Dissolved Oxygen PresentationDissolved Oxygen and Aquatic Primary Productivity Lab
A. KEY CONCEPTS:
1. Dissolved Oxygen Availability in ponds and lakes. Using the following diagram describe the effect that each of the factors has on availability of oxygen and explain why.
a. Temperature: As water raises its temperature, the power to hold oxygen decreases.
b. Light and Photosynthesis: bright like makes aquatic plants able to produce more oxygen.
c. Decomposition and Respiration: if organic material decays then microbials pocesses cosume oxygen
d. Mixing and Turbulence: River, streams, waves and turbulence in water increases aeration in the water
2. Productivity: Define each of these terms in your own words.
a. Primary productivity: the rate at which plants and other photosynthetic organisms produce organic compounds in an ecosystem.
b. Gross productivity: photosynthetic production of organic compounds in an ecosystem.
c. Net productivity: The organic materials that remain after photosynthetic organisms in the ecosystem have used some of the compounds for their cellular energy needs.
3. Why do we use dissolved oxygen as a measure of productivity? Does productivity include more than oxygen?
We use dissolved oxygen as a measure of productivity because it is the easiest thing to measure in respiration and photosynthesis. Other than oxygen, productivity also includes carbon dioxide.
4. Using the diagrams below explain:
1. Dissolved Oxygen Availability in ponds and lakes. Using the following diagram describe the effect that each of the factors has on availability of oxygen and explain why.
a. Temperature: As water raises its temperature, the power to hold oxygen decreases.
b. Light and Photosynthesis: bright like makes aquatic plants able to produce more oxygen.
c. Decomposition and Respiration: if organic material decays then microbials pocesses cosume oxygen
d. Mixing and Turbulence: River, streams, waves and turbulence in water increases aeration in the water
2. Productivity: Define each of these terms in your own words.
a. Primary productivity: the rate at which plants and other photosynthetic organisms produce organic compounds in an ecosystem.
b. Gross productivity: photosynthetic production of organic compounds in an ecosystem.
c. Net productivity: The organic materials that remain after photosynthetic organisms in the ecosystem have used some of the compounds for their cellular energy needs.
3. Why do we use dissolved oxygen as a measure of productivity? Does productivity include more than oxygen?
We use dissolved oxygen as a measure of productivity because it is the easiest thing to measure in respiration and photosynthesis. Other than oxygen, productivity also includes carbon dioxide.
4. Using the diagrams below explain:
a. How does putting a sample of pond water and algae/freshwater plants in the light enable us to measure gross productivity?
Putting a sample of pond water and algae/freshwater plants in the light enable us to measure gross productivity because it enables us to measure oxygen after photosynthesis.
b. How does putting a sample of pond water and algae/freshwater plants in the dark enable us to measure respiration?
Putting a sample of pond water and algae/freshwater plants in the dark enable us to measure respiration because it enables us to measure oxygen after respiration.
c. How does subtracting the two enable us to indirectly measure net productivity?
Subtracting respiration from photosynthesis enables us to measure the amount of oxygen left.
5. What are the three ways that primary productivity can be measured? Highlight the way will be used in this lab?.
a. We can measure net productivity directly by measuring oxygen production in the light, when photosynthesis is occurring.
b. We can also measure respiration without photosynthesis by measuring O2 consumption in the dark, when photosynthesis does not occur.
c. Since net productivity= gross productivity-respiration, we can calculate gross productivity.
B. LAB PART 1: EFFECT OF TEMPERATURE ON DISSOLVED OXYGEN
6. What is the relationship between water temperature and dissolved oxygen?
As water becomes warmer, its ability to hold oxygen decreases.
7. Explain why this relationship exist.
Oxygen is ssential for cellular respiration in most organism
8. So, now explain why the fish in the aquarium (on the LabBench Web site) above the radiator died?
The aquarium's water temperature got warmer, losing its ability to hold oxygen.
C. A MODEL OF PRODUCTIVITY AS A FUNCTION OF DEPTH IN A LAKE
Now we are going to look at the biological factors that affect dissolved oxygen in a body of water. We are taking a sample of pond water (with algae) and then modeling different depths in the pond by using screening to block out successive amounts of light. One hundred percent light for shallow depth, all the way to 0% light for deep ponds.
