What is the likely outcome if you were able to force water through fish gills in the opposite direction to how it normally flows over the gills?

Question

A.  There would be no effect, and maximal oxygenation of blood would still occur.
B.  The direction of blood flow would reverse through the gills to compensate for the reversed direction of water flow.
C.  Gas exchange would be inhibited and movement of oxygen into the blood would cease.
D.  The movement of carbon dioxide from the blood into the water would increase.
E.  The blood's oxygen concentration would not be able to exceed 50%.

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?
 
Gather Content
What do you already know about fish gills? What other information is related to the question?

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
 
Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

E.  The blood's oxygen concentration would not be able to exceed 50%.

Clarify Question
What is the key concept addressed by the question?
        · The question is asking you to apply what you know about fish respiration a new situation.
What type of thinking is required?
        · Apply level:
            o You are being asked to take what you already know apply, it to the reversal of water flow over fish gills.
 
Gather Content
What do you already know about fish gills? What other information is related to the question?
        · Water flows from the gill arch over the gill filaments.
        · The direction of water is the opposite of the direction of blood flow.
        · The countercurrent nature of the water and blood flow allows efficient gas exchange to occur, since equilibrium of oxygen levels cannot be reached.
 
Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
        · If water flow was reversed so that water and blood ran in the same direction in a fish gill, diffusion of oxygen would stop when the water and blood reached equal oxygen levels, which would be 50% oxygen in each. Once that point is reached, not further diffusion of oxygen would occur.
 
Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        · Apply level:
            o Answering this question correctly depended on your ability to use the principles of fish respiration in a new situation. If you got an incorrect answer, did you remember that the opposing nature of water flow in fish gills is necessary to maximize gas exchange, or that changing the direction of water flow would remove this advantage? Did you have trouble extending the principles of fish respiration to determine the correct answer?