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From a Kaplan subject test, don't know why they give 5 choices, but whatever.
3. The contractile vacuole of Euglena decreases its rate of contraction when the organism is transferred from fresh water to sea water. This is explained by
A. an increase in the osmotic pressure of the environment.
B. a decrease in the osmotic pressure of the environment.
C. the nitrogenous wastes can remain in the cell because of a higher salt concentration outside the cell.
D. excess salts are eliminated without the loss of water.
E. salt inhibits the contractile apparatus.
What would you say?
Answer is B.
I thought it was A, since it says "of the environment."
I thought osmotic pressure was the pressure to bring water in, and since there is a higher concentration of solute in the environment, there would be a greater osmotic pressure in the environment.
I think the osmotic pressure inside would remain the same, while the osmotic pressure on the outside would increase and so that is why net movement is outside.
Hydrostatic pressure on the inside increases as well... so is hydrostatic pressure on the inside = osmotic pressure on the outside???
3. The contractile vacuole of Euglena decreases its rate of contraction when the organism is transferred from fresh water to sea water. This is explained by
A. an increase in the osmotic pressure of the environment.
B. a decrease in the osmotic pressure of the environment.
C. the nitrogenous wastes can remain in the cell because of a higher salt concentration outside the cell.
D. excess salts are eliminated without the loss of water.
E. salt inhibits the contractile apparatus.
What would you say?
Answer is B.
I thought it was A, since it says "of the environment."
I thought osmotic pressure was the pressure to bring water in, and since there is a higher concentration of solute in the environment, there would be a greater osmotic pressure in the environment.
I think the osmotic pressure inside would remain the same, while the osmotic pressure on the outside would increase and so that is why net movement is outside.
Hydrostatic pressure on the inside increases as well... so is hydrostatic pressure on the inside = osmotic pressure on the outside???
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