9. Why do we take an initial reading of dissolved oxygen? What purpose does this serve in the experiment?
The amount of light available for photosynthesis drops with increasing depth in an aquatic environment.
10. Click on the closer look magnifying glass on the initial bottle. Why does the animation show oxygen being diffusing our of the freshwater plants? What does this signify?
Oxygen is diffusing out of the freshwater plants because oxygen is used up in respirtation and then is given off to photosynthesos
11. Click on the closer look magnifying glass on the foil covered bottle. Why does the animation show oxygen diffusing into the freshwater plants? What does this signify?
Oxygen is diffusing into the freshwater plants because O2 is used up in respiration but no photosynthesis occurs.
12. Click on the closer look magnifying glass on the 100% bottle under the light. Why does the animation show oxygen diffusing both into and out of the freshwater plants? What does this Signify?
Oxygen is diffusing both into and out of the freshwater plants because O2 used in respiration and is given off in photosynthesis.
D. ANALYSIS OF RESULTS
Lets look at the results that will allow you to calculate the different types of productivity.
13. Measuring Respiration: Remember that plants (producers) perform both photosynthesis and respiration. To measure the amount of respiration that is happening in the bottle, we measure the amount of dissolved oxygen in the initial sample and then the amount of oxygen in the bottle kept in the dark. As shown in the illustration below, you then subtract the amount of dissolved oxygen in the dark bottle from the amount of dissolved oxygen in the initial bottle to calculate the amount of oxygen consumed in respiration. I have added some possible measurements to help. Explain why this calculation works.
Putting a sample of pond water and algae/freshwater plants in the light enable us to measure gross productivity because it enables us to measure oxygen after photosynthesis.
b. How does putting a sample of pond water and algae/freshwater plants in the dark enable us to measure respiration?
Putting a sample of pond water and algae/freshwater plants in the dark enable us to measure respiration because it enables us to measure oxygen after respiration.
c. How does subtracting the two enable us to indirectly measure net productivity?
Subtracting respiration from photosynthesis enables us to measure the amount of oxygen left.
5. What are the three ways that primary productivity can be measured? Highlight the way will be used in this lab?.
a. We can measure net productivity directly by measuring oxygen production in the light, when photosynthesis is occurring.
b. We can also measure respiration without photosynthesis by measuring O2 consumption in the dark, when photosynthesis does not occur.
c. Since net productivity= gross productivity-respiration, we can calculate gross productivity.
B. LAB PART 1: EFFECT OF TEMPERATURE ON DISSOLVED OXYGEN
6. What is the relationship between water temperature and dissolved oxygen?
As water becomes warmer, its ability to hold oxygen decreases.
7. Explain why this relationship exist.
Oxygen is ssential for cellular respiration in most organism
8. So, now explain why the fish in the aquarium (on the LabBench Web site) above the radiator died?
The aquarium's water temperature got warmer, losing its ability to hold oxygen.
C. A MODEL OF PRODUCTIVITY AS A FUNCTION OF DEPTH IN A LAKE
Now we are going to look at the biological factors that affect dissolved oxygen in a body of water. We are taking a sample of pond water (with algae) and then modeling different depths in the pond by using screening to block out successive amounts of light. One hundred percent light for shallow depth, all the way to 0% light for deep ponds.
9. Why do we take an initial reading of dissolved oxygen? What purpose does this serve in the experiment?
The amount of light available for photosynthesis drops with increasing depth in an aquatic environment.
10. Click on the closer look magnifying glass on the initial bottle. Why does the animation show oxygen being diffusing our of the freshwater plants? What does this signify?
Oxygen is diffusing out of the freshwater plants because oxygen is used up in respirtation and then is given off to photosynthesos
11. Click on the closer look magnifying glass on the foil covered bottle. Why does the animation show oxygen diffusing into the freshwater plants? What does this signify?
Oxygen is diffusing into the freshwater plants because O2 is used up in respiration but no photosynthesis occurs.
12. Click on the closer look magnifying glass on the 100% bottle under the light. Why does the animation show oxygen diffusing both into and out of the freshwater plants? What does this Signify?
Oxygen is diffusing both into and out of the freshwater plants because O2 used in respiration and is given off in photosynthesis.
D. ANALYSIS OF RESULTS
Lets look at the results that will allow you to calculate the different types of productivity.
