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제목 [Roy Lee] osmotic pressure
15 Lesson_15_Cell Membranes 15
작성자 goe*** 등록일 2020-03-16 오후 11:07:52
in the lecture,  i learned that in hypotonic solution, since cell has higher concentration than surrounding, H20 goes into the cell and in the hypertonic solution, since the cell's concentration is higher than surrounding, the cell shrinks. However, in the problem i sent, i found what i know is opposite. But since i checked what i know is correct or not, i am in a confused state. Could you explain this problem & concept one more time? thank you
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2020-03-17 오전 1:03:13

Hello!

 

You're sort of on the right track...

But let's back up and go over the basics one more time.

 

If the solution is hypotonic (compared to the cell), 

it means the cell is hypertonic (compared to the solution),

meaning water from the solution will move into the cell 

in order to lower the concentration.

 

If the solution is hypertonic, 

it means the cell is hypotonic,

meaning water from the cell will move into the environment

in order to lower the concentration.

 

The underlying principle of water flowing to equalize concentrations on both sides is exactly the same.

That's the definition of osmosis.

 

The words "hypertonic" or "hypotonic" are adjectives used to describe/compare the concentrations of two different things.

So in the question you sent me, pay attention to the main thing we are asked about.

The question is asking about the inside of the carrot cells.... compared to 2 different environments.

 

One environment is pure water. No salt concentration.

So the carrot cell is hypertonic to the solution.

 

The other is a salty solution. So salty that water from the cell moves out.

So the carrot cell is hypotonic to the solution.

 

 

A lot of students get confused about this point, so take a few minutes to sort your thoughts.

Think hard and let me know if you have other questions!  :D

 

 

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