There will be no Biology Class on Oct. 10th. All other classes will be held at MMEC as planned, unless you hear from another specific subject teacher.
Test Date: October 24th
Sunday, September 28, 2008
Sept. 26: Homework and Lab Report Handout
Please catch up on your reading and turn in all of your homework this week!!!
If you have completed them during our lab time, please write either the cell lab report (there is no electronic version of this lab)or
The diffusion Lab report (below) answering all the questions associated with each lab.
Rate of Diffusion
Information
Scientists know that all matter is made of molecules and that these molecules are always moving—that is, the molecules present in matter have a kinetic energy. In liquids and gases the molecules can move from one place to another. Of course, as they move, they are constantly bumping into one another so that the movement is not in a direct line.
Diffusion can be defined as the random movement of molecules (because of kinetic energy) from a place of higher concentration to a place of lower concentration. Diffusion can happen through a membrane, too, if the material is permeable. Cell membranes are permeable to certain materials. In fact, that is how some material gets into a cell and how wastes get out.
A chemical called potassium permanganate (KMnO4) dissolves easily in water, and when it is dissolved, it will diffuse through a cell membrane. In addition, KMnO4 is purple, so it is easy to see. In this lab you will put pieces of potato into KMnO4 solutions and see how concentration and time affect the amount of diffusion into the potato.
Procedure
Part A
KMnO4 (Potassium Permanganate is Caustic!! Wear goggles and gloves and Handle Carefully!!!!)
1. Use a scalpel to cut a 1 cm thick slice from a potato. Then cut the slice into cubes that are 1 cm on a side.
2. Label 3 beakers: 4%, 2%, 1%, and 0.5% KMnO4. Add the same volume of each solution to each beaker (just enough to cover the potato piece).
3. Carefully place a potato cube into each beaker. Leave cubes in the solution for 30 minutes.
4. After 30 minutes, remove each cube from its beaker with forceps and cut the cube in half. Use a ruler to measure how far the solutions diffused into the cube. Dry the scalpel before you use it for each cube. Record the date in the table below:
Table 1: 30 minute incubation
Cube Number KMnO4 Concentration Diffusion (mm)
1 4%
2 2%
3 1%
4 0.5%
1. What is the relationship between concentration of the solution and amount of diffusion?
2. What is the ratio of the amount of diffusion to concentration (4%: 2%: etc.)
3. Graph your data.
Part B:
1. Place 6 of the potato cubes into a beaker.
2. Pour just enough KMnO4 solution into the beaker to cover the cubes.
3. Write down the start time here:
4. After 5 minutes, use forceps to remove one of the cubes from the solution. With a clean scalpel, cut the cube in half and measure the distance, in millimeters, that the solution has diffused into the cube. In Table 2, record the length of time the cube was in the solution and the distance that the solution diffused into the cube.
5. Repeat step 4 at 5 minute intervals until all the potato cubes have been cut and measured. Record the data for each cube.
Table 2: Diffusion of 4% KMnO4 into 1 cm Potato Cubes Over Time
Cube Number Time (min.) Diffusion (mm)
1 5
2 10
3 15
4 20
5 25
6 30
1. Which cube showed the greatest amount of diffusion:
2. Which cube showed the least amount of diffusion:
3. What is the relationship between the time and the amount of diffusion?
4. Can this relationship be expressed mathematically? If so, how?
5. Graph your data
6. Is it possible to make predictions from this model? What is your prediction?
7. Explain what is happening on a molecular level.
8. Why is it important the blade of the scalpel be dried between uses?
9. What effect would an increase in temperature have on the rate of diffusion?
10. Design an experiment that would test your
If you have completed them during our lab time, please write either the cell lab report (there is no electronic version of this lab)or
The diffusion Lab report (below) answering all the questions associated with each lab.
Rate of Diffusion
Information
Scientists know that all matter is made of molecules and that these molecules are always moving—that is, the molecules present in matter have a kinetic energy. In liquids and gases the molecules can move from one place to another. Of course, as they move, they are constantly bumping into one another so that the movement is not in a direct line.
Diffusion can be defined as the random movement of molecules (because of kinetic energy) from a place of higher concentration to a place of lower concentration. Diffusion can happen through a membrane, too, if the material is permeable. Cell membranes are permeable to certain materials. In fact, that is how some material gets into a cell and how wastes get out.
