chapter 9 classification section 2 domains and...

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Interactive Textbook 135 Classification

SECTION

2 Domains and KingdomsClassification

Name Class Date

CHAPTER 9

After you read this section, you should be able to answer these questions:

• How are prokaryotes classified?

• How are eukaryotes classified?

How Do Scientists Classify Organisms?For hundreds of years, all organisms were classified

as either plants or animals. However, as more organisms were discovered, scientists found some organisms that did not fit well into these two kingdoms. Some animals, for example, had characteristics of both plants and animals.

What would you call an organism that is green and makes its own food? Is it a plant? What if the organism moved and could also eat other organisms? Plants gener-ally do neither of these things. Is the organism a plant or an animal?

Members of genus Euglena have characteristics of both plants and animals.

The organism above belongs to genus Euglena. Its members show all of the characteristics just described. As scientists discovered organisms, such as Euglena,that didn’t fit easily into existing groups, they created new ones. As they added kingdoms, scientists found that members of some kingdoms were closely related to members of other kingdoms. Today, scientists group kingdoms into domains.

All organisms on Earth are grouped into three domains. Two domains, Bacteria and Archaea, are made up of prokaryotes. The third domain, Eukarya, is made up of all the eukaryotes. Scientists are still working to describe the kingdoms in each of the three domains.

BEFORE YOU READ National Science Education StandardsLS 1f, 2a, 4b, 4c, 5b

STUDY TIPList As you read this section, make a list of the domains and kingdoms scientists use to classify organisms.

Critical Thinking1. Apply Concepts In which domain would multicellular organisms be classifi ed? Explain your answer.



SECTION 2

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Domains and Kingdoms continued

How Are Prokaryotes Classified?A prokaryote is a single-celled organism that does not have

a nucleus. Prokaryotes are the oldest group of organisms on Earth. They make up two domains: Archaea and Bacteria.

DOMAIN ARCHAEADomain Archaea is made up of prokaryotes. The cell

walls and cell membranes of archaea are made of different substances than those of other prokaryotes. Many archaea can live in extreme environments where other organisms could not survive. Some archaea can also be found in more moderate environments, such as the ocean.

DOMAIN BACTERIAAll bacteria belong to domain Bacteria. Bacteria can

be found in the air, in soil, in water, and even on and inside the human body!

We often think of bacteria as bad, but not all bacteria are harmful. One kind of bacterium changes milk into yogurt. Escherichia coli is a bacterium that lives in human intestines. It helps break down undigested food and pro-duces vitamin K. Some bacteria do cause diseases, such as pneumonia. However, other bacteria make chemicals that can help us fight bacteria that cause disease.

The Grand Prismatic Spring in Yellowstone National Park contains water that is about 90°C (190°F). Most organisms would die in such a hot environment.

READING CHECK

2. Compare How are members of Archaea different from other prokaryotes?

READING CHECK

3. Explain Are all bacteria harmful? Explain your answer.

TAKE A LOOK 4. Apply Concepts What kind of prokaryotes do you think could live in this spring? Explain your answer.



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How Are Eukaryotes Classified?Organisms that have cells with membrane-bound

organelles and a nucleus are called eukaryotes. All eukaryotes belong to domain Eukarya. Domain Eukarya includes the following kingdoms: Protista, Fungi, Plantae, and Animalia.

Protista Plantae Fungi Animalia

This branching diagram shows the four kingdoms in domain Eukarya.

DomainEukarya

KINGDOM PROTISTAMembers of kingdom Protista are either single-celled or

simple multicellular organisms. They are commonly called protists. Scientists think that the first protists evolved from ancient bacteria about 2 billion years ago. Much later, plants, fungi, and animals evolved from ancient protists.

Kingdom Protista contains many different kinds of organisms. Some, such as Paramecium, resemble animals. They are called protozoa. Plantlike protists are called algae. Some algae, such as phytoplankton, are single cells. Others, such as kelp, are multicellular. Multicellular slime molds also belong to kingdom Protista.

Paramecium

STANDARDS CHECKLS 5a Biological evolution accounts for the diversity of species developed through gradual processes over many generations. Species acquire many of their unique characteristics through biological adaptation, which involves the selection of naturally occur-ring variations in populations. Biological adaptations include changes in structures, behaviors, or physiology that enhance sur-vival and reproductive success in a particular environment.

Word Help: selectionthe process of choosing

Word Help: variationa difference in the form or function

5. Identify Based on the branching diagram, which two kingdoms in Eukarya evolved most recently? How do you know?



SECTION 2

Name Class Date


KINGDOM FUNGIMolds and mushrooms are members of kingdom Fungi.

Some fungi (singular, fungus) are unicellular. That is, they are single-celled organisms. Yeast is unicellular. Most other fungi are multicellular. Unlike plants, fungi do not perform photosynthesis. However, they also do not eat food, as animals do. Instead, fungi use digestive juices to break down materials in the environment and absorb them.

