AP Lab 12--DISSOLVED OXYGEN & AQUATIC PRIMARY PRODUCTIVITY (LabBench)
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 becomes warmer, its ability to hold oxygen decreases.
b. Light & Photosynthesis: In bright light, aquatic plants are able to release more oxygen.
c. Decomposition & Respiration: When organic materials decay, microbial consume oxygen
d. Mixing & Turbulence: Wave action, waterfalls and rapids aerate water an increase oxygen concentration.
e. Salinity: As salt in water rise, its ability to hold oxygen decrease
2. Productivity: Define each of these terms in your own words.
a. Primary productivity: The rate of organisms when they release organic compounds
b. Gross productivity: The Photosynthetic production of organic compounds
c. Net productivity: Leftovers of organic materials after cellular respiration
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's involved in photosynthesis & respiration . Productivity 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 becomes warmer, its ability to hold oxygen decreases.
b. Light & Photosynthesis: In bright light, aquatic plants are able to release more oxygen.
c. Decomposition & Respiration: When organic materials decay, microbial consume oxygen
d. Mixing & Turbulence: Wave action, waterfalls and rapids aerate water an increase oxygen concentration.
e. Salinity: As salt in water rise, its ability to hold oxygen decrease
2. Productivity: Define each of these terms in your own words.
a. Primary productivity: The rate of organisms when they release organic compounds
b. Gross productivity: The Photosynthetic production of organic compounds
c. Net productivity: Leftovers of organic materials after cellular respiration
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's involved in photosynthesis & respiration . Productivity 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? It helps us 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?
It helps us measure oxygen after respiration
c. How does subtracting the two enable us to indirectly measure net productivity?
By measuring the left over oxygen
5. What are the three ways that primary productivity can be measured? Highlight the way will be used in this lab?
a. Amount of carbon dioxide used
b. Rate of sugar formation
c. Rate of oxygen production
B. LAB PART 1: EFFECT OF TEMPERATURE ON DISSOLVED OXYGEN
6. What is the relationship between water temperature and dissolved oxygen?The relationship between water temperature and dissolved oxygen is the higher the temperature water holds less oxygen
7. Explain why this relationship exists.
This relationship exists because more oxygen gets used in cellular respiration as the temperature gets higher
8. So, now explain why the fish in the aquarium (on the LabBench Web site) above the radiator died?
The water started to have an increase of heat, causing less oxygen in water
C. A MODEL OF PRODUCTIVITY AS A FUNCTION OF DEPTH IN A LAKE
9. Why do we take an initial reading of dissolved oxygen? What purpose does this serve in the experiment?
We take initial readings so when you take another reading you can compare results to later state what had changed
10. Click on the “closer look” magnifying glass on the “initial bottle”. Why does the animation show oxygen being diffusing out of the freshwater plants? What does this signify?
Plants are releasing oxygen because it's being used in respiration. This signifies photosynthesis.
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 plants because oxygen is being used in respiration but no photosynthesis is happening. This signifies respiration.
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 into and out of the plants because oxygen is being used in respiration and is transmitting through photosynthesis. This signifies respiration and photosynthesis.
D. ANALYSIS OF RESULTS
Let’s look at the results that will allow you to calculate the different types of productivity.
13. Measuring Respiration: Explain why this calculation works.
This calculation works because you're taking 6 and subtraction the dark amount which is 1 and getting the respiration of 5
b. How does putting a sample of pond water and algae/freshwater plants in the dark enable us to measure respiration?
It helps us measure oxygen after respiration
c. How does subtracting the two enable us to indirectly measure net productivity?
By measuring the left over oxygen
5. What are the three ways that primary productivity can be measured? Highlight the way will be used in this lab?
a. Amount of carbon dioxide used
b. Rate of sugar formation
c. Rate of oxygen production
B. LAB PART 1: EFFECT OF TEMPERATURE ON DISSOLVED OXYGEN
6. What is the relationship between water temperature and dissolved oxygen?The relationship between water temperature and dissolved oxygen is the higher the temperature water holds less oxygen
7. Explain why this relationship exists.
This relationship exists because more oxygen gets used in cellular respiration as the temperature gets higher
8. So, now explain why the fish in the aquarium (on the LabBench Web site) above the radiator died?
The water started to have an increase of heat, causing less oxygen in water
C. A MODEL OF PRODUCTIVITY AS A FUNCTION OF DEPTH IN A LAKE
9. Why do we take an initial reading of dissolved oxygen? What purpose does this serve in the experiment?
We take initial readings so when you take another reading you can compare results to later state what had changed
10. Click on the “closer look” magnifying glass on the “initial bottle”. Why does the animation show oxygen being diffusing out of the freshwater plants? What does this signify?
Plants are releasing oxygen because it's being used in respiration. This signifies photosynthesis.
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 plants because oxygen is being used in respiration but no photosynthesis is happening. This signifies respiration.
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 into and out of the plants because oxygen is being used in respiration and is transmitting through photosynthesis. This signifies respiration and photosynthesis.
