Potential energy is stored when a charge gradient is formedacross a
membrane. If holes are punched in the membrane and ions can movefreely
through these holes, what happens?
A. The ions move downtheir electro-chemical gradient, and the potential
energy is released as heat.
B. The ions move againstthe electro-chemical gradient, and work is performed.
C. The ions reachequilibrium across the gradient, and work is performed.
D. The ions move downtheir electro-chemical gradient, and work is performed.
Potential energy is stored when a charge gradient is formedacross a
membrane. If holes are punched in the membrane and ions can movefreely
through these holes, what happens?
| A. The ions move downtheir electro-chemical gradient, and the potential energy is released as heat. | |
| B. The ions move againstthe electro-chemical gradient, and work is performed. | |
| C. The ions reachequilibrium across the gradient, and work is performed. | |
| D. The ions move downtheir electro-chemical gradient, and work is performed. |
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Related questions
Cellular biology answer check. please check if my answers arecorrect or not.
1) The concentration of ions inside a cell is the same as theirconcentration outside of the cell. True or false? (i chose falsesince having equilibrium inside a cell is bad)
2) Membrane transport proteins...
| a)...transport membrane potentials between cells |
| b) | ...transport membranes from the ER to the Golgi |
| c) | ...are made up of phospholipids |
| d) | ...transport molecules across membranes |
i chose d
3)The electrochemical gradienttakes into account:
| a) | The concentration of solutes on either side of themembrane. |
| b) | The overall charge on either side of the membrane. |
| c) | Both of these. |
i chose C. (although i am sure that overall charge matters, Iwasn't sure if concentration of solutes are taken account.)
4) If no energywere expended by an animal cell:
| a) | Both gradients would be depleted |
| b)The K+ gradient would maintain itself. |
| c) | None of these |
| d) | The Na+ gradient would maintain itself. |
I chose d) mainly because I think Na+ gradient exist in animalcell and not K+ gradient.
5) Which of the following is a true statement aboutactin?
| a) | Once actin has polymerized, it never depolymerizes. |
| b) | Actin is a transmembrane protein. |
| c) | Actin can form branched networks. |
| d) | Actin filaments are organized into hollow tubes. |
I chose c. can't explain why.
6)Ion channels:
| a) | Form a hydrophobic channel through the membrane |
| b) | Have filters that let sugars through |
| c) | Are selective for particular ions (only the |
1A.
A <---> B
You measure the amount of molecules A and B for the reversible reaction above at a particular time point and find more of molecule A than of B. Your colleague believes that the reaction is at equilibrium. Which of the following statements about this reaction is correct? (select all that apply)
| A | A --> B is exergonic |
| B | B --> A is exergonic |
| C | B --> A is endergonic |
| D | A --> B is endergonic |
| E | Your colleague must be wrong. If the reaction were at equilibrium, there must be equal amounts of molecule A and B. |
1B. Which of the following is/are true of energy and chemical gradients? (select all that apply)
| A | A concentration gradient represents a form of potential (stored) energy. |
| B | Movement of a molecule down a concentration gradient across a membrane releases energy that can be used to do work. |
| C | If a molecules cross a membrane at equal rates in both directions (is at equilibrium) this movement is neither exergonic or endergonic. |
| D | Moving molecules against a concentration gradient is an endergonic process. |
