Classification

CLASSIFICATION

OBJECTIVES

Explain why and how organisms are classified.

List the eight levels of classification.

Explain scientific names.

Describe how dichotomous keys help in identifying organisms.

WHY CLASSIFY?

The classification of living things makes it easier for biologist to answer many important questions such as:

How many known species are there?

What are the defining characteristics of each species?

What are the relationships between these species?

HISTORY OF CLASSIFICATION

Greeks

Aristotle

English

John Ray

Swedes

Carolus Linnaeus

Taxonomy: science of describing, naming, and classifying things

Binomial Nomenclature

HOW DO SCIENTISTS CLASSIFY ORGANISMS?

Taxonomists use the eight-level system to classify living things based on shared characteristics.

On a branching diagram, several characteristics are listed along the line that points to the right. Each characteristic is shared by the organisms to the right of it.

LEVELS OF CLASSIFICATION

The eight levels of classification are:

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

SCIENTIFIC NAMES

A scientific name is always the same for a specific kind of organism no matter how many common names there might be.

Ex: Mountain lion, puma, cougar, panther are all the Puma concolor

The first part of a species' name is the genus name which is always capitalized. The second part of the name is the species name.

DICHOTOMOUS KEYS

A dichotomous key is a tool for identifying organisms that uses a series of paired descriptive statements.

By working through the statements in a dichotomous key in order, a person can eventually identify an unknown organism.

A GROWING SYSTEM

People are still discovering and classifying organisms.

Sometimes new organisms are found that are so different from other known organisms that new classes, phyla, and so on must be formed.

THINK/PAIR/SHARE

Why do scientists classify organisms?

What are the eight levels of classification?

How does a dichotomous key help scientists identify organisms?

BELLRINGER

List seven musical artists or bands.

Categorize the names on your list by style of music.

Describe in your notebook the categories you chose and explain which bands might fit into more than one category.

OBJECTIVES

Explain how classification developed as greater numbers of organisms became known.

Describe the three domains.

Describe four kingdoms in the domain Eukarya

WHAT IS IT?

Organisms are classified by their characteristics.

As scientists continue to learn about living things, they add classification categories that account for the characteristics of different organisms.

DOMAINS: ARCHAEA AND BACTERIA

Archaea are one of two kinds of prokaryotes. Prokaryotes are single-celled organisms that do not have a nucleus. Most are known to live in extreme environments.

Bacteria are another kind of prokaryote but they usually have a cell wall. Bacteria can be found in soil, water, and even on and inside the human body.

DOMAIN EUKARYA: KINGDOM PROTISTA

Today members of the kingdom Protista commonly called protists, are single-celled or simple multicellular organisms.

Protista contains many kinds of organisms, including protozoans, algae, and euglenoids.

DOMAIN EUKARYA: KINGDOM FUNGI

Molds and mushrooms are examples of the complex, multicellular members of the kingdom Fungi.

Fungi do not perform photosynthesis or eat food. Instead, fungi absorb nutrients from substances in their surroundings.

DOMAIN EUKARYA: KINGDOM PLANTAE

The kingdom Plantae consists of organisms that are eukaryotic, have cell walls, and make food through photosynthesis.

Examples: Sequoia trees, roses, grasses, ferns, and more

DOMAIN EUKARYA: KINGDOM ANIMALIA

The kingdom Animalia contains complex, multicellular organisms that don’t have cell walls, are usually able to move around, and have specialized sense organs.

Examples : Ants, beetles, lizards, fish, birds, apes, elephants, and more

Most animals are able to move, but sponges, a simple animal, cannot move.

THINK/PAIR/SHARE

What are the characteristics of each of the three domains?

What are the four kingdoms of the domain Eukarya?

Copyright © by Holt, Rinehart and Winston. All rights reserved.

ResourcesChapter menu

Reading

Read each of the passages. Then, answer the questions that follow each passage.

Standardized Test PreparationChapter C7



Passage 1 When organizing life on Earth into categories, we must remember that organisms are not equally distributed throughout the categories of our classification system. We often think of Earth’s living things as only the plants and animals that live onEarth’s surface. However, the largest domains in terms of mass are the domains Archaea and Bacteria. And a common home of archaea and bacteria may be deep within the Earth’s crust.




1. In the passage, what does distributed mean?

A divided

B important

C visible

D variable




1. In the passage, what does distributed mean?

A divided

B important

C visible

D variable




2. According to the passage, what are most of the organisms living on Earth?

F plants

G animals

H fungi

I archaea and bacteria




2. According to the passage, what are most of the organisms living on Earth?

F plants

G animals

H fungi

I archaea and bacteria




3. Which of the following statements is a fact according to the passage?

A All organisms are equally distributed over Earth’s surface.