A chemical called potassium permanganate (KMnO4) dissolves easily in water, and when it is dissolved, it will diffuse through a cell membrane. In addition, KMnO4 is purple, so it is easy to see. In this lab you will put pieces of potato into KMnO4 solutions and see how concentration and time affect the amount of diffusion into the potato.
Procedure
Part A
KMnO4 (Potassium Permanganate is Caustic!! Wear goggles and gloves and Handle Carefully!!!!)
1. Use a scalpel to cut a 1 cm thick slice from a potato. Then cut the slice into cubes that are 1 cm on a side.
2. Label 3 beakers: 4%, 2%, 1%, and 0.5% KMnO4. Add the same volume of each solution to each beaker (just enough to cover the potato piece).
3. Carefully place a potato cube into each beaker. Leave cubes in the solution for 30 minutes.
4. After 30 minutes, remove each cube from its beaker with forceps and cut the cube in half. Use a ruler to measure how far the solutions diffused into the cube. Dry the scalpel before you use it for each cube. Record the date in the table below:
Table 1: 30 minute incubation
Cube Number KMnO4 Concentration Diffusion (mm)
1 4%
2 2%
3 1%
4 0.5%
1. What is the relationship between concentration of the solution and amount of diffusion?
2. What is the ratio of the amount of diffusion to concentration (4%: 2%: etc.)
3. Graph your data.
Part B:
1. Place 6 of the potato cubes into a beaker.
2. Pour just enough KMnO4 solution into the beaker to cover the cubes.
3. Write down the start time here:
4. After 5 minutes, use forceps to remove one of the cubes from the solution. With a clean scalpel, cut the cube in half and measure the distance, in millimeters, that the solution has diffused into the cube. In Table 2, record the length of time the cube was in the solution and the distance that the solution diffused into the cube.
5. Repeat step 4 at 5 minute intervals until all the potato cubes have been cut and measured. Record the data for each cube.
Table 2: Diffusion of 4% KMnO4 into 1 cm Potato Cubes Over Time
Cube Number Time (min.) Diffusion (mm)
1 5
2 10
3 15
4 20
5 25
6 30
1. Which cube showed the greatest amount of diffusion:
2. Which cube showed the least amount of diffusion:
3. What is the relationship between the time and the amount of diffusion?
4. Can this relationship be expressed mathematically? If so, how?
5. Graph your data
6. Is it possible to make predictions from this model? What is your prediction?
7. Explain what is happening on a molecular level.
8. Why is it important the blade of the scalpel be dried between uses?
9. What effect would an increase in temperature have on the rate of diffusion?
10. Design an experiment that would test your
Lab Report Guidelines
Follow this link to the AP Biology Report Guidelines Page:
http://www.google.com/search?q=AP+Biology+Lab+reports&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
http://www.google.com/search?q=AP+Biology+Lab+reports&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
Sept. 19th Lab Report Additional Materials
Cell Lab—Estimating Sizes Under the Microscope
Hi Everyone,
There were a lot of questions about estimating size under the microscope and I know there was a lot of confusion about calculating the size of the field of vision. Please take a look at the images compared to each other.
Remember that we are just doing an estimate---this doesn’t have to be 100 % accurate but I hope this will help.
1. Print out the attached power point slides so that you can compare the cells.
2. Use a ruler to break up each field along the diameter (the line through the middle of the circle).
3. Start with the amoeba, which is the largest. Under high power (400x) the amoeba fills almost the entire field of vision which most of you calculated to be 450 microns.
4. Look at the amoeba under 100x which has a field of vision of 2,000 microns. Does the amoeba fill about 1/5th of the line along the diameter? Which is the easier magnification to do the estimate under
5. Please remember that bacteria, amoebas and frog blood cells are ALL single cells.
Please email or call if you are still having trouble!
Thanks for all of your hard work,
Teresa
Hi Everyone,
There were a lot of questions about estimating size under the microscope and I know there was a lot of confusion about calculating the size of the field of vision. Please take a look at the images compared to each other.
Remember that we are just doing an estimate---this doesn’t have to be 100 % accurate but I hope this will help.
1. Print out the attached power point slides so that you can compare the cells.
2. Use a ruler to break up each field along the diameter (the line through the middle of the circle).
3. Start with the amoeba, which is the largest. Under high power (400x) the amoeba fills almost the entire field of vision which most of you calculated to be 450 microns.
