Unit 3:  Diversity of Life

Module 1:  Taxonomy and Introduction to the Kingdoms

Learning Objectives:  1.1,1.2,1.3

Lesson 1:  Biological Classification

Lesson Objectives:

• To compare everyday examples of classification to the value of biological classification.
• To explore the ways that organisms are grouped into kingdoms.
• To examine the seven major units (levels) of classification.
• To understand the system of binomial nomenclature.

Evaluation:  Activity:  Biological Classification Questions - Self - Check

STOP

&

THINK

Examine the list of organisms that you have created.  How many of these organisms are animals?  How many are plants?  Are any of the organisms in your list living things other than plants or animals?

When asked to perform this task, many students have a tendency to record the names of common plants and animals.  However, a large diversity of many types of organisms exists on earth; many of these are neither plants nor animals.

Pictured below are some images of living things on earth.  How many of these organisms can you correctly identify? 

Because there is such a wide range of different organisms on earth, scientists organize them according to certain characteristics that they have in common.

Think of the large variety of books in a library or the thousands of different items found in a department store.  Can you imagine the confusion involved in trying to find a book on a particular subject or an item in a department store if the books or items were not organized?  In both of these cases, the books or the department store, items are grouped into particular areas, and then are further organized within their area.  For example, books in a library are grouped into areas such as fiction or non-fiction. Then, each of these, non-fiction for example, are further sub-divided into categories such as pure science, art history, or geography.  Finally, each book is labeled with a set of numbers and letters.  This system of organization makes it easy for a library patron to find the books they need and allows the librarian to catalogue and shelve new books.

The job of classifying organisms is such a large one that it has become a science of its own.  Taxonomy is the science of classifying organisms. 

In the 1700's a Swedish botanist, Carolus Linneaus, set up a system to organize all living things.  Linneaus' system of classification is the basis for the one that is still used by scientists today.

Originally all living things on earth were grouped into two main categories, plants and animals.  As more organisms were identified and advancing technology allowed for the study of more characteristics of organisms, scientists realized that there were living things on earth that did not fit the set of criteria outlined for the animal kingdom or the plant kingdom.

Three additional kingdoms with sets of criteria were eventually developed.  Kingdoms Monera, Protista, Fungi, Plantae and Animalia make up a five kingdom system of classification that is widely recognized and used.  However, once again as new organisms are identified and as advancing technology allows for the study of more characteristics of previously classified organisms some scientists are starting to further divide some of the kingdoms into newer kingdoms with their own sets of criteria.

A phylogenetic tree is a diagram the shows the relationships, from an evolutionary perspective, between the kingdoms of classification.  Most biology textbooks contain a diagram of a phylogenetic tree.

For example:

            Nelson Biology p. 423

            Biological Science:  An Ecological Approach  (Seventh Edition)  p.  261

Activity:  Biological Classification Questions

Using a biology text book, web sites, and any other suitable reference material, answer each of the following questions pertaining to biological classification.

1.  Determine whether each of the following statements about Carolus Linnaeus are true or false.  If the statement is false change it to make it true.

• a)  He was a Swedish zoologist.
• b)  He grouped plants and animals based on their structural likeness.
• c)  He insisted on using the common name for organisms.
• d)  Many of the names he gave organisms are still used today.
• e)  He gave each organisms a unique name in English.
• f)  His system consisted of a genus and a species name for an organism.
• g)  In his system genus names can be used for more than one group.

2.  List the seven of classification from the largest grouping to the smallest.

3.  List the seven levels of classification from the smallest grouping to the largest.

4.  To what kingdom do you belong?

• What is your phylum?
• To what class do you belong?
• What is your order?
• To what family do you belong?
• What is your genus? 
• To what species do you belong?

5.  What is your scientific name?

6.  What is the scientific name for a grizzly bear?

7.  How does the number of characteristics shared by all members of a classification level change as you progress from species to kingdom?

8.  How does the number of organisms at each level of classification change as you progress from species to kingdom?

9.  Why is Latin used for naming organisms?

10. Taxonomy is largely based on structural similarity.  However, modern technology has allowed taxonomists to use additional traits to classify organisms.  Can you name any of these additional traits?

Binomial Nomenclature:

Once you have answered the questions above, you have had some experience with binomial nomenclature.  Binomial nomenclature is a system of scientific naming where all organisms are assigned a two-part name.  The scientific name for each organism that has been classified consists of the genus and species names for the organism. (From question 2 above you should realize that the genus and species are the last two levels of classification.)

For example, the scientific name for humans is Homo sapiens.

The next example provides the scientific name for two different species of oak trees.  The trees both belong to the same genus but have their own species name.

            White Oak -  Quercus alba

            Red Oak  -    Quercus rubra

Two rules that apply to this system of naming are that the genus name can never be used for any other group and the species name cannot be used for any other species within the same genus.  Recall that species are groups of organisms that share many characteristics and that can interbreed to produce fertile offspring.

All scientific names must appear in the same format as in the examples outlined above.  The genus name should begin with an upper case letter, and the species name should begin with a lower case letter.  The entire name should be italicized (or underlined).

The Five Kingdoms:

As previously explained, organisms are divided into kingdoms on the basis of certain characteristics that they display. The information provided below outlines the name of the each five main kingdoms, a few of the main characteristics of each kingdom, as well as a few examples of the types of organisms that belong to each kingdom.

You may want to make a copy of this information to keep in your notes.  As we study each of the kingdoms you could add characteristics and example organisms to this information.

Before you read through the chart, it is essential that you understand each of the four terms listed below.  Record the definitions for these terms, as they are used frequently throughout the study of biology.

• Prokaryotic
• Eukaryotic
• Autotrophic
• Heterotrophic