F.4 bio. osmosis

chi ming

2010-02-14 2:16 am

A raw potato was cut into the shape of a cup.Concentrated sucrose solution was put inside the well and the potato cup was immersed in a petri dish containing distilled water.

a)How did the sucrose solution level change after an hour?Explain your answer.
b)How will the sucrose solution level change if the potato is boiled?Explain your anwer.
c)In another experiment, a potato cup containing distilled water was put into a petri dish of sucrose solution.What was happened to the water level of the well after an hour?Why?

回答 (1)

wallace.

2010-02-14 3:13 am

✔ 最佳答案

a) The sucrose solution level rises. The water potential of sucrose solution is lower than that of distilled water. Water osmoses from distilled water to sucrose solution.
b) The sucrose solution level drops until both sucrose solution and distilled water reach the same level. Since the potato is boiled, its membrane is freely permeable instead of selectively permeable. Due to gravity, the sucrose solution drops.
c) The water level drops. The water potential of distilled water is higher than that of sucrose solution. Water osmoses from distilled water to sucrose solution.

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