CH 7 AP Bio
Active transport requlres a cell to expend energy. Which of the following statements is true?
All of the above
The internal solute concentration of a plant cell is about 0.8 M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution?
1.0 M
Green olives may be preserved in brine, which is a 30% salt solutlon. How does this method of preservation prevent contamination by microorganisms?
A 30% salt solution is hypertonic to the bacteria, so they lose too much water and cannot survive.
Which of the following is (are) true about facilitated diffusion?
All of the above
Cells A and B are the same size, shape, and temperature, but cell A is metabolically quiet and cell B is actively consuming oxygen. Oxygen will diffuse more quickly into cell ____ because _____
B ... the diffusion gradient in cell B is steeper
Which of these statements describes some aspect of facilitated diffusion?
Facilitated diffusion of solutes may occur through channel or transport proteins in the membrane.
Which one of the following statements about diffusion Is true?
It is a passive process.
Which one of the following statement concerning carbohydrates associated with the plasma membrane is correct?
Membrane carbohydrates function primarily in cell-cell recognition.
Which one of the following statements about the sodium-potassium pump is correct?
The sodium-potassium pump is electrogenic.
Which one of the following molecules is most likely to diffuse freely across the lipid bilayer of the plasma membrane without the involvement of a transport protein?
carbon dioxide
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.
If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells?
Both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall.
A single plant cell is placed in an isotonic solution. Salt is then added to the solution. Which of the following would occur as a result of the salt addition?
Water would leave the cell by osmosis, causing the volume of the cytoplasm to decrease.
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
Glucose is a six-carbon sugar that diffuses slowly through artificial membranes. The cells lining the small intestine, however, rapidly move glucose from the gut into their cytoplasm. This occurs whether the gut concentrations of glucose are higher or lower than the glucose concentrations in intestinal cell cytoplasm. Using this information, which transport mechanism is most likely responsible for the glucose transport in intestinal cells?
active transport
Which of the following functional processes results) from the presence of proteins in or on the plasma membrane?
all of the above
Which of the following is/are a function of membrane proteins?
all of the above
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
A cell has a membrane potential of -100 mV (more negative inside than outside) and has 1,000 times more calcium ions outside the cell than inside. Which of the following best describes a mechanism by which Ca?* enters the cell?
facilitated diffusion of Ca?* into the cell down its electrochemical gradient
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
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
Which one 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
Which one of the following cell structures exhibits selective permeability between a cell and its external environment?
plasma membrane
Which of the following types of information is (are) most likely to be derived from freeze fracture of biological samples?
proteins embedded in membrane bilayers
Which of the following structures is most consistent with the selective permeability property of biological membranes?
proteins embedded in two layers of phospholipid
The transmission of nerve impulses between adiacent nerve cells requires the release of a neurotransmitter (a molecule or small peptide) by exacytosis. Which of the following would best reverse the process that resulted in the release of neurotransmitter, returning the cell to its original state?
receptor-mediated endocytosis
Which of the following enables a cell to pick up and concentrate a specific kind of molecule?
receptor-mediated endocytosis
Which statement(s) about the sidedness of the plasma membrane is (are) correct?
All of the listed responses are correct.
Which of the following statements about cotransport of solutes across a membrane is correct?
Cotransport proteins allow a single ATP-powered pump to drive the active transport of many different solutes.
Which of the following correctly describes a general property of all electrogenic pumps?
Electrogenic pumps create a voltage difference across the membrane.
Which of the following processes, normally assoclated with membrane transport, must occur to account for an increase in the surface area of a cell?
Exocytosis
Imagine two solutions separated by a selectively permeable membrane that allows water to pass, but not sucrose or glucose. The membrane separates a 0.2-molar sucrose solution from a 0.2-molar glucose solution. With time, how will the solutions change?
Nothing happens because the two solutions are isotonic to one another.
Which of the following statements about passive transport is correct?
Passive transport permits the transported molecule to move in either direction, but the majority of transport occurs down the concentration gradient of the molecule.
Which of the following statements about the role of phospholipids in forming membranes Is correct?
Phospholipids form a selectively permeable structure.
The plasma membrane is referred to as a "fluid mosaic" structure. Which of the following statements about that model is true?
The fluid component of the membrane is phospholipid, and the mosaic is protein.
Consider the transport of protons and sucrose into a plant cell by the sucrose-proton cotransport protein. Plant cells continuously produce a proton gradient by using the energy of ATP hydrolysis to pump protons out of the cell. Why, in the absence of sucrose, don't protons move back into the cell through the sucrose-proton cotransport protein?
The movement of protons through the cotransport protein cannot occur unless sucrose also moves at the same time.
The concentration of solutes in a red blood cell is about 2%, but red blood cells contain almost no sucrose or urea. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions?
a hypertonic sucrose solution
