Focus on California Life Science 7th Grade Unit 3 - Chapter 9 Viruses Bacteria Protists and Fungi

Chapter Viruses , Bacteria , and Fungi Preview All living organisms are composed of cells , from just one to many trillions . whose details usually are visible only through a microscope . know cells function similarly in all living organisms A typical cell of any organism contains genetic instructions that fy ifs milks . Those traits may be fied by environmental . As a basis for understanding this concept know the differences between the life cycles and duction methods of sexual and asexual organisms Yhe anatomy and physiology of plants and animals illustrate the mentary nature oi structure and tion . Asa basis for understanding this concept a . Students know plants and animals have levels of organization for ture and function , including cells , tissues , organs , organ systems , and the whole organism Scientific progress is made by asking meaningful questions and ducting careful investigations . As a basis for understanding this concept and addressing the content in the other three strands , students should develop their own questions and . Students will Construct scale models , maps , and appropriately labeled diagrams to communicate scientific knowledge , motion of Earth plates and . cell structure ) Bacteria ( blue and purple rods ) and other microorganisms lurk in a kitchen sponge . 312

. and Fungi Focus on the BIG Idea How do structure and function vary among organisms in different domains and kingdoms ?

Check What You Know Suppose you find a seaweed such as the one below . If you were to study one of the leafy structures under a microscope , what would you expect to see ?

What is the basic unit of structure in seaweeds ?

Sea palm , a seaweed The images shown here represent some of the key terms In this chapter . You can use this vocabulary skill to help you understand the meaning of some key terms in this chapter . Prefixes When you talk about word parts , a root is the part of the word that carries the basic meaning . A prefix is a word part placed in front of the root to change the meaning of the root or to form a new word . Look at the examples in the table below . Prefix I Meaning of Prefix and Meaning of ! two , twice bicolor Having two colors with , together compare To look at together to note similarities and differences down . from , reverse defrost the action of To remove ice or frost Apply Itl Answer the following questions . After reading the chapter , check . award fission

Chapter nah Vocabulary Section ( page 318 ) virus host parasite bacteriophage vaccine Section ( page conjugation , bacteria flagellum binary fission asexual reproduction sexual reproduction conjugation endospore pasteurization decomposer Section protist protozoan pseudopod contractile vacuole cilia symbiosis mutualism algae spore Section ( page 344 ) fungi fruiting body lichen . Build Science Vocabulary . online . Visit , Web Code Chapter 315

! dead adding Compare and Contrast Science texts often make comparisons . When you compare and contrast , you examine similarities and differences between two things . You can compare and contrast by using a Venn diagram . Follow these steps to set up a Venn diagram in your notebook . Draw two overlapping circles . Label each circle with one of the two items being compared . In the example below , oranges and lemons are being compared . In the area where the circles overlap , write the characteristics that the items share . Think of how the items are different . Write these differences in the parts of the circles that do not overlap . Orange Lemon Apply It ! Review the Venn diagram above . Then answer the questions . In the Venn diagram above , what are the similarities between lemons and oranges ?

What are the differences written in the Venn diagram ?

When you read Section , draw a Venn diagram comparing viruses and organisms .

A Mushroom Life Cycle The fungi you most familiar with are probably mushrooms . in some ways , mushrooms resemble plants , often growing near plants or even on them like small umbrellas . But mushrooms are very different from plants in some important ways . In this investigation , you learn about these differences . Your Goal To determine the conditions needed for mushrooms to grow and reproduce To complete this investigation , you must choose one variable and design a way to test how it affects mushroom growth make daily observations and record them in a data table prepare a poster that describes the results of your experiment follow the safety guidelines in Appendix A Plan It ! List possible hypotheses about the way variables such as light or moisture could affect the growth and reproduction of mushrooms . Choose one variable and write out a plan for testing that variable . After your teacher approves your plan , start growing your mushrooms !

Section integrating Health Standards Focus 0000 Students know the between the life cycles and reproduction methods of sexual and asexual organisms . The anatomy and physiology of plants and animals illustrate the complementary nature of structure and function . How are viruses like organisms ?

What is the structure of a virus ?

How do viruses multiply ?

How can you treat a viral disease ?

Key Terms virus I host parasite I bacteriophage vaccine 318 Standards Which Lock Does the Key Fit ?

Your teacher will give you a key . Study the key closely . Think about what shape the keyhole on its lock must have . on a piece of paper , draw the shape of the keyhole . The lock for your key is contained in the group of locks your teacher will provide . Try to match your key to its lock without inserting the key into the keyhole . Think It Over Inferring How might a unique lock on its surface help a cell protect itself from invading organisms ?

It is a dark and quiet night . An spy slips silently across the border . invisible to the guards , the spy creeps cautiously along the edge of the road , heading toward the command center . the spy sneaks by the centers security system and reaches the door . Breaking into the control room , the spy takes command of the central computer . The enemy is in control . What Is a Virus ?

Although this spy story may read like a movie script , it describes events similar to those that can occur in your body . The spy acts very much like a virus invading an organism . Characteristics of Viruses A virus is a tiny , nonliving particle that invades and then multiplies inside a living cell . Viruses are not cells . They do not have the characteristics of organisms . The only way in which viruses are like isms is that they oan multiply . Although viruses can multiply . their reproduction is different than the reproduction of isms . Viruses can only multiply when they are inside a living cell . No organisms are safe from viruses The organism that a virus multiplies inside is called a host . A host is a living thing that provides a source of energy for a virus or an organism . Viruses act like parasites ( PA ruh ) organisms that live on or in a host and cause it harm . Almost all viruses destroy their host cells .

The Structure of Viruses Viruses are smaller than cells and vary in size and shape . Some viruses are round . Others are shaped like rods , bricks , threads , or bullets . There are even viruses that have complex , shapes , such as the bacteriophage in Figure . A bacteriophage ( bak TEER ee oh ) is a virus that infects bacteria . In fact , its name means bacteria Although viruses may look different from one another , they all have a similar structure . All viruses have two basic parts a protein coat that protects the virus and an inner core made of genetic material . A virus genetic material contains the instructions for making new viruses . Some viruses are also surrounded by an additional outer membrane , or envelope . The proteins on the surface of a play an important role during the invasion of a host celL Each virus contains unique surface proteins . The shape of the surface proteins allows the virus to attach to certain cells in the host . Like keys , a virus only into certain locks , or proteins , on the surface of a host cells . Figure shows how the action works . Because the action of a virus is , a tain virus can attach only to one or a few types of cells . For example , most cold viruses infect cells only in the nose and throat of humans . These cells are the ones with proteins on their surface that complement or fit those on the virus . Reading What information does a Virus genetic material . 10 ) contain ?

Wu , Genetic material Protein coat Cell ! surface proteins Host all Bacteriophage This virus infects bacteria . FIGURE Virus Structure and Infection All viruses consist of genetic material surrounded by a protein coat Some viruses , like the ones shown here , are surrounded by an outer membrane envelope . A virus can attach to a cell only if the virus surface proteins can fit those on the cell . Virus outer membrane proteins

How Viruses Multiply After a virus attaches to a cell , it enters the cell . Once inside a cell , a virus genetic material takes over many of the cell functions . It instructs the cell to produce the virus proteins and genetic material . These proteins and genetic material then assemble into new viruses . Some viruses take over cell functions immediately . Other viruses wait for a while . Active Viruses After entering a cell , an active virus goes into action . The virus genetic material takes over cell functions , and the cell quickly begins to produce the virus ) proteins and genetic material . Then these parts assemble into FIGURE new viruses . Like a photocopy machine left in the on Active and tion , the invaded cell makes copy after copy of new viruses . Hidden Viruses When it is full of new viruses , the host cell bursts open , Active viruses enter host cells and ing hundreds Of new ' as it dies . immediately begin to multiply , leading to the quick death of the invaded cells . Hidden viruses hide for a while inside host cells before becoming active . A virus attaches to the surface of a bacterium . A i The bacterium bursts open , releasing new viruses . The viruses 90 . on to infect more cells . The virus injects its genetic material Active Virus into the bacterium . The proteins and genetic material ' assemble into new viruses that fill the bacterium . The virus genetic material takes over the cell functions of the bacterium . The cell starts to produce the virus proteins and genetic material .

