BIO 152 EXAM 2 LEARNING WITH
CORRECT ANSWERS 2025
Provide a definition of common ancestry. correct answers >>
- two organisms whose lineage converges at some point in time
List and explain four sources of evidence for common ancestry.
correct answers >> 1) similar species tend to be found
geographically close to each other (biogeography)
2) transitional forms in temporal sequences of fossils (fossil
record)
3) similarities among organisms (homology)
4) there is a hierarchical nesting of biological taxa (classification)
Explain why evidence of common ancestry means that evolution
must have occurred. correct answers >> - similarities
demonstrate two species came from similar orgin
- however, they are now two separate species
- circumstance (environment, needs, etc.) enabled certain
adaptations that led to evolution because of change in genetic
composition
- new features became favorable so eventually species evolved
that demonstrated favorable traits
Be able to state whether evolution happened given the
frequency of alleles or heritable traits in a population at two
times. correct answers >> - populations tend to become
better at surviving and reproducing over time
,- genetic change in a population over time
Explain why natural selection tends to improve organismal
adaptiveness correct answers >> - natural selection is the
idea that organisms better equipped to their environment will
survive
- genetic variants that improve organismal function tend to
increase in frequency over time
- those who have favorable adaptations survive better and
reproduce
Identify the different parts of a phylogenetic tree (clade, root,
node, branch, sister taxa) correct answers >> - taxa are most
recent in terms of evolution
- sister taxa share same common ancestor
- clase comprises all descendants of an ancestral lineage
- node describes the most recent common ancestor
- root is where the rest of the tree evolves from
Explain how geographic isolation can result in lineage splitting
and associate this phenomenon with nodes in a phylogenetic tree.
correct answers >> - species no longer are able to interact
- begin forming adaptations and reproducing
- offspring continue to form adaptations
- two linages continue to do this so they become too different to
mate and produce fertile offspring
- no longer recognize each other as a mate
,- nodes describe where the two lineages share their most recent
common ancestor
List the clades present in a phylogenetic tree and use this to
determine if two trees have the same topology. correct
answers >> - clade is comprised of all the descendants of an
ancestral lineage
- if they don't have the same lineage, they don't have the same
topology
Determine the relative degree of evolutionary relationship from
phylogenetic trees of various types. correct answers >> - to
determine relatedness, must look at common ancestry
- must remember time is moving from left to right
- determine if closest shared ancestor is grandparent or great
grandparent
- ignore tip proximity, node numbers, or physical similarity
Explain why evolutionary advancement is not a meaningful
concept. correct answers >> - all living species are equally
evolved and have the same number of ancestors
- not considered progress
- story can be told for any living taxon
Describe the evolutionary history of a clade of interest in non-
progressive terms. correct answers >> - must look at most
recent ancestors
- see how all descendants of an ancestral lineage align
- compare this information to other clades
, - see common ancestry
List the expected characteristic of tips based on changes mapped
onto a tree correct answers >> - look at red lines
- animals above the line have the train and those below do not
Correctly associate trait changes with internodes (not nodes)
correct answers >> - traits change at nodes, not internodes
Identify clades, and only clades, as worthy of formal names
correct answers >> - branches of a phylogenic tree that include
all descendants of a single ancestral lineage
Explain why tree-like relationships yield a nested hierarchical
taxonomy so long as the taxonomy is based on traits that arise
only once and are never lost. correct answers >> - provides
evidence for common
- as nest gets bigger, more diverse traits (less common traits) are
introduced
Determine the most-parsimonious history (or histories) of
character state changes for a binary trait on a given tree.
correct answers >> - hypothesis that invokes the fewest
changes is most likely to be true
- helps make inferences regarding where traits changed
- typically assume gains and losses are equally likely
Determine whether a character state in two taxa is homologous,
given a mapping of trait changes on a tree. correct answers
CORRECT ANSWERS 2025
Provide a definition of common ancestry. correct answers >>
- two organisms whose lineage converges at some point in time
List and explain four sources of evidence for common ancestry.
correct answers >> 1) similar species tend to be found
geographically close to each other (biogeography)
2) transitional forms in temporal sequences of fossils (fossil
record)
3) similarities among organisms (homology)
4) there is a hierarchical nesting of biological taxa (classification)
Explain why evidence of common ancestry means that evolution
must have occurred. correct answers >> - similarities
demonstrate two species came from similar orgin
- however, they are now two separate species
- circumstance (environment, needs, etc.) enabled certain
adaptations that led to evolution because of change in genetic
composition
- new features became favorable so eventually species evolved
that demonstrated favorable traits
Be able to state whether evolution happened given the
frequency of alleles or heritable traits in a population at two
times. correct answers >> - populations tend to become
better at surviving and reproducing over time
,- genetic change in a population over time
Explain why natural selection tends to improve organismal
adaptiveness correct answers >> - natural selection is the
idea that organisms better equipped to their environment will
survive
- genetic variants that improve organismal function tend to
increase in frequency over time
- those who have favorable adaptations survive better and
reproduce
Identify the different parts of a phylogenetic tree (clade, root,
node, branch, sister taxa) correct answers >> - taxa are most
recent in terms of evolution
- sister taxa share same common ancestor
- clase comprises all descendants of an ancestral lineage
- node describes the most recent common ancestor
- root is where the rest of the tree evolves from
Explain how geographic isolation can result in lineage splitting
and associate this phenomenon with nodes in a phylogenetic tree.
correct answers >> - species no longer are able to interact
- begin forming adaptations and reproducing
- offspring continue to form adaptations
- two linages continue to do this so they become too different to
mate and produce fertile offspring
- no longer recognize each other as a mate
,- nodes describe where the two lineages share their most recent
common ancestor
List the clades present in a phylogenetic tree and use this to
determine if two trees have the same topology. correct
answers >> - clade is comprised of all the descendants of an
ancestral lineage
- if they don't have the same lineage, they don't have the same
topology
Determine the relative degree of evolutionary relationship from
phylogenetic trees of various types. correct answers >> - to
determine relatedness, must look at common ancestry
- must remember time is moving from left to right
- determine if closest shared ancestor is grandparent or great
grandparent
- ignore tip proximity, node numbers, or physical similarity
Explain why evolutionary advancement is not a meaningful
concept. correct answers >> - all living species are equally
evolved and have the same number of ancestors
- not considered progress
- story can be told for any living taxon
Describe the evolutionary history of a clade of interest in non-
progressive terms. correct answers >> - must look at most
recent ancestors
- see how all descendants of an ancestral lineage align
- compare this information to other clades
, - see common ancestry
List the expected characteristic of tips based on changes mapped
onto a tree correct answers >> - look at red lines
- animals above the line have the train and those below do not
Correctly associate trait changes with internodes (not nodes)
correct answers >> - traits change at nodes, not internodes
Identify clades, and only clades, as worthy of formal names
correct answers >> - branches of a phylogenic tree that include
all descendants of a single ancestral lineage
Explain why tree-like relationships yield a nested hierarchical
taxonomy so long as the taxonomy is based on traits that arise
only once and are never lost. correct answers >> - provides
evidence for common
- as nest gets bigger, more diverse traits (less common traits) are
introduced
Determine the most-parsimonious history (or histories) of
character state changes for a binary trait on a given tree.
correct answers >> - hypothesis that invokes the fewest
changes is most likely to be true
- helps make inferences regarding where traits changed
- typically assume gains and losses are equally likely
Determine whether a character state in two taxa is homologous,
given a mapping of trait changes on a tree. correct answers
