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 produce more oxygen.
c. Decomposition & Respiration:As organic material decays, microbial processes consume oxygen.
d. Mixing & Turbulence: Wave action, waterfalls, and rapids all aerate water and increase the oxygen concentration
e. Salinity: As water becomes more salty, its ability to hold oxygen decreases.
2. Productivity: Define each of these terms in your own words.
a. Primary productivity: Used to describe the rate at which plants and other photosynthetic organisms produce organic in an ecosystem.
b. Gross productivity: the entire 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 these compounds for their cellular energy needs.
3. Why do we use dissolved oxygen as a measure of productivity? Does productivity include more than
oxygen?
one of the most easily measured products of both photosynthesis and respiration, a good way to gauge primary productivity in an aquatic ecosystem is to measure dissolved oxygen.
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?
Photosynthesis putting a sample of pond water and algae/freshwater plants in the light enable us to measure gross productivity.
b. How does putting a sample of pond water and algae/freshwater plants in the dark enable us
to measure respiration?
Respiration putting a sample of pond water and algae/freshwater plants in the dark enable us to measure respiration.
c. How does subtracting the two enable us to indirectly measure net productivity?
To indirectly measure net productivity is photosynthesis minus respiration.
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
We actually did this part of the lab already. Remind yourself of our experiment, our procedures,
and our conclusions. We were investigating the effect of the physical factor of temperature on
the percent dissolved oxygen in a body of water.
6. What is the relationship between water temperature and dissolved oxygen?
The cooler the water, the more dissolved oxygen it can contain. This is one reason why areas of upwelling are so rich in sea life. Upwelling occurs along the western coasts of continents, where deep water rises to the surface, bringing with it that cold water, dissolved oxygen, and the abundant life that goes with it. However, note that this is not "bad" for the oceans of the Earth.
7. Explain why this relationship exists.
The warmer waters where there is less dissolved oxygen is where the phytoplankton bloom. The sunlight is abundant, and they produce oxygen for all of us to breathe. They do not require the same abundance of oxygen in the water.
8. So, now explain why the fish in the aquarium (on the LabBench Web site) above the radiator
died?
A saltwater aquarium, also known as an oceanarium, is an aquarium specifically for fish, mammals and plants that live and grow in the ocean
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.
Look at the experimental design on the LabBench Web site
(http://www.phschool.com/science/biology_place/labbench/lab12/model.html). 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 off sharply with increasing depth in an aquatic environment. You model this condition by wrapping water- with increasing layers of screen.
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?
When it O2 (used up in respiration) gose into the leaf, then it turn out on the other side which is O2 (given off in photosynthesis. It turn out 2 O2.
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?
On the side O2 (used up in respiration) two O2 gose into the leaf but it doesn't come out to the other side which is no photosynthesis occurs. On that side the amount of O2 is still the same.
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?
this time is different, the left side (O2 is used up in respiration) it have two of the O2 is go into the leaf but they goes one by one. the same with the first one, it came out to the other way (O2 is given off in photosynthesis, it go out two O2 per one O2 on the left side.
D . ANALYSIS OF RESULTS
Let’s 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.
Calculating respiratory rate is done best when the patient is not aware you are watching them breathe, as they tend to change the rate of respiration when they become self-conscious. Respiration is counted as part of vital signs --temperature, blood pressure, pulse and respiration - and are usually taken right after pulse while the caregiver is still holding the patient's wrist.
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.
So the illustration shows us 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 (the full photosynthetic
production in this ecosystem) of the algae in the bottle is the 5mg dissolved oxygen lost to
respiration added back to the 10 mg dissolved oxygen accumulated 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. And remember, the oxygen is an indirect measurement of the sugars
produced in photosynthesis and lost in respiration.
Now, in your own words, explain why this calculation works.
The 10 mg oxgen gained ( from photosynthesis) plus the 5 mg oxygen lost (to respiration) when I add the 10 mg to 5 mg then it equal 15 mg oxygen as gross pruductivity.
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.