Hidden Viruses Other viruses do not immediately become active . Instead , they hide for a while . After a hidden virus enters a host cell , its genetic material becomes part of the cell genetic materiaL The virus does not appear to affect the cell A functions and may stay in this inactive state for years . Each time the host cell divides , the virus genetic material is copied along with the host genetic material . Then , under certain conditions , the virus genetic material suddenly becomes active . It takes over the cell functions in much the same way that active do . Soon , the cell is full of new viruses and bursts open . The virus that causes cold sores is an example of a hidden virus . It can remain inactive for months or years inside nerve cells in the face . While hidden , the virus causes no symptoms . When it becomes active , the virus causes a swollen , painful sore to form near the mouth . Strong sunlight and stress are two factors that scientists believe may activate a cold sore virus . Go After an active period , the virus once again hides in the nerve ' cells until it becomes active again . landing Where In a host cell does a hidden Active and Hidden Viruses activity . while is inactive ?

Visit Web Code A virus attaches to the surface of a bacterium . The new viruses crowd , the bacterium . Finally . the cell bursts open and Hidden Virus releases the new viruses . The virus injects its genetic material into the bacterium . The cell beams to duce the virus proteins and genetic material , which assemble into new . The genetic material After some time . the becomes part of the genetic genetic material removes , material of the bacterium . itself and becomes active . Gunter ! 321

Home Viral Diseases Although there is currently no cure for viral diseases , there are ways to treat the symptoms and prevent their transmission . Relating Cause and Effect Why does the flu often pass quickly from one family member to another ?

INFLUENZA ( Flu ) Symptoms Contact Treatment 322 Viruses and Disease If you ve ever had a cold or been sick with the , you know that viruses can cause disease . Some diseases , such as colds , are are sick for a short time but soon recover . Other diseases , such as acquired syndrome , or AIDS , have much more serious consequences on the body . Viruses also cause diseases in organisms other than humans . For example , apple trees infected by the apple mosaic virus may produce less fruit . House pets , such as dogs and cats , can get deadly viral diseases , such as rabies and distemper . The of Viral Diseases Viral diseases can be spread in various ways . For example , some viral diseases can be spread through contact with a contaminated object , while others are spread through the bite of an infected animal . Some viruses , such as cold and viruses , can travel in tiny drops of moisture that an infected person sneezes or coughs into the air . Other viruses can spread only through contact with body , such as blood . Treating Viral Diseases There are currently no cures for viral diseases . However , many medicines can help relieve symptoms of a viral infection . While they can make you feel better , these medicines can also delay your recovery if you resume your normal routine while you are still sick . The best treatment for viral infections is often bed rest . Resting , drinking plenty of , and eating meals may be all you can do while you recover from a viral disease . fever can throat headache cough minted owe ?

Fever rod . Itchy rash droplets How It Spreads Contact with the rash ' inhaling droplets ' for Treatment drug . the ( elderly , and young ) , Target Reading Skill compare and Contrast ( Reviewing Key Concepts Preventing Viral Diseases Of course , you probably rather not get sick in the place . An important tool that helps prevent the spread of many viral diseases is vaccines . A vaccine is a substance introduced into the body to stimulate the production of chemicals that destroy causing viruses and organisms . A viral vaccine may be made from weakened or altered viruses . Because they have been weakened or altered , the viruses in the vaccine do not cause disease . Instead , they trigger the body natural defenses . In effect , the vaccine puts the body on If that virus ever invades the body , it is destroyed before it can cause ease . You may have been vaccinated against diseases such as polio , measles , and chickenpox . Another important way to protect against viral diseases is to keep your body healthy . You need to eat nutritious food , as well as get enough sleep , and exercise . You can also yourself by washing your hands often and by not sharing eating or drinking utensils . Unfortunately , despite your best efforts , you probably get viral infections , such as colds , from time to time . When you do get ill , get plenty of rest , and follow your doctor . Also , its very important to try not to infect others . why do vaccines cause disease themselves ?

Assessment FIGURE Vaccine Veterinarians can give pets vaccine injections that protect the animals against many viral diseases . i . Writing . Reading Complete the Venn diagram viruses and organisms . Use the diagram to help answer Question below . a . Defining What is a virus ?

a . Reviewing How does an active virus multiply ?

Sequencing List the additional steps that occur when a hidden virus multiplies . Classifying Do you think that the cold virus is an active virus or a hidden virus ?

Explain . a . Reviewing What is often the best treatment . Comparing and Contrasting How are for viral diseases ?

ruse ?

mu ?

Explaining How are vaccines important in Inferring Scientists hypothesize that viruses diseases ?

could not have existed on Earth before organisms appeared . Use what you know about viruses to support this hypothesis . identifying What basic structure do all viruses share ?

Relating Cause and Effect What role do the proteins in a virus outer coat play in the invasion of a host cell ?

Writing in Science A ' 323 . How Many Viruses Fit on a ?

Problem How can a model help you understand how small . Next . find the area in mete Of Virus Viruses are ?

particle at the enlarged size . Remember that the area of a square equals side side . Skills FOCUS . Now divide the area of the pinhead that you calculating , making models calculated in Step by the area of one virus particle to find out how many viruses could fit on the pinhead . might pin . long grip of paper . pend . Exchange your work with a partner , and meter stick scissors tape check each other calculations . aI ( optional ) Analyze and conclude Procedure . Calculating Approximately how many . Examine the head of a straight pin . Write a prediction about the number of viruses that could fit on the pinhead . CAUTION Avoid pushing the pin against anyone skin . Assume that the pinhead has a diameter of about . If the pinhead were enlarged times , then its diameter would sure 10 Create a model of the pinhead by cutting and taping together narrow strips of paper to make a strip that is 10 long . The strip of paper represents the diameter of the enlarged pinhead . Lay the strip of paper on the floor of viruses can fit on the head of a pin ?

Predicting How does your calculation pare with the prediction you made ?

If the two numbers are very different , explain why your prediction may have been inaccurate . Making Models What did you learn about the size of viruses by magnifying both the viruses and pinhead to times their actual size ?

Communicating In a paragraph . explain why scientists sometimes make and use enlarged models of very small things such as viruses . your classroom or in the hall . ing a large circle that had the strip as its diameter . The circle would be the pinhead at the enlarged size . Calculate the area of the enlarged pinhead using this formula Area Radius ?

More to Explore Think of another everyday object that you could use to model some other facts about viruses , such as their shapes or how they infect cells . Describe your model and explain why the object would be a good choice . Remember that you can find the radius by dividing the diameter by . A virus particle may measure 200 on each side ( equals a billionth of a meter ) If the virus were enlarged times , each side would measure Cut out a square by to serve as a model for a virus . Hint . 32 These papilloma viruses , which cause warts . are about 50 in diameter .

Section All living organisms are composed of cells . from just one to many trillions , whose details usually are visible only through a microscope . Students know the between the life cycles and reproduction methods of sexual and asexual organisms . How do the cells of bacteria differ from those of ?

What do bacteria need to survive ?

Under what conditions do bacteria thrive and reproduce ?

What positive roles do bacteria play In people lives ?

Key Terms bacteria flagellum binary fission asexual reproduction I sexual reproduction conjugation endospore pasteurization decomposer Bacteria ?

How Quickly Can Bacteria Multiply ?

