BIOB51 EXAM REVIEW
QUESTIONS WITH
COMPLETE SOLUTIONS
Macroevolution - Answer- Evolution occurring above the species level. It involves the
origination, diversification, and extinction of species over time. It helps understand
patterns of biodiversity through space and time.
Mass extinctions - Answer- Widespread and rapid decreases in the amount of life on
Earth, distinct from background extinctions. The 'big five' extinctions had different
causes and affected different organisms.
Maximum likelihood - Answer- An approach used in phylogeny reconstruction to find the
tree topologies that are most likely, given a precise model for molecular evolution and a
particular data set. It determines the probability of the data given a hypothetical tree and
evolutionary model.
Maximum parsimony - Answer- A principle that guides the selection of the most
compelling hypothesis among several choices. In cladistics, scientists search for the
tree topology with the least number of character-state changes.
Messenger RNA (mRNA) - Answer- Molecules of RNA that carry genetic information
from DNA to the ribosome, where it can be translated into protein.
Metapopulation - Answer- A group of spatially separated populations of the same
species that interact at some level, with significant gene flow between them indicating a
shared gene pool.
Microevolution - Answer- Evolution occurring within populations. It involves adaptive
and neutral changes in allele frequencies.
Microsatellite - Answer- A noncoding stretch of DNA containing a string of short (one to
six base pairs), repeated segments. The number of repetitive segments can be highly
polymorphic, making them valuable genetic characters.
Mimicry - Answer- A coevolutionary phenomenon where different forms of mimicry can
evolve.
,Mobile genetic element - Answer- A type of DNA that can move around in the genome,
such as transposons ('jumping genes') and plasmids. They contribute significantly to
genome size variation.
Molecular clock - Answer- A concept derived from the neutral theory of molecular
evolution, where neutral mutations accumulate in a clocklike fashion in genomes.
Scientists can use this to estimate the origin of diseases and major clades.
Monophyletic - Answer- Describes a group of organisms that form a clade, including a
common ancestor and all of its descendants.
Monotremes - Answer- The deepest branch of living mammals that produce milk
(secreted through glands) and lay eggs, including the duck-billed platypus and echidna.
Morphology - Answer- Refers to the form and structure of organisms.
Muller's ratchet - Answer- The process by which genomes of asexual populations
accumulate irreversible, deleterious mutations over generations, potentially driving them
to extinction. Sexual reproduction can counteract this by purging genetic load through
recombination.
Mutation - Answer- Any change to the genomic sequence of an organism. Mutations are
the ultimate source of heritable genetic variation. They can be harmful, beneficial, or
neutral, and are caused by copy errors during DNA replication or environmental factors.
Mutation-selection balance - Answer- Occurs when the introduction of new alleles by
mutation is balanced by allele loss through negative selection.
Mutualism - Answer- A positive/positive relationship between species that raises each
other's fitness.
Narrow sense heritability (h²) - Answer- The proportion of phenotypic variance that is
due to the additive effects of alleles (additive genetic variance). It is the component of
variance that causes offspring to resemble their parents and causes populations to
evolve predictably in response to selection. It can be calculated from an offspring-parent
regression.
Natural selection - Answer- A mechanism that can lead to evolution, whereby differential
survival and reproduction of individuals cause some genetic types to replace
(outcompete) others. It arises when there is variation in phenotypes and this variation
causes some individuals to perform better. Only natural selection produces adaptation.
Negative frequency-dependent selection (NFDS) - Answer- A type of balancing
selection where common phenotypes are selected against, and rare phenotypes are
favored.
, Neutral theory of molecular evolution - Answer- Proposed by Motoo Kimura, it states
that most evolution at the molecular level is neutral (due to drift) and that neutral
mutations become fixed in lineages at a regular, clock-like rate. It provides a null
hypothesis for recognizing cases of natural selection.
Nodes - Answer- In gene trees, nodes represent coalescence (common ancestry) when
tracing backward in time. In phylogenetic trees, internal nodes represent ancestral
populations or species.
Notochord - Answer- A flexible, rod-shaped structure found in the embryos of all
chordates. It served as the first 'backbones' in early chordates.
Nucleotide - Answer- The structural unit that links together to form DNA (and RNA).
Each nucleotide includes a sugar (like deoxyribose or ribose) and a base.
Null hypothesis - Answer- A default hypothesis that there is no relationship between two
measured phenomena. Rejecting it provides evidence that a relationship may exist. The
Hardy-Weinberg theorem serves as a fundamental null model in population genetics.
Null model - Answer- In population genetics, it shows what happens to allele
frequencies across generations if none of the mechanisms of evolution are operating.
Origination rate (α) - Answer- A driver of macroevolution, referring to speciation.
Originations - Answer- Occur when the fossil record (or genetic evidence) indicates that
a lineage split into distinct clades/taxa, representing the first appearance of a particular
distinct lineage.
Orthologous genes (orthologs) - Answer- Genes in different species that evolved from a
common ancestral gene by speciation.
Outgroup - Answer- Used in phylogenetics to infer what is ancestral and what is
derived.
Parapatric speciation - Answer- A model of speciation that occurs when populations
have partial geographic overlap.
Parsimony - Answer- A principle that guides the selection of the most compelling
hypothesis among several choices. The hypothesis requiring the fewest assumptions or
steps is usually (but not always) best.
Phenotype - Answer- An observable, measurable characteristic of an organism. This
can include morphological structure, developmental process, physiological process,
performance trait, or behavior, and can even be molecules produced by genes.
