Module 3 Intro

Module 3—Ecosystems and Their Diversity

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Much like the periodic table of elements is universal to all scientists to identify the natural elements, biologists have developed rules of taxonomy that allow scientists to easily identify and communicate about species in an ecosystem.

 

There is estimated to be somewhere between 10 and 100 million different species of organisms in the world. The field of taxonomy is the practice of classifying organisms. All organisms are classified into three domains. The three domains are Bacteria, Archaea, and Eukarya.

 

These rules of taxonomy are why a robin and a human are named differently. Different names are given to different organisms so that people are able to communicate better. If there wasn’t a name for a robin, it would take a long time to describe the type of bird sitting outside your window.

 

To learn more about the development of modern taxonomy practices, read pages 85 to 88 in your textbook.

 

Self-Check

 

SC 1. Why are fungi not in the same kingdom as plants?

 

SC 2. What is the benefit for scientists to use binomial nomenclature rather than common names?

 

 

Watch and Listen

 

View the following animation to review the three-domain system of classification. The domain system is an evolutionary model of classification based on cell structure. This system proposes that a common ancestor cell gave rise to three different cell types, each representing a domain.

 

The three domains are the Archaea (archaebacteria), the Bacteria (eubacteria), and the Eukarya (eukaryotes). The Eukarya are then divided into four kingdoms: Protists, Fungi, Animalia, and Plantae. Organisms are placed into kingdoms depending on cell type, their ability to make food, and the number of cells in their body. For example, a daisy is classified as part of the Plantae kingdom because it is multicellular, it contains a nucleus, it contains a chloroplast that carries out photosynthesis, and the cells have a cell wall.

 

The following animation reviews the three-domain system of classification and introduces the six kingdoms.

 

Design a table to organize the kingdoms within their proper domains. Place this table in your course folder.

 

Read

 

Domains are subdivided into kingdoms. There are four kingdoms in the Eukarya domain: Protista, Fungi, Plantae, and Animalia. Each of these kingdoms is further subdivided into phyla, then class, order, family, genus, and species. Within each subdivision, the groups become more and more similar in physical characteristics and genetic makeup.

 

The following mnemonic table may help you remember the order of the subdivisions from domain to species.

 

Domain	Danish
Kingdom	King
Phylum	Phillip
Class	Came
Order	Over
Family	For
Genus	Green
Species	Spinach

 

Try This

 

TR 1. In this self-marking quiz, drag and drop the categories in hierarchical order, beginning with domain.

 

TR 2. Arthropod Activity

 

Insects belong to the kingdom Animalia, the phylum Arthropoda, and the class Insecta. About one million species of insects have been classified, and there are probably several times that number still to be named.

 

The phylum Arthropoda not only contains insects but also contains organisms like lobsters, spiders, scorpions, and centipedes. Two out of three living things on Earth belong to the phylum Arthropoda. In the following activity you will use organisms’ anatomical or morphological characteristics to categorize arthropods into the different classes.

 

Open the Classifying Arthropods activity and classify the four arthropods available on the table. Follow the procedures found along the left side of the screen. Use the table at the bottom of the animation to record your observations. This table can be found in your Module 3: Lesson 2 Assignment. Record your observations in the table, and complete the related questions.

 

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