Your teacher will give you some beans and paper cups . Number the cups through . Each bean will represent a bacterial cell . Put one bean into cup to represent the first generation of bacteria . Approximately every 20 minutes , a bacterial cell reproduces by dividing into two cells . Put two beans into cup to represent the second generation of bacteria . Calculate how many bacterial cells there would be in the third generation if each cell in cup divided into two cells . Place the correct number of beans in cup . Repeat Step five more times . All the cups should now contain beans . How many cells are in the eighth generation ?

How much time has elapsed since the first generation ?

Think It Over Inferring Based on this activity , explain why the number of bacteria can increase rapidly in a short period of time . They thrive in your container of yogurt . They lurk in your kitchen sponge . They coat your skin and swarm inside your nose . You can not escape them because they live almost rocks , in the ocean , and all over your body . In fact , there are more of these organisms in your mouth than there are people on Earth ! You do notice them because they are very small . These organisms are bacteria . The Bacterial Cell Although there are billions of bacteria on Earth , they were not discovered until the late . A Dutch merchant named Anton van ( LAY hook ) found them by dent . made microscopes as a hobby . One day , while using one of his microscopes to look at scrapings from his teeth , he saw some tiny , wormlike organisms in the sample . However , microscopes were not powerful . enough to see any details inside these organisms . Chapter 325

FIGURE Bacterial Cell Structures This model shows the structures found in a typical bacterial cell . Relating Diagrams and Photos What structure does the Salmonella bacterium in the photograph use to move ?

326 i I i ( Cell wall Cell membrane Cytoplasm A Cell Structures What saw were organisms called bacteria ( singular bacterium ) Bacteria are . The genetic material in their cells is not contained in a nucleus . A bacterial cell lacks a nucleus and also lacks many other structures , such as mitochondria and Golgi bodies , that are found in the cells of . Most bacterial cells , like plant cells , are surrounded by a rigid cell wall . Iust inside the cell wall is the cell membrane . Located in the cytoplasm are ribosomes and the genetic rial , which looks like a tangled string . lfyou could untangle the genetic material , you would see that it forms a circular shape . A bacterial cell may also have a ( um ) plural ) a long , whiplike structure that helps a cell to move . A moves the cell by spinning in place like a propeller . A bacterial cell can have many , one , or none . Most bacteria that do not have can not move on their own . Instead , they are carried from place to place by the air , water currents , objects , or other methods . Cell Sizes and Shapes Bacteria vary greatly in size . The largest known bacterium is about as big as the period at the end of this sentence . An average bacterium , however , is much smaller . For example , strep throat bacteria are about to micrometer in diameter . Most bacterial cells have one of three basic shapes spherical , or spiral . The chemical makeup of the cell wall determines the shape of a bacterial cell .

, Obtaining Food and Energy Like other organisms , there are differences among bacteria that live in different environments . For example , bacteria live in extremely hot geysers . They contain enzymes that help them function at high temperatures . However , no matter how different , all bacteria need tain things to survive . Bacteria must have a source of food and a way of breaking down the food to release its energy . Obtaining Food Some bacteria are autotrophs and make their own food . Autotrophic bacteria make food in one of two ways . Some capture and use the sun energy as plants do . Others , such as bacteria that live deep in mud , do not use the sun energy . Instead , these bacteria use the energy from chemical substances in their environment to make their food . Some bacteria are and can not make their own food . Instead , these bacteria consume other organisms or the food that other organisms make . Heterotrophic ria Consume a Variety of milk and meat , which you might also eat , to the decaying leaves on a forest floor . Respiration Like all organisms . bacteria need a constant supply of energy . This energy comes from breaking down food in the process of respiration . Like many other organisms , most bacteria need oxygen to break down their food . But a few kinds of bacteria , such as coli living in your intestines , do not need oxygen for respiration . Some kinds of bacteria will even die if exposed to oxygen . What do most bacteria need in order to break down their food ?

A These heterotrophic bacteria , found in yogurt , break down the sugars in milk for food . A The autotrophic bacteria that cause the green , cloudy scum in some ponds use the suns energy to make food . Bacteria for Breakfast . Put on your apron . Add water to plain yogurt to make a thin mixture . with a plastic dropper , place drop of the mixture on a glass slide . Use another plastic dropper to add one drop of methylene blue dye to the slide . CAUTION This dye can stain your skin . Put a on the slide . Observe the slide under both the and lenses of a microscope . Observing Draw what you see under high power . FIGURE Obtaining Food Bacteria obtain food in several ways . A These autotrophic bacteria , found in hot springs , use chemical energy from their environment to make food . Chapter 321

Reproduction When bacteria have enough food , the right temperature , and other suitable conditions , they thrive and reproduce frequently . Under these ideal conditions , some bacteria can reproduce as often as once every 20 minutes . So his a good thing that growing conditions for bacteria are rarely ideal ! For More on bacteria Visit Web Code Asexual Reproduction Bacteria reproduce by a process called binary , in which one cell divides to form two identical cells . Binary is a form of asexual reproduction . Asexual reproduction is a reproductive process that involves only one parent and produces offspring that are identical to the parent . During binary , a cell first duplicates its genetic material and then divides into two separate cells . Each new cell gets its own complete copy of the parent ceil genetic material as well as some of the parent ribosomes and cytoplasm . Sexual Reproduction Some bacteria may at times undergo a form of sexual reproduction . In sexual reproduction , two parents combine their genetic material to produce a new organism , which differs from both parents . During a process called conjugation ( kahn GAY shun ) one bacterium some genetic material to another bacterium through a threadlike bridge . After the transfer , the cells separate . Conjugation results in bacteria with new combinations of genetic material . Then . when these bacteria divide by binary , the new combinations of genetic material pass to the offspring . Conjugation does not increase the number of bacteria . However , it does result in bacteria that are genetically different . FIGURE Bacterial Reproduction In binary fission , one cell divides to form two identical cells . During conjugation , one bacterium transfers genetic material to another bacterium . Conjugation 328

Reviewing Math Algebra and Functions ' QI ! An Data Bacterial Reproduction by Binary Fission Population Explosion Suppose a bacterium reproduces by binary fission every 20 minutes . The new cells survive and reproduce at the same rate . This graph shows how the bacterial population would grow from a single bacterium . Reading Graphs What variable is being plotted on the horizontal axis ?

What is being plotted on the vertical axis ?

Interpreting Data According to the graph , how many cells are there after 20 minutes ?

After hour ?

After hours ?

Drawing Conclusions Describe the pattern you see in the way the bacterial population increases over hours . Number of Bacterial Cells 40 60 so ( minutes ) 10 ! 120 Endospore Formation Sometimes . conditions in the become unfavorable for the growth of bacteria . For example , food sources can disappear , water can dry up , or the temperature can fall or rise dramatically . Some bacteria can survive harsh conditions by forming like those in Figure . An endospore is a small , rounded , ing cell that forms inside a bacterial cell . It contains the cells genetic material and some of its cytoplasm . Because can resist freezing , heating , and drying , they can survive for many years . For example , the bacteria that cause botulism , Clostridium botulinum , produce that can survive in improperly canned foods . are also a breeze can carry them to new places . If an endospore lands where conditions are suitable , it opens up . Then the bacterium can begin to grow and multiply . Under what conditions do form ?

The red circles within these bacteria are that can survive for years . When conditions in the environment become favorable , the bacteria can begin to grow and multiply . Chapter 329 The Role of Bacteria in Nature When you hear the word bacteria , you may think about getting sick . After all , strep throat , many ear infections , and other eases are caused by bacteria . However , most bacteria are either harmless or helpful to people . In fact , in many ways , people depend on bacteria Bacteria are involved in oxygen and food production , environmental recycling and cleanup , and in health maintenance and medicine production . Oxygen Production Would it surprise you to leam that the air you breathe depends in part on bacteria ?

