pltw biology (MEMBRANE)
The solutions in the two arms of this U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal. Which are the most likely results for side A after it sits for 3-days?
1.5 M sucrose, 1.5 M glucose
Which of the following statements is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal?
A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose.
The sodium glucose symporter is a great example of a membrane co-transport system. Which accurately describes how it works?
Energy is used to push sodium ions against their concentration gradient. When these ions flow back in, that energy is used to transport glucose.
A researcher notices that as her test cell fills up with greater concentrations of magnesium, it also increases its levels of ADP. What is the best inference given these findings?
Magnesium moves across membranes in an active transport system
A phospholipid bilayer with equal amounts of saturated and unsaturated fatty acids displays a specific permeability to glucose. What effect will increasing the proportion of unsaturated fatty acids in the bilayer have on the membrane's permeability to glucose?
Permeability to glucose will increase.
A patient was involved a serious accident and lost a large quantity of blood. In an attempt to replenish body fluids, distilled water—equal to the volume of blood lost—is added to the blood directly via one of his veins. What will be the most probable result of this transfusion?
The patient's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells.
Vesicles are an important mechanism for transporting molecules around the cell and into and out of the cell. Which structural feature allows them to transport materials across these different areas?
They are essentially a bubble of phospholipids that can merge with other bubbles of phospholipids like the cell membrane and organelle membranes to deliver their contents.
The sodium potassium pumps found in the cell membranes of cells can best be categorized as....
active transport
For a protein to be an integral membrane protein, it would have to be ________.
amphipathic, with at least one hydrophobic region
Which of the following types of molecules lack hydrophilic domains?
cholesterol
The membranes of winter wheat are able to remain fluid when it is extremely cold by ________.
increasing the proportion of unsaturated phospholipids in the membrane
Which of the following membrane activities requires energy from ATP hydrolysis?
movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid
A sodium-potassium pump ________.
moves three sodium ions out of a cell and two potassium ions into a cell using energy from ATP hydrolysis
If you forget to water a potted plant, its leaves wilt. A likely reason for this wilting is that
vacuoles lose water, reducing the turgor pressure in the cells.