Reading Essentials for Biology Glencoe (794133), страница 50
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Another flagellate lives inside theguts of termites. This protozoan produces an enzyme that digestswood, allowing the termite and the flagellate to use nutrientsfrom the wood.Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What are the ciliates?Ciliates got their name from cilia, the hairlike projections thatcover their bodies. They beat the cilia to move through the wateryplaces in which they live.Paramecia are one of the largest unicellular organisms.
Theillustration on page 210 shows the parts of a paramecium. You cansee that it has many organelles and structures. Many structuresmay work together to perform one important life function. Forexample, a paramecium uses its cilia, oral groove, gullet, and foodvacuoles for digestion.Paramecia reproduce asexually by dividing into two cells. Theyalso are able to reproduce through conjugation, which is a formof sexual reproduction. In an earlier chapter you learned that conjugation happens when an organism places its genetic material inanother organism. In this process two paramecia join and exchangegenetic material.
Then they separate and each one divides throughasexual reproduction, passing on the new genetic mixture.3. Summarize Name thetwo ways that parameciacan reproduce.________________________________________________What are the sporozoans?Most of the organisms in the group of protozoans calledsporozoans produce structures called spores. A spore is a reproductive cell with a hard outer coat that produces a new organismwithout fertilization.READING ESSENTIALSChapter 19209NameDateClassSection19.1The World of Protists, continuedE Anal poreA CiliaWaste materials leave thecell through the anal pore.The cell is encased by an outercovering through which thousandsof tiny, hairlike cilia emerge. Theparamecium can move by beatingits cilia.B Oral grooveParamecia feed primarily onbacteria that are swept intothe gullet by cilia that linethe oral groove.F Contractile vacuoleBecause a paramecium livesin a freshwater, hypotonicenvironment, water constantlyenters its cell by osmosis.
Apair of contractile vacuolespump out the excess water.C GulletFood moves into the gullet,becoming enclosed at the endin a food vacuole. Enzymes breakdown the food, and the nutrientsdiffuse into the cytoplasm.D Micronucleus andmacronucleusThe small micronucleusplays a major role in sexualreproduction. The largemacronucleus controls theeveryday functions of the cell.All sporozoans are parasites. They usually live inside a hostorganism at the site of a steady food supply, such as in the animal’sblood or intestines. Malaria is a disease caused by a sporozoan.Usually occurring in tropical climates, malaria is spread by certaintypes of mosquitoes. When an infected mosquito bites someone,the sporozoan that causes malaria is passed from the mosquito tothe person it bites.210Chapter 19READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.PoreNameDateClassSection19.1The World of Protists, continued◗ After You ReadMini Glossaryalgae: photosynthetic, plantlike, autotrophicprotistsprotozoans (proh tuh ZOH uhnz): unicellular,heterotrophic, animal-like protistsasexual reproduction: type of reproductionwhere one parent produces one or moreidentical offspring by dividing into two cellspseudopodia (sew duh POH dee uh): in protozoans, extensions of the plasma membrane;aid in movement and feedingciliates: group of protozoans with short hairlikecilia that aid in movementspore: type of cell with a hard outer coat thatforms a new organism without fertilizationflagellates: protists that have one or more flagellasporozoans: group of parasitic protozoans thatreproduce by spore production1.
Read the key terms and their definitions in the Mini Glossary above. Circle the key termsthat identify three of the four groups that protozoans are divided into. Write the name ofthe missing group on the line below.____________________________________________________________________________________2. Fill in the numbered boxes to complete the chart.Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.ProtistsProtozoans1.Algae2.Fungus like3.4.3.
Write a fact for each numbered box on the lines below.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Visit the Glencoe Science Web site at science.glencoe.com to findyour biology book and learn more about the world of protists.READING ESSENTIALSChapter 19211NameDateClassSection19.2 Algae: Plantlike Protists◗ Before You ReadSC.F.1.4.2 The student knows that body structures are uniquely designed and adapted fortheir function.