Amanita is a poisonous fungus. You should never eat wild fungi.

KINGDOM PLANTAEAlthough plants differ in size and appearance, most

people can easily identify the members of kingdom Plantae. Kingdom Plantae contains organisms that are eukaryotic, have cell walls, and make food by photosynthesis. Most plants need sunlight to carry out photosynthesis. Therefore,plants must live in places where light can reach.

The food that plants make is important for the plants and also for other organisms. Many animals, fungi, protists, and bacteria get nutrients from plants. When they digest the plant material, they get the energy stored by the plant. Plants also provide homes for other organisms.

The giant sequoia is one of the largest members of kingdom Plantae. A giant sequoia can measure 30 m around the base and grow more than 91 m tall!

READING CHECK

6. Describe How do fungi get food?

Math Focus7. Calculate The average student’s arms extend about 1.3 m. How many students would have to join hands to form a human chain around a giant sequoia?



SECTION 2

Name Class Date


KINGDOM ANIMALIAKingdom Animalia contains complex, multicellular

organisms. Organisms in kingdom Animalia are com-monly called animals. The following are some character-istics of animals:

• Their cells do not have cell walls. • They are able to move from place to place.• They have sense organs that help them react quickly to

their environment.

STRANGE ORGANISMSSome organisms are not easy to classify. For example,

some plants can eat other organisms to get nutrition as animals do. Some protists use photosynthesis as plants do but also move around as animals do.

Red Cup Sponge

What kind of organism is this red cup sponge? It does not have sense organs and cannot move for most of its life. Because of this, scientists once classified sponges as plants. However, sponges cannot make their own food as plants do. They must eat other organisms to get nutrients. Today, scientists classify sponges as animals. Sponges are usually considered the simplest animals.

TAKE A LOOK 8. Identify Which animal characteristic from above can be seen in this bald eagle?

Critical Thinking9. Apply Concepts To get nutrients, a Venus’ fl ytrap uses photosynthesis and traps and digests insects. Its cells have cell walls. Into which kingdom would you place this organism? Explain your answer.



Name Class Date

Section 2 Review NSES LS 1f, 2a, 4b, 4c, 5b

SECTION VOCABULARY

Animalia a kingdom made up of complex, multicellular organisms that lack cell walls, can usually move around, and quickly respond to their environment

Archaea in a modern taxonomic system, a domain made up of prokaryotes (most of which are known to live in extreme environments) that are distinguished from other prokaryotes by differences in their genetics and in the makeup of their cell wall; this domain aligns with the traditional kingdom Archaebacteria

Bacteria in a modern taxonomic system, a domain made up of prokaryotes that usually have a cell wall and that usually reproduce by cell division. This domain aligns with the traditional kingdom Eubacteria

Eukarya in a modern taxonomic system, a domain made up of all eukaryotes; this domain aligns with the traditional kingdoms Protista, Fungi, Plantae, and Animalia

Fungi a kingdom made up of nongreen, eukaryotic organisms that have no means of movement, reproduce by using spores, and get food by breaking down substances in their surroundings and absorbing the nutrients

Plantae a kingdom made up of complex, multicellular organisms that are usually green, have cell walls made of cellulose, cannot move around, and use the sun’s energy to make sugar by photosynthesis

Protista a kingdom of mostly one-celled eukaryotic organisms that are different from plants, animals, bacteria, and fungi

1. Compare What is one major difference between domain Eukarya and domains Bacteria and Archaea?

2. Explain Why do scientists continue to add new kingdoms to their system of classification?

3. Analyze Methods Why do you think Linnaeus did not include classifications for archaea and bacteria?

4. Apply Concepts Based on its characteristics described at the beginning of this sec-tion, in which kingdom would you classify Euglena?


Interactive Textbook Answer Key 9 Life Science

Life Science Answer Key continued

10. a meteorite or comet impact

11. about 65.5 million years ago

12. Fossils from the Cenozoic are closer to the surface and easier to find. They have had less time to be destroyed.

Review 1. Precambrian time, Paleozoic era, Mesozoic

era, Cenozoic era

2. Paleozoic era

3. The atmosphere contained very little oxy-gen. Impacts were more common. There was no ozone layer.

4. Through photosynthesis, cyanobacteria increased the oxygen levels in the atmo-sphere. They also lowered the carbon diox-ide levels in the atmosphere.

5. a mass extinction

6. Birds and mammals could probably survive cooler temperatures than reptiles could.

7. Global temperatures drop, and ice sheets and glaciers grow larger.

SECTION 3 HUMANS AND OTHER PRIMATES 1. front-facing eyes and flexible fingers

2. during the early Cenozoic

3. chimpanzee

4. The human spine has an S-shaped curve, and the gorilla’s spine has a C-shaped curve.

5. The oldest hominid fossils are found in Africa.

6. Two feet—all hominids are bipedal.

7. australopithecines

8. Possible answers: They were more like humans; they had larger brains, rounder skulls, and flatter faces.

9. They use information from bones.

10. Possible answers: fossils of hominids together with tools, preserved clothing

11. one

Review 1. All hominids are bipedal.