Because water is both a reactant and a product, the equation can be simplified accounting for net water consumption, Photosynthesis is a lot more complicated than the simplified diagram above. Actually, photosynthesis doesn't actually produce glucose; rather, it produces a 3-carbon compound which is a precursor to glucose.
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.
I can't print the Sample Problem it because I can't see the picture, it not showing.
17. Print out the Lab Quiz and attach it to this lab to show me that you completed it.
1. D, A cold mountain stream dropping over a series of small rock falls.
2. C, Any intensity below 10%
3. A, It is a measure of the organic products of photosynthesis that accumulate after cellular respiration by those organisms is taken into account, and it is calculated by subtracting the amount of oxygen in the dark bottle from the amount in the light bottle.
4. C, The net productivity for culture A will be negative at greater light intensity than that for culture B.
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 can assume that the stream is a stream with a good current, so oxygen will get incoorperated with the water through turbulance. There is more turbulance in a stream than in a lake. This factor will result in higher concentrations of DO in a stream. Also, the overall temperature in a stream is lower because the sun cannot heat moving water as fast as it can heat non-mobile water.Both of these factors will result in a higher DO in the stream than in the lake.
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'm expect the DO to be lower in the morning. Photosynthesis doesn't occur at night and the DO would drop overnight due cell respiration.
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?
Both are considered limiting factors in vegetative growth. Both are two of the main components (potassium is the third) found in fertilizers. Nitrogen is necessary to make proteins, and it's a component of DNA and RNA molecules (it's found in the ATCG and U, which is why they're called 'nitrogenous bases'). Phosphorous is a part of the "energy currency" of every cell. Without enough nitrogen or phosphorous, the growth of plants and algae is limited, since they can't form as many new cells. If these elements are available in abundance, plants and algae can grow rapidly.
b. What is meant by algal bloom? (Look it up!)
An algal bloom or marine bloom or water bloom is a rapid increase in the population of algae in an aquatic system. Algal blooms may occur in freshwater as well as marine environments. Typically only one or a few phytoplankton species are involved and some blooms may be recognized by discoloration of the water resulting from the high density of pigmented cells.
c. What problems do algal blooms cause in ponds & lakes? Why isn’t a lot more producers a good thing?
(Look it up!)
Algae can range from microscopic, single-cell organisms tolarge structures that resemble full-fledged plants. Algae is almost always present in small amounts in freshwater lakes and ponds but when conditions are right the algae can bloom, causing significant issues for the pond and the other organisms living nearby.
d. What is meant by eutrophication? (Look it up!)
Eutrophication is the process of nutrient enrichment of water bodies and subsequentgrowth of plants on the surface of water.
21. At what depth—shallow or deep—will there be more primary productivity in a pond or a lake? Explain.
All production happens at the meeting of two phases. Water and air, water and dirt, leaf and sunlight, etc. I don't know what is considered "primary" but it has to be near the surface.
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
class data will be better because it have more idea and different kind of idea of different. Student group data is good but not good than class data it because they don't have idea, I mean they have some but not a lot like class data.
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 primary production (GPP) is the rate at which an ecosystem's producers capture and store a given amount of chemical energy as biomass in a given length of time. Some fraction of this fixed energy is used by primary producers for cellular respiration and maintenance of existing tissues.
b. Describe a method to determine net and gross primary productivity in a freshwater pond over a 24-
hour period.
Gross Primary Productivity- Total amount of chemical energy stored by photosynthesis. Net Primary Productivity- Remaining energy, which is available to the consumers as food.
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.
Basic on the graph that show me the net primary productivity the freshwater pound is going down which is depth of water (meters) . it go pass the line that is 0. The freshwater is going down which is not good because the is not going straight down but it going curly down.
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.
For the protein questions I explained different structures for protein, like primary, secondary, and tertiary. For the flower one, I explained self-incompatibility and genetic diversity. They would become overly dependent on insects, so they would develop prettier petals and more pleasing smells to attract. Also, some plants just develop male or female gametophyte (i.e. mango).
For the net productivity one, I basically explain the overall relationship displayed on the graph. The two variables form positive correlation; in other words, as one goes down, the other one goes down as well.
