Erythrocytes swell or shrink rapidly in response to changes in the osmolarity of the blood by moving water molecules through plasma membrane channels call aquaporins (aqp). aqp1 is a tetramer that consists of four identical monomers, each of which has a transmembrane pore. a human erythrocyte has approximately 2 × 105 aqp1 monomers and a total volume of 5 × 10–11 ml. water molecules flow through the plasma membrane at a rate of 5 × 108 molecules per aqp1 tetramer per second.

calculate the number of water molecules in an erythrocyte. assume that the erythrocyte consists entirely of water. calculate the amount of time that it takes for the erythrocyte to lose half of its volume of water when it encounters the high osmolarity (1 m) in the interstitial fluid of the renal medulla.

7. using your knowledge of colligative properties explain whether sodium chloride or calcium chloride would be a more effective substance to melt the ice on a slick sidewalk. use 3 – 4 sentences in your explanation. 8. when a 2.5 mol of sugar (c12h22o11) are added to a certain amount of water the boiling point is raised by 1 celsius degree. if 2.5 mol of aluminum nitrate is added to the same amount of water, by how much will the boiling point be changed? show all calculations leading to your answer or use 3 – 4 sentences to explain your answer. 9. if 5.40 kcal of heat is added to 1.00 kg of water at 100⁰c, how much steam at 100⁰c is produced? show all calculations leading to an answer. 10. the freezing of water at 0⁰c can be represented as follows: h2o (l) ↔ h2o(s) the density of liquid water is 1.00 g/cm3. the density of ice is 0.92 g/cm3. in 3 – 4 sentences explain why applying pressure causes ice to melt.

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation: