basic neutral acidic ph 1 2 3 4 5 6 7 8 9 10 11 12 13 14 organisms and ph 012-10972 r1.04
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Basic
Neutral
Acidic
pH
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1011121314
Organisms and pH 012-10972 r1.04
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The Journal is where snapshots are stored and viewed.
The Share button is used to export or print your journal to turn in your work.
IntroductionJournals and Snapshots
Organisms and pH
Each page of this lab that contains the symbol
should be inserted into your journal. After completing a lab page with the snapshot symbol, tap (in the upper right hand corner) to insert the page into your journal.
Note: You may want to take asnapshot of the first page ofthis lab as a cover page for your journal.
Lab Challenge
• What effect does pH have on the health of organisms?
• What effect do man-made and biological buffers have on pH?
Organisms and pH
Background
• pH is a measure of the acidity/alkalinity of water.
• Solutions with very low pH are highly acidic; solutions with very high pH are highly alkaline (basic). A pH equal to 7 is neutral.
• Solutions that are acidic produce a large number of H+ ions, which affects biological molecules in the solution. Proteins can become denatured (unraveled) when the pH of the surrounding solution changes.
Hig
her H
+H
ighe
r OH
-
Basic
Neutral
Acidic
pH
Drain CleanerBleach
Soapy DetergentsAmmoniaMilk of MagnesiaBaking SodaSea Water
Distilled WaterSalivaBlack CoffeeLemon Juice
Sulfuric AcidBattery Acid1
23456
87
9
1011121314
Stomach Acid, Vinegar
Organisms and pH
This image is a reminder totap to take a snapshot of the page after you have entered your response.
Self-Check1. A solution with a very low pH is _______. An
example is _________.
a) basic : bleach
b) acidic : stomach acid
c) basic : orange juice
d) neutral : sea water
e) acidic : soapy water
Organisms and pH
...Background
• An organism’s pH can be changed by adding carbon dioxide (CO2) to its bloodstream. Mammals have an enzyme in the bloodstream called carbonic anhydrase. This enzyme combines CO2 with H2O to form carbonic acid (H2CO3). Carbonic acid increases the amount of CO2 the blood can hold and transport. Some of the carbonic acid molecules break down, releasing H+ ions.
• The more an organism exerts itself, the more carbonic acid is produced, decreasing blood pH. When CO2 is removed from the bloodstream, pH increases. Low blood pH triggers a breathing response in the brain, causing the lungs to expel CO2. Breathing is one way an organism controls pH.
Organisms and pH
2. When CO2 is added to the bloodstream, what is the overall effect?
a) decrease in carbonic anhydrase
b) no change in pH
c) increase in pH
d) decrease in pH
e) increase in huffing and puffing
Organisms and pH
Self-Check
...Background
• Another way organisms control pH is through the use of buffers.
• A buffer is a compound that can combine chemically with free H+ ions in solution. Because these extra H+ ions are neutralized, the organism’s overall pH does not change.
• A buffer can also release H+ ions when combined with an alkaline (basic) substance. These extra H+ ions neutralize the OH- ions produced by the base. The overall pH does not change. If an acidic or basic substance is added to a buffered solution, the solution’s pH will not be significantly changed – until the buffer is used up.
• One common buffer is sodium bicarbonate, NaHCO3, more commonly known as baking soda.
Organisms and pH
3. How does a buffer neutralize alkaline/basic substances?
a) by producing H+ ions
b) by capturing H+ ions
c) by producing OH- ions
d) magic
Organisms and pH
Self-Check
Safety
• Use all standard laboratory safety procedures.
• Wear safety glasses and lab coats or aprons.
• Dispose of chemicals and solutions as instructed.
Organisms and pH
Materials and EquipmentCollect all of these materials before beginning the lab.
• pH sensor• Sensor extension cable• Beaker (6), 50mL • Beaker, 250mL• Erlenmeyer flask (2), 1L• Graduated cylinder, 10mL• Disposable pipettes (2)
• Detergent solution• Lemon juice• Distilled Water• White vinegar• Liver suspension• Buffer solution
Organisms and pH
The steps to the left are part of the procedure for this lab activity. They are not in the right order. Determine the correct sequence of the steps, then take a snapshot of this page.
Sequencing Challenge
A. Measure the initial pH of various solutions.
B. Set up your equipment.
C. Record pH data as you add detergent to water, buffer, and liver.
D. Clean up.
E. Analyze the data and determine if any biological solutions are good buffers.
Organisms and pH
Prediction: Water + Lemon Juice
Q1:What do you predict will happen to the pH of the water when lemon juice is added?
