Which of the following statements is/are consistent with the known facts about membrane transport? (Select all that apply.) Active transport moves an uncharged substance from a region in which its concentration is lower to one in which its concentration is higher. Transport does not involve any pores or channels in membranes. It is possible for some species to diffuse through the membrane. Active transport always employs ATP hydrolysis to provide the energy for the transporter. The rate of transport of a species through a protein channel does not depend solely on the concentration gradient. None of the Above
Added by James M.
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" - Active transport is defined as the movement of substances against their concentration gradient, which means from lower to higher concentration. - This applies to both charged and uncharged substances. - Therefore, this statement is **true**. Show more…
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1. In an experiment involving lipid bilayers, a solution of table salt (sodium and chloride ions in water) is added on the left side of the membrane while pure water is added on the right side. After 30 minutes the researchers test for the presence of ions on each side of the membrane. The right side tests negative for ions. What can you conclude? A) The experiment failed. B) The water somehow blocked the movement of ions across the membrane. C) Ions cannot cross the lipid bilayer because they are hydrophobic. D) Ions cannot cross the lipid bilayer because they are electrically charge. 2. In an experiment involving lipid bilayers, a sugar solution is added on the left side of the membrane while pure water is added on the right side. After 30 minutes the researchers test for the presence of sugar on each side of the membrane. The right side tests negative for sugar. This is because: A) of the nonpolar nature of membranes. B) of the polar nature of membranes. C) sugars cannot cross the lipid bilayer because they are nonpolar D) sugars are hydrophobic. 3. With regard to fatty acids, which of the following is the best explanation for why animal fat is a solid at room temperature while vegetable oils are liquid? A) Vegetable oil has fewer double bonds than animal fats. B) Animal fat has fewer double bonds than vegetable oil. C) Animal fats have shorter fatty-acid tails. D) Vegetable oil has longer fatty-acid tails. 4. Which of the following means of transport would most likely be used for moving a medium-sized molecule (like a monosaccharide or an amino acid) from a low concentration on the outside of a cell to a high concentration on the inside of a cell? A) facilitated diffusion through an ion channel protein B) facilitated diffusion through a transporter protein C) active transport through a "pump" protein D) passive transport 5. Integral membrane proteins stay in membranes because of ______. A) osmotic pressure from proteins outside the cell B) diffusion of proteins from the cytoplasm to the membrane C) the locations of their polar and nonpolar amino acids D) their small size, which does not allow them to pass through the membrane 6. Which one of the following statements are true? A) Transverse movement of membrane proteins and lipids cannot occur across the lipid bilayer spontaneous (without using external energy).
Supreeta N.
36. Pumps include: antiporters. symporters. ATPases. uniporters. None of the above. 37. Which of these molecules would be most likely to use channel proteins to move through membranes? 1. NO 2. bicarbonate (HCO3-) 3. urea 4. Ions 5. glucose 38. Which of the following statements regarding membrane transport proteins is NOT true? Uniporters move ions faster through membranes than do ion channels. Uniporter transport is fast, reversible, and highly specific. Both transporter proteins and ATP-powered pumps represent active transport. Facilitated transport is required to move any molecule against its concentration gradient. 39. Which of the following statements regarding glucose transporters is true? GLUT1 will transport glucose, mannose and galactose with similar affinity. The Vmax for glucose import into a cell cannot be altered without changing the type of GLUT transporter expressed by the cell. The high Km of GLUT2 leads to more drastic glucose uptake rate changes when blood glucose concentration increases after a meal. The high Km of GLUT3 in neuronal cells leads to (low) high rates of glucose uptake by these cells when blood glucose concentrations are low. 40. Which of the following statements about ATP-powered pumps is NOT true? P-, F-, and V-class pumps transport ions. P-class and V-class pumps can transport the same ion but in opposite directions. ATP-powered pumps contain at least one transmembrane domain. ATP-transporters are found in organisms ranging from bacteria to humans. Aquaporins are: barrel proteins in the outer membrane of bacteria. proteins. uniporters.
Sri K.
30. Which statement describes the mode of action of the ABCB1 transporter (the first eukaryotic ABC transporter to be recognized)? a. During transport, the ligand binding site is alternately exposed to the exoplasmic and the cytoplasmic side of the membrane. b. During transport, a conserved aspartate residue is phosphorylated. c. This class of pumps transports only H+ ions. d. This transporter acts as a chloride channel. 31. The resting membrane potential in animal cells depends largely on nongated ______ channels. a. Ca2+ b. H+ c. K+ d. Na+ 32. Parietal cells acidify the stomach contents while maintaining a neutral cytosolic pH by: a. exporting "excess" cytosolic OH- as HCO3-. b. exchanging HCO3- for Cl-. c. preserving electroneutrality by accompanying the movement of each Cl- ion into the stomach lumen by a K+. d. all of the above. 33. Which of the following would increase the rate of glucose uptake in cultured liver cells? a. Transfect cells with the wild-type GLUT-1 gene. b. Increase the concentration of glucose in the medium. c. Decrease the concentration of calcium in the medium. d. Decrease the concentration of glucose in the medium. e. Both A and B 34. Which of the following statements regarding transcellular transport is NOT true? a. Tight junctions are specialized regions of the plasma membrane that mediate separation of the apical and basolateral membranes. b. The movement of glucose into the blood is mediated by GLUT2 transporters. c. The Na+ concentration gradient across the membrane is the only gradient required to drive uptake of glucose from the intestine. d. Transcellular transport moves glucose across epithelia asymmetrically
Madhur L.
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