Today in Biology the class participated in a cell structure and function lab. This lab included a microscope to observe the cells. The cells came from different substances and objects such as tomato skin, potato skin, frog blood, streptococcus lactis, onions, algae, elodea leaves and the inside of human cheeks. The cells were observed in a slide. Substances such as iodine, water and methylene were put on the slide as well to help make the cells visible. The lab did not include a true experiment involving control and independent variables but was more of observations and the study of cells. The lab was divided into two different parts; part two was considerably longer with the observation of six different cells. There was also a prelab and homework.
Prelab (pgs. 23-26)
Before students could participate in the lab they had to complete a prelab that was divided into two different parts. Part one dealt with prokaryotic cells and their organelles/structures. There was a picture of a prokaryotic and five different structures students had to label and describe their functions. On the second page of part one there was two pictures of eukaryotic cells; one was of a plant cell, the other,an animal cell. Once again the students had to label eighteen different structures and describe their functions. Part two was the comparison of plant and animal cells. There was a chart that had to be filled out with organelles that were unique in only one of the cell types, plant or animal. This was followed by pre lab questions that dealt with previewing the lab and answering questions about the materials and connecting them to the previous activity.
Part I (pg. 27-28)
Part one of the lab dealt with the observation of the prokaryotic cells from streptococcus lactis and eukaryotic cells from the skin of an onion. The streptococcus lactic was put on a slide with a cover slip and observed under 400x power of a microscope. The students than had to draw what they observed. The students than had to peel off the transparent membrane of an onion and place it on a slide with one drop of iodine and a cover slip. Once the slide was prepared the slide was observed under the microscope at 400x power. Once again what was seen under the microscope was drawn out on the designated area in the packet.
Part II (pgs. 28-30)
Part two of the lab was the observation of eukaryotic cells, both plant and animal. Students had to first pull off an elodea leaf with tweezers and place it on a wet mount slide with a cover slip. This leaf was than observed under the microscope at low power and high power. The observations were than drawn on the packet, the students could choose whether to draw the image at low power or the 400x power (high). The elodea leaf was than observed in a slide that now had iodine. The iodine stain maid the organelles more visible. The students than had to sketch what the elodea leaf looked like under high power. The students than had to take a toothpick and rub the inside of their cheek and mix the cells on the toothpick on to a wet mount slide with methylene blue stain. After placing a cover slip over the slip the slide was to be placed under the microscope and the cells observed under low than high power. The students than had to sketch their observations of the cheek cell under high power and label the parts of the cheek cell. The next substance to be observed was frog blood. Students had to take a pre prepared slide of frog blood. The students must than title the magnification they chose to observe the frog blood cells under. The students than had to cut off a piece of potato skin and place it on a wet mount slide with a cover slip. The potato skin was than observed under the microscope power of choosing and the observations sketched out on the designated area on the packet. The students than had to cut off a piece of tomato skin and place it on a wet mount slide with a cover slip. The slide was than to be placed under the microscope and observed under the power of choosing, the observations were than to be sketched in the packet. The last substance to be observed was a piece of algae. The algae was placed on a wet mount slide and observed under the microscope and the observations were sketched out.
Post lab/ homework (pgs. 31-32)
The homework for this lab was to answer analysis questions on pg. 31 and to label the parts of the cell pictures on pg. 32. Also to finish up any unfinished questions on pgs. 27-30.