Reading Essentials for Biology Glencoe (794133), страница 54
Текст из файла (страница 54)
Meiosisoccurs, producing fourhaploid nuclei thatdevelop intobasidiospores.sefuieclnudiploHa+–D Hyphae fusionWhen different hyphaemeet, they fuse and forma new mycelium containingcells with two haploid nuclei.ButtonE Button formationThe mycelium forms acompact mass, a button,just below the soil’ssurface. A button developsinto a stalk and cap.NewmyceliumDeuteromycotesUnlike the zygomycotes, ascomycotes, and basidiomycotes, thedeuteromycotes only reproduce asexually.
It may be possible thatthey have a sexual reproduction phase, but scientists have notobserved it.Deuteromycotes have many commercial uses. They are usedto make foods, such as soy sauce and bleu cheese. They also areused to produce citric acid. Citric acid gives jams, jellies, fruitflavored candies, and soft drinks a tart taste.
Penicillin, an antibioticprescribed by doctors to treat bacterial infections like strep throat,is produced from a deuteromycote.READING ESSENTIALSChapter 20229NameDateClassSection20.2The Diversity of Fungi, continuedMutualism: Mycorrhizae and Lichens4. What are the two typesof symbiotic relationshipsthat fungi share withother organisms?________________________________________________Some fungi live in close association with other organisms. Thisis called mutualism. When both organisms benefit from the association, it is a symbiotic relationship.There are two symbiotic relationships that fungi share withother organisms.
One type is known as mycorrhiza, the other isknown as lichen.5. What percent of plantshave a mycorrhizalrelationship?________________________________________________________________________A mycorrhiza (my kuh RHY zuh) is a mutualistic relationshipin which a fungus lives symbiotically with a plant. Most of thefungi that form mycorrhizae are basidiomycotes.Fine, threadlike hyphae grow around the plant’s roots withoutharming the plant.
More nutrients can enter the plant’s rootsbecause the hyphae increase the absorptive surface of the plant’sroots. Minerals in the soil are absorbed by the hyphae and thenreleased into the roots. The hyphae help to maintain wateraround the roots. The fungus benefits from the relationship too.The fungus receives organic nutrients such as amino acids andsugars from the plant.Mycorrhizae are associated with the roots of 80 to 90 percentof all plants.
Plants that have mycorrhizae grow larger and aremore productive than plants that do not. Some species cannotsurvive without mycorrhizae.What is lichen?A lichen (LI kun) is a symbiotic association between a fungusand green algae or cyanobacteria. The fungus is usually anascomycote.
The algae or cyanobacteria are photosynthetic.The fungus portion of the lichen forms a dense web of hyphae.The algae or cyanobacteria grow inside the web. Together, thefungus and its photosynthetic partner form a structure that lookslike a single organism.Lichens need only light, air, and minerals to grow. Here is howthe relationship works. The photosynthetic partner provides foodfor both organisms. The fungus provides its partner with waterand minerals that it absorbs from rain and the air. The fungusprotects the partner from changes in environmental conditions.230Chapter 20READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.How does a plant benefit from a mycorrhizalrelationship?NameDateClassSection20.2The Diversity of Fungi, continuedLichens are found all over the world.
They are often the firstto colonize an area. They can live in dry deserts or on bare rocksexposed to cold wind. On the arctic tundra, lichens are the mostcommon form of vegetation. Caribou graze on lichen just as cattlegraze on grass.Lichens indicate pollution levels in the air. The fungus easilyabsorbs material from the air. If pollutants are present, the fungusdies.
Without the fungal part of the lichen, the photosyntheticpartner dies.Origins of FungiScientists hypothesize that zygomycotes evolved first.Basidiomycotes and ascomycotes evolved later from a commonancestor. Scientists use fossils to provide clues as to how andwhen organisms evolved.
