BSC2005 Exam 3 Final Exam Module 10
review Questions and Correct Answers
2026-2027 Updated.
Approximately how many species are there on Earth right now? Approximately what
percent are animals vs. plants vs. fungi vs. unicellular organisms? How would that
change if we looked at estimated species vs. described species? - Answer oThere are millions
of species on Earth right now (exact ranges is estimated
between 30 million to 2 billion).
oAnimals: 63.5%
oPlants: 14.4%
oFungi: 2.9%
oUnicellular: unknown on a grand scale
oThese percentages would change drastically if we looked t estimated vs.
described. Unicellular organisms would most likely make up the bulk of known
species on Earth.
Define biodiversity. Why is it important? - Answer oBiodiversity: the variety of life on Earth at
all its levels, from genes to
ecosystems.
oBiodiversity is important as it can encompass the evolutionary, ecological, and
cultural processes that sustain life.
Define biogeography. What can the movement of the continents tell us about the
evolution of life? Explain some examples. - Answer oBiogeography: the study of how
organisms are distributed in geographical space.
oThe movement of continents tells us why some species may live in particular
places (because that's where their ancestors lived).
oAround 3 mya, Isthmus of Panama connected North and South America, which
allowed migration.
▪Placental species migrated south, and outcompeted most marsupials,
which caused extinction.
What is an adaptive radiation? Why/how does it occur? - Answer oAdaptive radiation: a
species or group of species adapts and diversifies to fill
open niches, producing many daughter species.
, oWill usually occurs due to ecological opportunity.
oThis may occur due to extinction of another group or to exploit an unoccupied
niche.
What's the difference between gradualism vs. punctuated equilibrium? - Answer oGradualism:
small, incremented changes through time
oPunctuated equilibrium: large, rapid changes (usually at time of speciation) and
then long periods of stasis.
What is binomial nomenclature, and why is it important? - Answer oThe system of
nomenclature in which two terms are used to denote a species of
living organism, the first one indicating the genus and the second the specific
epithet.
oThis naming system is important because it allows people throughout the world to
communication unambiguously about animal species.
What are the levels of Linnean taxonomy, from most inclusive to least inclusive? - Answer
oKingdom, Phylum, Class, Order, Family, Genus, Species
What is a phylogenetic tree, and how is it similar to / different from Linnean taxonomy? -
Answer oPhylogenetic tree: a visual representation of evolutionary history; depicts
relationships between a set of tips based on shared characteristics that we infer to
have evolved.
oBoth are methods of establishing meaningful ways to classify species, however
Linnean taxonomy relies heavily on ranking these different groups.
Given a phylogenetic tree (drawn in a variety of ways), be able to identify: - Answer othe
common ancestor/root and the tips of the tree. What does this imply about how time is
depicted using a tree?
othe most recent common ancestor of any two organisms on that tree.
othe closest relative of any organism on a tree.
othe clades that that tree contains
oidentical trees with rotated branches
What are nodes on phylogenetic trees? What event in the evolutionary history of a group
of organisms do they represent? - Answer oA node represents a branching point from the
ancestral population.
review Questions and Correct Answers
2026-2027 Updated.
Approximately how many species are there on Earth right now? Approximately what
percent are animals vs. plants vs. fungi vs. unicellular organisms? How would that
change if we looked at estimated species vs. described species? - Answer oThere are millions
of species on Earth right now (exact ranges is estimated
between 30 million to 2 billion).
oAnimals: 63.5%
oPlants: 14.4%
oFungi: 2.9%
oUnicellular: unknown on a grand scale
oThese percentages would change drastically if we looked t estimated vs.
described. Unicellular organisms would most likely make up the bulk of known
species on Earth.
Define biodiversity. Why is it important? - Answer oBiodiversity: the variety of life on Earth at
all its levels, from genes to
ecosystems.
oBiodiversity is important as it can encompass the evolutionary, ecological, and
cultural processes that sustain life.
Define biogeography. What can the movement of the continents tell us about the
evolution of life? Explain some examples. - Answer oBiogeography: the study of how
organisms are distributed in geographical space.
oThe movement of continents tells us why some species may live in particular
places (because that's where their ancestors lived).
oAround 3 mya, Isthmus of Panama connected North and South America, which
allowed migration.
▪Placental species migrated south, and outcompeted most marsupials,
which caused extinction.
What is an adaptive radiation? Why/how does it occur? - Answer oAdaptive radiation: a
species or group of species adapts and diversifies to fill
open niches, producing many daughter species.
, oWill usually occurs due to ecological opportunity.
oThis may occur due to extinction of another group or to exploit an unoccupied
niche.
What's the difference between gradualism vs. punctuated equilibrium? - Answer oGradualism:
small, incremented changes through time
oPunctuated equilibrium: large, rapid changes (usually at time of speciation) and
then long periods of stasis.
What is binomial nomenclature, and why is it important? - Answer oThe system of
nomenclature in which two terms are used to denote a species of
living organism, the first one indicating the genus and the second the specific
epithet.
oThis naming system is important because it allows people throughout the world to
communication unambiguously about animal species.
What are the levels of Linnean taxonomy, from most inclusive to least inclusive? - Answer
oKingdom, Phylum, Class, Order, Family, Genus, Species
What is a phylogenetic tree, and how is it similar to / different from Linnean taxonomy? -
Answer oPhylogenetic tree: a visual representation of evolutionary history; depicts
relationships between a set of tips based on shared characteristics that we infer to
have evolved.
oBoth are methods of establishing meaningful ways to classify species, however
Linnean taxonomy relies heavily on ranking these different groups.
Given a phylogenetic tree (drawn in a variety of ways), be able to identify: - Answer othe
common ancestor/root and the tips of the tree. What does this imply about how time is
depicted using a tree?
othe most recent common ancestor of any two organisms on that tree.
othe closest relative of any organism on a tree.
othe clades that that tree contains
oidentical trees with rotated branches
What are nodes on phylogenetic trees? What event in the evolutionary history of a group
of organisms do they represent? - Answer oA node represents a branching point from the
ancestral population.
