Lab Topic Three

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NucleusFigure 3.10.CytoplasmicstranosChloroplastElodea. Elodeais an aquatrc Plantcommonly grown in freshwateraquaria. The cell strLtctures may bedifficult to see because of the threedimensionalcel1 shape and thepresence of a large central vacuole.(See Color Plate 6.)<strong>Lab</strong> Study C. Multicellular OrganismsMaterialsmicroscope slidesdropper bottles of watertoothpickscoverslipsEIodeamethylene bluelntroductionMultlcellular organisms are composed of groups of specialized ce1ls, calledtissues, that together perform particular funclions for the organism. Tissues,in turn, may be grouped to form organs' and organs may be grouped intoorgan systems. In this lab study, you will examine some of the ceiis that compoiethe basic tissue types of plants and animals.ProcedurePlant Cells1. The major characteristics of a typical plant ce11 are readily seen in theleal celis ol E;odea. a common aquaric plant lFigure ].l0) Prepare awet mount and exami.ne one of the youngest (smallest) leaves from a sprigof Elodeaunder the compound microscope.2. Identify the following structures:The cell wall is the rigrd outel framework sunounding the cell. This strucruregives rhe cell a definite shape and suppoft. It is not found in animalcells.Protoplasm is the organized conlents of the cell, exclusive of thece11wall.cytoplasm rs the protoplasm of the cel1, exclusive of the nucleus.Chloroplasts are the green, spherical organelles often seen movingwithin tie cyroplasm. These organelles carry the pigment chlorophyllthat is involved in photoslnthesis. As the microscope light heats up thecells, the chloroplasts may begin to move quite rapidly rn a plocesscalled cytopl asmic streaming. or cyclosis.The nucleus is the usually spherical, transparent organelle within thecytoplasm. This structure controls cell metabolism and division.The vacuole is a membrane-bound sac within the cytoplasm that isfilled with water and dissolved substances. This structure serves to storemetabolic wastes and gives the ce1l suppoft by means of turgor pressure.Animal ce1ls also have vacuoles, but they are not as large and conspicuousas those found in Plants.What three structures observed inElodea are unlque to plants?etfr\FEf,€n-lttncnIf,t==37FFFfeF
_T-4. Compare your observations ol Elodeausing the compound scope withthose made in Exercise 3.3 using the stereoscopic sc.pe . List the structuresseen wlth each:Stereoscopic:Compound:Animal Cellsl. Animals are multicelluiar heterotrophic organisms that ingest organrcmaner. They are composed of ce11s that can be categorized into fourmajor tlssue groups: epithelial, connective, muscle, and nervous trs_sue. In this lab study, you r,vi11 examine epithelial cel1s. similar to theepidermal cells of plants, epithelial cells occur on the outside of animalsand serve to prorect the animal from water loss, mechanical ir-r.]ury,and loreign invaders. in addltlon, epithelial cells line interior cavrtiesand ducts in animals. Examine the epirheliar cells (Figure 3.11) thar /^\form tl-re linlng of yourCyinneroolasrrcheek. To obtain a speciJen, follow thlsprocedure:a. with a clean toothpick, gentl)/ scrape the rnside of your cheek severaltlmes.b R:rll the scraping into a drop of warer on a clean microscope slide,add a srnall drop of methylene blue, and cover wirh a coveislip.c. Using the compound microscope, r,-iew the cells under higher powers.2. observe that these ce1ls are extremeiy flat and so may be folded over onthemselves. Arrempt to locate several ce11s that u." ,-rot badly iolded,and study their detail.] ldcnrify rhc following srrucrures;The cell membrane is the boundary that separates the cell from itssurroundings.The nucleus is the 1arge, circular organelre near the micldle of the cell.cytoplasm is the granular contents of the ce1l, exclusive of the nucleus.uelimembraneNrc.ersFigure 3.11.Human epithelial cells. The epirhellalcel1s that line your cheek are thtn, flatcells that you can remove easily fromyour cheek by scraping ir with a toorhpick.(See Color Plate 7.)<strong>Lab</strong> Study D. UnknownsMaterialsmicroscope slidescoverslipspond water or culture of unknownsIntroductionuse this lab study to see if you ha'e met the objectives of this lab toprc. asyou carry our this lab study, (1) think carefully about using correcr microscopictechniqr-res; (2) dlstinguish organisms wirh differenicellular organrz-ationor configuratlon; (3) note how the clifferenr organisms are similai yetdifferent; and (,1) nore cell differences.
Page 1 and 2: and Cells3. Define the following te
Page 3: a. To obtain a specimen, use a diss
Page 7: l. In your own words, describe the

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