BSC-116-001 Chapter 26

Animals that possess homologous structures probably _____.
A. have increased genetic diversity
B. evolved from the same ancestor
C. are not related
D. are the result of convergent evolution
E. are the result of similar environmental pressures in different evolutionary lineages

B. evolved from the same ancestor Homologous structures are similar because of common ancestry.

By definition a clade is _____.

A. parsimonious
B. polyphyletic
C. paraphyletic
D. analogous
E. monophyletic

E. monophyletic A clade is defined as a group that includes an ancestral species and all of its descendants.

Fossil evidence indicates that some dinosaurs had feathers. If birds are indeed descended from dinosaurs, feathers are what kind of character?

A. analogous character
B. shared derived character
C. polyphyletic character
D. cladistic character
E. shared ancestral character

E. shared ancestral character A shared ancestral character is one that originated in an ancestor of the taxon. In this case it appears that feathers originated in some dinosaur lineages and were passed down to birds.

What process actually increases the number of genes in an organism’s genome?
What process actually increases the number of genes in an organism’s genome?

A.mutation
B.parsimony
C. gene duplication
D. cladistics
E. independent assortment

C. gene duplication Mutations that lead to duplications actually increase the number of genes in a genome. When an organism has two copies of a gene, one can perform its function while the other is free to accumulate mutations to the point that it may take on a new and advantageous function.

Why do researchers use rRNA in investigations of relationships between taxa that diverged hundreds of millions of years ago?

A. rRNA is traditionally the nucleic acid chosen for recent comparisons.
B. rRNA is never the nucleic acid chosen for comparisons.
C. rRNA cannot mutate.
D. DNA coding for rRNA changes relatively slowly.
E. rRNA mutates rapidly.

D. DNA coding for rRNA changes relatively slowly.

Molecular clocks are based on the idea that _____.

A.directional selection occurs at a constant rate
B. molecules resonate at a certain frequency that can be measured
C. on average neutral mutations arise at a constant rate
D. mutations occur once every generation
E. advantageous mutations arise at a constant rate

C. on average neutral mutations arise at a constant rate The idea of a molecular clock rests on the assumption that neutral mutations can arise and become fixed in populations. The rate of occurrence of these mutations is not affected by natural selection, so it is assumed that the rate is relatively constant over time.

Which process occurred frequently in the early history of the three domains on Earth, and makes determining phylogenetic relationships of that time difficult?

A. horizontal gene transfer
B. alternative RNA splicing
C. meiosis
D. binary fission
E. mitosis

A. horizontal gene transfer Horizontal gene transfer permits gene flow from one organism’s genome to another organism’s genome, It occurs commonly between prokaryotes of different species, and even between prokaryotes and eukaryotes.

Which observation supports the position of eukaryotes at the convergence of the "ring of life"?

A. The nuclear genome of eukaryotes contains genes from archaeans and from bacteria.
B. Introns are rare in both bacteria and archaeans.
C. Circular chromosomes are present in both bacteria and archaeans.
D. Eukaryotes and archaeans both lack peptidoglycan in their cell walls.
E. Only eukaryotes perform mitosis.

A. The nuclear genome of eukaryotes contains genes from archaeans and from bacteria. A leading hypothesis proposes that eukaryotes are the result of fusion involving a bacterium and an archaean, thereby explaining the presence of both kinds of genes.

Prokaryotic cells are found in the domain(s) _____.

A. Bacteria and Archaea
B. Bacteria and Eukarya
C. Bacteria and Protista
D. Bacteria
E. Protista and Archaea

A. Bacteria and Archaea Both of these domains are composed of prokaryotic cells.

In the five-kingdom system, prokaryotes are placed in the kingdom _____.

A. Protista
B. Animalia
C. Fungi
D. Plantae
E. Monera

E. Monera All monerans are prokaryotes.

A human is classified in domain _____ and kingdom _____.

A. Eukarya … Fungi
B. Eukarya … Protista
C. Eukarya … Plantae
D. Eukarya … Animalia
E. Bacteria … Archaea

D. Eukarya … Animalia Humans are animals, and animals are eukaryotes.

A rose bush is classified in domain _____ and kingdom _____.