As autotrophic use the sun energy to produce food , they also release gen into the air . Billions of years ago , there was little oxygen in Earth atmosphere . Scientists think that autotrophic bacteria were responsible for first adding oxygen to Earth atmosphere . the distant offspring of those bacteria help keep oxygen . levels in the air stable . Science and Bacteria and Foods of the World Ancient cultures lacked refrigeration and other modern methods of preventing food spoilage . People in these developed ways of using bacteria to preserve foods . You may enjoy some of these foods today . 1000 Pickled . left . 330

Food Production Do you like cheese , sauerkraut , or les ?

The activities of helpful bacteria produce all of these foods and more . For example , bacteria that grow in apple cider change the cider to vinegar . Bacteria that grow in milk produce dairy products such as buttermilk , yogurt , sour cream , and cheeses . However , some bacteria cause food to spoil when they break down the food chemicals . Spoiled food ususally smells or tastes foul and can make you very sick . Refrigerating and heating foods are two ways to slow down food spoilage . Another method , called pasteurization , is most often used to treat beverages such as milk and juice . During pasteurization ( pas ih shun ) the food is heated to a temperature that is high enough to kill most harmful bacteria without changing the taste of the food . As you might have guessed , this I process was named after Louis Pasteur , its inventor . I Ence Research and write Use the Internet to find out more about one of these ancient methods and the culture that developed it . Write a report about the importance of the food to the culture . 331

FIGURE 10 Environmental Recycling Decomposing bacteria are at work recycling the chemicals in these leaves . Predicting What might a forest be like if there were no decomposing bacteria in the Soil ?

FIGURE 11 Environmental Cleanup Scientists use bacteria such to help clean up oil spills . 331 Environmental Recycling If you recycle glass or plastic , then you have something in common with some heterotrophic bacteria . These bacteria . which live in the soil , are that break down large chemicals in dead organisms into small chemicals . are nature They return basic chemicals to the environment for other living things to reuse . For example , the leaves of many trees die in autumn and drop to the ground . Decomposing bacteria spend the next months breaking down the chemicals in the dead leaves . The chemicals mix with the soil and can then be absorbed by the roots of nearby plants . Another type of recycling bacteria , called bacteria , help plants survive . bacteria live in the soil and in swellings on the roots of certain plants , such as nut , pea , and soybean . These helpful bacteria convert nitrogen gas from the air into nitrogen products that plants need to grow . On their own , plants can not use nitrogen present in the air . Therefore , bacteria are vital to the plants survival . Environmental Cleanup Some bacteria help to clean up Earth land and water . Can you imagine having a bowl of oil for dinner instead of soup ?

Well , some bacteria prefer the oil . They convert the poisonous chemicals in oil into harmless stances . Scientists have put these bacteria to work cleaning up oil spills in oceans and gasoline leaks in the soil under gas stations . Reading what role do bacterial play in the ' environment ?

Health and Medicine Did you know that many of the living in your body actually keep you healthy ?

In your digestive system , for example , your intestines teem with ria . Some help you digest your food . Some make vitamins that your body needs . Others compete for space with causing organisms , preventing the harmful bacteria from attaching to your intestines and making you sick . Scientists have put some bacteria to work making medicines and other substances . The bacteria were made in the 19705 . By manipulating the bacteria genetic material , scientists engineered bacteria to produce human lin . Although healthy people can make their own insulin , those with some types of diabetes can not . Many people with diabetes need to take insulin daily . Thanks to bacteria fast rate of duction , large numbers of bacteria can be grown in huge vats . The human insulin they produce is then and made into medicine . FIGURE 12 Bacteria and Digestion Bacteria living naturally in your intestines help you digest food . section Assessment Vocabulary Skill Prefixes The means Inferring Why might bacteria that undergo Use the meaning of the to conjugation be better able to survive when contrast asexual reproduction and sexual conditions become less than ideal ?

reproduction . a . Listing A friend states that all bacteria are harmful to people . List three reasons why this statement is inaccurate . Applying Concepts In what ways might bacteria contribute to the success of a garden in which pea plants are growing ?

Reviewing Key Concepts a . Reviewing Where is the genetic material located in a bacterial cell ?

Describing What is the role of in a bacterial cell ?

a . Listing What are the three ways in which bacteria obtain food ?

Describing How do bacteria obtain energy ' At A vi to carry out their functions ?

ty Inferring You have just discovered a new bacterium that lives inside sealed cans of Edible Bade member How do you think these around your kitchen for foods that are made Obtain food and energy using bacteria . Read the food labels to see if what is ?

bacteria are used in the food production . Discuss with your family member the helpful roles that bacteria play in people lives . Explaining Under what conditions do bacteria thrive and reproduce frequently by binary ?

Chapter 333 ( Standards Focus Students know plants and animals have levels of organization for structure and function . ing cells . tissues , organs , organ , and the whole organism . What are the characteristics of , plantlike , and funguslike ?

How do algae vary in organization , structure , and function ?

Key Terms protist protozoan pseudopod contractile vacuole cilia I symbiosis mutualism algae spore 13 Diatoms These glasslike organisms are classified as . 334 Standards What Lives in a Drop of Pond Water ?

Use a plastic dropper to place a drop of pond water on a microscope slide . Put the slide under your microscope power lens . Focus on the objects you see . Find at least three different objects that you think might be organisms . Observe them for a few minutes . Draw the three organisms in your notebook . Below each sketch , describe the movements or behaviors of the organism . Wash your hands thoroughly when you have finished . Think It Over Observing What characteristics did you observe that made you think that each organism was alive ?

Look at the objects in Figure 13 . What do they look like to you ?

Jewels ?

Beads ?

Stained glass ornaments ?

You might be prised to learn that these beautiful , delicate structures are the walls of unicellular organisms called diatoms . live in both fresh water and salt water and are an important food source for many marine organisms . They have been called the jewels of the sea .

A These shells are the remains of unicellular , called . What Is a Protist ?

Diatoms are only one of the vast varieties of . are that can not be as animals . plants , or fungi . The word that best describes is diversity . For example , most are unicellular , but some are multicellular . Some are , some are autotrophs . and others are both . Some can not move , while others can . In fact , are so diverse some scientists think that belong in separate kingdoms . Biologists continue to study the DNA sequences and evolutionary histories of the various groups of . Despite their diversity , do share some characteristics . In addition to being , all live in moist . Most reproduce cells simply grow and divide . However , some types of can reproduce sexually as well . One useful way of grouping is to divide them into three categories , based on characteristics they share with organisms in other kingdoms , plantlike , and funguslike . What image pops into your head when you think of an animal ?

A tiger chasing its prey ?

A snake slithering onto a rock ?

Most people immediately associate animals with movement . In fact , movement is with an important function of food . All animals are that must obtain food by eating other organisms . animals , are . and most are able to move from place to place to obtain food . But unlike animals , or tuh ) are unicellular . can be into four groups , based on the way they move and live . mun 14 include , plantlike , and funguslike organisms . Comparing and Contrasting In what way do differ from one another ?