However, fossils of fungi are rarebecause the fungi are made of soft materials. Scientists have discovered fungi fossils that are over 400 million years old.6. Why are fossils of fungiso rare?________________________________________________________________________Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.◗ After You ReadMini Glossaryascospores: sexual spore of ascomycote fungithat develop within an ascusascus: tiny, saclike structure in ascomycotes inwhich ascospores developlichen: organism formed from a symbioticassociation between a fungus, usually anascomycote, and a photosynthetic greenalgae or cyanobacteriabasidia: club-shaped hyphae of basidiomycotefungi that produce sporesmycorrhiza: mutualistic relationship in which afungus lives symbiotically with a plantbasidiospores: spores produced in the basidia ofbasidiomycotes during sexual reproductionrhizoids: fungal hyphae that penetrate food andanchor a mycelium; secrete enzymes forextracellular digestionconidia: chains or clusters of asexual ascomycote spores that develop on the tipsof conidiophoresconidiophores: in ascomycotes, elongated,upright hyphae that produce conidia attheir tipsstolons: fungal hyphae that grow horizontallyalong a surface and rapidly produce amyceliumzygospores: thick-walled spores of zygometesthat can withstand unfavorable conditionsgametangium: structure that contains a haploid nucleus; formed by the fusion ofhaploid hyphaeREADING ESSENTIALSChapter 20231NameDateClassSection20.2The Diversity of Fungi, continued1.
Review the terms and their definitions in the Mini Glossary on page 231. Circle the twoterms that have to do with symbiotic relationships and mutualism. Then on the lines belowuse those terms in a sentence that explains the interaction between organisms.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________2. Fill in the numbered boxes to complete the chart below.
Use the following terms: sporangia,rhizoids, hyphae, stolons, mycelium.Bread mold consists of1.2.that grow horizontallyand produce acalled3.that grow upwardand end in4.that absorb food5.3. When you transplant flowers, shrubs, or trees, why should you not disturb the soil around aplant’s roots? Write your response on the lines below.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Visit the Glencoe Science Web site at science.glencoe.com to findyour biology book and learn more about the diversity of fungi.232Chapter 20READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.calledNameDateClassSection21.1 Adapting to Life on Land◗ Before You ReadSC.F.1.4.2 The student knows that body structures are uniquely designed and adaptedfor their function.
SC.F.2.4.1 The student understands the mechanisms of asexual andsexual reproduction and knows the different genetic advantages and disadvantages ofasexual and sexual reproduction. Also covers SC.D.1.4.4Think of all the things that plants provide for us. They are an important source of food. They alsoprovide oxygen through photosynthesis.
Some plants are valuable sources of medicine. What aresome other things that plants provide? Write your ideas on the lines below.______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________◗ Read to LearnCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Origins of PlantsIn earlier sections you learned that some organisms that are notplants have plantlike characteristics.
In this section you will learnexactly what a plant is and more about the plant kingdom.Plants have many characteristics. A plant is a multicellulareukaryote. That means it is made of cells that have a true nucleusand membrane-bound organelles. Plants have thick cell wallsmade of a carbohydrate called cellulose.
The stems and leavesof plants have a waxy waterproof coating called a cuticle(KYEWT ih kul). The cuticle helps in reducing water loss. Mostplants are able to produce their own food through the processof photosynthesis.Make Flash Cards For eachparagraph, think of a question your teacher might askon a test. Write the questionon one side of a flash card.Then write the answer on theother side. Quiz yourself untilyou know the answers.Where did plants come from?A billion years ago there were no plants. In fact, the land wasquite bare.
However, the shallow waters of the oceans containedbacteria, algae, and simple animals such as corals, sponges, jellyfish, and worms. Scientists hypothesize that the algae at the edgesof the inland seas and oceans adapted to life on land.How might that have happened? It is possible that plants evolvedfrom threadlike green algae that lived in ancient oceans. Some ofthe evidence to support this hypothesis can be found in modernmembers of the algae and plant groups.
Modern green algae andplants have cell walls that contain cellulose. Both groups use thesame type of chlorophyll in photosynthesis and store food in theform of starch.READING ESSENTIALS1. What are the main characteristics of plants?________________________________________________________________________Chapter 21233NameDateClassSection21.1Adapting to Life on Land, continuedPlants first began to appear in the fossil record over 440 million years ago.
The plants were simple and did not have leaves.2. What is the purpose ofthe cuticle?________________________________________________________________________Identify MainParts Highlight the appropriate part of the illustrationafter you read about it.234Chapter 21Life on land has challenges. All living things need water to survive.
![](https://s.studizba.com/z.php?f=/templates/si/i/noavatar.png&w=100&h=100&t=1"){kind=avatar}