SC.G.1.4.1 The student knows of the great diversity and interdependenceof living things. Also covers SC.F.2.4.1You probably come into contact with algae every day. Diatoms are a type of algae whose remainsbecome a powdery, porous rock called diatomite. Diatomite is highly absorbent. It is used in pet litter and to clean up chemical spills. It also is used as an abrasive in household cleaners. It is evenadded to paint to add sparkle. Now that you know that diatomite is absorbent, sparkling, and abrasive, see if you can imagine some additional uses for it. Write your ideas on the lines below.______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________◗ Read to LearnIn Your Own Words As youread this section, stop afterevery paragraph and put whatyou just read into your ownwords.1.
What do scientists callunicellular photosynthesizing algae?________________________Protists that photosynthesize are called algae. Photosynthesis isthe use of chlorophyll to trap energy from the sun and convertcarbon dioxide and water into simple sugars. All algae have up tofour kinds of chlorophyll, as well as other various pigments. Thepigments produce a variety of colors in algae.
You can find purple,yellow, rusty-red, olive-brown, and golden-brown algae. Scientistsuse color as one way to classify algae.Algae can be unicellular or multicellular. Unicellular photosynthesizing algae are called phytoplankton (fi toh PLANK tun).Phytoplankton live in water environments. There is so much phytoplankton that they are one of the major producers of nutrientsand oxygen in water environments. Through photosynthesis, algaeproduce much of the oxygen used on Earth.Seaweed is a multicellular algae. It looks like a plant, but it isnot.
Algae do not have roots, stems, or leaves.________________________________________________Diversity of AlgaeAlgae are classified into six different phyla. Three of the phyla—the euglenoids, diatoms, and dinoflagellates—include only theunicellular species. In the other three phyla—red, green, andbrown algae—most of the species are multicellular.212Chapter 19READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What are algae?NameDateClassSection19.2Algae: Plantlike Protists, continuedWhat are the euglenoids?Euglenoids (yoo GLEE noydz) are unusual algae because theyhave both plant and animal characteristics. They are plantlikebecause most contain chlorophyll and photosynthesize.
However,they do not have a cell wall made of cellulose. They also differfrom plants because, when light is not available, they can ingestfood in ways that are similar to protozoans. They also have one ormore flagella to help them move around. They use the flagella tomove toward light or food.Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.What type of algae has shells?Diatoms (DI uh tahmz) are members of another phylum.
Theyare unicellular photosynthesizing organisms that make up a largepart of the phytoplankton in both freshwater and sea water ecosystems. The fact that they have shells made of silica sets diatomsapart from other algae.The delicate shells of diatoms actually come in two parts, similar to a box with a lid. Each species of diatom has its own uniquedesign and shape.Diatoms contain chlorophyll and another pigment calledcarotenoid. This gives the diatoms a golden-yellow color. Thefood that diatoms make is stored as oil in the organism. Theoil in the diatom helps the organism to float near the surfacewhere more sunlight is available.
Fishes who feed on diatomshave an oily taste.2. How does storing food asoil help diatoms?________________________________________________________________________How do diatoms reproduce?Diatoms have two different ways of reproducing, asexually andsexually.
In asexual reproduction, the two halves of the shells (thebox and the lid) separate. Each half then produces a new half tofit inside itself. This means that one of the new diatoms will besmaller than the original. As they continue reproducing this way,half of the diatoms will get smaller and smaller. When diatomsare one-quarter of their original size they begin to reproduce sexually.
That means they will produce gametes that join to becomea fertilized cell known as a zygote. The process of asexual andsexual reproduction is pictured on page 214.When diatoms die, their shells sink to the ocean floor. Theshells are then dredged up and used to make the many productsmentioned in the Before You Read activity.READING ESSENTIALSChapter 19213NameDateClassSection19.2Algae: Plantlike Protists, continuedMitosisWall formationaround cellAsexual reproductionMeiosisSexual reproductionZygoteGametesSpermreleasedWhat are the dinoflagellates?3. Identify Describe thefood chain that leadsfrom dinoflagellates tohumans.________________________________________________________________________Dinoflagellates get their name from two flagella located ingrooves. The cell spins slowly as the flagella beat.Most of the dinoflagellates live in salt water as phytoplankton.Some species of dinoflagellates produce toxins, or poisons.Occasionally they produce enough toxins to kill large numbers offishes.
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