Organisms and pH
Collect Data: Water + Lemon Juice
1. Connect the pH sensor to the SPARK Science Learning System.
2. Pour 25 mL of distilled water into a 50 mL beaker.
3. Rinse the pH sensor with distilled water and place it into the beaker.
4. Wait a few seconds, then tap to start data collection.
5. Record the initial pH for Water + Lemon Juice in the data table on the next page.
Organisms and pH
To Enter Data into a Table: 1. Tap to open the tool
palette.2. Tap then tap a cell in
the data table to highlight it in yellow.
3. Tap to open the Keyboard screen.
Organisms and pH
Collect Data: Water + Lemon Juice
6. Continue recording data as you add 30 drops of lemon juice using a clean pipette. Use the glass stirring rod to gently mix the solution in the beaker while adding the lemon juice.
7. Wait 30 seconds following the last drop of lemon juice and then tap to stop data collection.
8. Record the final pH for Water + Lemon Juice in the data table on the previous page.
Organisms and pH
Prediction: Water + Detergent
Q2:What do you predict will happen to the pH of the water when detergent is added?
Organisms and pH
Collect Data: Water + Detergent
1. Pour 25 mL of distilled water into a clean 50 mL beaker.
2. Rinse the pH sensor with distilled water and place it into the beaker.
3. Wait a few seconds, then tap to start data collection.
4. Record the initial pH for Water + Detergent in the data table on the next page.
Organisms and pH
To Enter Data into a Table: 1. Tap to open the tool
palette.2. Tap then tap a cell in
the data table to highlight it in yellow.
3. Tap to open the Keyboard screen.
Organisms and pH
Collect Data: Water + Detergent
5. Continue recording data as you add 30 drops of detergent using a clean pipette. Use the glass stirring rod to gently mix the solution in the beaker while adding the detergent.
6. Wait 30 seconds following the last drop of detergent and then tap to stop data collection.
7. Record the final pH for Water + Detergent in the data table on the previous page.
Organisms and pH
Prediction: Buffer + Lemon Juice
Q3:What do you predict will happen to pH of the buffer solution as lemon juice is added?
Organisms and pH
Collect Data: Buffer + Lemon Juice
1. Pour 25 mL of buffer solution into a clean 50 mL beaker.
2. Rinse the pH sensor with distilled water and place it into the beaker.
3. Wait a few seconds, then tap to start data collection.
4. Record the initial pH for Buffer + Lemon Juice in the data table on the next page.
Organisms and pH
To Enter Data into a Table: 1. Tap to open the tool
palette.2. Tap then tap a cell in
the data table to highlight it in yellow.
3. Tap to open the Keyboard screen.
Organisms and pH
Collect Data: Buffer + Lemon Juice
6. Continue recording data as you add 30 drops of lemon juice using a clean pipette. Use the glass stirring rod to gently mix the solution in the beaker while adding the lemon juice.
7. Wait 30 seconds following the last drop of lemon juice and then tap to stop data collection.
8. Record the final pH for Buffer + Lemon Juice in the Data Table on the previous page.
Organisms and pH
Prediction: Buffer + Detergent
Q4:What do you predict will happen to the pH of the buffer solution when detergent is added?
Organisms and pH
Collect Data: Buffer + Detergent
1. Pour 25 mL of buffer solution into a clean 50 mL beaker.
2. Rinse the pH sensor with distilled water and place it into the beaker.
3. Wait a few seconds, then tap to start data collection.
4. Record the initial pH for Buffer + Detergent in the data table on the next page.
Organisms and pH
To Enter Data into a Table: 1. Tap to open the tool
palette.2. Tap then tap a cell in
the data table to highlight it in yellow.
3. Tap to open the Keyboard screen.
Organisms and pH
Collect Data: Buffer + Detergent6. Continue recording data as you add 30 drops of
detergent using a clean pipette. Use the glass stirring rod to gently mix the solution in the beaker while adding the detergent.
7. Wait 30 seconds following the last drop of detergent and then tap to stop data collection.
8. Record the final pH for Buffer + Detergent in the Data Table on the previous page.
Organisms and pH
Prediction: Liver + Lemon Juice
Q5:What do you predict will happen to the pH of the liver solution when lemon juice is added?
