20.E: Phylogenies and the History of Life (Exercises)
20.1: Organizing Life on Earth
Review Questions
What is used to determine phylogeny?
- mutations
- DNA
- evolutionary history
- organisms on earth
- Answer
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C
What do scientists in the field of systematics accomplish?
- discover new fossil sites
- organize and classify organisms
- name new species
- communicate among field biologists
- Answer
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B
Which statement about the taxonomic classification system is correct?
- There are more domains than kingdoms.
- Kingdoms are the top category of classification.
- Classes are divisions of orders.
- Subspecies are the most specific category of classification.
- Answer
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D
On a phylogenetic tree, which term refers to lineages that diverged from the same place?
- sister taxa
- basal taxa
- rooted taxa
- dichotomous taxa
- Answer
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A
Free Response
How does a phylogenetic tree relate to the passing of time?
- Answer
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The phylogenetic tree shows the order in which evolutionary events took place and in what order certain characteristics and organisms evolved in relation to others. It does not relate to time.
Some organisms that appear very closely related on a phylogenetic tree may not actually be closely related. Why is this?
- Answer
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In most cases, organisms that appear closely related actually are; however, there are cases where organisms evolved through convergence and appear closely related but are not.
List the different levels of the taxonomic classification system.
- Answer
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domain, kingdom, phylum, class, order, family, genus, species
20.2: Determining Evolutionary Relationships
Review Questions
Which statement about analogies is correct?
- They occur only as errors.
- They are synonymous with homologous traits.
- They are derived by similar environmental constraints.
- They are a form of mutation.
- Answer
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C
What do scientists use to apply cladistics?
- homologous traits
- homoplasies
- analogous traits
- monophyletic groups
- Answer
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A
What is true about organisms that are a part of the same clade?
- They all share the same basic characteristics.
- They evolved from a shared ancestor.
- They usually fall into the same classification taxa.
- They have identical phylogenies.
- Answer
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B
Why do scientists apply the concept of maximum parsimony?
- to decipher accurate phylogenies
- to eliminate analogous traits
- to identify mutations in DNA codes
- to locate homoplasies
- Answer
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A
Free Response
Dolphins and fish have similar body shapes. Is this feature more likely a homologous or analogous trait?
- Answer
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Dolphins are mammals and fish are not, which means that their evolutionary paths (phylogenies) are quite separate. Dolphins probably adapted to have a similar body plan after returning to an aquatic lifestyle, and, therefore, this trait is probably analogous.
Why is it so important for scientists to distinguish between homologous and analogous characteristics before building phylogenetic trees?
- Answer
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Phylogenetic trees are based on evolutionary connections. If an analogous similarity were used on a tree, this would be erroneous and, furthermore, would cause the subsequent branches to be inaccurate.
Describe maximum parsimony.
- Answer
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Maximum parsimony hypothesizes that events occurred in the simplest, most obvious way, and the pathway of evolution probably includes the fewest major events that coincide with the evidence at hand.
20.3: Perspectives on the Phylogenetic Tree
Review Questions
The transfer of genes by a mechanism not involving asexual reproduction is called:
- meiosis
- web of life
- horizontal gene transfer
- gene fusion
- Answer
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C
Particles that transfer genetic material from one species to another, especially in marine prokaryotes:
- horizontal gene transfer
- lateral gene transfer
- genome fusion device
- gene transfer agents
- Answer
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D
What does the trunk of the classic phylogenetic tree represent?
- single common ancestor
- pool of ancestral organisms
- new species
- old species
- Answer
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A
Which phylogenetic model proposes that all three domains of life evolved from a pool of primitive prokaryotes?
- tree of life
- web of life
- ring of life
- network model
- Answer
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C
Free Response
Compare three different ways that eukaryotic cells may have evolved.
- Answer
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Some hypotheses propose that mitochondria were acquired first, followed by the development of the nucleus. Others propose that the nucleus evolved first and that this new eukaryotic cell later acquired the mitochondria. Still others hypothesize that prokaryotes descended from eukaryotes by the loss of genes and complexity.
Describe how aphids acquired the ability to change color.
- Answer
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Aphids have acquired the ability to make the carotenoids on their own. DNA analysis has demonstrated that this ability is due to the transfer of fungal genes into the insect by HGT, presumably as the insect consumed fungi for food.