Solutions Problem Set 1) Which statement is NOT true?

M Membranes are often perforated by integral proteins. ESome membranes have proteins with channels to allow certain substances through. C Hydrophilic substances are unable to pass through the membrane. DThe current model of the membrane is described as a fluid mosaic model, fc The lipid bilayer serves as a hydrophobic barrier between two fluid regions.

2) The rate of diffusion through a semi-permeable membrane will be lowest when which of the following is (are) true? I. Concentration gradients are steep

II. Temperatures are low III. Solute molecules are small

A I only B II only C ill only j D II and ill only r I, II and III

3) A single-celled freshwater organism is moved to salt water. Which is most likely to happen? /\s

Salt will move out of the cell _ C Cell will shrink - r - . v O Enzymes will flow out of the cell t No change ^ •

4) Which statement is true? (assume isotonic means relative to human cells) A Movement of solvent occurs from the hypotonic solution into an isotonic solution. & Only solute moves from an isotonic solution to a hypotonic solution.

> C The concentration of solute is greater in an isotonic solution than in a hypertonic solution. \ The concentration of the solvent is greater in a hypertonic solution than in an isotonic soLi.w.,. ^ Osmosis involves on hypertonic solutions.

5) A cell that lacks external carbohydrate chains or glycoproteins would most likely be inefficient in ,4 transporting ions against an electrochemical gradient. (J) cell to cell recognition. C maintaining fluidity of the phospholipid bilayer. D attaching to the cytoskeleton. g establishing the diffusion barrier to charged particles.

6) A cell that lacks internal peripheral proteins vw)uld most likely be inefficient in A transporting ions against an electrochemical gradient. 6) cell to cell recognition. C maintainingfluidity of the phospholipid bilayer. "D attaching to the cytoskeleton. ^ establishing the diffusion barrier to charged particles.

/J Glucose diffuses slowly through an artificial phospholipid bilayer. The cells lining the small intestine, however, move large quantities of glucose rapidly into the blood stream. Which mechanism is functioning in these cells?

A Simple diffusion l3 Phagocytosis C Ion pumps P Exocytosis

Fadlltated diffusion

8)

9)

Two similar-sized animal cells are placed in a 0.5% sucrose (sugar) solution. Cell A enlarges in size for a while, then stops. Cell B continues to enlarge and finally ruptures. Which of the following was true at the beginning of the experiment?

Pi Cell A was hypotonic to the solution and cell B was hypertonic /"~\ Cell A was hypertonic to the solution and cell B was hypotonic - ' Cell A was hypertonic to cell B Ceil B was hypertonic to cell A , Cells A and B were isotonic to each other

6 C D t

A eel! with an internal concentration of 0.02 molar glucose is placed in a test tube containing 0.02 molar glucose solution. Assuming that glucose is not actively transported into the cell, which of the following terms describes the internal concentration of the cell relative to its environment?

isotonic \j hypertonic • ' C hypotonic • p A or B, depending on temperature ^ B or C, depending on temperature A t

Use the diagram of the U-tube set-up to answer the following 2 questions. The solutions in the two arms of this U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is filled with a solution of 2 M sucrose and 1IVI glucose. Side B is filled with 1 M sucrose and 2 M glucose.

2M sucrose IMglucose 2A<f glucose

Differentially permeable membrane

10) Initially, the solution in side A, with respect to the solution in side B, is f\. B plasmolyzed. C isotonic D saturated,

hypertonic.

11) After the system reached equilibrium, what changes are observed? A The concentration of sucrose and glucose are equal on both sides P) The concentration of glucose is higher in side A than in side B

The concentration of sucrose is increased in side A D The water level is unchanged > ^ The water level is higher in side A than side B. ,1 -

: 5 £ - 2 ~ :c answer the following question. Suppose i i«ataseiectve7 permeable membrane at the bottom of

£ tube is permeable to both glucose and NaCi in the same way that a plasma membrane of a cell is permeable to both. It takes the system 4 hours to reach equilibrium.

MembruB

12) In a few minutes, ,A The water level on side A would be higher than on side B. 6 Water would no longer move across the membrane. t The glucose and NaCI would be at equilibrium, but osmosis would continue. V More glucose than NaCi would have passed through the membrane. t More NaCI than glucose would have passed through the membrane.

The ^ides t of this Use the diagram of the

. f̂ollowing 3 question-V j)-tube are separated by a membrane that is permeable_̂ to

NaCI but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M NaCl. Side B is filled with 0.8M glucose and 0.4 M NaCI. Initiallv both volumes would be the same.

SIDE StDZ iBitUlisap B

t.lMffiaaae

Ucatanu

13) At the beginning of the experiment, A Side A is hypertonic to side B. 5 Side A is hypotonic to side B. C Side A is isotonic to side B. D Side A is hypertonic to side B with respect to glucose. F Side A is hypertonic to side B with respect to NaCI.

14) If you examine side A after 3 days, you should find A A decrease in the concentration of NaCI and glucose and an increase in the water level. 6 A decrease in the concentration of NaCI, an increase in the water level, and no change in the glucose. C- No net change in the system.-P A decrease in the concentration of NaCI and a decrease in the water level. f=̂ ' No change in the concentration of NaCI and glucose and an ipcrease in the water level.

15) At eouiltbrium, in side B, you would find A an increase in NaCI concentration but a decrease in glucose concentration.'" 16 a decrease in the concentration of glucose and NaCI. C peripheral proteins. ]> cholesterol. F glycoproteins.

6 5 _ 4 * 3 « 2

- 5

I"'

•1

ID 20 30 40 50 so Tone (minute^

16) Which line represents the bag that contained a solution isotonic to the 0.6 molar solution at the beginning of the experiment?

A A h B C c

17) Which line represents the bag with the highest initial concentration of sucrose? A A b ^ . . • o c ^

D E r P

18) Which line or lines represents b?gs that contain a solution that is hypertonic at the end of 60 minutes? A AandB fo B C c D D Cr DandE

19) Which line or lines represents bags that contain a solution that is isotonic at the end of 60 minutes? A 6 c D e

A and B BandC A, C and E Conly A, B, C, D, E

20) What is the best explanation for the shape of line e. after 50 minutes? f\r is no longer leaving the bag f> Water is not longer entering the bag G Water is leaving and entering the bag at the same rate p Water is entering the bag at the same rate that sucrose is leaving the bag. ^ Water is neither entering nor leaving the bag.