13. Measuring Respiration: Remember that plants (producers) perform both photosynthesis and respiration. To measure the amount of respiration that is happening in the bottle, we measure the amount of dissolved oxygen in the initial sample and then the amount of oxygen in the bottle kept in the dark. As shown in the illustration below, you then subtract the amount of dissolved oxygen in the dark bottle from the amount of dissolved oxygen in the initial bottle to calculate the amount of oxygen consumed in respiration. I have added some possible measurements to help. Explain why this calculation works.
6mg of dissolved oxygen- 1mg of dissolved oxygen= 5mg of dissolved oxygen.
14. Measuring Gross Productivity: Remember gross productivity is the total amount of sugars and oxygen produced by the plants in an ecosystem. I don't like how this web site shows you how to calculate gross productivity. The equation is correct, but it is a short cut, so it makes it more difficult to understand. So follow me with the illustrations and the possible measurements below.
14. Measuring Gross Productivity: Remember gross productivity is the total amount of sugars and oxygen produced by the plants in an ecosystem. I don't like how this web site shows you how to calculate gross productivity. The equation is correct, but it is a short cut, so it makes it more difficult to understand. So follow me with the illustrations and the possible measurements below.
there was 10mg increase in dissolved oxygen in the jar as a result of photosynthesis in the last 24 hours and there was 5mg decrease in dissolved oxygen in the jar as a result of respiration in the last 24 hours. So the gross productivity of the algae in the bottle is the 5mg dissolved oxygen lost to respiration added back to the 10mg dissolved oxygen in the bottle kept in the light. So what the algae really produced in the bottle was a total of 15mg dissolved oxygen, it just lost 5mg to respiration.
Now, in your own words, explain why this calculation works.
there was a 10mg oxygen gain from photosynthesis and 5mg oxygen lost to respiration. The 5mg dissolved oxygen lost added back to the 10mg dissolved oxygen making the gross productivity of 15mg oxygen.
15. Measuring Net Productivity: Remember net productivity is the amount of sugars and dissolved oxygen produced by the plants in an ecosystem once you subtract out what the producers have consumed in respiration. So we actually already calculated that in the last example; I just called it net photosynthesis. Explain why this calculation works.
there was a 10mg oxygen gain from photosynthesis and 5mg oxygen lost to respiration. The 5mg dissolved oxygen lost added back to the 10mg dissolved oxygen making the gross productivity of 15mg oxygen.
15. Measuring Net Productivity: Remember net productivity is the amount of sugars and dissolved oxygen produced by the plants in an ecosystem once you subtract out what the producers have consumed in respiration. So we actually already calculated that in the last example; I just called it net photosynthesis. Explain why this calculation works.
This calculation works because the light dissolved oxygen had 16mg dissolved oxygen over 24 hours- the initial dissolved oxygen 6mg dissolved oxygen over 24 hours. The net productivity is 10mg dissolved oxygen.
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SUMMARY QUESTIONS
18.Would you expect the dissolved oxygen levels in water sampled from a stream entering a lake to be higher or lower than the dissolved oxygen levels in water sampled from the lake itself? Explain.
I would expect the DO levels in water sampled from a stream to lake to be lower than the lake itself, because the stream can have warm water, which can cause the lake temperature to become warm as well. Having warm water means having less DO.
19. Would you expect the dissolved oxygen levels in water sampled from a lake at 7AM to be higher or lower
than the dissolved oxygen levels in water sampled at 5PM? Explain.
I would expect DO levels in water at 7am to be higher than at 5pm., because it is cold in the morning, which will affect the temperature of the water to be colder.
20. One of the major sources of water pollution is the runoff from fertilizer used in agriculture and on suburban lawns as well as golf courses. In particular, the nitrogen and phosphorus nutrients in the fertilizer creates problems in the
streams and ponds it flows into. They cause algal blooms and eutrophication in lakes.
a. Why do nitrogen and phosphorus promote a lot of plant/algal growth?
Nitrogen and phosporus have a lot of algae growth
b. What is meant by algal bloom? (Look it up!)
Algal bloom is when there is a fast increase of algae in an aquatic environment.
21. At what depth—shallow or deep—will there be more primary productivity in a pond or a lake? Explain.
Shallow water will have more primary productivity, because there is plenty of sunlight in shallow water, and in deep water, there will be less light for organisms to go through photosynthesis.
22. In an experiment, why do we use the mean of class data to make conclusions rather than individual student group data?