Organisms and pH
Collect Data: Liver + Lemon Juice
1. Pour 25 mL of liver suspension into a clean 50 mL beaker.
2. Rinse the pH sensor with distilled water and place it into the beaker.
3. Wait a few seconds, then tap to start data collection.
4. Record the initial pH for Liver + Lemon Juice in the data table on the next page.
Organisms and pH
To Enter Data into a Table: 1. Tap to open the tool
palette.2. Tap then tap a cell in
the data table to highlight it in yellow.
3. Tap to open the Keyboard screen.
Organisms and pH
Collect Data: Liver + Lemon Juice6. Continue recording data as you add 30 drops
of lemon juice using a clean pipette. Use the glass stirring rod to gently mix the solution in the beaker while adding the lemon juice.
7. Wait 30 seconds following the last drop of lemon juice and then tap to stop data collection.
8. Record the final pH for Liver + Lemon Juice in the data table on the previous page.
Organisms and pH
Prediction: Liver + Detergent
Q6:What do you predict will happen to the pH of the liver solution when detergent is added?
Organisms and pH
Collect Data: Liver + Detergent
1. Pour 25 mL of liver suspension into a clean 50 mL beaker.
2. Rinse the pH sensor with distilled water and place it into the beaker.
3. Wait a few seconds, then tap to start data collection.
4. Record the initial pH for Liver + Detergent in the data table on the next page.
Organisms and pH
To Enter Data into a Table: 1. Tap to open the tool
palette.2. Tap then tap a cell in
the data table to highlight it in yellow.
3. Tap to open the Keyboard screen.
Organisms and pH
Collect Data: Liver + Detergent6. Continue recording data as you add 30 drops of
detergent using a clean pipette. Use the glass stirring rod to gently mix the solution in the beaker while adding the detergent.
7. Wait 30 seconds following the last drop of detergent and then tap to stop data collection.
8. Record the final pH for Liver + Detergent in the Data Table on the previous page.
Organisms and pH
1. Calculate the change in pH for each of the six experiments. Record your results in the data table.
To Enter Data into a Table: 1. Tap to open the tool
palette.2. Tap then tap a cell in
the data table to highlight it in yellow.
3. Tap to open the Keyboard screen.
Data AnalysisOrganisms and pH
2. Which solution had the greatest increase in pH? Which had the greatest decrease?
Data AnalysisOrganisms and pH
Analysis
1. What is significant about the pH change in the liver suspension? What does it tell us about biological compounds, in general?
Organisms and pH
2. List the following common compounds in order from most acidic to most basic: distilled water, detergent solution, lemon juice.
Organisms and pH
Analysis
3. Do organisms appear to have effective ways to avoid large changes in pH? Give an example using experimental evidence.
Organisms and pH
Analysis
Synthesis
1. There are buffers in the human blood system. Why is that important for you?
Organisms and pH
2. Hemoglobin in red blood cells binds to oxygen from the lungs. The hemoglobin somehow “knows” to release this oxygen when the blood passes near oxygen-starved tissues. How is this possible?
Organisms and pH
Synthesis
Multiple Choice
1. Which of the following biochemical substances located in the human body is not maintained at a neutral pH?
a) blood
b) stomach fluids
c) internal material of living cells
d) lymph
Organisms and pH
TrypsinPepsin
Rate
of E
nzym
e Ac
tivity
Multiple Choice
A. More enzymes are present at a higher pH.
B. Pepsin is less sensitive to pH than trypsin.
C. Pepsin is less effective at low pH than trypsin.
D. pH affects the activity rate of enzymes.
2. Which choice it true for the graph shown?
Organisms and pH
Multiple Choice
3. 5 mL of lemon juice was added to 10 mL of each of the following substances and the results recorded. Which substance has the best buffering capacity?
a) Milk pH change = -3.2
b) Liver pH change = -3.0
c) Tap water pH change = -4.0
d) Egg whites pH change = -2.8
Organisms and pH
You have completed the lab.Congratulations!
Please remember to follow your teacher's instructions for cleaning-up and submitting your lab.
Organisms and pH
Images are taken from PASCO documentation, public domain clip art, or Wikimedia Foundation Commons.
http://www.flickr.com/photos/moorthygounder/2228827558/ See attribution of license terms at: http://creativecommons.org/licenses/by/2.0/deed.enhttp://commons.wikimedia.org/wiki/File:Dolphins_300.jpghttp://commons.wikimedia.org/wiki/File:Fried_egg,_sunny_side_up.jpghttp://commons.wikimedia.org/wiki/File:Glass-of-water.jpg
ReferencesOrganisms and pH