D. ANALYSIS OF RESULTS
Let’s look at the results that will allow you to calculate the different types of productivity.
13. Measuring Respiration: Explain why this calculation works.
This calculation works because you're taking 6 and subtraction the dark amount which is 1 and getting the respiration of 5
14. Measuring Gross Productivity: Now, in your own words, explain why this calculation works.
This calculation works because there was an increase of 10 mg of oxygen and a decrease of 5 mg of oxygen which was then added to the 10 mg of oxygen gained because the equation changed to net + respiration = gross productivity
This calculation works because there was an increase of 10 mg of oxygen and a decrease of 5 mg of oxygen which was then added to the 10 mg of oxygen gained because the equation changed to net + respiration = gross productivity
15. Measuring Net Productivity: Explain why this calculation works.
This calculation works because the light DO subtracted from the initial DO equals net productivity which is the difference between the two.
This calculation works because the light DO subtracted from the initial DO equals net productivity which is the difference between the two.
16. Print out the completed calculation table from Sample Problem page of the LabBench Web site, fill in your predictions on the graph as well, and attach it to this lab to show me that you have completed it.
17. Print out the Lab Quiz and attach it to this lab to show me that you completed it
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 levels from water entering a lake to have lower than the lake itself because the steam is able to have warm water which can cause the lake temperature to be warm also. Having warm water means having less dissolved oxygen
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 7 am to be higher than at 5 pm, because it's cold in the morning which can affect the water temperature. At 5 pm, the water could have gone through the intense heat of the afternoon, causing the water to be warm, therefore making the water to hold less oxygen.
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 phosphorus promote a large amount of plant/algal growth because it is a nutrient that is needed by plants
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.
c. What problems do algal blooms cause in ponds & lakes? Why isn’t a lot more producers a good thing? (Look it up!)
Algae blooms take up nutrients that can be used by other plants as well as use so muchoxygen that the animals cannot survive.
d. What is meant by eutrophication? (Look it up!)
When water has so many nutrients and is consumed by plants underwater which results in depletion ofoxygen, suffocating other fish
21. At what depth—shallow or deep—will there be more primary productivity in a pond or a lake? Explain.
Shallow waters hold more primary productivity because there is more than enough sunlight that area,while in deep waters there is less light for organisms to go through the photosynthesis process.
22. In an experiment, why do we use the mean of class data to make conclusions rather than individual student group data?
We use the mean of class data to make conclusions rather than individual student group data because finding the
average amount from data will give one a more accurate reading of what is being shown
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.
First record the initial amount of oxygen in the pond, then after 24-hours, record the amount of oxygen. By subtracting the initial amount of oxygen from the final amount of oxygen.
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 graphs shows that the lower the water, the less primary production is occurs. In fact, there is a point in which net primary production is less than zero. 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.
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 levels from water entering a lake to have lower than the lake itself because the steam is able to have warm water which can cause the lake temperature to be warm also. Having warm water means having less dissolved oxygen
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 7 am to be higher than at 5 pm, because it's cold in the morning which can affect the water temperature. At 5 pm, the water could have gone through the intense heat of the afternoon, causing the water to be warm, therefore making the water to hold less oxygen.
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 phosphorus promote a large amount of plant/algal growth because it is a nutrient that is needed by plants
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.
c. What problems do algal blooms cause in ponds & lakes? Why isn’t a lot more producers a good thing? (Look it up!)
Algae blooms take up nutrients that can be used by other plants as well as use so muchoxygen that the animals cannot survive.
d. What is meant by eutrophication? (Look it up!)
When water has so many nutrients and is consumed by plants underwater which results in depletion ofoxygen, suffocating other fish
21. At what depth—shallow or deep—will there be more primary productivity in a pond or a lake? Explain.
Shallow waters hold more primary productivity because there is more than enough sunlight that area,while in deep waters there is less light for organisms to go through the photosynthesis process.
22. In an experiment, why do we use the mean of class data to make conclusions rather than individual student group data?
We use the mean of class data to make conclusions rather than individual student group data because finding the
average amount from data will give one a more accurate reading of what is being shown
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.
First record the initial amount of oxygen in the pond, then after 24-hours, record the amount of oxygen. By subtracting the initial amount of oxygen from the final amount of oxygen.
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 graphs shows that the lower the water, the less primary production is occurs. In fact, there is a point in which net primary production is less than zero. 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.
d. Describe how the relationship between net primary productivity and depth would be expected to differ if new data were collected in mid-summer from the same pond. Explain your prediction.
The relationship of primary productivity and depth would be that the lower depth had no change of productivity.
Because the amount of sunlight in mid-summer, meaning more productivity. It would also have less dissolved oxygen because the water would be warmer.
The relationship of primary productivity and depth would be that the lower depth had no change of productivity.
Because the amount of sunlight in mid-summer, meaning more productivity. It would also have less dissolved oxygen because the water would be warmer.