4. Look at the amoeba under 100x which has a field of vision of 2,000 microns. Does the amoeba fill about 1/5th of the line along the diameter? Which is the easier magnification to do the estimate under
5. Please remember that bacteria, amoebas and frog blood cells are ALL single cells.
Please email or call if you are still having trouble!
Thanks for all of your hard work,
Teresa
Sept. 19th Lab Report Handout:: Using the Compound Microscope
Using the Compound Microscope
Information
The microscope is designed for the study of objects too small to be seen with unaided eye. In work with organisms, biologist use differnt types of microscopes with various powers of magnification. Various models of the compound microscope magnify up to 1,000 times (abbreviated 1,000x). Electron microscopes magnify to more than 100,000 times (100,000x). Usually, you will work with a compound microscope that magnifies images form 100x to 430x. The microscope is the most important tool you will in biology.
Part A. Setting up the microscope
Locate on your microscope the parts in the diagram below:
Take a few moments to familiarize yourself with the parts of the microscope.
Part B: How to Prepare Materials
In a newspaper, find some fine print that includes a lower case “e”. Cut this letter from the news paper in a piece about 1 cm square. Pick up your slide an cover glass and place the piece of newspaper on the center of the slide, with the letter “e” right side up. With a medicine dropper put one drop of water on the piece of paper and put the cover glass over the paper. You have now prepared a wet mount of a piece of paper.
Part C: How to Focus the Microscope
Place the prepared slide on the stage of the microscope under the low power objective. Center the “e” on the slide over the opening in the stage.
While looking through the ocular slowly turn the course adjustment to lower the body tube until the printed letter comes into view. Then turn the fine adjustment of make the focus as sharp as possible.
1. How does the image of the letter “e” that you see through the microscope differ from its actual orientation on the slide?
2. Now slowly move the slide on the stage from right to left. Which way does the image that you see through the microscope move.
3. Move the slide away from you. Which way does the image move?
Determining Size Under the Microscope
Information
Not only does the microscope reveal objects invisible to the unaided eye, but it can also be used to measure tiny objects. Quantitative biological data are thus obtained. The more accurate your measurements, the more precise will be you date conclusions.
Measurements in science are made in the metric system. It is an easier system to use than any other because metric units are always related to one another by powers of 10.The basic unit of length in the metric system is the meter, slightly longer than a yard in the English system. Extremely small units of the metric system are used to measure things that can be seen only with the aid of a microscope.
Units of the Metric System
FRACTIONAL PARTS METRIC PREFIXES METRIC UNITS
1/10 or 0.1 deci- 1 decimeter (dm)
1/100 or 0.01 centi- 1 centimeter
1/1000 or 0.001 milli- 1 millimeter
1/millionth or 0.000001 micro- 1 micron (μ)
1 billionth or
.000000001 millimicro- 1 millimicron
1/10 billionth or
0.0000000001 1 Angstrom
Part A: Measurements Under the Microscope
The magnification of a microscope is the product of the magnification of the lenses in the ocular times the magnification of the lenses in the objective. These magnifications are usually stamped on the ocular and the objective.
1. If the ocular is stamped “10x” and the low-power objective is stamped “10x” what is the total magnification of the microscope under low power?
2. Check the ocular on the microscope you are using and the objectives. Calculate the total magnification of each of the oculars below:
An image of 90x or 250x or any other magnification is the indicated number of time longer and wider r than the object being viewed. But what is the original size of the object?
How can you measure a magnified image?
Method number 1:
Determining the diameter of the field of view using each objective:
1. Swing the objective down to low power.
2. Position the millimeter ruler so that the scale cuts across the center of the field. Focus on the part of the scale in view and read the diameter of the field in millimeters. Draw what you see below. Repeat for the second highest objective, but not the highest.
Magnification: Magnification:
Field of view in microns: Field of view in microns:
3. Convert your measurements into microns (millimeters multiplied by 1,000) and record above.
4. The ruler will not fit under the high powered objective, so how can we determine what diameter the field of view is in microns?
5. Use the ratio method to calculate the field of vision of the medium powered objective and compare to the value you got from measuring it.
6. Now let’s estimate the size of some single cells using what we know about the field of vision looking at medium and high power:
Amoeba: Draw a single amoeba in each space. Determine the size using the medium objective and draw details under the higher objective.
