Bio-111 Quiz Questions Ch 6-

6. Ions diffuse across membranes through specific ion channels down ________. a) their electrochemical gradients b) their concentration gradients c) their electrical gradients d) the osmotic potential gradients e) their chemical gradients

a)

5. Which of the following is TRUE of osmosis? a) In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration. b) Osmosis only takes place in red blood cells. c) In osmosis, solutes move across a membrane from areas of lower water concentration to areas of higher water concentration. d) Osmosis is an energy-demanding or "active" process.

a) In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

4. Which of the following factors would tend to increase membrane fluidity? a) a relatively high protein content in the membrane b) a greater proportion of unsaturated phospholipids c) a lower temperature d) a greater proportion of saturated phospholipids e) a greater proportion of relatively large glycolipids compared with lipids having smaller molecular masses

b) a greater proportion of unsaturated phospholipids

7. Under what circumstances does membrane transport require energy? a) whenever an ion moves through a phospholipid bilayer membrane b) whenever a solute is moved against its electrochemical gradient c) whenever oxygen moves through a phospholipid bilayer membrane d) wherever large molecules are moved within a cell

b) whenever a solute is moved against its electrochemical gradient

3. The membranes of winter wheat are able to remain fluid when it is extremely cold by ________. a) cotransport of glucose and hydrogen b) using active transport c) increasing the percentage of unsaturated phospholipids in the membrane d) decreasing the number of hydrophobic proteins in the membrane e) increasing the percentage of cholesterol molecules in the membrane

c) increasing the percentage of unsaturated phospholipids in the membrane

2. Which of the following crosses lipid bilayers the fastest? a) a sodium ion b) a large, polar molecule like glucose c) a small, polar molecule like water d) a small, nonpolar molecule like oxygen (O2)

d) a small, nonpolar molecule like oxygen (O2)

1. Lipids that form membranes have what kind of structure? a) polar heads and polar tails, which allows them to interact with water on both sides of the membrane b) polar heads and nonpolar tails; the nonpolar tails interact with water c) completely polar, which allows them to dissolve in water d) polar heads and nonpolar tails; the polar heads interact with water

d) polar heads and nonpolar tails; the polar heads interact with water