This red alga is a multicellular , plantlike found on ocean floors . A The yellow slime mold oozing off the leaf is a funguslike protist . Chapter 335 FIGURE 15 Amoeba Amoebas are that live in either water or soil . They feed on bacteria and smaller . Food Vacuole when the ends of two Pseudopod around food , they form a food vacuole . Food A amoeba uses IS broken down inside the food vacuole to move and feed . in the ( form when cytoplasm flows toward one location and the rest of ' the amoeba i follows . The nucleus controls the cell functions and is involved in reproduction . Contractile Vacuole Amoebas usually reproduce The contractile vacuole collects by binary fission . excess water from the cytoplasm and expels it from the cell . Cell Membrane Because the cell membrane is very thin and flexible , an amoeba shape changes constantly Go With The amoeba 111 Figure 15 ac I ( ark belongs to the group of called . dines move and feed by forming ( duh ) bulges of the cell . The word pseudopod means false foot . form when cytoplasm toward one location and the rest of the organism follows . enable to move . For example , amoebas use to move away from bright light . also use to trap food . The organism extends a pseudopod on each side of the food particle . The two pods then join together , trapping the particle inside . that live in fresh water , such as amoebas , have aproblem . Small particles , like those of water , pass easily through the cell membrane into the cytoplasm . If excess water were to build up inside the cell , the amoeba would burst . Fortunately , amoebas have a contractile vacuole ( kun til yoo ohl ) a structure that collects the extra water and then expels it from the cell . Web Code 3360

FIGURE 16 Paramecium are that live mostly in fresh water . Like A Stiff bUt feed on Call ?

the Pellicle . bacteria and smaller . paramecium and gives it shape . Contractile vacuoles largo Nucleus Two contractile vacuoles collect ' excess water from the cytoplasm . and expel it from the cell . Anal Pore Wastes leave through the anal pore . I The oral groove is a indentation lined with cilia . The cilia move water containing food into the vacuole that forms at the end of the oral groove . Food vacuole Thousands of cilia project through A food vacuole forms and pinches off the pellicle . The beating cilia enable from the oral groove . It moves into the a paramecium to move smoothly cytoplasm . Inside the vacuole . the food in one direction . is broken down and then distributed . Protozoan with Cilia The second group of are the . have structures called cilia ( SIL ee uh ) which are hairlike projections from cells that move with a wavelike motion . use their cilia to mom and obtain food . Cilia act something like tiny oars to move a ciliate . Their movement sweeps food into the organism . The cells of , like the paramecium in Figure 16 , are complex . Notice that the paramecium has two contractile that expel water from the cell . It also has more than one nucleus . The large nucleus controls the everyday tasks of the cell . The small nucleus functions in reproduction . usually reproduce asexually by binary . Sometimes , however , reproduce by conjugation . This occurs when two join together and exchange some of their genetic material . What are cilia ?

Chapter ! 0337 FIGURE 17 When people drink from freshwater streams and lakes , they can get hiker disease . Giardia ( inset ) is the protozoan responsible for this disease . Inferring Why is it important for hikers to filter stream water ?

338 with The third group of are ( uh lits ) that use long . whiplike to move . A flagellate may have one or more . Some of these live inside the bodies of other organisms . For example , one type of lives in the tines of termites . There , they digest the wood that the termites eat , producing sugars for themselves and for the termites . In turn , the termites protect the . The interaction between these two species is an example of symbiosis ( sim bee OH sis ) close relationship in which at least one of the . When both partners from living together . the relationship is a type of symbiosis called mutualism . Sometimes . however , a protozoan harms its host . For example , is a parasite in humans . animals , such as beavers , deposit Giardia in freshwater streams , rivers , and lakes . When a person drinks water containing Giardia . these attach to the persons intestine , where they feed and reproduce . The person develops a serious intestinal condition commonly called hiker disease . That Are Parasites The fourth type of are characterized more by the way they live than by the way they move . They are all parasites that feed on the cells and body of their hosts . These move in a variety of ways . Some have , and some depend on hosts for transport . One even produces a layer of slime that allows it to slide from place to place ! Many of these parasites have more than one host . For ple , Plasmodium is a proto that causes malaria , a disease of the blood . Two hosts are involved in life humans and a species of mosquitoes found in tropical areas . The disease spreads when a healthy mosquito bites a person with malaria . The mosquito then becomes infected with . When the mosquito next bites a healthy person , the mosquito passes the Plasmodium to that person . Symptoms of malaria include high fevers that alternate with severe chills . i What is symbiosis ?

FIGURE 18 Malaria Mosquito Anopheles mosquitoes can carry the parasitic protozoan Plasmodium , which causes malaria in people , Plantlike Plantlike , which are commonly called algae ( AL jee ) are extremely diverse . Like plants , algae are autotrophs . Most are able to use the sun energy to make their own food . They An , Activity Watching In this activity you will can perform photosynthesis . the interaction between Algae play a role in many environments . For paramecium , an example , algae that live near the surface of ponds , lakes , and ' oceans are an important food source for other organisms in the ' water . In addition , much of the oxygen in Earth atmosphere is made by these algae to place drop of paramecium culture on a microscope slide . Add some cotton fibers to slow down the . Use the microscope power objective to find some . Add drop of to the paramecium culture on your slide . Switch to high power and locate a paramecium . Algae vary greatly in cell organization , structure , and function . Some algae are unicellular . Other algae are multicellular with differentiated tissues and organs . Still others are groups of unicellular organisms that live together in colonies . Algal colonies can contain from a few cells up to thousands of cells . In a colony , most cells carry out all tions . But , some cells may become specialized to perform tain functions , such as reproduction . Algae exist in a wide variety of colors because they contain many types of pigments . You may recall that pigments are chemicals that produce color . Depending on their pigments , Observe what happens . algae can be green , yellow , red , brown , orange , or even black . The wash you , hands Diatoms Diatoms are unicellular with beautiful ' fE ' a ' glasslike cell walls . Some near the surface of lakes or hete , a oceans . Others attach to objects such as rocks in shallow water . are auto Diatoms are a food source for in the water . diatoms can move by oozing chemicals out of slits in their cell walls . They then glide in the slime . When diatoms die , their cell walls collect on the bottoms of oceans and lakes . Over time , they form layers of a coarse stance called diatomaceous ( dy uh tuh MAY ) earth . earth makes a good polishing agent and is used in household scouring products . It is even used as an the diatoms sharp cell walls puncture the bodies of insects . dy noh FLA uh lits ) are unicellular algae surrounded by stiff plates that look like a suit of armor . Because they have different amounts of green , orange , and other pigments , exist in a variety of colors . All have two held in grooves between their plates . When the beat , the am the writer Dinoflagellates whirl any ow in . ey up ocean su ace through the water with when disturbed by a passing boat or swimmer . their 339

FIGURE 20 The is a common euglenoid that lives in fresh water . contain chlorophyll , which gives them the green color . In sunlight . many can make their own food . Without sunlight , they obtain food from their environment . Interpreting Diagrams What structures help a find and move toward light ?

Predicting Predict what will happen when you pour a culture of into a petri dish , and then cover half the dish with aluminum foil . Give a reason for your prediction . Then carry out the ment with a culture of in a plastic petri dish . Cover half the dish with foil . After 10 minutes , uncover the dish . What do you observe ?

Was your diction correct ?

Explain why behave this way . 3406 Eyespot Contractile vacuole Chloroplast ( used in food production ) yoo GLEE ) are green , algae that are found mostly in fresh water . Unlike other algae . have one can be under certain conditions . When sunlight is available , most are autotrophs that produce their own food . However , when sunlight is not available , will act like by obtaining food from their ment . Some live entirely as . In Figure 20 , you see a , which is a common noid . Notice the long , that helps the ism move . Locate the eyespot near the . Although the eyespot is not really an eye , it contains pigments . These ments are sensitive to light and help the recognize the direction of a light source . You can imagine how important this response is to an organism that needs light to make food . Red Algae Almost all red algae are multicellular seaweeds . Divers have found red algae growing more than 260 meters below the ocean surface . Their red pigments are especially good at absorbing the small amount of light that is able to reach deep ocean waters . People use red algae in a variety of ways . ka ruh nun ) and agar are substances extracted from red algae . These substances are used in products such as ice cream and hair conditioner . For people in many Asian cultures , red algae are a food that is eaten fresh , dried , or toasted .