Magnification: 100x Magnification: 400x
Estimated size in microns: Comment on size and details
Frog Blood: Draw a single cell outline in the first space. Determine the size using the medium objective and draw details under the higher objective.
Magnification: 100x Magnification: 400 x
Estimated size in microns: Comment on size and details
Bacteria: Draw a single cell outline in the first space. Determine the size using the medium objective and draw details under the higher objective.
Magnification: Magnification:
Estimated size in microns: Comment on size and details
Questions:
1. Are single cells all the same size?
2. Are the cells we looked at prokaryotic or eukaryotic cells? In each case explain why you think so.
3. Without looking anything up, speculate on why an amoeba is the size that it is and the advantages and disadvantages of its size are.
4. Please don’t alter what you have already written, then look up the amoeba in your textbook or on line and compare what you have learned about it to what you inferred about it.
5. Without looking anything up, speculate on why a frog blood cell is the size that it is and what the advantages and disadvantages of its size are.
6. Please don’t alter what you have already written, then look up the function of blood cells in your textbook or on line and compare what you have learned about it to what you inferred about it.
7. Without looking anything up, speculate on why an bacterium is the size that it is and the advantages and disadvantages of its size are.
8. Please don’t alter what you have already written, then look up bacteria in your textbook or on line and compare what you have learned about it to what you inferred about it.
Information
The microscope is designed for the study of objects too small to be seen with unaided eye. In work with organisms, biologist use differnt types of microscopes with various powers of magnification. Various models of the compound microscope magnify up to 1,000 times (abbreviated 1,000x). Electron microscopes magnify to more than 100,000 times (100,000x). Usually, you will work with a compound microscope that magnifies images form 100x to 430x. The microscope is the most important tool you will in biology.
Part A. Setting up the microscope
Locate on your microscope the parts in the diagram below:
Take a few moments to familiarize yourself with the parts of the microscope.
Part B: How to Prepare Materials
In a newspaper, find some fine print that includes a lower case “e”. Cut this letter from the news paper in a piece about 1 cm square. Pick up your slide an cover glass and place the piece of newspaper on the center of the slide, with the letter “e” right side up. With a medicine dropper put one drop of water on the piece of paper and put the cover glass over the paper. You have now prepared a wet mount of a piece of paper.
Part C: How to Focus the Microscope
Place the prepared slide on the stage of the microscope under the low power objective. Center the “e” on the slide over the opening in the stage.
While looking through the ocular slowly turn the course adjustment to lower the body tube until the printed letter comes into view. Then turn the fine adjustment of make the focus as sharp as possible.
1. How does the image of the letter “e” that you see through the microscope differ from its actual orientation on the slide?
2. Now slowly move the slide on the stage from right to left. Which way does the image that you see through the microscope move.
3. Move the slide away from you. Which way does the image move?
Determining Size Under the Microscope
Information
Not only does the microscope reveal objects invisible to the unaided eye, but it can also be used to measure tiny objects. Quantitative biological data are thus obtained. The more accurate your measurements, the more precise will be you date conclusions.
Measurements in science are made in the metric system. It is an easier system to use than any other because metric units are always related to one another by powers of 10.The basic unit of length in the metric system is the meter, slightly longer than a yard in the English system. Extremely small units of the metric system are used to measure things that can be seen only with the aid of a microscope.
Units of the Metric System
FRACTIONAL PARTS METRIC PREFIXES METRIC UNITS
1/10 or 0.1 deci- 1 decimeter (dm)
1/100 or 0.01 centi- 1 centimeter
1/1000 or 0.001 milli- 1 millimeter
1/millionth or 0.000001 micro- 1 micron (μ)
1 billionth or
.000000001 millimicro- 1 millimicron
1/10 billionth or
0.0000000001 1 Angstrom
Part A: Measurements Under the Microscope
The magnification of a microscope is the product of the magnification of the lenses in the ocular times the magnification of the lenses in the objective. These magnifications are usually stamped on the ocular and the objective.
1. If the ocular is stamped “10x” and the low-power objective is stamped “10x” what is the total magnification of the microscope under low power?
2. Check the ocular on the microscope you are using and the objectives. Calculate the total magnification of each of the oculars below:
An image of 90x or 250x or any other magnification is the indicated number of time longer and wider r than the object being viewed. But what is the original size of the object?
How can you measure a magnified image?