QUESTIONS WITH
COMPLETE SOLUTIONS
Macroevolution - Answer- Evolution occurring above the species level. It involves the
origination, diversification, and extinction of species over time. It helps understand
patterns of biodiversity through space and time.
Mass extinctions - Answer- Widespread and rapid decreases in the amount of life on
Earth, distinct from background extinctions. The 'big five' extinctions had different
causes and affected different organisms.
Maximum likelihood - Answer- An approach used in phylogeny reconstruction to find the
tree topologies that are most likely, given a precise model for molecular evolution and a
particular data set. It determines the probability of the data given a hypothetical tree and
evolutionary model.
Maximum parsimony - Answer- A principle that guides the selection of the most
compelling hypothesis among several choices. In cladistics, scientists search for the
tree topology with the least number of character-state changes.
Messenger RNA (mRNA) - Answer- Molecules of RNA that carry genetic information
from DNA to the ribosome, where it can be translated into protein.
Metapopulation - Answer- A group of spatially separated populations of the same
species that interact at some level, with significant gene flow between them indicating a
shared gene pool.
Microevolution - Answer- Evolution occurring within populations. It involves adaptive
and neutral changes in allele frequencies.
Microsatellite - Answer- A noncoding stretch of DNA containing a string of short (one to
six base pairs), repeated segments. The number of repetitive segments can be highly
polymorphic, making them valuable genetic characters.
Mimicry - Answer- A coevolutionary phenomenon where different forms of mimicry can
evolve.
,Mobile genetic element - Answer- A type of DNA that can move around in the genome,
such as transposons ('jumping genes') and plasmids. They contribute significantly to
genome size variation.
Molecular clock - Answer- A concept derived from the neutral theory of molecular
evolution, where neutral mutations accumulate in a clocklike fashion in genomes.
Scientists can use this to estimate the origin of diseases and major clades.
Monophyletic - Answer- Describes a group of organisms that form a clade, including a
common ancestor and all of its descendants.
Monotremes - Answer- The deepest branch of living mammals that produce milk
(secreted through glands) and lay eggs, including the duck-billed platypus and echidna.
Morphology - Answer- Refers to the form and structure of organisms.
Muller's ratchet - Answer- The process by which genomes of asexual populations
accumulate irreversible, deleterious mutations over generations, potentially driving them
to extinction. Sexual reproduction can counteract this by purging genetic load through
recombination.
Mutation - Answer- Any change to the genomic sequence of an organism. Mutations are
the ultimate source of heritable genetic variation. They can be harmful, beneficial, or
neutral, and are caused by copy errors during DNA replication or environmental factors.
Mutation-selection balance - Answer- Occurs when the introduction of new alleles by
mutation is balanced by allele loss through negative selection.
Mutualism - Answer- A positive/positive relationship between species that raises each
other's fitness.
Narrow sense heritability (h²) - Answer- The proportion of phenotypic variance that is
due to the additive effects of alleles (additive genetic variance). It is the component of
variance that causes offspring to resemble their parents and causes populations to
evolve predictably in response to selection. It can be calculated from an offspring-parent
regression.
Natural selection - Answer- A mechanism that can lead to evolution, whereby differential
survival and reproduction of individuals cause some genetic types to replace
(outcompete) others. It arises when there is variation in phenotypes and this variation
causes some individuals to perform better. Only natural selection produces adaptation.
Negative frequency-dependent selection (NFDS) - Answer- A type of balancing
selection where common phenotypes are selected against, and rare phenotypes are
favored.
, Neutral theory of molecular evolution - Answer- Proposed by Motoo Kimura, it states
that most evolution at the molecular level is neutral (due to drift) and that neutral
mutations become fixed in lineages at a regular, clock-like rate. It provides a null
hypothesis for recognizing cases of natural selection.
Nodes - Answer- In gene trees, nodes represent coalescence (common ancestry) when
tracing backward in time. In phylogenetic trees, internal nodes represent ancestral
populations or species.
Notochord - Answer- A flexible, rod-shaped structure found in the embryos of all
chordates. It served as the first 'backbones' in early chordates.
Nucleotide - Answer- The structural unit that links together to form DNA (and RNA).
Each nucleotide includes a sugar (like deoxyribose or ribose) and a base.
Null hypothesis - Answer- A default hypothesis that there is no relationship between two
measured phenomena. Rejecting it provides evidence that a relationship may exist. The
Hardy-Weinberg theorem serves as a fundamental null model in population genetics.
Null model - Answer- In population genetics, it shows what happens to allele
frequencies across generations if none of the mechanisms of evolution are operating.
Origination rate (α) - Answer- A driver of macroevolution, referring to speciation.
Originations - Answer- Occur when the fossil record (or genetic evidence) indicates that
a lineage split into distinct clades/taxa, representing the first appearance of a particular
distinct lineage.
Orthologous genes (orthologs) - Answer- Genes in different species that evolved from a
common ancestral gene by speciation.
Outgroup - Answer- Used in phylogenetics to infer what is ancestral and what is
derived.
Parapatric speciation - Answer- A model of speciation that occurs when populations
have partial geographic overlap.
Parsimony - Answer- A principle that guides the selection of the most compelling
hypothesis among several choices. The hypothesis requiring the fewest assumptions or
steps is usually (but not always) best.
Phenotype - Answer- An observable, measurable characteristic of an organism. This
can include morphological structure, developmental process, physiological process,
performance trait, or behavior, and can even be molecules produced by genes.