Green Algae Green algae , which contain green pigments , are quite diverse . Most green algae are unicellular . Some , however , form colonies . and a few are multicellular . Most green algae live in either fresh water or salt water . The few that live on land are found on rocks , in the crevices of tree bark , or in moist soils . Green algae are actually very closely related to plants that live on land . Green algae and plants contain the same type of and share other important similarities . In fact , some scientists think that green algae belong in the plant kingdom . Brown Algae Many of the organisms that are commonly called seaweeds are brown algae . In addition to their brown pigment , brown algae also contain green , yellow , and orange pigments . All brown algae are multicellular . This group has the most complex structure of all the algae . Some brown algae even have differentiated tissues and organs that resemble structures found in plants . Figure 22 shows a typical brown alga . anchor the alga to rocks . Stalks support the blades , which are the structures of the alga . Many brown algae also have sacs called bladders that allow the algae to upright . Brown algae in cool . rocky waters . Brown algae called rockweed live along the Atlantic coast of North America . Giant , which can grow as long as 100 meters , live in some coastal waters . The giant form large underwater forests where many organisms , including sea otters and lone , live . What color pigments can brown algae contain ?

FIGURE 22 Brown Algae Giant are brown algae that have many plantlike organs . Interpreting Diagrams What plant structures do the holdfasts and blades resemble ?

FIGURE 21 Green Algae Green algae range in size from unicellular organisms to multicellular seaweeds . This multicellular sea lettuce , lives in oceans . Chapter 341 FIGURE 23 Slime Molds The chocolate tube slime mold first forms a mass ( top ) when conditions become harsh , the mass grows producing stalks ( right ) The stalks , or chocolate tubes , are covered with millions of brown spores . 3420 Funguslike The third group of are the funguslike . You may recall that fungi include organisms such as mushrooms and yeast . Until you learn more about fungi , you can think of fungi as the sort of like organisms . Fungi are sort of like animals because they are . They are sort of like plants because their cells have cell walls . in addition , most fungi use spores to reproduce . A spore is a tiny cell that is able to grow into a new organism . Like fungi , funguslike are , have cell walls , and use spores to reproduce . All funguslike are able to move at some point in their lives . The three types of funguslike are slime molds , water molds , and downy . Slime Molds Slime molds are often brilliantly colored . They live on forest and other moist , shady places . They ooze along the surfaces of decaying materials , feeding on bacteria and other microorganisms . Some slime molds are so small that you need a microscope to see them . Others may cover an area of several meters ! Slime molds begin their life cycle as tiny , individual cells . The cells use to feed and creep around . Later , the cells grow bigger or join together to form a giant , jellylike mass . In some species , the giant mass is cellular and forms when food is scarce . In others , the giant mass is actually a giant with many nuclei . The mass oozes along as a single unit . When mental conditions become harsh , grow out of the mass and release spores . Eventually the spores develop into a new generation of slime molds .

' of Water Molds and Downy Most water molds and downy live in water or moist places . These isms often grow as tiny threads that look like fuzz . Figure 24 shows a attacked by a water mold and a leaf covered by downy mildew . Water molds and downy attack many food crops , such as potatoes , corn , and grapes . A water mold impacted tory when it destroyed the Irish potato crops in 1845 and 1846 . The loss of these crops led to a famine . More than one million people in Ireland died , and many others moved to the United States and other countries . i In what environments are water molds found ?

A Water mold on Downy mildew on grape leaf FIGURE 24 Water Molds and Downy Many water molds are posers of dead aquatic organisms . Others are parasites of fish and other animals . Downy are parasites of many food crops . Section Assessment Vocabulary Skill Prefixes In the word pseudopod , the means What do you think the root means ?

Activity Algae Scavenger Hunt Look around your house with a family member to find products that contain substances made from algae . Look at both food and nonfood items . Before you begin , tell your family member that substances such as diatomaceous earth , algin , and are products that come from algae . Make a list of the products and the ingredients they contain . Share your list with the class . Reviewing Key Concepts a . Listing List the four types of . How does each type move or live ?

Comparing and Contrasting How are these four types of similar to animals ?

How are they different ?

Classifying You observe an protist under the microscope . It has no hairlike or whiplike structures . moves by forming temporary bulges of cytoplasm . How would you classify this protist ?

a . Reviewing What characteristics do diatoms . and other plantlike share ?

I ) Making Generalizations In what ways are plantlike different from one another ?

Comparing and Contrasting Describe the similarities and differences in the organization . structure . and function of and brown algae . a . Listing What are the three types of ?

Describing How are funguslike like fungi ?

Chapter 343 Section Fungi Standards Focus Standards Students know cells Do A Molds Look Alike ?

tion similarly in ail organisms . Student , know the differ . Your teacher will give you two sealed , clear plastic between the me ( ycie , and containing moldy bread and another containing moldy fruit . reproduction methods of CAUTION Do not open the sealed bags at any time . and asexual . In your notebook , describe what you see . Next , use a hand lens to examine each mold . Sketch each . mold in your notebook and list its characteristics . How do fungi reproduce ?

Return the sealed bags to your teacher . Wash your hands . What roles do fungi play in Ova I . name observing How are the molds similar ?

How are they different ?

germs A speck of dust lands on a cricket back . But this is no ordinary . is alive ! Tiny glistening threads emerge from the dust . body and begin to grow into the crickets moist body . As they grow , budding the threads release chemicals that slowly dissolve the crickets lichen tissues . Soon , the cricket body is little more than a hollow shell filled with a tan of the threads . Then the threads be in to grow up and out of the dead cricket , producing long stalks with knobs at their tips . When a knob breaks open , it will release thousands of specks , which the wind can carry to new victims . What Are Fungi ?

The strange organism is a member of the fungi kingdom . Although you may not have heard of a fungus before , you are probably familiar with other kinds of fungi . For example , the molds that grow on stale bread and the mushrooms that sprout in yards are all fungi . Most fungi share several important tics . Fungi are that have cell walls , are that feed by absorbing their food , and use spores to reproduce . In addition , fungi need moist , warm places in which to grow . They thrive on moist foods , damp tree barks , lawns coated with dew , and even wet bathroom tiles . A killer fungus has attacked this bush cricket . 3446

FIGURE 25 Structure of a Mushroom The in the stalk and cap of a mushroom are packed tightly to form firm structures . Underground are arranged loosely . Inferring What function might underground perform ?

Cell Structure Fungi range in size from tiny unicellular yeasts to large multicellular fungi . The cells of all fungi are rounded by cell walls . Except for the simplest fungi , such as yeast , the cells of most fungi are arranged in structures called . HY fee ) singular hypha ) are the branching , threadlike tubes that make up the bodies of multicellular fungi . The of some fungi are continuous threads of cytoplasm that contain many nuclei . Substances move quickly and freely through the . What a fungus looks like depends on how its are arranged . In some fungi , the threadlike are loosely tan . molds that grow on old foods have loosely tangled . Other fungi have tightly packed . The stalks and caps of mushrooms are made of packed so tightly that they appear solid . Underground , however , a mush room form a loose , threadlike maze in the soil . Obtaining Food Fungi absorb food through that grow into a food source . First , the fungus grows into the food source . Then digestive chemicals ooze from the into the food . The chemicals break down the food into small substances that can be absorbed by the . As an analogy , imagine yourself sinking your down into a chocolate cake and dripping digestive chemicals out of your . Then imagine your absorbing the digested particles of the cake ! Reading What do the bodies of multicellular fungi ) consist of ?