2. between 30 million and 6 million years ago

3. Possible answers: slender bodies, humanlike jaws and teeth, apelike skulls, habitation of forests and grasslands

4. Homo erectus: 1.8 million years ago

Homo habilis: 2.4 million years ago

Homo sapiens: 150,000 to 100,000 years ago

5. Possible answers: smaller, flatter face; rounder skull; extinction of Neanderthals

6. They have found fossils.

7. Answers will vary but may include: increased ability to reason, ability to make more advanced tools, better ability to adapt to changes, ability to communicate more clearly

Chapter 9 ClassificationSECTION 1 SORTING IT ALL OUT 1. based on their structure and characteristics

2. Organisms that share many characteristics are more closely related than those that do not.

3. at the top

4. brown bear and platypus

5. Some organisms have more than one common name; names are different in different languages.

6. genus and species

7. class

8. There are fewer organisms in each level.

9. The key would have to include characteris-tics of all organisms on Earth. It would be impossibly long.

10. Left to right: long-tailed weasel, woodchuck

Review 1. domain, kingdom, phylum, class, order,

family, genus, species

2. Ferns have tissues that transport materials.

3. The pine tree is the most similar; the moss is the least similar.

4. genus and species

5. No, the key in this section could only be used for some mammals. You would need a key that described lizards.

SECTION 2 DOMAINS AND KINGDOMS 1. Eukarya; all multicellular organisms are

eukaryotes.

2. Their cell walls and cell membranes are made of different materials. Many can live in extreme environments.

3. No, only some bacteria cause disease. Other bacteria are helpful.

4. Archaea—some can live in extreme environments.

5. Fungi and Animalia—the groups closest to the top evolved most recently.


Interactive Textbook Answer Key 10 Life Science

Life Science Answer Key continued

6. They break down materials in the environ-ment and absorb them.

7. 23

8. ability to move

9. Answers may vary. Venus’ flytrap is in king-dom Plantae.

Review 1. Domain Eukarya is made up of only

eukaryotes. Domains Bacteria and Archaea are made up of only prokaryotes.

2. As scientists discover more organisms that do not fit into existing groups, they add new groups.

3. Linnaeus probably did not know that many of these organisms existed. Because they are so small, and because many archaea live in extreme environments, Linnaeus would not have been able to study the characteristics of these organisms.

4. kingdom Protista

Chapter 10 Bacteria and VirusesSECTION 1 BACTERIA AND ARCHAEA 1. They are single-celled and have no nucleus.

2. a single loop inside the cell

3. by binary fission

4. They are the same.

5. bacilli, cocci, spirilla

6. Cocci don’t dry out as quickly.

7. Bacilli have a large surface area to help them take in nutrients.

8. as producers, consumers, or decomposers

9. Not all archaea have cell walls. When they do, the walls are made of different materials than those in bacterial cell walls.

10. methane makers

11. Archaea—they can survive in harsher envi-ronments than most bacteria.

Review 1. Bacteria, Archaea, Eukarya

2. Bacteria: Some can form endospores to survive harsh conditions; they are the most plentiful organisms on Earth.

Archaea: Some can live in extreme environ-ments; not all have cell walls.

Center: prokaryotes, no nucleus, single-celled, reproduction by binary fission

3. Some scientists think that bacteria similar to cyanobacteria started living in larger cells. The bacteria made food for themselves and the larger cells. The larger cells gave the bacteria protection. This relationship may have led to the first plant cells.

4. heat lovers, salt lovers, methane makers

5. Yes; although some archaea can live in harsh environments where bacteria cannot sur-vive, some archaea live in more moderate places, such as the ocean. Bacteria live in most places, other than the most extreme environments, so they are likely to be found in the same environments as some archaea.

SECTION 2 BACTERIA’S ROLE IN THE WORLD 1. by eating plants

2. 700 billion

3. It lets them make products that are hard to find in nature.

4. The insulin can be taken out of the bacteria and given to people with diabetes.

5. antibiotics

Review 1. Nitrogen fixation is a process in which cer-

tain bacteria take in nitrogen from the air and change it to a form that plants can use.

2. Nitrogen from the air passes into the soil.

Bacteria in the soil and on plant roots change nitrogen to another form. Plants use this form.

Animals eat the plants to get nitrogen.

3. Possible answers: Bacteria in soil turn nitro-gen into a form that plants can use. Some bacteria break down dead plant and animal matter. This makes nutrients available to other living things.

4. In genetic engineering, scientists change the genes of bacteria or any living thing. Scientists can put genes from one organism into another.

5. They get into a host organism and take nutrients from the host’s cells.

6. nitrogen

SECTION 3 VIRUSES 1. Viruses change quickly.

2. They cannot reproduce without a host; they cannot eat or grow.

3. DNA and RNA

4. spacecraft shape

chapter 9 classification section 2 domains and...

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