PCB 3043: Final || 100% Actual Answers.
Commensalism correct answers A relationship between two organisms in which one organism
benefits and the other is unaffected (+, 0)
Feeding commensalism correct answers Cattle Egrets and Cattle- Livestock rustle up insects
while feeding that the birds can capture easily
Shelter commensalism correct answers Hermit crabs depend on snail created shells but never
interact with the live snail
Transportation commensalism correct answers Ramoras ride on sharks across oceans and feed on
scraps left after feeding, but don't affect shark
Habitat commensalism correct answers Whale barnacles occur only on the skin of whales
(obligate), but there are no documented positive or negative effects on the whale's fitness
Reproductive/dispersal commensalism correct answers The barbed seeds of many plants get
stuck in the hair (or socks) of animals and may be transported great distances. Major fitness
advantage to the plant, major annoyance but minor fitness cost to animal
Mutualism correct answers A direct or indirect species interaction where both species benefit
(incur net positive effects)(+,+)
benefits; cost correct answers To have (+, +) relationship, ___________ to both species fitness
must outweigh ________ of relationship
Acacia tree and ant study (Janzen) correct answers -Removed ants from some Acacia trees in
Mexico and measured growth rates and survival versus trees with ants
-Found that Acacias do much better with ants present regardless of the cost of producing
specialized structures
Food for protection correct answers Mutualism relationship where one species provides
protection for another species that provides a food source (Acacia and ants)
Food for reproduction correct answers Mutualism relationship where one species has evolved
characteristics that allow another species to feed while also helping reproduction/dispersal
(Hummingbirds and hummingbird flowers)
Food for parasite removal correct answers Mutualism relationship where one species allows
another species to feed on parasites present on the host species; allows one species to feed and
the other to be rid of parasites (On reefs, large fish will seek out small fish, even prey species, to
remove external parasites )
, Food for nutrients correct answers Mutualism relationship where one species provides nutrients
to another in exchange for a food source (Corals and Zooxanthellae)
Obligate mutualism correct answers Mutualism in which is required for the survival or fitness of
one or both species
Facultative mutualism correct answers Mutualism which is not required for the survival of both
species, but increases fitness when it happens
Transient mutualism correct answers Mutualism which occurs for a brief time or one phase of
life
Permanent mutualism correct answers Mutualism which occurs for the length of an organisms
life
Direct mutualism correct answers Some physical contact between partners
Indirect mutualism correct answers When the indirect interaction is beneficial to both species
Facilitation correct answers Occurs when one species changes the environment to be more
suitable for a second species. Basically, an indirect and special form of commensalism (+,0)
(examples: Spartina stabilizing marsh soil; Azolla fixing nitrogen on rice paddies; Serengetti
grazers)
predator; parasite correct answers Mutualisms likely evolve out of _____________ or
_____________ interactions
Community correct answers An assemblage of populations of living organisms in a prescribed
area or habitat that interact with one another, directly or indirectly
Ecosystem correct answers All the interacting parts of the physical and biological worlds
Association correct answers Group of species living in the same place
Guild correct answers Species in the same community utilizing resources in the same way, often
competitors
Phytosociology correct answers The study of the composition and structure of plant communities
Endosymbiotic theory correct answers Theory that eukaryotic cells formed from a symbiosis
among several different prokaryotic organisms; Ancestors of mitochondria and plastids was
prokaryotes that came to live in a host cell
Species richness correct answers The number of different species in a community
Species eveness correct answers The relative proportion of different species in a given area
Commensalism correct answers A relationship between two organisms in which one organism
benefits and the other is unaffected (+, 0)
Feeding commensalism correct answers Cattle Egrets and Cattle- Livestock rustle up insects
while feeding that the birds can capture easily
Shelter commensalism correct answers Hermit crabs depend on snail created shells but never
interact with the live snail
Transportation commensalism correct answers Ramoras ride on sharks across oceans and feed on
scraps left after feeding, but don't affect shark
Habitat commensalism correct answers Whale barnacles occur only on the skin of whales
(obligate), but there are no documented positive or negative effects on the whale's fitness
Reproductive/dispersal commensalism correct answers The barbed seeds of many plants get
stuck in the hair (or socks) of animals and may be transported great distances. Major fitness
advantage to the plant, major annoyance but minor fitness cost to animal
Mutualism correct answers A direct or indirect species interaction where both species benefit
(incur net positive effects)(+,+)
benefits; cost correct answers To have (+, +) relationship, ___________ to both species fitness
must outweigh ________ of relationship
Acacia tree and ant study (Janzen) correct answers -Removed ants from some Acacia trees in
Mexico and measured growth rates and survival versus trees with ants
-Found that Acacias do much better with ants present regardless of the cost of producing
specialized structures
Food for protection correct answers Mutualism relationship where one species provides
protection for another species that provides a food source (Acacia and ants)
Food for reproduction correct answers Mutualism relationship where one species has evolved
characteristics that allow another species to feed while also helping reproduction/dispersal
(Hummingbirds and hummingbird flowers)
Food for parasite removal correct answers Mutualism relationship where one species allows
another species to feed on parasites present on the host species; allows one species to feed and
the other to be rid of parasites (On reefs, large fish will seek out small fish, even prey species, to
remove external parasites )
, Food for nutrients correct answers Mutualism relationship where one species provides nutrients
to another in exchange for a food source (Corals and Zooxanthellae)
Obligate mutualism correct answers Mutualism in which is required for the survival or fitness of
one or both species
Facultative mutualism correct answers Mutualism which is not required for the survival of both
species, but increases fitness when it happens
Transient mutualism correct answers Mutualism which occurs for a brief time or one phase of
life
Permanent mutualism correct answers Mutualism which occurs for the length of an organisms
life
Direct mutualism correct answers Some physical contact between partners
Indirect mutualism correct answers When the indirect interaction is beneficial to both species
Facilitation correct answers Occurs when one species changes the environment to be more
suitable for a second species. Basically, an indirect and special form of commensalism (+,0)
(examples: Spartina stabilizing marsh soil; Azolla fixing nitrogen on rice paddies; Serengetti
grazers)
predator; parasite correct answers Mutualisms likely evolve out of _____________ or
_____________ interactions
Community correct answers An assemblage of populations of living organisms in a prescribed
area or habitat that interact with one another, directly or indirectly
Ecosystem correct answers All the interacting parts of the physical and biological worlds
Association correct answers Group of species living in the same place
Guild correct answers Species in the same community utilizing resources in the same way, often
competitors
Phytosociology correct answers The study of the composition and structure of plant communities
Endosymbiotic theory correct answers Theory that eukaryotic cells formed from a symbiosis
among several different prokaryotic organisms; Ancestors of mitochondria and plastids was
prokaryotes that came to live in a host cell
Species richness correct answers The number of different species in a community
Species eveness correct answers The relative proportion of different species in a given area
