MOD 1: Cell membrane Function, Lec 7 & 8, L. Lluka

Question 1

Ionic chemicals, such as Na+ and phosphate (PO4 ^3-),

A. are lipophilic
B. have low solubility in water
C. can readily move across membranes by passive diffusion
D. are hydrophobic
E. prefer to dissolved in aqueous solutions rather than lipid environments

Answer 1

E. prefer to dissolved in aqueous solutions rather than lipid environments -

Question 2

What are the osmolarities of the following soltions in order: 1. 1 M glucose, 2. 150 mM NaCl, 3. a solution containing 100 mM fructose and 25 mM MgCl2 (in mOsmol/l)?

A. 1, 150 and 125
B. 1, 300 and 100
C. 1000, 150 and 125
D. 1000, 300 and 175
E. cannot be calculated from the information given

Answer 2

D. 1000, 300 and 175

(1M of glucos = 1000 mOsmol/l), 150 dobles, so 300; 100 stays the same + 3 x 25)

Question 3

Compare the tonicities of each of the following with the contents of red blood cells:

1. water, 2. 150 mM NaCl and 3. a solution containing 50 mM fructose + 250 mM ethanol.

Which statement is CORRECT?

A. 1. and 3. are hypotonic
B. 2. and 3. are isotonic
C. 3. is hypotonic, 2. is isotonic and 1. is isotonic
D. 1. and 3. are hypotonic and 2. is isotonic
E. 1. 2. and 3. are all isotonic

Tip:

Answer 3

D. 1. and 3. are hypotonic and 2. is isotonic

Beacause: Water is hypotonic; 150 mM of NaCl is isotonic; and 50 mM of Fructose is