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Questions tagged [osmosis]

The process by which a solvent, especially water, tends to flow towards areas of higher solute concentration.

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6
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1answer
564 views

Why do we have wrinkly fingers after swimming?

I found an explanation for my question here http://www.pitara.com/science-for-kids/5ws-and-h/why-do-we-have-wrinkly-fingers-after-swimming/, which suggests that water washes out sebum (special oil, ...
6
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1answer
571 views

Do saltwater fish need to drink? [duplicate]

In my biology class we got the question if saltwater fish need to drink. We need to use the term osmosis, but I cannot think of a valid answer and we were allowed to ask help.
5
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1answer
2k views

Can I kill bacteria with distilled water?

Given that bacteria are hypertonic (contain more salts) compared to distilled water, and that they rely on ion concentration differences across the plasma membrane to survive, can I kill a bacterial ...
5
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3answers
15k views

Why does a high osmotic pressure pull water in, yet a high hydrostatic pressure pushes water out?

When I normally think of high pressure, I think of it as pushing something away from the zone of high pressure. Yet for a high osmotic pressure, water is pulled IN to this high osmotic pressure ...
5
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2answers
11k views

Diffusion of Hypotonic solution into solution with glucose and starch

Cell walls are selectively permeable to ions and organic molecules. Sometimes the selectivity is passive and a reflection of the physical laws governing diffusion. We can do simple experiments that ...
5
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1answer
463 views

How does a Na+/H+ antiporter drive osmosis in this “osmotic motor”?

This recent paper in Cell describes a cancer cell using osmotic pressure to move in confined spaces. The cell preferentially inserts Na+/H+ antiporters in the leading membrane. I want someone to ...
4
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1answer
2k views

What happens to the red blood cell in CaCl₂ solution?

Here's the problem: One red blood cell is placed in a hypertonic solution of NaCl, another is placed in a solution of CaCl2 equimolar with the NaCl solution. What would you expect to happen and why? ...
4
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1answer
167 views

Can saltwater fishes survive in sugar solution?

I know saltwater fishes can't survive in freshwater because of osmosis that water would rush into the body of fishes. How about sugar solution? Does sugar solution provide similar conditions as salt ...
3
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1answer
254 views

Why don't cells of aquatic animals burst?

We know that if we keep plant cells in water, they don't burst because of a cell wall. But the cells of aquatic animals lack cell walls but they still survive. Why?
3
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2answers
6k views

Does osmosis take place in prokaryotic cells?

As far as I know, osmosis occurs in Eukaryotic cells, and I'm wondering if it could take place in prokaryotic cells too.
3
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1answer
109 views

Osmotic Pressure Clarification

My textbook states that the higher concentration of solutes, the greater the osmotic pressure will be and the greater the pull of water in will be. However, osmotic pressure is defined "as the ...
3
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2answers
4k views

Does osmosis require a protein channel?

Earlier today, I undertook an exam which featured a question regarding the stickiness of mucus in a person diagnosed with CF's. We had to explain why they had stickier mucus than a 'normal' person, ...
3
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2answers
54 views

Speed of electric signal vs chemical diffusion

I'm currently reading the book, "An Introduction to Nervous Systems" by Ralph J. Greenspan. On page 20, there is a sentence that confused me. It was, "Electrical signaling has the advantage of being ...
3
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1answer
34k views

What is the difference between osmotic potential and osmotic pressure?

Which term is used to calculate water potential? Does osmotic potential mean the same as solute potential?
2
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2answers
868 views

Osmotic Pressure and Enzyme Activity

Is it true that in an enzyme-catalyzed reaction, the rate of reaction does not vary with varying osmotic pressure? Instead of just a true or false answer, why does it, or why does it not vary with ...
2
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1answer
6k views

Osmolarity vs. Tonicity

We're learning about osmoregulation in AP Biology and the terms Tonicity and Osmolarity are really confusing me. I watched this video on Khanacademy to try to understand what the difference is, and ...
2
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1answer
238 views

Why is a urea solution hypotonic relative to RBC?

If I place a RBC in 0.5M urea we see haemolysis. My textbook says that "the solution is hypotonic. Urea enters the RBC down it's concentration gradient. Water follows the movement of urea by osmosis. ...
2
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2answers
6k views

Why do stomata close in salt water?

Why do the guard cells of the stomata close when they come in contact with salt water? I recognize it has something to do with osmosis and the fact that osmosis makes the water drain in some sort, ...
2
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2answers
2k views

How does the peptidoglycan layer of a bacterial cell wall help prevent osmotic lysis? [duplicate]

I recently read that penicillin works by damaging the peptidoglycan layers of a bacterial cell wall causing osmotic lysis, which is when the bacteria cell bursts due to osmotic pressure. I just ...
2
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1answer
2k views

When does DIFFUSION occur and not OSMOSIS, and the otherwise?

For example, I do know that red blood cells have both the Na+/Cl- co-transporter and Aquaporin (water channel) that allows both Na/Cl and water molecules to pass through. But why in biology textbooks ...
2
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0answers
27 views

Osmosis/ Facilitated diffusion

Water can move across the (Semipermeable non polar lipid) membrane by simple diffusion (osmosis). But polar molecules cannot pass through the non polar lipid bilayer, they require carrier proteins to ...
2
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0answers
74 views

Why does blood come out of leach when salt is put on it?

