Lab - Comparing Plant and Animal Cells

8/13/2019 Lab - Comparing Plant and Animal Cells

1/6

Comparing Animal and Plant Cells Lab

ObjectivesExamine the similarities and differences between the structure of cells in animalsand the structure of cells in plants.

Materials dropper bottles of iodine and methylene blue compound light microscope forceps elodea microscope slides and cover slips toothpicks prepared slides of three unknowns

Background

n this investigation! you will use a compound light microscope to observecells from animals and plants. "irst! you will make and view your own slide of aleaf from Elodea! a pond weed and common a#uarium plant. $hen you will makeand view a slide of your own cheek cells.

Based on your observations of human cheek cells and Elodea leaf cells!you will be asked to classify three slides of unknown cells as either animal orplant cells.

Before you examine any cells! list the structural characteristics thatdistinguish animal cells from plant cells.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


2/6

PART A: PLANT CELLS&. 'arefully tear off one small leaf near the top of an Elodea sprig. (sing forceps!place the whole leaf in a drop of water on a slide. Be sure it is flat and not foldedover. )lace a cover slip on top of the leaf.*. Observe the leaf under low power. $he outermost part of the cell is the cell

wall. $he many small! green organelles in the cells are chloroplasts.+. ,ocate a cell that you can see clearly! and move the slide so that the cell is inthe center of the field of view. Examine this cell under high power.-. "ind an Elodea cell that is large enough to allow you to see the cell wall andthe chloroplasts clearly. Make a drawing of the entire field of view including thiscell in the space below. ,abel the cell wall and several chloroplasts in yourdrawing.

. $he chloroplasts may be moving in someof the cells. f you observe no movement! warm the slide in your hand or shine abright lamp on it for a minute or two. $hen! reexamine the slide under highpower! and look for the movement of the cell/s contents. $his movement is calledcytoplasmic streaming.

Because the cell membrane is pressed against the cell wall! you may not see it.0lso! the abundance of chloroplasts may hide other organelles in the cells. 1oucan make the cell membrane! vacuole! nucleus! and nucleolus more visible bymaking a stained wet2mount slide of Elodea.

. )repare a wet2mount slide of Elodea as you did in step -! but substituteiodine solution! a stain! for the water. 0llow the iodine solution to diffusethroughout the leaf.3. Observe the stained cells under low and high power. Make a drawing of asingle stained Elodea cell under high power in the space below. ,abel the central


3/6

vacuole! nucleus! nucleolus! chloroplasts! cell wall! and cell membrane if they arevisible.

PART B: ANIMAL CELLS&. )lace a drop of water in the center of a clean glass slide.*. (sing the flat end of a toothpick! gently scrape the inside of your cheek. $he

end of the toothpick will have several cheek cells stuck to it even though youmay see nothing but whitish gook.

+. 4tir the water on the slide with the end of the toothpick to mix the cheek cells

with the water. $hrow away the toothpick.-. )ut one drop of methylene blue stain on top of the drop of water containingthe cheek cells. 5ait one minute! and then carefully place a cover slip overthe stained cheek cells.

. 1ou next must remove the excess stain from under the cover slip and replaceit with clear water in order to see the cheek cells. $o do this! place a papertowel at one edge of the cover slip. $hen place a drop of water at the edge ofthe cover slip on the opposite side. $he stain under the cover slip will beabsorbed by the paper towel! and as the stain is removed the clear water willbe drawn under the cover slip. 6iscard the paper towel after it has absorbedthe stain. See the diagram on the next page.


4/6

3. 0fter the excess stain is removed! use the low power objective to locate a fewcheek cells under the microscope. 0djust the diaphragm to reduce the lightintensity and achieve greater clarity. 1ou may need to move the slide around tofind intact cells.

7. Observe a few cheek cells under high power. 6raw the entire field of view.dentify and label the cell membrane! the cytoplasm! thenuclear envelope! and the nucleus of one of the cells in your drawing..

PART C: IENTI!"IN# $N%N&'N CELLS

&. Obtain prepared slides of three unknown specimens.*. Observe each specimen under low and high power. 8ecord your observationsas described in the data table on the next page.+. 'lean up your materials! and wash your hands before leaving the lab.

Classi(i)ation o( $n*no+n Spe)imens


5/6

$n*no+n,)oden-mber

Classi(i)ation,plant oranimal

Reasons (or )lassi(i)ation

Anal/sis and Con)l-sions&. 5hat is the shape of an Elodea cell9

*. 5hat is the general location of the nucleus in an Elodea cell9

+. 5hat is the shape of the cheek cell9

-. 5hat is the general location of the nucleus in a cheek cell9

. 5hy are stains such as iodine and methylene blue used when observing cellsunder the microscope9

3. 0ccording to your observations in this investigation! list several ways that plantand animal cells are structurally similar and several ways that they are different.


6/6

7. 5hat do you think might be the function of cytoplasmic streaming in a plantcell9

:.5hich organelles that you read about in this chapter did you not see in thisinvestigation9 5hy do you think you were unable to see these organelles in yourslides9

;. n general! the surface of a tree has a harder

Lab - Comparing Plant and Animal Cells

Documents

Transcript of Lab - Comparing Plant and Animal Cells