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 produce more oxygen.
c. Decomposition & Respiration:As organic material decays, microbial processes consume oxygen.
d. Mixing & Turbulence: Wave action, waterfalls, and rapids all aerate water and increase the oxygen concentration
e. Salinity: As water becomes more salty, its ability to hold oxygen decreases.
2. Productivity: Define each of these terms in your own words.
a. Primary productivity: Used to describe the rate at which plants and other photosynthetic organisms produce organic in an ecosystem.
b. Gross productivity: the entire 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 these compounds for their cellular energy needs.
3. Why do we use dissolved oxygen as a measure of productivity? Does productivity include more than
oxygen?
one of the most easily measured products of both photosynthesis and respiration, a good way to gauge primary productivity in an aquatic ecosystem is to measure dissolved oxygen.
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?
Photosynthesis putting a sample of pond water and algae/freshwater plants in the light enable us to measure gross productivity.
b. How does putting a sample of pond water and algae/freshwater plants in the dark enable us
to measure respiration?
Respiration putting a sample of pond water and algae/freshwater plants in the dark enable us to measure respiration.
c. How does subtracting the two enable us to indirectly measure net productivity?
To indirectly measure net productivity is photosynthesis minus respiration.
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
We actually did this part of the lab already. Remind yourself of our experiment, our procedures,
and our conclusions. We were investigating the effect of the physical factor of temperature on
the percent dissolved oxygen in a body of water.
6. What is the relationship between water temperature and dissolved oxygen?
The cooler the water, the more dissolved oxygen it can contain. This is one reason why areas of upwelling are so rich in sea life. Upwelling occurs along the western coasts of continents, where deep water rises to the surface, bringing with it that cold water, dissolved oxygen, and the abundant life that goes with it. However, note that this is not "bad" for the oceans of the Earth.
7. Explain why this relationship exists.
The warmer waters where there is less dissolved oxygen is where the phytoplankton bloom. The sunlight is abundant, and they produce oxygen for all of us to breathe. They do not require the same abundance of oxygen in the water.
8. So, now explain why the fish in the aquarium (on the LabBench Web site) above the radiator
died?
A saltwater aquarium, also known as an oceanarium, is an aquarium specifically for fish, mammals and plants that live and grow in the ocean
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.
Look at the experimental design on the LabBench Web site
(http://www.phschool.com/science/biology_place/labbench/lab12/model.html). 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 off sharply with increasing depth in an aquatic environment. You model this condition by wrapping water- with increasing layers of screen.
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?
When it O2 (used up in respiration) gose into the leaf, then it turn out on the other side which is O2 (given off in photosynthesis. It turn out 2 O2.
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?
On the side O2 (used up in respiration) two O2 gose into the leaf but it doesn't come out to the other side which is no photosynthesis occurs. On that side the amount of O2 is still the same.
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?
this time is different, the left side (O2 is used up in respiration) it have two of the O2 is go into the leaf but they goes one by one. the same with the first one, it came out to the other way (O2 is given off in photosynthesis, it go out two O2 per one O2 on the left side.
D . ANALYSIS OF RESULTS
Let’s 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.
Calculating respiratory rate is done best when the patient is not aware you are watching them breathe, as they tend to change the rate of respiration when they become self-conscious. Respiration is counted as part of vital signs --temperature, blood pressure, pulse and respiration - and are usually taken right after pulse while the caregiver is still holding the patient's wrist.
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.
So the illustration shows us 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 (the full photosynthetic
production in this ecosystem) of the algae in the bottle is the 5mg dissolved oxygen lost to
respiration added back to the 10 mg dissolved oxygen accumulated 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. And remember, the oxygen is an indirect measurement of the sugars
produced in photosynthesis and lost in respiration.
Now, in your own words, explain why this calculation works.
The 10 mg oxgen gained ( from photosynthesis) plus the 5 mg oxygen lost (to respiration) when I add the 10 mg to 5 mg then it equal 15 mg oxygen as gross pruductivity.
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.
