Unit B: Taxonomy
Finding Order in Diversity
1. How are living things organized for study?
Biologists use a classification system to name organisms with a universally accepted
name. They also group organisms in a logical manner. Organisms placed into a
particular group are more similar to one another than they are to organisms in other
groups.
2. Describe the system for naming species that Linnaeus developed.
Each species is assigned a two-part scientific name.
3. What are the seven taxonomic categories of Linnaeus’s classification system? Rank
these taxa in hierarchical order, beginning with the largest level and ending with the
smallest.
Kingdom, phylum, class, order, family, genus, species
4. Why do scientists avoid using common names when discussing organisms?
Because common names vary among languages and even among regions within a single
country.
5. What is binomial nomenclature?
A two-word naming system.
6. Look at Figure 18-5. Are foxes more closely related to sea stars or to snakes:
Explain.
They are more closely related to snakes, because they are in the same phylum.
Explanatory Paragraph
Think of a classification system that you use in everyday life, and then write a paragraph
explaining how the classification system organizes objects or other things. Hint: Before you
write, make a diagram that shows the organization of the classification system.
Modern Evolutionary Classification
1. How is information about evolutionary, or phylogenetic, relationships useful in
classification?
Organisms are placed in various taxonomic groups based on evolutionary descent.
2. How are genes used to help scientists classify organisms?
Scientists compare the DNA of different organisms to establish similarities between them
and reconstruct possible evolutionary relationships.
3. What is the principle behind cladistic analysis?
Cladistic analysis traces the process of evolution in a group of organisms by focusing on
unique features that appear in some organisms but not in others.
4. What gene indicates that yeasts and humans share a common ancestor?
A gene that codes for the protein myosin.
5. Describe the relationship between evolutionary time and the similarity of genes in
two species.
The longer it has been since two species descended from a common ancestor, the more
different their genes are likely to be.
6. Would a barnacle’s DNA be more similar to the DNA of a crab or that of a limpet?
Explain.
It would be more similar to the DNA of a crab, because barnacles and crabs have a closer
evolutionary relationship.
Constructing a Chart
Draw a cladogram of a manufactured item, such as an automobile or a household item, that has
changed over the years. Label derived characters that appeared as new models arose. For
example, automobiles came to have electronic fuel injection and antilock brakes.
Kingdoms & Domains
1. What are the six kingdoms of life as they are now identified?
The six kingdoms are Archaebacteria, Eubacteria, Protista, Plantae, Fungi and Animalia.
2. What are the three domains of life?
The three domains are Archaea, Bacteria and Eukarya.
3. Why was the kingdom Monera divided into two separate kingdoms?
Monera was divided into two kingdoms because scientists have come to recognize
profound differences among two broad groups of Monera.
4. Why might kingdom Protista be thought of as the “odds and ends” kingdom?
Members of the kingdom Protista display the greatest variety, sharing characteristics with
plants, fungi, or animals; protists cannot be classified in any other group.
5. How are members of the kingdom Fungi different from members of the kingdom
Plantae? How are members of the two kingdoms similar?
Fungi are heterotrophic; Plantae are autotrophic. Both are nonmotile.
6. Which kingdoms include only prokaryotes? Which kingdoms include only
heterotrophs?
Eubacteria and Archaebacteria include only prokaryotes. Fungi and Animalia contain
only heterotrophs.
Unity and Diversity
Review what you learned in Chapter 7 about how the cells of various organisms differ. Then,
write a riddle (What kingdom am I?) describing the characteristics of members of a particular
kingdom. Exchange your riddle with a classmate, and see if you can guess the kingdom being
described.