Underground FIGURE 26 Mold Growing on Food Source The mold often grows on old fruits such as oranges . Some of its grow deep into the food source . Chapter 345 Reproduction in Fungi . Try This Activity ' A Like it or not , are everywhere . The way they reproduce spreading spores helps guarantee their survival and spread . usually In this activity , you will make The ' a model body . surroundedby a protective covering and can be carried easily through air or water to new sites . Fungi produce millions of spores , more than can ever survive . Only a few spores will fall where conditions are right for them to grow . Fungi produce spores in reproductive structures called fruiting bodies . The appearances of fruiting bodies vary among different fungi . For some fungi , such as mushrooms , the part of the fungus that you see is the fruiting body . in other fungi , such as bread molds , the fruiting bodies are tiny , like that grow upward from the rest of the . A . Break a cotton ball into five equal pieces . Roll each piece into a tiny ball . Insert the cotton balls into a balloon . Repeat Steps and until the balloon is almost full . the balloon . lie a knot in its neck . Tape the It ed . knoblike spore case at the tip of each stalk the spores . stand the stick upright in a you can imagine , the structure of the body is very mound of modding important to the fungi success in reproduction . Po th , wish 31 00 Asexual Reproduction Most fungi reproduce both what happen , asexually and sexually . When there is adequate moisture and food , the fungi make spores asexually . Cells at the tips of their divide to form spores . The spores grow into fungi that are genetically identical to the parent . Unicellular yeast cells undergo a form of asexual duction called budding . In budding , no spores are . Instead , a parent cell undergoes mitosis and a small yeast cell grows from the parent cell . This process is what similar to the way a bud forms on a tree branch . The new cell then breaks away and lives on its own . Making Models Draw a diagram of the model you made . Label the stalk . the spore case , and the spores . Use your model to explain why fungi are found just about everywhere . Sexual Reproduction Most fungi can also reproduce sexually , especially when growing conditions become able . sexual reproduction , the of two fungi grow , together and genetic material is exchanged . Eventually , a new , reproductive structure grows from the joined and Budding is a form of duces spores . The spores develop into fungi that differ cally from either parent . Applying Concepts How is a new yeast cell formed by asexual Classification of Fungi Figure 28 shows three major groups , a , to of fungi . The groups are named for the appearance of their iu parent cell ?

structures . Additional groups include water species that produce spores with and those that form tight tions with plant roots . What is budding ?

The Role of Fungi in Nature Fungi affect humans and other organisms in many different ways . Many fungi provide foods for people . Fungi play important roles as and recyclers on Earth . Some fungi cause disease while others disease . Still other fungi live in symbiosis with other organisms . Food and Fungi Yeasts , molds , and mushrooms are tant food sources . Bakers add yeast to bread dough to make it rise . Yeast cells use the sugar in the dough for food and produce bon dioxide gas as they feed . The gas forms bubbles , which cause the dough to rise . You see these bubbles as holes in a slice of bread . Molds are used to make foods such as some cheeses . The blue streaks in blue cheese , for example , are actually growths of . People enjoy eating mushrooms in salads and on pizza . You should never pick or eat wild mushrooms . however , because some mushrooms are extremely poisonous . FIGURE 28 Classification of Fungi Three major groups of fungi include sac fungi , club fungi , and zygote fungi . Sac truffles . A Club Fungi Club fungi produce spores in tiny structures . This group includes mushrooms , rusts , and puffballs , such as these . Sac fungi produce spores in structures that look like long sacs , such as these . The largest group of fungi , they include yeasts , morels , and A Zygote Fungi Zygote fungi produce very resistant spores . This group includes many common fruit and bread molds , like this Rhizopus . VIII ! Hill Ill ennui mun and Fungi Chapter 341

FIGURE 29 Root Associations An extensive system of fungal has grown in association with the roots of the pine seedling in the middle . Classifying What type of symbiosis do these two organisms exhibit ?

Environmental Recycling Like bacteria , many fungi are . For example , many fungi live in the soil and break down the chemicals in dead plant matter . This process returns important nutrients to the soil . Without fungi and , Earth would be buried under dead plants and animals ! Fungi In 1928 , a Scottish biologist named Alexander Fleming was examining dishes in which he was growing bacteria . To his surprise , Fleming noticed a spot of a mold growing in one dish . Curiously , no bacteria were growing near the mold . Fleming hypothesized that the mold , a fungus named , pro a substance that killed the bacteria near it . Fleming work contributed to the development of the antibiotic , penicillin . Since the discovery of penicillin , many antibiotics have been isolated from both fungi and bacteria . Fungi Many fungi are parasites that cause serious diseases in plants . The sac fungus that causes Dutch elm disease is responsible for killing millions of elm trees in North America and Europe . Corn smut and wheat rust are two club fungi that cause diseases in important food crops . Fungal plant diseases also affect other crops , including rice , cotton , and beans , resulting in huge crop losses every year . Some fungi cause diseases in humans . Athlete foot fungus causes an itchy irritation in the damp places between toes . Ringworm . another fungal disease , causes an itchy , circular rash on the skin . Because the fungi that cause these diseases produce spores at the site of infection , the diseases can spread easily from person to person . Both diseases can be treated with antifungal medications . Root Associations Some types of fungi help plants grow larger when their grow into , or on , the plants roots . The spread out and absorb water and nutrients from the soil for the plant . With more water and nutrients , the plant grows larger than it would have grown without its fungal partner . The plant is not the only panner that . The fungi get to feed on the extra food that the plant makes and stores . Most plants have fungal partners . Many plants are so dependent on the fungi that they can not survive without them . For example , orchid seeds can not develop without their fungal partners .

' FIGURE 30 Lichens The British soldier lichen consists of a fungus and an alga . The inset shows how entwined the alga is among the fungus . lichens A lichen ( LY kun ) consists of a fungus and either algae or autotrophic bacteria that live together in a mutualistic relationship . You have probably seen some familiar irregular , crusty patches that grow on tree barks or rocks . The fungus from the food produced by the algae or bacteria . The algae or bacteria , in turn , obtain shelter , water , and minerals from the fungus . Lichens are often called pioneer organisms because they are the first organisms to appear on the bare rocks in an area after a volcanic eruption , or rock slide has occurred . Over time , the lichens break down the rock into soil in which other organisms can grow . lichens are also useful as indicators of air pollution . Many species of lichens are very sensitive to ants and die when pollution levels rise . By monitoring the pen , fungi growth of lichens , scientists can assess the air quality in an area . Visit . Web ( ode What two organisms make up a lichen ?

Go ! i . writing Section I ?

Assessment , Target Reading Skill Compare and Contrast Identifying Name six roles that fungi play Construct a Venn diagram to help you answer in nature . Question below . Predicting Suppose all the fungi in a forest disappeared . What do you think the forest Reviewing Key concepts would be like without fungi ?

a . Listing List three characteristics that a bread mold shares with a mushroom . Comparing and Contrasting How are the In Ce cells of a bread mold arranged ?

How are . the cells of a mushroom arranged ?

food my , Summarizing How does the cell structure of of a fungus help it obtain food ?

lam . mid a . Reviewing What role do spores play in the an . it reproduction of fungi ?

93 . II ! Sequencing Outline the steps by which fungi hem , produce spores by sexual reproduction . mom prop . my to mum mam Inferring Why is it advantageous to a fungus a your to produce millions of spores ?

Chapter 349 I . What for Lunch ?

ma . Problem . Gently stretch each of the balloons How does the presence of sugar or salt affect the that they Mme 935 ) respiration of yeast ?

Using the marking pen , label the bottles A , and . Skills FOCUS . Use a beaker to fill each bottle with the same amount of Warm Wa er . Glass is fragile . Handle the beaker gently to avoid Materials breakage . Do not touch broken glass . small plastic bottles ' 25 ' round balloons plastic straws . Put 25 of sugar into bottles and dry Yea It . Put 50 of sugar into bottle warm water ( marking pen , bake , graduated cylinder , metric ruler . Put of powdered yeast Into bottle A , Wing and stir the mixture with a clean straw . Remove the straw and discard it . Immediately place a balloon over the . ing of bottle A . Make sure that the balloon . very tightly around the neck of functions . Copy the data table into your notebook , Then read over the entire 10 . Repeat Steps and for bottle , bottle , procedure to see how you will test and ' the respiration activity of the yeast cells in bottles A through Write a prediction about what will happen in each bottle .

