1)Archaea
2)Bacteria
3)Eukaryota
Endosymbiont Theory Definition - Answer Eukaryotes evolved from prokaryotes based on
similarities found between bacteria and mitochondria
Microbe Definition - Answer microscopic living organism that may be single celled
(prokaryotic) or multicellular (eukaryotic)
_____________ is abundant in the atmosphere but only a few species of microbes can use it in
this form - Answer Nitrogen
The total biomass on Earth of bacteria is approaching that of ________ - Answer plants
There are typically ____________ bacteria in a gram of soil and __________________ bacteria
in a mL of fresh water - Answer 50 million; 1 million
A human consists of __________ more bacteria cells than human cells and ____________ more
microbial genes than human genes - Answer 10x; 100x
Photosynthetic bacteria (cyanobacteria) produce _____________________ - Answer 50% of
the oxygen we breathe
STUDY CHART W DIFFERENCES BW EUKARYOTES & PROKARYOTES - Answer
Major difference in structure of eukaryotes vs prokaryotes - Answer Eukaryotes have
membrane bound organelles and prokaryotes do not
Explain the endosymbiotic theory - Answer 1)Eukaryotes evolved from prokaryotes based on
similarities bw bacteria and mitochondria
2)Mitochondria & chloroplasts evolved from free-living bacteria via symbiosis within a
eukaryotic host cell
3)2 key diffs bw bacteria & miochondria= these organelles contain their own DNA & distinct
translation system
, What are the 2 theories of mitochondrial symbiosis/endosymbiont hypothesis - Answer
1)Archezoan Scenario
2)Symbiogenesis Scenario
Define symbiosis - Answer Living together or close association of 2 dissimilar organisms, each
of these organisms being known as a symbiont
Archezoan Scenario - Answer -one of the theories of mitochondrial symbiosis
-A primitive mitochondrial eukaryote cell phagocytosed an a-proteobacterium which led to
evolution of mitochondrion
-fallen out of favour
Symbiogenesis Scenario - Answer -theory of endosymbiont theory/mitochondrial symbiosis
1)States complexity of eukaryotic cell and its defining features emerged after mitochondrial
symbiosis, not before
2)Single endosymbiotic event involving the uptake of an a proteobacterium by an archaeal cell
led to generation of mitochondria and then the evolution of nucleus & compartmentalization of
eukaryotic cell occured
Phylogeny definition - Answer The evolution of a genetically related group of organisms as
distinguished from the development of the individual organisms
What did initial efforts to map phylogenetic relationships rely on? - Answer comparing
ribosomal RNA data between organisms to create a tree of life
What was the major finding of the older version of the tree of life? - Answer The close
relationship between archaea and Eukaryota
Phylogenetic tree vs phylogenomic tree - Answer phylogenetic-compared rRNA sequences
phylogenomic-compared entire genomes
Original tree of life depicted the evolutionary distance between archaea and eukaryotes to be
___________________ than it actually is - Answer much further
Horizontal Gene Transfer - Answer The movement of genetic material between organisms
other than via vertical transmission (transition of DNA from parent to child)
Complete Answers.
3 Domains - Answer 1)Archaea
2)Bacteria
3)Eukaryota
Endosymbiont Theory Definition - Answer Eukaryotes evolved from prokaryotes based on
similarities found between bacteria and mitochondria
Microbe Definition - Answer microscopic living organism that may be single celled
(prokaryotic) or multicellular (eukaryotic)
_____________ is abundant in the atmosphere but only a few species of microbes can use it in
this form - Answer Nitrogen
The total biomass on Earth of bacteria is approaching that of ________ - Answer plants
There are typically ____________ bacteria in a gram of soil and __________________ bacteria
in a mL of fresh water - Answer 50 million; 1 million
A human consists of __________ more bacteria cells than human cells and ____________ more
microbial genes than human genes - Answer 10x; 100x
Photosynthetic bacteria (cyanobacteria) produce _____________________ - Answer 50% of
the oxygen we breathe
STUDY CHART W DIFFERENCES BW EUKARYOTES & PROKARYOTES - Answer
Major difference in structure of eukaryotes vs prokaryotes - Answer Eukaryotes have
membrane bound organelles and prokaryotes do not
Explain the endosymbiotic theory - Answer 1)Eukaryotes evolved from prokaryotes based on
similarities bw bacteria and mitochondria
2)Mitochondria & chloroplasts evolved from free-living bacteria via symbiosis within a
eukaryotic host cell
3)2 key diffs bw bacteria & miochondria= these organelles contain their own DNA & distinct
translation system
, What are the 2 theories of mitochondrial symbiosis/endosymbiont hypothesis - Answer
1)Archezoan Scenario
2)Symbiogenesis Scenario
Define symbiosis - Answer Living together or close association of 2 dissimilar organisms, each
of these organisms being known as a symbiont
Archezoan Scenario - Answer -one of the theories of mitochondrial symbiosis
-A primitive mitochondrial eukaryote cell phagocytosed an a-proteobacterium which led to
evolution of mitochondrion
-fallen out of favour
Symbiogenesis Scenario - Answer -theory of endosymbiont theory/mitochondrial symbiosis
1)States complexity of eukaryotic cell and its defining features emerged after mitochondrial
symbiosis, not before
2)Single endosymbiotic event involving the uptake of an a proteobacterium by an archaeal cell
led to generation of mitochondria and then the evolution of nucleus & compartmentalization of
eukaryotic cell occured
Phylogeny definition - Answer The evolution of a genetically related group of organisms as
distinguished from the development of the individual organisms
What did initial efforts to map phylogenetic relationships rely on? - Answer comparing
ribosomal RNA data between organisms to create a tree of life
What was the major finding of the older version of the tree of life? - Answer The close
relationship between archaea and Eukaryota
Phylogenetic tree vs phylogenomic tree - Answer phylogenetic-compared rRNA sequences
phylogenomic-compared entire genomes
Original tree of life depicted the evolutionary distance between archaea and eukaryotes to be
___________________ than it actually is - Answer much further
Horizontal Gene Transfer - Answer The movement of genetic material between organisms
other than via vertical transmission (transition of DNA from parent to child)