We use mean of class data to make conclusions, because some of data could be way off from other data. Finding average amount will help get more exact data for our conclusions.
23. AP exam FRQ (2008). Consumers in aquatic ecosystems depend on producers for nutrition.
a. Explain the difference between gross and net primary productivity.
Gross productivity is amount of oxygen use for photosynthesis. Net productivity is amount of oxygen used in respiration and released in photosynthesis.
b. Describe a method to determine net and gross primary productivity in a freshwater pond over a 24-hour period.
Place a native plant into a freshwater pond. Find initial amount of oxygen in air. For 12 hours, leave plant in sunlight. Measure oxygen levels after 12 hours. Then, place plant in a dark place for another 12 hours. Measure oxygen levels after 12 hours. Add oxygen levels after photosynthesis and respiration to get net. To get gross, subtract initial amount of oxygen to amount of oxygen after photosynthesis.
c. In an experiment, net primary productivity was measured, in the early spring, for water samples taken from different depths of a freshwater pond in a temperate deciduous forest. Explain the data presented by the graph, including a description of the relative rates of metabolic processes occurring at different depths of the pond.
The data shows that, lower depth of water, more primary production there is . Net primary productivity is at its height at 0 meters depth in pond. At depth of 25 meters in water, net primary production has no increase or decrease. After 30 meters of depth, productivity goes down. The lowest point, 40 meters, has lowest amount of primary production.
18.Would you expect the dissolved oxygen levels in water sampled from a stream entering a lake to be higher or lower than the dissolved oxygen levels in water sampled from the lake itself? Explain.
I would expect the DO levels in water sampled from a stream to lake to be lower than the lake itself, because the stream can have warm water, which can cause the lake temperature to become warm as well. Having warm water means having less DO.
19. Would you expect the dissolved oxygen levels in water sampled from a lake at 7AM to be higher or lower
than the dissolved oxygen levels in water sampled at 5PM? Explain.
I would expect DO levels in water at 7am to be higher than at 5pm., because it is cold in the morning, which will affect the temperature of the water to be colder.
20. One of the major sources of water pollution is the runoff from fertilizer used in agriculture and on suburban lawns as well as golf courses. In particular, the nitrogen and phosphorus nutrients in the fertilizer creates problems in the
streams and ponds it flows into. They cause algal blooms and eutrophication in lakes.
a. Why do nitrogen and phosphorus promote a lot of plant/algal growth?
Nitrogen and phosporus have a lot of algae growth
b. What is meant by algal bloom? (Look it up!)
Algal bloom is when there is a fast increase of algae in an aquatic environment.
21. At what depth—shallow or deep—will there be more primary productivity in a pond or a lake? Explain.
Shallow water will have more primary productivity, because there is plenty of sunlight in shallow water, and in deep water, there will be less light for organisms to go through photosynthesis.
22. In an experiment, why do we use the mean of class data to make conclusions rather than individual student group data?
We use mean of class data to make conclusions, because some of data could be way off from other data. Finding average amount will help get more exact data for our conclusions.
23. AP exam FRQ (2008). Consumers in aquatic ecosystems depend on producers for nutrition.
a. Explain the difference between gross and net primary productivity.
Gross productivity is amount of oxygen use for photosynthesis. Net productivity is amount of oxygen used in respiration and released in photosynthesis.
b. Describe a method to determine net and gross primary productivity in a freshwater pond over a 24-hour period.
Place a native plant into a freshwater pond. Find initial amount of oxygen in air. For 12 hours, leave plant in sunlight. Measure oxygen levels after 12 hours. Then, place plant in a dark place for another 12 hours. Measure oxygen levels after 12 hours. Add oxygen levels after photosynthesis and respiration to get net. To get gross, subtract initial amount of oxygen to amount of oxygen after photosynthesis.
c. In an experiment, net primary productivity was measured, in the early spring, for water samples taken from different depths of a freshwater pond in a temperate deciduous forest. Explain the data presented by the graph, including a description of the relative rates of metabolic processes occurring at different depths of the pond.
The data shows that, lower depth of water, more primary production there is . Net primary productivity is at its height at 0 meters depth in pond. At depth of 25 meters in water, net primary production has no increase or decrease. After 30 meters of depth, productivity goes down. The lowest point, 40 meters, has lowest amount of primary production.