I know osmosis is the reason for the water to come out of cells - When you sprinkle salt over a leech, it creates concentration gradient and forces the water out of the cells. But why does a lot of ...
2
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1answer
201 views

Osmosis in red blood cells and bacteria

This is a question from an exam in my biology course. Bacterial cells and human red blood cells were inserted into one solution. Upon testing one hour later the blood cells exploded, while the ...
1
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1answer
974 views

What would kill you first water or cola? [closed]

After discussing this with some colleagues, I devised the theory that you could drink more coca-cola in a single sitting than you could water, without killing you. Defining the volume it would take ...
1
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1answer
105 views

Confused about definition of bulk flow of water by osmosis

As a teacher of high school and introductory college chemistry, I used textbooks that defined osmosis as a flow of water (only) through a membrane that prevents other substances such as dissolved ...
1
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1answer
29 views

Osmosis vs protein-binding in preserving foods through salting

I had assumed that the preservative function of covering foods with NaCl or brine was due to osmosis killing the microorganisms on the food by dehydration. However, I am now wondering to what extent ...
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3answers
2k views

when does osmosis stop

I have a question about osmosis that goes a bit deeper than most basic textbooks so I cannot find the answer.Here's the problem: Imagine an animal cell, say a red blood cell, in a slightly hypotonic ...
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1answer
2k views

Why does NaCl react differently with a boiled potato and with a raw one

Well my question is based on this question down below. For those who don't speak german: You have two potato slices one of them is boiled the other one is just raw. Now you scatter some salt over ...
1
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1answer
179 views

Trees ability to transport water [duplicate]

How can trees be able to transport hundreds of liters of water all the way up to the crown and out in the leaves?
1
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1answer
85 views

Is the PCT of the nephrons of the kidneys of marine vertebrates to minimize the natural tendency for exosmosis?

For marine vertebrates, the concentration of salts outside their body (in the water, that is) is more than that inside their body. So, there is a natural tendency for exosmosis to occur. To minimise ...
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0answers
93 views

Why does solute potential go up as temperatures go down?

So the closer a solution's solute potential is to zero, the more water potential said solution would eventually have. The solute potential equation is -iCRT. If the temperature is 0, -iCRT would be ...
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0answers
202 views

Why is ethanol osmotically active if it can enter through the plasma membrane easily?

This has been bugging me for a while, and I can't seem to find an answer to it, and I am sorry if I am asking a lot with this question(s). Firstly, I keep finding sources suggesting that ethanol is ...
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0answers
296 views

While preparing Jam we use sugar.Why? (can you elaborate in science language) [closed]

Actually I was trying to find out the basic necessity of adding sugar in preparing jam.
1
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1answer
858 views

How does an isotonic environment affect fish? [closed]

Fish receive oxygen needed from water that passes through their gills. If fish were isotonic to their watery environment, what problems would this pose to them?
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0answers
1k views

Solute potential of sucrose relative to NaCl

Does 1M NaCl or 1M sucrose solution have a more negative solute potential? I was thinking that for the same volume of solution, (eg 1 dm^3) there will be 2 mol of ions in NaCl solution and 1 mol of ...
1
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0answers
87 views

I am not understanding how water passes through root hair cells

Why do people say that water moves into the cell because the water concentration of the cell sap is low ? the cell sap is surrounded by a membrane so if any water moves into the cell it must be ...
1
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0answers
226 views

“Imperviate” is it a word what can be substituted? [closed]

Sentence: The aquaporins allow water to pass through the membrane and imperviate any solute molecules from diffusing across. I'm looking for a word that pretty much is the opposite of perviate or to ...
1
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0answers
53 views

Oncotic (Osmotic Pressure) in the blood pressure

I just wanted to ask, why is the oncotic pressure more negative in the blood plasma even though the hydrostatic pressure is higher since the blood comes from the pumping of the heart?
0
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1answer
34 views

Water potiental

I think solution x should be present at Z as this solution has moved out of cell causing cell to be plasmolysed but the answer is Y. How?
0
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1answer
97 views

Osmosis- basic questions [closed]

Hi there, For the first picture: can someone please explain in simple terms (I started learning biology a few days ago), why the answer to this osmosis question is no? For the second picture: The ...
0
votes
1answer
828 views

Why is it not advisable for humans to drink distilled water? [duplicate]

Distilled water is pure and it does not contain any minerals, so may not be advisable for drinking. Although laboratory made distilled water is completely pure, industry made water may still contain ...
0
votes
1answer
762 views

Why is the swelling of bread when placed in water not considered to be caused by osmosis? [closed]

Why is bread swelling up when placed in water not considered to be caused by osmosis? Is there a property of water that should make it leave the bread instead of enter?
0
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0answers
16 views

same osmotic pressure of different solution

For example, There is a sugar solution with concentration $A_{1}$, how to determine the concentration of a NaCl solution which produce same osmotic pressure as the previous sugar solution toward ...
0
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0answers
16 views

Can water travel through glycoprotein cell walls?

I'm a bit confused as to why the protist, Chlamydomonas, has contractile vacuoles if it has a cell wall like this. Is the glycoprotein still permeable to water?
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0answers
131 views

Do hydrogen ions contribute to water potential?

I was thinking about lysosomes and how they maintain an acidic pH inside themselves by pumping H+ ions from the cytosol. Do hydrogen ions set up a concentration gradient that causes water to move by ...
-1
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1answer
3k views

Osmotic Pressure in Capillaries [closed]

In this diagram, D is apparently the point at which "the osmotic pressure into the capillaries is the greatest", but I cannot figure out why. Any help would be much appreciated!
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1answer
362 views

What are internal and external osmotic pressures when referring to a cell?

I've seen the term used but cannot find a clear answer: What are internal and external osmotic pressures when referring to a cell?
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1answer
47 views

Question about osmosis

The concentration of water outside potatoes B and C is more than the concentration of water inside the potatoes. So water will flow inside the potato. Now, since the concentration of water in the ...