Download Honors Biology Lab

Integrated Science II Lab
Cells Unit
Name ________________________________
Period _________ Date _________________
Observing and Comparing Different Types of Cells
/20
Although cells have many structures in common, they can differ in size, complexity, and appearance. Plant and animal
cells are eukaryotes, which are cells that have true organelles. Plant cells have a rigid cell wall, and, if they are
green, they also have chloroplasts. Animal cells lack a cell wall, chloroplasts, and the large central vacuole common to
plant cells. Bacteria cells are tiny prokaryotes that lack organelles and a nucleus, but have cell walls. In this lab
activity, you will observe and compare plant, animal, and bacteria cells. You will first examine the following plant
cells: moss leaf cells, tomato cells, and potato cells. You will then examine epithelial cells from the inside of your
cheek. Epithelium is a type of tissue that covers the surfaces of many organs and cavities of the body. Finally you will
observe 3 types of prokaryotic cells on a prepared slide of bacteria cells and in a yogurt culture.
Problem: How are plant, animal, and bacteria cells similar? How are they different?
Hypothesis:
A. List 2 similarities you expect to see between eukaryotic and prokaryotic cells: ______________________________
_____________________________________________________________________________________________
B. List 3 differences you expect to see between plant, animal, and bacteria cells: _____________________________
_____________________________________________________________________________________________
Procedure:
A. Moss Leaf Cells
1. Break off a small leaf near the tip of the moss plant. Prepare a wet mount of the moss leaf. Make sure the
outside of the slide is dry, blot with a paper towel.
2. View the leaf under low power. Look for an area where you can see the cells most clearly and center in your
field of view. Move to medium power, refocus and center. Move to high power and use fine adjustment to
focus.
3. Draw an accurate detailed sketch of a single moss cell about 4 cm long.
Label cell wall, cytoplasm, chloroplast and any other structures you see.
4. What is the shape of the cells?
________________________________________
5. What gives the cell its shape?
________________________________________
6. Why is the cell green?
________________________________________
7. How do the chloroplasts move within the cell?
________________________________________
Moss Leaf Cell (400x) showing cell wall, cytoplasm, chloroplasts
B. Tomato Cells
1. Obtain a small rice-sized bit of pulp tissue from a tomato. Place the tomato tissue and a drop of water on a
glass slide and press a cover slip on it to create a 'smear'.
2. Examine the tomato tissue under low power. Look for an area where the cells are clear (no air bubbles) and
center in your field of view. Move to medium power, refocus and center. Move to high power and use fine
adjustment to focus.
3. Draw an accurate sketch of 3 - 4 tomato cells under
high power. Label cell wall, cytoplasm, plastids
(organelle containing pigment), and vacuole (if visible).
4. What structure indicates these are plant cells?
________________________________________
5. What do the plastids contain?
________________________________________
6. Why do fruit and flower cells have plastids?
________________________________________
Tomato Cell (100x) showing cell wall, cytoplasm, plastids
C. Potato Cells
1. Place a thin slice of potato tissue, a drop of iodine stain, and a cover slip on your slide, and blot dry.
2. Examine the potato tissue under low power. Look for an area where the cells are clear (no air bubbles) and
center in your field of view. Move to medium power.
3. Draw an accurate sketch of a 3 - 4 potato cells.
Label cell wall, cytoplasm, and leucoplasts.
4. Describe what the cells look like?
________________________________________
5. What is stored within the leucoplasts?
________________________________________
6. What color did the iodine stain turn the leucoplasts?
________________________________________
Potato Cells (100x) showing cell wall, cytoplasm, and leucoplasts
D. Human Epithelial Cells
1. To obtain epithelial cells, gently scrape the inside of your cheek with a clean toothpick. Stir the material from
the toothpick in a drop of methylene blue stain on a clean slide. Add a cover slip, and blot dry.
2. Examine the slide under low power. Locate some individual cells and center in your field of view. Move to
medium power, refocus and center. Move to high power and use fine adjustment to focus.
3. Make a sketch of a 2 - 3 epithelial cells under high power in the space below. Teacher's initials ____________
Label cell membrane, cytoplasm, and nucleus.
4. When you have a cheek cell clearly visible
in high power, get teacher.
5. What is the shape of the cells?
________________________________________
6. Describe the appearance of the cytoplasm.
________________________________________
7. Do your cheek cells have a cell wall?
________________________________________
Human Epithelial Cells (400x) showing cell membrane, cytoplasm, nucleus
E. Bacteria Cells:
1. Obtain a prepared slide, and examine under low power, medium, and high power of the microscope. Each
slide has 3 smears of a culture each of coccus (spherical), bacillus (rod-like), and spirillum (spiral) bacteria.
2. Draw and label bacteria under high power.
Coccus
Bacillus
Spirillum
3. How do the bacteria appear under low power?
________________________________________
4. Compare bacteria cells to eukaryotic cells?
________________________________________
5. Can you see any structures within the cells?
________________________________________
Clean your slide and your lab station, wrap the cord
around your microscope and put it away .
Analysis:
Bacteria Cells (400x)
A. List at least 2 structures you observed that human epithelial cells have in common with the plant cells.
1.___________________________________________________________________________________________
2.___________________________________________________________________________________________
B. Name 2 structures you observed that moss, tomato, and potato cells have in common?
1.___________________________________________________________________________________________
2.___________________________________________________________________________________________
C. Name 2 differences you observed between prokaryotic and eukaryotic cells?
1.___________________________________________________________________________________________
2.___________________________________________________________________________________________