Retake Objective 5: Stability, change, and biodiversity.

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7 questions

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This is a two part question: Which ecosystem has more biodiversity? Explain how you know!

Which of the following provides evidence to support the claim: If all the phytoplankton were killed in both ecosystems, ecosystem A would remain more stable.

In ecosystem A phytoplankton are the only producer, in ecosystem B phytoplankton are not the only producers. 

In ecosystem A, the phytoplankton are the energy source for krill. In ecosystem B the phytoplankton is the food source for penguins.   

In ecosystem A the absence of phytoplankton would result in the absence of 6 species, in ecosystem B the absence of phytoplankton would result in the absence of all species.

In ecosystem A the absence of phytoplankton would result in the absence of all species, in ecosystem B the absence of phytoplankton would result in the absence of all species except the whale. 

Which of the following statements would be included in a reasoning that supports the claim: This ecosystem would not remain stable if the wolves were removed. SELECT 1 ANSWER!

If the voles were removed, the elk and coyote would keep the grass grains and fruits in check.

If the voles were removed the gray wolves would die.

If the wolves were removed the elk, coyote and vole would increase in population but not drastically.

If the wolves were removed the elk, coyote and vole would increase to too large of a population size that they would completely destroy all the grass grains and fruits and eventually decrease in population size themselves due to overgrazing. (Just like the rabbits did that were introduced to Australia)

If the voles were removed, the grasses, grains and fruits would grow out of control.

If the voles were removed the gray wolves would eat coyote or elk instead.

This is a two part question. In the ecosystem pictured, which of the following would result in the LARGEST decrease in BIODIVERSITY? Explain your reasoning in GREAT detail!
A. A virus wiping out the seaweed population.
B. A bacteria infesting all the crabs.
C. A fisherman killing 10 fish in one day.
D. A Dead Zone as described in question 7

Which graph below represents the response of the rainbow trout population to a ban on fishing? Note: The star in each graph marks the start of the fishing ban. You may add a comment to defend your answer, but you don't have to---sometimes you can select the wrong answer but defend it well enough that I can mark it correct.

A

B

C

D

Students looked at the evidence below, they made a claim to answer the question: Which factor below is the main factor leading to the decreasing clarity in Lake Tahoe? They then wrote a reasoning to support their claim. Which students' answer is BEST?

Secchi disk data showing the clarity in Lake Tahoe over time.

Graph showing the clarity of Lake Tahoe in relationship to the Mysis Shrimp presence. The first caption is from 2011.

This graph shows the nitrogen concentration in Lake Tahoe from runoff, over time.

This graph shows the phosphorous concentration in Lake Tahoe from runoff, over time.

Sediment:

Suzi: Nitrogen runoff is the main cause of the decreasing clarity in Lake Tahoe. Overtime, the clarity in Lake Tahoe decreases as the secchi disk can be seen less and less deep down each year. Overtime, nitrogen runoff increases as the amount of nitrogen in the Lake recently reached a high of 20 micrograms per liter. Clearly, nitrogen levels are the largest factor responsible for the lack of clarity in Lake Tahoe. 

Kelly: Mysis Shrimp are the main cause of the decreasing clarity in Lake Tahoe. Overtime, the clarity in Lake Tahoe decreases as the secchi disk can be seen less and less deep down each year. Mysis Shrimp populations have risen in population size each year since their introduction in the 1960's just as clarity has decreased in that time. It is clear this is the factor responsible for the lack of clarity in Lake Tahoe because unlike the other factors, shortly after 2011 when the Mysis shrimp disappeared, the Lake clarity increased in 2014. Then when the shrimp were back, the Lake Clarity decreased again. This factor shows a stronger correlation, than all the others, with the clarity data.  

Tom: Phosphorous runoff is the main cause of the decreasing clarity in Lake Tahoe. Overtime, the clarity in Lake Tahoe increases as the secchi disk can be seen less and less deep down each year. Overtime, phosphorous runoff decreases as the amount of phosphorous in the Lake recently reached a low of 1.5 micrograms per liter. Clearly, nitrogen levels are the largest factor responsible for the lack clarity in Lake Tahoe.

Mackenzie: Sediments are the main cause of the decreasing clarity in Lake Tahoe. The images show what an ecosystem with high sediment runoff accumulation looks like and what that of Lake Tahoe currently looks like. These images look very similar so we can assume the sediment from excessive rainfall and parking lots are the cause of the decreasing clarity in Lake Tahoe. 

What evidence could BEST be used to support the claim: Dead zones decrease biodiversity in ecosystems as stability is not able to be maintained.

Bacteria perform cellular respiration as they decompose algae and plants. In this process they take in oxygen from the water and expel carbon dioxide. 