11 . Place a balloon over bottle without adding yeast to the bottle . 12 . Place the five bottles in a warm spot away from drafts Every ten minutes for 40 minutes , measure the circumference of balloon by placing a string around the balloon at its widest point . Include your measurements in the data table . Yeast and 25 of salt ) Yeast and 26 of sugar ) Yeast and 50 of sugar ) No yeast and 25 of sugar ) Analyze and conclude . Measuring Which balloons changed in size during this lab ?

How did they change ?

inferring Explain why the balloon size in some bottles and not in others . What caused that change in size ?

Interpreting Data How did the results from bottles and compare ?

why was it tant to include bottle in this investigation ?

Drawing Conclusions Do yeast use salt or sugar as a food source ?

How do you know ?

Communicating in a paragraph , summarize what you learned about yeast from this . Be sure to support each of your conclusions with the evidence you gathered . Design an Experiment Develop a hypothesis about whether ture affects the activity of yeast cells . Then design an experiment to test your hypothesis . Obtain your teacher permission before carrying out your investigation . Go For Data sharing Visit Web Code 351

Chapter Study Guide BIG Idea ?

Viruses Key Concepts The only way in which viruses are like organisms is that they can multiply . All viruses have two basic parts an outer coat that protects the virus and an inner core made of genetic material . Once inside a cell , a virus genetic material takes over many of the cell functions . The genetic material instructs the cell to produce the virus proteins and genetic material , which then assemble into new viruses . Resting , drinking plenty of , and eating meals may be all you can do while you recover from a viral disease . Key Terms virus host parasite bacteriophage vaccine Bacteria Key Concepts , Bacteria are . The genetic material in their cells is not contained in a nucleus . Bacteria must have a source of food and a way of breaking down the food to release its energy . When bacteria have plenty of food . the right temperature , and other suitable conditions , they thrive and reproduce frequently . Bacteria are involved in oxygen and food production , environmental recycling and cleanup , and in health maintenance and medicine production . Key Terms bacteria conjugation flagellum endospore binary pasteurization asexual reproduction decomposer sexual reproduction 352 Key Concepts Like animals , are Organisms in different domains and kingdoms display varying levels of organization , from single cells to more complex structures . and most are able to move from place to place to obtain food . Like plants , algae are autotrophs . Like fungi , funguslike are , have cell walls , and use spores to reproduce . Key Terms protist symbiosis protozoan mutualism pseudopod algae contractile vacuole spore cilia Fungi ( Key Concepts Fungi are that have cell walls , are that feed by absorbing their food , and use spores to reproduce . Fungi usually reproduce by making spores . The lightweight spores are surrounded by a protective covering and can be carried easily through air or water to new sites . Many fungi provide foods for people . Fungi play important roles as and recyclers on Earth . Some fungi cause disease while others disease . Still other fungi live in symbiosis with other organisms . Key Terms fungi fruiting body budding lichen

Review and Assessment For Visit Web Code Target Reading Skill Va Compare and Contrast To review part of . Section , copy the Venn diagram , which ' compares an amoeba to a paramecium . Add at least one additional similarity and one additional difference . Moves by Reviewing Key Terms Choose the letter of the best answer . Complete the following sentences so that . are viruses that attack and ' a ' a ' the ' Viruses act like parasites , which are ot er viruses . bacteria . id Ian . Binary , a onn asexual ' reproduction , does not result in genetically different organisms because ' and . When excess water enters an amoeba , a I Ce the amoeba does not burst because it has a ' ii I , th bacterium . contract at protist . fungus . When a protozoan living inside a termite ' helps the termite digest wood , the relationship is called mutualism because 91 protective structure called the cell wall . cell . 10 . mold have loosely tangled protein coat . ac ar ' I . Which of the following characteristics In Ce describes all ?

They are Il ' I Ill Create pamphlet . They can be seen with the unaided eye . tad ' Their cells have nuclei . WhU ! live . their They are unable to move on their own . A lichen is a symbiotic association between fungi and plant roots . algae and fungi . algae and bacteria . and algae . Haul School and Fungi , Chapter 353

Review and Assessment Checking Concepts 11 . Explain why a certain virus will attach to only one type or a few types of cells . 12 . Describe how a hidden virus multiplies . 13 . Describe how bacteria reproduce . 14 . How do the bacteria that live in your intestines help you ?

15 . How does an amoeba obtain food ?

16 . Compare how . plantlike , and funguslike obtain food . 17 . How does sexual reproduction occur in fungi ?

Thinking Critically 18 . Comparing and Contrasting Describe the similarities and differences between active and hidden viruses . 19 . Problem Solving Bacteria will grow in the laboratory on a substance called agar . Viruses will not grow on agar . If you needed to grow viruses in the laboratory , what kind of substance would you have to use ?

Explain your reasoning . 20 . Comparing and Contrasting Identify the organisms below . Describe the method by which each obtains food . 21 . Predicting If all algae suddenly disappeared from Earth waters . what would happen to living things on Earth ?

Explain your answer . 22 . Making Judgments You see an advertisement for a new , powerful fungicide guaranteed to kill most fungi on contact . What should people take into consideration before choosing to buy this fungicide ?

3540 Applying Skills Use the graph to answer Questions . When yeast is added to bread dough , the yeast cells produce carbon dioxide , which causes the dough to rise . The graph below shows how temperature affects the amount of carbon dioxide that is produced . Temperature and Carbon Dioxide Production Volume of Carbon Dioxide ( 15 30 45 Temperature ( 23 . Interpreting Data Based on the graph , at what temperature does yeast produce the most carbon dioxide ?

24 . Inferring Use the graph to explain why yeast is dissolved in warm water , rather than in cold water , when it is used to make bread . 25 . Predicting Based on the graph , would you expect bread dough to rise if it were placed in a refrigerator ( which is kept at about to ) Explain . 26 . Drawing Conclusions Explain how temperature affects the amount of carbon dioxide that the yeast cells produce . Standards Investigation Performance Assessment Create a poster that summarizes your experiment for the class . your poster . your hypothesis and describe the conditions that produced the best mushroom growth . Use diagrams and graphs to display your results . Did the investigation raise any new questions about mushrooms for you ?

If so , how could you answer those questions ?

Standards Practice Choose the letter of the best answer . Ifyou know that an organism is a , you know that A its cell does not contain a nucleus . its cell does not contain ribosomes . the organism is a . the organism can not move on its own . Which of the following statements about a paramecium is correct ?

A It has two contractile vacuoles that remove excess water from the cytoplasm . It uses cilia to move . has two nuclei . all of the above . Which of the following statements about fungus reproduction is true ?

A Fungi reproduce sexually by budding . Fungi reproduce by making spores . Fungi reproduce asexually when two join together and exchange genetic material . Fungi do not reproduce sexually . Use the diagram below and your knowledge of science to answer Question . What will most likely happen after the virus in the diagram attaches to the bacterial cell ?

A The virus will inject its proteins into the bacterial cell . The virus will inject its genetic material into the bacterial cell . The bacterial cell will inject its proteins into the . The bacterial cell will inject its genetic material into the virus . success it at . Which of the following statements about viruses is not true ?

A Viruses can multiply only inside a living cell . Viruses have genetic material . Virus particles are smaller than bacterial cells . Viruses are composed of cells . Use the diagram below and your knowledge of science to answer Question . Which structure tells you that the shown is an autotroph ?

A eyespot nucleus chloroplast . Paola grew a new culture of bacteria and measured the populations growth over time . The number of bacteria increased sharply over the first few hours but then tapered off . Which of the following statements about these observations is true ?

A The initial conditions for bacterial growth were favorable . The number of bacteria increased as the bacteria reproduced asexually . After a period of time , the bacteria started to run out of food , space , and other resources . all of the above . Compare and contrast viruses and bacteria with respect to their sizes , structures , and methods of reproduction . Chapter ! 0355