Answers to End-of-Chapter Questions – Brooker et al ARIS site
Chapter 26
Test Yourself Questions
1. The study of biological diversity based on evolutionary relationships is
a. paleontology.
b. evolution.
c. systematics.
d. ontogeny.
e. both a and b.
Answer: c. Systematics is the study of biological diversity based on evolutionary relationships.
2. Which of the following is the correct order of the taxa used to classify organisms?
a. kingdom, domain, phylum, class, order, family, genus, species
b. domain, kingdom, class, phylum, order, family, genus, species
c. domain, kingdom, phylum, class, family, order, genus, species
d. domain, kingdom, phylum, class, order, family, genus, species
e. kingdom, domain, phylum, order, class, family, species, genus
Answer: d. The correct order of taxa used to classify organisms is domain, kingdom, phylum, class,
order, family, genus, species.
3. When considering organisms within the same taxon, which level includes organisms with the
greatest similarity?
a. kingdom
b. class
c. order
d. family
e. genus
Answer: e. The lowest taxon would include organisms with the greatest similarity. In this case, the
lowest taxon would be genus.
4. Which of the following characteristics is not shared by prokaryotes and eukaryotes?
a. DNA is the genetic material.
b. Messenger RNA encodes the information to produce proteins.
c. All cells are surrounded by a plasma membrane.
d. The cytoplasm is compartmentalized into organelles.
e. Both a and d.
Answer: d. Only eukaryotes have compartmentalized organelles.
5. The characteristics that define organisms in the kingdom Plantae include
a. unicellular.
b. photosynthetic.
c. multicellular.
d. a and b only.
e. b and c only.
Answer: e. The kingdom Plantae include multicellular species that are nearly all photosynthetic.
6. The evolutionary history of a species is
a. ontogeny.
b. taxonomy.
c. evolution.
d. phylogeny.
e. embryology.
Answer: d. The evolutionary history of a species is phylogeny.
7. A group composed of all species derived from a common ancestor is referred to as a
a. a phylum.
b. a monophyletic group or clade.
c. a phenogram.
d. an outgroup.
e. a taxon.
Answer: b. A group of composed of all species derived from a common ancestor is referred to as a
monophyletic group or clade.
8. The goal of modern taxonomy is to
a. classify all organisms based on morphological similarities.
b. classify all organisms in monophyletic groups.
c. classify all organisms based solely on genetic similarities.
d. determine the evolutionary relationships between similar species.
e. none of the above
Answer: b. The goal of taxonomy, the field of biology concerned with classifying organisms, is to classify
all organisms into monophyletic groups.
9. The concept that the preferred hypothesis is the one that is the simplest is
a. phenetics.
b. cladistics.
c. the principle of parsimony.
d. maximum likelihood.
e. both b and d.
Answer: c. The concept that the preferred hypothesis is the one that is the simplest is the principle of
parsimony.
10. Researchers believe that horizontal gene transfer is less prevalent in eukaryotes because of
a. the presence of organelles.
b. multicellularity.
c. sexual reproduction.
d. all of the above.
e. b and c only.
Answer: e. Researchers believed that horizontal gene transfer is less prevalent in eukaryotes because
of multicellularity and sexual reproduction.
Conceptual Questions
1.
Explain binomial nomenclature and give an example.
Answer: The scientific name of every species has two parts, which are the genus name and the species
epithet. The genus name is always capitalized while the species name is not. Both names are italicized.
An example is Canis lupus.
2.
Explain both the usefulness and potential pitfalls of morphological analysis.
Answer: Morphological analysis focuses on morphological features of extinct and modern species.
Many traits are analyzed to obtain a comprehensive picture of two species’ relatedness. Convergent
evolution leads to similar traits that arise independently in different species as they adapt to similar
environments. Convergent evolution can, therefore, cause errors if a researcher assumes that a
particular trait arose only once, and that all species having the trait have the same common ancestor.
3.
Explain the value of a molecular clock.
Answer: If neutral mutations occur at a relatively constant rate, they act as a molecular clock on which to
measure evolutionary time. Genetic diversity between species that is due to neutral mutation gives an
estimate of the time elapsed since the last common ancestor.
Experimental Questions
1. What is molecular paleontology? What was the purpose of the study conducted by Cooper et al.?
Answer: Molecular paleontology is the sequencing and analysis of DNA obtained from extinct species.
Tissue samples from specimens of extinct species may contain DNA molecules that can be extracted,
amplified, and sequenced. The DNA sequences can then be compared to living species to study
evolutionary relationships between modern and extinct species.
The researchers extracted DNA from tissue samples of moas, extinct flightless birds that lived in New
Zealand. The DNA sequences from the moas were compared to the DNA sequences of modern species
of flightless birds to determine the evolutionary relationships of this particular group of organisms.
2. What birds were examined in the Cooper study and what are their geographical distributions? Why
were the different species selected for this study?
Answer: The researchers compared the DNA sequences of the extinct moas and modern kiwis of New
Zealand to the emu and cassowary of Australia and New Guinea, the ostrich of Africa and rheas of
South America. All of the birds are flightless birds. With the birds selected, the researchers could look
for similarities between birds over a large geographical area.
3. What results did Cooper obtain by comparing these DNA sequences? How did the results of this
study impact the proposed phylogeny of flightless birds?
Answer: The sequences were very similar among the different species of flightless birds. Interestingly,
the sequences of the kiwis of New Zealand were more similar to those of the modern species of
flightless birds found on other land masses than they were to those of the moas found in New Zealand.
The researchers constructed a new evolutionary tree that suggests that kiwis are more closely related to
the emu, cassowary and ostrich. Also, based on the results of this study, the researchers suggested
that New Zealand was colonized twice by ancestors of flightless birds. The first ancestor gave rise to the
now extinct moas. The second ancestor gave rise to the kiwis.
Collaborative Questions
1. Discuss taxonomy and its hierarchical organization.
Answer: Taxonomy is the field of biology that is concerned with the theory, practice, and rules of
classifying living and extinct organisms and viruses. In taxonomy, scientists place organisms into distinct
groups based on similarities and differences. In doing so, scientists examine the evolutionary
relationships between species and determine which species are more closely related. Every species is
placed into the following groups: domain, kingdom, phylum, class, order, family, genus, and species. As
we proceed down the taxonomic hierarchical ladder, each higher level of taxonomy is divided into the
smaller groups that follow it. Domains are the broadest, followed by kingdoms, phyla, and so on down
the ladder. At the end of this system, we have the genus and the species. It is at these two levels that
individual organisms are named, and these names are referred to together as the scientific name of the
organism.
2. Discuss systematics and the concept of a phylogenetic tree.
Answer: Systematics is the study of biological diversity based on evolutionary relationships that places
organisms into taxonomic groups. By studying similarities and differences among species, biologists
gain information about the evolutionary history of an organism (its phylogeny) and this helps scientists
understand the relationship between ancestors and their descendants. A goal of systematics is to create
a phylogenetic tree which is a diagram that describes an organism’s phylogeny. By studying the
branching points of a phylogenetic tree, biologists can group species according to common ancestors.
Systematics attempts to organize species into monophyletic groups, which means that each group
includes an ancestral species and all of its descendants leading to the species in question. As new
information becomes available to scientists, trees are revised to accommodate that information.