B Plants are the most important organisms on Earth.

C Many bacteria may live deep within Earth’s crust.

D Archaea and bacteria are equally distributed over Earth’s surface.




3. Which of the following statements is a fact according to the passage?

A All organisms are equally distributed over Earth’s surface.

B Plants are the most important organisms on Earth.

C Many bacteria may live deep within Earth’s crust.

D Archaea and bacteria are equally distributed over Earth’s surface.




Passage 2 When you think of an animal, what do you imagine? You may think of a dog, a cat, or a parrot. All of those organisms are animals. But the animal kingdom also includes some members that might surprise you, such as worms, insects, corals, and sponges.




1. In the passage, what is coral?

A a kind of animal

B a kind of insect

C a color similar to pink

D an organism found in lakes and streams




1. In the passage, what is coral?

A a kind of animal

B a kind of insect

C a color similar to pink

D an organism found in lakes and streams




2. What can you infer from the passage?

F All members of the animal kingdom are visible.

G Parrots make good pets.

H Not all members of the animal kingdom have DNA.

I Members of the animal kingdom come in many shapes and sizes.




2. What can you infer from the passage?

F All members of the animal kingdom are visible.

G Parrots make good pets.

H Not all members of the animal kingdom have DNA.

I Members of the animal kingdom come in many shapes and sizes.




3. Which of the following can you infer from the passage?

A Worms and corals make good pets.

B Corals and cats have some traits in common.

C All organisms are animals.

D Worms, corals, insects, and sponges are in the same family.




3. Which of the following can you infer from the passage?

A Worms and corals make good pets.

B Corals and cats have some traits in common.

C All organisms are animals.

D Worms, corals, insects, and sponges are in the same family.




4. In the passage, what does members mean?

F teammates

G limbs

H individuals admitted to a club

I components




4. In the passage, what does members mean?

F teammates

G limbs

H individuals admitted to a club

I components




Interpreting Graphics

The Venn diagrams below show two classification systems. Use the diagrams toanswer the questions that follow.




1. For Classification system A, which of the following statements is true?

A All organisms ingroup 6 are in group 7.

B All organisms ingroup 5 are in group 4.

C All organisms ingroup 6 are in group 1.

D All organisms ingroup 2 are in group 1.













F All organisms ingroup 3 are in group 2.

G All organisms ingroup 3 are in group 4.

H All organisms ingroup 3 are in group 1.

I All organisms in group 3 are in every other group.





F All organisms ingroup 3 are in group 2.

G All organisms ingroup 3 are in group 4.

H All organisms ingroup 3 are in group 1.

I All organisms in group 3 are in every other group.




3. For Classification system B, which of the following statements is true?

















F All organisms in group 4 are in group 1, 2, and 5.

G All organisms in group 4 are in groups 3 and 5.

H All organisms in group 4 are in groups 5 and 6.

I All organisms in group 4 are in groups 1, 5, and 6.





F All organisms in group 4 are in group 1, 2, and 5.

G All organisms in group 4 are in groups 3 and 5.

H All organisms in group 4 are in groups 5 and 6.

I All organisms in group 4 are in groups 1, 5, and 6.




5. In Classification system B, which group contains organisms that are not in group 1?

A 2

B 4

C 5

D 6




5. In Classification system B, which group contains organisms that are not in group 1?

A 2

B 4

C 5

D 6




Math

Read each question, and choose the best answer.




1. Scientists estimate that millions of species have not yet been discovered and classified. About 1.8 million species have been discovered and classified. If scientists think that this 1.8 million makes up only 10% of the total number of species on Earth, how many species do scientists think exist on Earth?

A 180 million

B 18 million

C 1.8 million

D 180,000




1. Scientists estimate that millions of species have not yet been discovered and classified. About 1.8 million species have been discovered and classified. If scientists think that this 1.8 million makes up only 10% of the total number of species on Earth, how many species do scientists think exist on Earth?

A 180 million

B 18 million

C 1.8 million

D 180,000




2. Sequoia trees can grow to more than 90 m in height. There are 3.28 feet in 1 meter. How many feet are in 90 m?

F 27.4 ft

G 95.2 ft

H 270 ft

I 295.2 ft




2. Sequoia trees can grow to more than 90 m in height. There are 3.28 feet in 1 meter. How many feet are in 90 m?

F 27.4 ft

G 95.2 ft

H 270 ft

I 295.2 ft


Education

Classification