Question 1

what are two features of modern bacteria that prevent them from engulfing other prokaryotes?

Accepted Answer

-rigid peptidoglycan layer 
-lack of any cytoskeletal element

Question 2

what are two arguments suggesting the protocell membrane could not have been a phospholipid bilayer?

Accepted Answer

-phospholipid bilayer is composed of hydrophilic layers surrounding a hydrophobic layer that mlcls cannot cross w/o specialized pores and use of ATP
-no way for mlcls to get into/be removed from the first cells if they were surrounded by a membrane of ph

Question 3

where do humans acquire their gut microbiome?

Accepted Answer

from the surrounding environment (external)

Question 4

why are experimental approaches the only scientific way to explore life on earth before LUCA?

Accepted Answer

the steps before and after the origin of life were before LUCA so we cannot infer the characteristics of the organisms earlier using phylogenetic inference.

Question 5

what evidence suggests that the endosymbiotic event that led to mitochondria occurred prior to the endosymbiosis of a plastid?

Accepted Answer

all organisms have mitochondria and some organisms have plastids. if both events occurred one, then mitochondria preceded plastids

Question 6

why does genome duplication immediately result in prezygotic isolation?

Accepted Answer

tetraploid and diploid individuals of the same species are reproductively isolated because their hybrid offspring are triploid, so usually the offspring are sterile.

Question 7

incomplete gut and coelom compare/contrast

Accepted Answer

incomplete gut: internal digestive cavity that has one opening where food comes in and waste products go out 
coelom: body cavity w/o an opening 
both are cavities but the coelom is to increase girth while gut is for digestion

Question 8

conjugation and binary fission compare/contrast

Accepted Answer

binary fission: asexual reproduction in bacteria that results in 2 exact copies of daughter cells 
conjugation: transfer of genetic material by cell-to-cell contact 
fission increases # of cells but doesn't change genetic composition, opposite for conj.

Question 9

choanocytes and choanoflagellates

Accepted Answer

choanocytes: specialized cells in porifera that allow them to filter feed
choanoflagellates: closest relative of Animalia that are composed of a cell body and flagella for locomotion
choanocytes are specialized cells while choanoflagellates are organis

Question 10

define biological species concept and explain if the dinosaurs are valid species according to BSC

Accepted Answer

BSC defines species as members of a population that are actually/potentially inbreeding. it cannot be used to differentiate extinct or fossilized organisms b/c we cannot test if they interbreed.

Question 11

why are beneficial mutations rarely found when they are polymorphic?

Accepted Answer

when mutations are beneficial they are favored by natural selection and go to fixation

Question 12

pleistocene overkill hypothesis

Accepted Answer

proposed that the colonization of humans into the western hemisphere was responsible for the extirpation of the large mammal fauna about 12,000 yrs ago

Question 13

what would it look like if genes were under positive selection?

Accepted Answer

the non-synonymous substitutions would have a higher rate of subs because selection is favoring the amino acids to change

Question	Answer
what are two features of modern bacteria that prevent them from engulfing other prokaryotes?	-rigid peptidoglycan layer -lack of any cytoskeletal element
what are two arguments suggesting the protocell membrane could not have been a phospholipid bilayer?	-phospholipid bilayer is composed of hydrophilic layers surrounding a hydrophobic layer that mlcls cannot cross w/o specialized pores and use of ATP -no way for mlcls to get into/be removed from the first cells if they were surrounded by a membrane of ph
where do humans acquire their gut microbiome?	from the surrounding environment (external)
why are experimental approaches the only scientific way to explore life on earth before LUCA?	the steps before and after the origin of life were before LUCA so we cannot infer the characteristics of the organisms earlier using phylogenetic inference.
what evidence suggests that the endosymbiotic event that led to mitochondria occurred prior to the endosymbiosis of a plastid?	all organisms have mitochondria and some organisms have plastids. if both events occurred one, then mitochondria preceded plastids
why does genome duplication immediately result in prezygotic isolation?	tetraploid and diploid individuals of the same species are reproductively isolated because their hybrid offspring are triploid, so usually the offspring are sterile.
incomplete gut and coelom compare/contrast	incomplete gut: internal digestive cavity that has one opening where food comes in and waste products go out coelom: body cavity w/o an opening both are cavities but the coelom is to increase girth while gut is for digestion
conjugation and binary fission compare/contrast	binary fission: asexual reproduction in bacteria that results in 2 exact copies of daughter cells conjugation: transfer of genetic material by cell-to-cell contact fission increases # of cells but doesn't change genetic composition, opposite for conj.
choanocytes and choanoflagellates	choanocytes: specialized cells in porifera that allow them to filter feed choanoflagellates: closest relative of Animalia that are composed of a cell body and flagella for locomotion choanocytes are specialized cells while choanoflagellates are organis
define biological species concept and explain if the dinosaurs are valid species according to BSC	BSC defines species as members of a population that are actually/potentially inbreeding. it cannot be used to differentiate extinct or fossilized organisms b/c we cannot test if they interbreed.
why are beneficial mutations rarely found when they are polymorphic?	when mutations are beneficial they are favored by natural selection and go to fixation
pleistocene overkill hypothesis	proposed that the colonization of humans into the western hemisphere was responsible for the extirpation of the large mammal fauna about 12,000 yrs ago
what would it look like if genes were under positive selection?	the non-synonymous substitutions would have a higher rate of subs because selection is favoring the amino acids to change

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Bio 111 Exam 2 KEY