A. Eukarya … Fungi
B. Eukarya … Protista
C. Eukarya … Plantae
D. Eukarya … Animalia
E. Bacteria … Archaea

C. Eukarya … Plantae Rose bushes are plants.

In the five-kingdom system, which kingdom consists primarily of unicellular eukaryotes?

A. Fungi
B. Protista
C. Plantae
D. Animalia
E. Monera

B. Protista Protists are mostly unicellular eukaryotes, though they also include multicellular algae.

In the two-kingdom system, why were fungi classified in the kingdom Plantae?

A. They are sedentary.
B. They are heterotrophs.
C. They lack cell walls.
D. They are unicellular.
E. They are autotrophs.

A. They are sedentary. This is why fungi were placed in the same kingdom as plants.

There is(are) _____ eukaryotic domain(s).

A. one
B. two
C. three
D. four
E. five

A. one The only eukaryotic domain is the domain Eukarya.

This figure shows a phylogenetic tree of birds and their close relatives. Identify the monophyletic taxon.

A. Birds and the common ancestor of dinosaurs and birds
B. Birds and crocodiles and their common ancestor
C. Birds and dinosaurs and their common ancestor

C. Birds and dinosaurs and their common ancestor This grouping is monophyletic becuase it includes the common ancestor and all of its descendents. Read about monophyletic groups called clades.

Homology

Similarity due to shared ancestry

Analogy

Similarity due to convergent evolution

Clade

Is a monophyletic grouping that includes an ancestral species and all of its descendants

Orthologous genes

Are homologous genes found in different species as a result of speciation

Paralogous genes

are homologous genes within a species that result from gene duplication

The three great domains

1.) Bacteria 2.) Archae 3.) Eukarya

In comparison of birds and mammals, the condition of having four limbs is

A. a shared ancestral character.
B. a shared derived character.
C. a character useful for distinguishing birds from mammals
D. an example of analogy rather than homology

A. a shared ancestral character.

To apply parsimony to constructing a phylogenetic tree,

A. choose a tree that assumes all evolutionary changes are equally probable.
B. choose a tree in which the branch points are based on as many shared derived characters as possible.
C. choose the tree the represents the fewest evolutionary changes, in either DNA sequences or morphology.
D. choose the tree with the fewest branch points.

C. choose the tree the represents the fewest evolutionary changes, in either DNA sequences or morphology.

Three living species X,Y, and Z share a common ancestor T, as do distinct species U and V. A grouping that consists of species T, X, Y, and Z (but not U or V) makes up

A. a monophyletic taxon.
B. an ingroup, with species U as the outgroup.
C. a paraphyletic group.
D. a polyphyletic group.

C. a paraphyletic group.

If you were to build a phylogenetic tree of cats, which of the following would be the best outgroup?

A. wolf
B. domestic cat
C. lion
D. leopard

A. wolf

Phylogeny

The evolutionary history of a species or group of species.

Systematics

A discipline focused on classifying organisms and determining their evolutionary relationships.

The taxonomic / Linnaean system

Domain -> Kingdom -> Phylum -> Class -> Order -> Family -> Genus -> Species

Branch Point

Represents the divergence of two evolutionary lineages from a common ancestor.

Sister taxa

Groups of organisms that share an immediate common ancestor.

Basal taxon

Refers to a lineage that diverges early in the history of a group.

Polytomy

A branch point from which more than two descendant groups emerge.

Homoplasies

Analogous structures that arose independently are also called homoplasies.

Cladistics

An approach to systematics where ancestry is the primary criterion used to classify organisms.

Paraphyletic

A group which consists of an ancestral species and some, but not all, of its descendants.

Polyphyletic

A group which includes distantly related species but does not include their most common ancestor.

Shared ancestral character

A character that originated in an ancestor of the taxon.

Shared derived character

An evolutionary novelty unique to a clade.

Outgroup

Is a species or group of species from an evolutionary lineage that is known to have diverged before the lineage that includes the species we are studying.

Ingroup

The lineage that includes the species we are studying.

Molecular clock

An approach for measuring the absolute time of evolutionary change based on the observation that some genes and other regions of genomes appear to evolve at constant rates.