While eating lobster for dinner one night your friend asks what you think might happen if this marine invertebrate, which is normally isosmotic with respect to the surrounding seawater, were to be moved to a bay with a slightly lower salt concentration instead of being caught. You reply that, in order for the lobster to be isosmotic with respect to new environment,

Question

A.  it must move water in to match the solute concentration of its new environment.
B.  it regulates its internal concentration of solutes to match that of its new environment.
C.  it must move water out to match the solute concentration of its new environment.
D.  it moves water in or out and regulates its internal concentration of water as needed.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?

Gather Content
· What do you know about adaptation to a change in the salinity? What other information is related to the question?

Choose Answer
· Given what you now know, what information and/or problem solving approach 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

B.  it regulates its internal concentration of solutes to match that of its new environment.

Clarify Question
· What is the key concept addressed by the question?
        o The question asks about adaptation to a change in the salinity.
· What type of thinking is required?
        o You are being asked to apply your knowledge about adaptation to a change in the salinity.

Gather Content
· What do you know about adaptation to a change in the salinity? What other information is related to the question?
        o Some organisms that live in the ocean adjust their internal concentration of solutes to match that of the surrounding seawater. Because they are isosmotic with respect to their environment, no net flow of water occurs into or out of these cells.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o If the lobster allowed a lot of water to enter its body to keep the salt concentration equal to that of the surrounding water it would become swollen. Instead it adjusts its internal concentration of salts to maintain water balance.

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?
        o This question asked you to apply your knowledge about adaptation to a change in the salinity. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you think the lobster would take in large amounts of water to maintain salt balance?Did you think that the lobster could secrete water from its body?