Nitrates from fertilizers on farms get washed into a lake, this causes algae populations to rise. 

Algae populations decrease after nutrients start to run out.  

With all the oxygen depleted by overpopulation of bacteria, all the animals in the dead zone suffocate and die. 

Which of the following provides evidence to support the claim: If all the phytoplankton were  killed in both ecosystems, ecosystem A would remain more stable. 

In ecosystem A phytoplankton are the only producer, in ecosystem B phytoplankton are not the only producers. 

In ecosystem A, the phytoplankton are the energy source for krill. In ecosystem B the phytoplankton is the food source for penguins.   

In ecosystem A the absence of phytoplankton would result in the absence of 6 species, in ecosystem B the absence of phytoplankton would result in the absence of all species.

In ecosystem A the absence of phytoplankton would result in the absence of all species, in ecosystem B the absence of phytoplankton would result in the absence of all species except the whale. 

Which of the following statements would be included in a reasoning that supports the claim: This ecosystem would not remain stable if the wolves were removed. SELECT 1 ANSWER! 

If the voles were removed, the elk and coyote would keep the grass grains and fruits in check.

If the voles were removed the gray wolves would die.

If the wolves were removed the elk, coyote and vole would increase in population but not drastically.

If the wolves were removed the elk, coyote and vole would increase to too large of a population size that they would completely destroy all the grass grains and fruits and eventually decrease in population size themselves due to overgrazing. (Just like the rabbits did that were introduced to Australia)

If the voles were removed, the grasses, grains and fruits would grow out of control.

If the voles were removed the gray wolves would eat coyote or elk instead.

Which graph below represents the response of the rainbow trout population to a ban on fishing? Note: The star in each graph marks the start of the  fishing ban. You may add a comment to defend your answer, but you don't have to---sometimes you can select the wrong answer but defend it well enough that I can mark it correct. 

A

B

C

D

Students looked at the evidence below, they made a claim to answer the question: Which factor below is the main factor leading to the decreasing clarity in Lake Tahoe? They then wrote a reasoning to support their claim. Which students' answer is BEST?  

Secchi disk data showing the clarity in Lake Tahoe over time. 

Graph showing the clarity of Lake Tahoe in relationship to the Mysis Shrimp presence. The first caption is from 2011. 

This graph shows the nitrogen concentration in Lake Tahoe from runoff, over time. 

This graph shows the phosphorous concentration in Lake Tahoe from runoff, over time. 

Sediment:

Suzi: Nitrogen runoff is the main cause of the decreasing clarity in Lake Tahoe. Overtime, the clarity in Lake Tahoe decreases as the secchi disk can be seen less and less deep down each year. Overtime, nitrogen runoff increases as the amount of nitrogen in the Lake recently reached a high of 20 micrograms per liter. Clearly, nitrogen levels are the largest factor responsible for the lack of clarity in Lake Tahoe. 

Kelly: Mysis Shrimp are the main cause of the decreasing clarity in Lake Tahoe. Overtime, the clarity in Lake Tahoe decreases as the secchi disk can be seen less and less deep down each year. Mysis Shrimp populations have risen in population size each year since their introduction in the 1960's just as clarity has decreased in that time. It is clear this is the factor responsible for the lack of clarity in Lake Tahoe because unlike the other factors, shortly after 2011 when the Mysis shrimp disappeared, the Lake clarity increased in 2014. Then when the shrimp were back, the Lake Clarity decreased again. This factor shows a stronger correlation, than all the others, with the clarity data.  

Tom: Phosphorous runoff is the main cause of the decreasing clarity in Lake Tahoe. Overtime, the clarity in Lake Tahoe increases as the secchi disk can be seen less and less deep down each year. Overtime, phosphorous runoff decreases as the amount of phosphorous in the Lake recently reached a low of 1.5 micrograms per liter. Clearly, nitrogen levels are the largest factor responsible for the lack clarity in Lake Tahoe.

Mackenzie: Sediments are the main cause of the decreasing clarity in Lake Tahoe. The images show what an ecosystem with high sediment runoff accumulation looks like and what that of Lake Tahoe currently looks like. These images look very similar so we can assume the sediment from excessive rainfall and parking lots are the cause of the decreasing clarity in Lake Tahoe. 

What evidence could BEST be used to support the claim: Dead zones decrease biodiversity in ecosystems as stability is not able to be maintained. 

Bacteria perform cellular respiration as they decompose algae and plants. In this process they take in oxygen from the water and expel carbon dioxide. 

Nitrates from fertilizers on farms get washed into a lake, this causes algae populations to rise. 

Algae populations decrease after nutrients start to run out.  

With all the oxygen depleted by overpopulation of bacteria, all the animals in the dead zone suffocate and die. 