1. Suppose you were having a party. You wish to serve crisp celery, but your cel

Question

1. Suppose you were having a party. You wish to serve crisp celery, but your celery has become limp, and the stores are closed. What might you do to make the celery crisp (turgid) again? Explain your answer. Refer to the diagram below to separated by a membrane that is permeable to w sucrose. Side B is filled with 20% sucrose. answer the following questions. The solutions in the two arms of the U-tube are 40% ater and but not to sucrose. Side A is filled with a solution o 40% sucr se 20% sucrose Selectively permeable membrane with respect to that in side B. c) saturated 2. Initially, the solution on Side A, is a)hypotonic b) isotonic d) hypertonic 3. Will the net flow of water be: Answer a) A to B b) B to A 4. Explain how a hydration shell will affect the movement of water. 5. After the system reaches equilibrium, what changes are observed? Choose Two Answers and a) The concentration of sucrose is equal on the both sides. b) The concentration of sucrose is higher in side A than in side B. c) The concentration of sucrose is increased in side B. d) The water level is unchanged in both sides e) The water level is higher in side A than in side B

Explanation / Answer

1) Two solutions having different solute concentrations when are kept seperate from each other by a selectively permeable membrane, the solvent from the region of its higher concentration gets transported to the region of its lower concentration until an equilibrium of the solute concentration is established. This process is called osmosis. Plant cells in hypoosmotic or hypotonic environment (where water concentration is higher) absorbs water and this influx of water causes the cells to expand and press against the cell walls. This ultimately stiffens the structure. So, celery becomes droopy when they get dehydrated. Therefore, in order to make celery crispy again one needs to immerse the celery sticks in a glass of pure water. After almost an hour, when water will get into the cells via osmosis, celery sticks will again become crispy or turgid.   

2) The solution on side A is hypertonic with respect to that in the side B. During osmosis, the solution with higher solute concentration is called hypertonic or hyperosmotic with respect to the solution of lower solute concentration. On the other hand the solution with lower solute concentration is called hypotonic or hypoosmotic with respect to the solution of higher solute concentration. When the concentrations of the two solutions become equal, then they are called isotonic or isoosmotic solution.

3. As the solute concentration in the side B is lower or the water concentration in the side B is higher in comparison to that in side A, therefore water will flow in the direction from B to A.

4. water is a polar molecule with a high dielectric constant. Therefore, it can dissolve a large spectrum of solutes and split them into their constituting ions. Thus, a three dimensional and continous cluster of water molecules gets formed surrounding the solute ions which is called hydration shell.Hydration shells allow the solute molecules to get dispersed evenly in water. Now, water molecules are constantly moving in a solution in a random manner but the presence of any solute restrict the free movement of water molecules. Therefore, when water forms "hydration shells" around a solute molecule, its activity (water potential) also goes down. Thus, with higher solute concentration water potential goes down. Saying a little elaborately, water molecules in the hydration shell can't move via osmosis regardless of what the concentration gradient is. Therefore, in the side A of the U-tube shown above there will be lesser number of free water molecules as more water molecules are in the form hydration shell around the solute whereas the the reverse is true in the side B where the concentration of water molecule is relatively high. Therefore, in order to osmosis takes place more free water molecules are required.     

5. When equilibrium is established then a) the concentration of sucrose becomes equal on the both sides and as the water will flow from B to A therefore e) the water level is higher in side A than in side B.     

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.