Exam 2 Instapolls, Homework, AE Sep 22-Oct 7

3. As they cool down slowly which membranes will remain more fluid and flexible?

A. phospholipids with saturated H-C chains

B. phospholipids with unsaturated H-C chains

B. phospholipids with unsaturated H-C chains

double bonds and kinks make it looser

4. As they cool down slowly, which membranes will remain more fluid and flexible

A. membranes containing cholesterol

B. membranes with no cholesterol

A. membranes containing cholesterol

Membranes with cholesterol stay more fluid as they cool because cholesterol disrupts the regular packing of phospholipids, preventing them from solidifying. So, membranes containing cholesterol remain more fluid and flexible at lower temperatures.

5. Glucose cannot cross simply through the phospholipid bilayer because glucose is

A. hydrophobic

B. small, uncharged polar

C. large, uncharged polar

D. an ion

C. large, uncharged polar

6. A sodium ion cannot cross simply through the phospholipid bilayer because it is

A. hydrophobic

B. small, uncharged polar

C. large uncharged polar

D. an ion

D. an ion

7. A solution of 0.5M sodium ions (Na+) is on side A of a cell membrane, and a 0.2M Na+ solution is on side B. If the membrane contains sodium ion channel proteins (allowing Na+ diffusion), there would be a net movement of sodium ions in which direction?

A. from side A to side B

B. from side B to side A

C. no net movement

A. from side A to side B

Sodium ions move from high concentration to low concentration by diffusion. Side A has 0.5M Na+, side B has 0.2M Na+, so Na+ moves from A to B to equalize concentration. That’s why the answer is A.

8. What net movement would occur if there were no Na+ ion channels in the semi-permeable membrane?

A. water

B. Na+

C. both

D. neither

A. water

9. which best describes the movement of water through an aquaporin?

A. Water is pumped across the membrane

B. Water diffuses across the phospholipid bilayer

C. Water diffuses through a passive channel

D. Two of these correctly describe it

C. Water diffuses through a passive channel

10. Which describes the net movement of water across a membrane?

A. Net movement towards higher solute concentration

B. Net movement towards lower solute concentration

A. Net movement towards higher solute concentration

2. The net movement of water will be in which direction across a membrane that is permeable to water but not to sucrose?

Side X  0.4M sucrose

Side Y. 0.8M sucrose

A. from X to Y

B. from Y to X

C. No net movement of water

D. water will move only if sucrose moves

E. I have no idea

A. from X to Y

3. Which kind of cell "work" can a solute gradient do?

A. Moving water by osmosis

B. Pumping water using ATP

C. Pumping solute using ATP

D. Two of these

A. Moving water by osmosis

4. How can an electrical charge gradient across a membrane do cell work?

A. Moving water by osmosis

B. Pumping water using ATP

C. Pumping solutes using ATP

D. Pumping ions using ATP

E. Moving ions through passive ion channels

E. Moving ions through passive ion channels

5. How could a cell use ATP indirectly to pump water across a membrane?

A. Aquaporins can pump water across using ATP.

B. Na+ ion pumps use ATP to build a solute gradient and water follows

C. Water crosses through the phospholipid bilayer by osmosis

D. Two of these are true

B. Na+ ion pumps use ATP to build a solute gradient and water follows

6. When Na+ ions move from outside to inside, which of the following happens?

(A) inside becomes relatively more positive

(B) inside becomes relatively more negative

(C) there is no change in electrical charge

(A) inside becomes relatively more positive

7. If Na+ ion channels open, the membrane will tend to 

A. depolarize

B. hyperpolarize

A. depolarize (positive to negative)

8. If Cl- ion channels open, the membrane will tend to

A. depolarize

B. hyperpolarize

B. hyperpolarize

2. Which of the following describes the action of the sodium-potassium pump with respect to ion concentration gradients?

 

A. transports Na+ ions against (up) their gradient and K+ ions down (with) their gradient

 

B. transports K+ ions against their gradient and Na+ ions down their gradient

 

C. transports both Na+ ions and K+ ions down their gradients

 

D. transports both Na+ ions and K+ ions against their gradients

D. transports both Na+ ions and K+ ions against their gradients

3. With the co-transport protein shown, what is the source of energy moving H+ into the cell down its concentration gradient?

 

A. Diffusion of H+ ions

 

B. Diffusion of sucrose

 

C. ATP hydrolysis.

A. Diffusion of H+ ions

4. With the co-transport system pictured here, what is the source of energy to move sucrose into cell against its concentration gradient?

 

A. Diffusion of H+ ions

 

B. Diffusion of sucrose

 

C. ATP hydrolysis

A. Diffusion of H+ ions

5. Look at the concentration gradients in this figure. What happens when passive Na+ channels open?

 

A. Na+ ions flow into the cell

 

B. Na+ ions flow out of the cell

 

C. There’s no net movement of Na+

A. Na+ ions flow into the cell

1. In energy terms, which of these terms mean the same as "entropy"?

A. randomness

B. disorder

C. A and B

D. Neither A nor B

C. A and B

2. Which pairing correctly matches the term with its delta G value?

A. Endergonic reaction—negative deltaG; exergonic reaction—positive deltaG

B. Endergonic reaction—positive deltaG; exergonic reaction—negative deltaG

C. Both endergonic and exergonic reactions have negative deltaG

D. endergonic and exergonic reactions describe delta H not delta G

B. Endergonic reaction—positive deltaG; exergonic reaction—negative deltaG

3. Which of the following describes an endergonic reaction?

A. Reactants contain more potential energy than the products. delta G is negative

B. There is a net release of energy during the reaction

C. Energy from the surroundings is required; reaction is non-spontaneous

C. Energy from the surroundings is required; reaction is non-spontaneous

4. Which of these is associated with an exergonic spontaneous process?

A. positive delta G

B. negative delta G

C. change in free energy

D. A and C

E. B and C

E. B and C

5. Which one of these states has higher free energy?

A. high entropy

B. high enthalpy

C. high randomness

B. high enthalpy

6. With energy-coupled reactions, what is happening?

A. Exergonic process is driven by energy from endergonic process

B. Endergonic process is driven by energy from exergonic process

C. Exergonic and endergonic processes must occur near each other in time and space

D. A and C

E. B and C

E. B and C

7. Can these reactions be energetically coupled and proceed?
[please see reactions on the slide]

A. yes

B. no

A. yes

8. Can these reactions be energetically coupled and proceed?

A. yes

B. no

B. no

9. Consider the list of reactions A-D listed on the slide. Can one or more of these be energy coupled and driven by the reaction   A + B -> C + D.   delta G= -6 kcal/mol

Choose the letter of the reaction farthest down the list that can be driven by that reaction 

A. reaction 1

B. reaction 2

C. reaction 3

D. reaction 4

B. reaction 2