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In what way do the membranes of a eukaryotic cell vary? |
Certain proteins are unique to each membrane. |
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According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly |
embedded in a lipid bilayer. |
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Which of the following factors would tend to increase membrane fluidity? |
a greater proportion of unsaturated phospholipids |
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Which of the following processes includes all others? |
passive transport |
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Based on Figure 7.18, which of these experimental treatments would increase the rate of sucrose transport into the cell? |
decreasing extracellular pH |
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Which of the following cell structures exhibits selective permeability between a cell and its external environment? |
the plasma membrane |
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Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct? |
Phospholipids form a selectively permeable structure. |
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The plasma membrane is referred to as a "fluid mosaic" structure. Which of the following statements about that model is true? |
The fluid aspect of the membrane is due to the lateral and rotational movement of phospholipids, and embedded proteins account for the mosaic aspect. |
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Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the plasma membrane would cholesterol most likely be found? |
in the interior of the membrane |
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Which of the following is NOT a function of membrane proteins? |
energy, carbon, and nitrogen storage |
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Which of the following functions of membrane proteins is important in tissue formation during embryonic development in animals? |
Membrane proteins with short sugar chains form identification tags that are recognized by other cells. |
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Which of the following statements concerning carbohydrates associated with the plasma membrane is correct? |
Membrane carbohydrates function primarily in cell-cell recognition. |
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Consider the currently accepted fluid mosaic model of the plasma membrane. Where in the membrane would carbohydrates most likely be found? |
on the outside (external) surface of the membrane |
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Which of the following molecules is most likely to passively diffuse across the plasma membrane? |
carbon dioxide |
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Which of the following would be LEAST likely to diffuse through a plasma membrane without the help of a transport protein? |
a large, polar molecule |
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Which of the following statements about passive transport is correct? |
Passive transport permits the solute to move in either direction, but the net movement of solute molecules occurs down the concentration gradient of the molecule. |
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Cells A and B are the same size, shape, and temperature, but cell A is metabolically less active than cell B. and cell B is actively converting oxygen to water in cellular respiration. Oxygen will diffuse more rapidly into cell __________ because __________. |
B … the diffusion gradient in cell B is steeper |
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Which of the following statements about diffusion is true? |
It is a passive process. |
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Which of these statements describes some aspect of facilitated diffusion? |
Facilitated diffusion of solutes may occur through channel or transport proteins in the membrane. |
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Which of the following is FALSE in regard to facilitated diffusion? |
Facilitated diffusion requires the hydrolysis of ATP. |
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Active transport requires an input of energy and can also generate voltages across membranes. Based on this information, which of the following statements is true? |
The sodium-potassium pump hydrolyzes ATP and results in a net positive change outside the cell membrane. |
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Glucose can be moved into cells via an active transport mechanism when the concentration of glucose inside the cell is higher than the concentration of glucose outside of the cell. This active transport mechanism moves glucose and sodium into the cell at the same time. The glucose moves up its gradient and the sodium moves down its gradient. Which of the following statements about this mechanism is accurate? |
To pump glucose up its concentration gradient, sodium moves down its concentration gradient, and the distribution of sodium ions across the membrane forms an electrochemical gradient that drives this mechanism. |
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Which of the following is a correct difference between active transport and facilitated diffusion? |
Active transport requires energy from ATP, and facilitated diffusion does not. |
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Which of the following statements about the sodium-potassium pump is correct? |
The sodium-potassium pump moves Na+ and K+ in opposite directions, resulting in a net negative charge inside the cell. |
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Which of the following enables a cell to pick up and concentrate a specific kind of molecule? |
receptor-mediated endocytosis |
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Which of the following processes and organelles account for the replacement of lipids and proteins lost from the plasma membrane? |
exocytosis and smooth ER and rough ER |
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A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother’s milk. These molecules probably enter the cells lining the baby’s digestive tract via which process? |
endocytosis |
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Which of the following pairs correctly matches a membrane transport process to its primary function? |
pinocytosis: the uptake of water and small solutes into the cell by formation of vesicles at the plasma membrane |
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