Method number 1:
Determining the diameter of the field of view using each objective:
1. Swing the objective down to low power.
2. Position the millimeter ruler so that the scale cuts across the center of the field. Focus on the part of the scale in view and read the diameter of the field in millimeters. Draw what you see below. Repeat for the second highest objective, but not the highest.
Magnification: Magnification:
Field of view in microns: Field of view in microns:
3. Convert your measurements into microns (millimeters multiplied by 1,000) and record above.
4. The ruler will not fit under the high powered objective, so how can we determine what diameter the field of view is in microns?
5. Use the ratio method to calculate the field of vision of the medium powered objective and compare to the value you got from measuring it.
6. Now let’s estimate the size of some single cells using what we know about the field of vision looking at medium and high power:
Amoeba: Draw a single amoeba in each space. Determine the size using the medium objective and draw details under the higher objective.
Magnification: 100x Magnification: 400x
Estimated size in microns: Comment on size and details
Frog Blood: Draw a single cell outline in the first space. Determine the size using the medium objective and draw details under the higher objective.
Magnification: 100x Magnification: 400 x
Estimated size in microns: Comment on size and details
Bacteria: Draw a single cell outline in the first space. Determine the size using the medium objective and draw details under the higher objective.
Magnification: Magnification:
Estimated size in microns: Comment on size and details
Questions:
1. Are single cells all the same size?
2. Are the cells we looked at prokaryotic or eukaryotic cells? In each case explain why you think so.
3. Without looking anything up, speculate on why an amoeba is the size that it is and the advantages and disadvantages of its size are.
4. Please don’t alter what you have already written, then look up the amoeba in your textbook or on line and compare what you have learned about it to what you inferred about it.
5. Without looking anything up, speculate on why a frog blood cell is the size that it is and what the advantages and disadvantages of its size are.
6. Please don’t alter what you have already written, then look up the function of blood cells in your textbook or on line and compare what you have learned about it to what you inferred about it.
7. Without looking anything up, speculate on why an bacterium is the size that it is and the advantages and disadvantages of its size are.
8. Please don’t alter what you have already written, then look up bacteria in your textbook or on line and compare what you have learned about it to what you inferred about it.
Homework assigned on Sept. 19th, due Sept. 26th
Homework: write up lab report (2 labs really) and answer questions at the end.
Finish reading the cell chapter up to page 193 and jot down vocabulary words.
Finish reading the cell chapter up to page 193 and jot down vocabulary words.
Homework assigned on Sept. 12th, due Sept. 19th
MMEC HS Biology Day Lab 1 Sept. 12th 2008—Scientific Method and Writing Lab Reports
For this class you will need a 2 inch 3 ring binder and 3 separators
1 section for labs and class journaling and notes,
1 section for completed lab reports
1 section for reading and vocabulary
For each reading assignment, you should log the high-lighted vocabulary words and write a brief definition. These will be part of the monthly quiz, along with questions about concept explored in the labs.
For next week please read and log vocabulary for pages 3-28 stop to answer questions 3, 4, and 5 no pg 7
Questions 1, 2, and 5 on pg 15
Questions 30, 32 and 33 on pg. 32
Read and jot down vocabulary for pg 166-181
from page 171 in my book:
1. What three statements describe the cell theory?
2. What are the differences between prokaryotic cells and eukaryotic cells?
From page 181 in my book:
Questions 5 Critical thinking: Inferring
You examine an unknown cell under the microscope and discover that the cell contains chloroplasts. What type of organism could you infer that the cell came from?
For this class you will need a 2 inch 3 ring binder and 3 separators
1 section for labs and class journaling and notes,
1 section for completed lab reports
1 section for reading and vocabulary
For each reading assignment, you should log the high-lighted vocabulary words and write a brief definition. These will be part of the monthly quiz, along with questions about concept explored in the labs.
For next week please read and log vocabulary for pages 3-28 stop to answer questions 3, 4, and 5 no pg 7
Questions 1, 2, and 5 on pg 15
Questions 30, 32 and 33 on pg. 32
Read and jot down vocabulary for pg 166-181
from page 171 in my book:
1. What three statements describe the cell theory?
2. What are the differences between prokaryotic cells and eukaryotic cells?
From page 181 in my book:
Questions 5 Critical thinking: Inferring
You examine an unknown cell under the microscope and discover that the cell contains chloroplasts. What type of organism could you infer that the cell came from?
Thursday, September 11, 2008
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