Because water is both a reactant and a product, the equation can be simplified accounting for net water consumption, Photosynthesis is a lot more complicated than the simplified diagram above. Actually, photosynthesis doesn't actually produce glucose; rather, it produces a 3-carbon compound which is a precursor to glucose.
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.
I can't print the Sample Problem it because I can't see the picture, it not showing.
17. Print out the Lab Quiz and attach it to this lab to show me that you completed it.
1. D, A cold mountain stream dropping over a series of small rock falls.
2. C, Any intensity below 10%
3. A, It is a measure of the organic products of photosynthesis that accumulate after cellular respiration by those organisms is taken into account, and it is calculated by subtracting the amount of oxygen in the dark bottle from the amount in the light bottle.
4. C, The net productivity for culture A will be negative at greater light intensity than that for culture B.
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 can assume that the stream is a stream with a good current, so oxygen will get incoorperated with the water through turbulance. There is more turbulance in a stream than in a lake. This factor will result in higher concentrations of DO in a stream. Also, the overall temperature in a stream is lower because the sun cannot heat moving water as fast as it can heat non-mobile water.Both of these factors will result in a higher DO in the stream than in the lake.
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'm expect the DO to be lower in the morning. Photosynthesis doesn't occur at night and the DO would drop overnight due cell respiration.
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?
Both are considered limiting factors in vegetative growth. Both are two of the main components (potassium is the third) found in fertilizers. Nitrogen is necessary to make proteins, and it's a component of DNA and RNA molecules (it's found in the ATCG and U, which is why they're called 'nitrogenous bases'). Phosphorous is a part of the "energy currency" of every cell. Without enough nitrogen or phosphorous, the growth of plants and algae is limited, since they can't form as many new cells. If these elements are available in abundance, plants and algae can grow rapidly.
b. What is meant by algal bloom? (Look it up!)
An algal bloom or marine bloom or water bloom is a rapid increase in the population of algae in an aquatic system. Algal blooms may occur in freshwater as well as marine environments. Typically only one or a few phytoplankton species are involved and some blooms may be recognized by discoloration of the water resulting from the high density of pigmented cells.
c. What problems do algal blooms cause in ponds & lakes? Why isn’t a lot more producers a good thing?
(Look it up!)
Algae can range from microscopic, single-cell organisms tolarge structures that resemble full-fledged plants. Algae is almost always present in small amounts in freshwater lakes and ponds but when conditions are right the algae can bloom, causing significant issues for the pond and the other organisms living nearby.
d. What is meant by eutrophication? (Look it up!)
Eutrophication is the process of nutrient enrichment of water bodies and subsequentgrowth of plants on the surface of water.
21. At what depth—shallow or deep—will there be more primary productivity in a pond or a lake? Explain.
All production happens at the meeting of two phases. Water and air, water and dirt, leaf and sunlight, etc. I don't know what is considered "primary" but it has to be near the surface.
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
class data will be better because it have more idea and different kind of idea of different. Student group data is good but not good than class data it because they don't have idea, I mean they have some but not a lot like class data.
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 primary production (GPP) is the rate at which an ecosystem's producers capture and store a given amount of chemical energy as biomass in a given length of time. Some fraction of this fixed energy is used by primary producers for cellular respiration and maintenance of existing tissues.
b. Describe a method to determine net and gross primary productivity in a freshwater pond over a 24-
hour period.
Gross Primary Productivity- Total amount of chemical energy stored by photosynthesis. Net Primary Productivity- Remaining energy, which is available to the consumers as food.
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.
Basic on the graph that show me the net primary productivity the freshwater pound is going down which is depth of water (meters) . it go pass the line that is 0. The freshwater is going down which is not good because the is not going straight down but it going curly down.
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.
For the protein questions I explained different structures for protein, like primary, secondary, and tertiary. For the flower one, I explained self-incompatibility and genetic diversity. They would become overly dependent on insects, so they would develop prettier petals and more pleasing smells to attract. Also, some plants just develop male or female gametophyte (i.e. mango).
For the net productivity one, I basically explain the overall relationship displayed on the graph. The two variables form positive correlation; in other words, as one goes down, the other one goes down as well.