Membrane transport Flashcards
from Alistair question booklet - theme 5
Facilitated diffusion
a. requires energy input
b. is against the electrochemical gradient
c. is required for water transport
d. uses the energy from a down-gradient movement to produce an up- gradient movement
e. is required for glucose transport
e
a. Facilitated diffusion does not require energy input from the cell; instead, it relies on the concentration gradient of the solute being transported.
b. Facilitated diffusion moves substances down their concentration gradient, not against it. Therefore, it moves substances along the electrochemical gradient rather than against it.
c. Water transport, also known as osmosis, is a separate process from facilitated diffusion. While facilitated diffusion can involve the transport of water-soluble molecules, it is not specifically required for water transport.
d. Facilitated diffusion does not produce an up-gradient movement. It moves substances down their concentration gradient, from an area of higher concentration to an area of lower concentration.
A high partition coefficient (Kow) indicates that a molecule is
a. amphipathic
b. highly water-soluble
c. small
d. highly oil-soluble
e. charged
d
An aquaporin is
a. a transmembrane ion channel
b. a transmembrane water channel constitutively allowing passive diffusion
c. a small gap in the lipid bilayer through which water passes
d. a protein which actively transports water across the cell membrane
e. a transmembrane water channel which is only opened in the presence of ADH
b
Facilitated diffusion generally requires
a. a transmembrane channel to be constitutively open
b. a ligand-gated transmembrane channel
c. energy from the hydrolysis of ATP
d. cotransport with a molecule moving down its concentration gradient
e. a change in conformation of a transmembrane carrier protein
e
Rate of uptake via facilitated diffusion
a. approaches an asymptote which indicates Vmax
b. is maximum at the substrance concentration of Km
c. is directly proportional to substrate concentration
d. approaches an asymptote which indicates Km
e. is inversely proportional to substrate concentration
a
A low Km for a substrate indicates
a. high affinity for its transporter
b. low affinity for its transporter
c. low Vmax for the uptake of the substrate d. high specificity for its transporter
e. low specificity for its transporter
a
GLUT-5 transports
a. glucose
b. maltose
c. fructose
d. sucrose
e. galactose
c
GLUT1-4 transporters transport glucose via
a. primary active transport
b. endocytosis
c. facilitated diffusion
d. co-transport with Na+
e. secondary active transport
c
The transporter with a high Km and high Vmax for glucose is useful
a. when glycogenolysis is occurring
b. when blood glucose levels are high
c. in the fasting state
d. when blood glucose levels are normal
e. in starvation
b
the body needs to release glucose into the bloodstream to maintain blood glucose levels. A transporter with high Km (Michaelis constant) and high Vmax (maximum velocity) for glucose would allow for rapid uptake of glucose from the bloodstream into cells, supporting the process of glycogenolysis
The SGLUT transporter
a. is an example of facilitated diffusion
b. is found mainly in liver cells
c. is important for the absorption of dietary glucose
d. uses the movement of glucose down its concentration gradient to move sodium out of cells
e. is found only in intestinal epithelial cells
c
not E because while SGLT transporters are indeed found in intestinal epithelial cells, they are also present in other tissues such as the kidneys and the heart. They are not exclusive to intestinal epithelial cells.
Secondary active transport is used in cholera treatment to
a. drive glucose replacement via a high intestinal sodium concentration
b. drive sodium replacement via a high intestinal chloride concentration
c. drive chloride replacement via a high intestinal glucose concentration
d. drive sodium replacement via a high intestinal glucose concentration
e. drive glucose replacement via a high intestinal chloride concentration
d
Vibrio cholerae causes oversecretion of
a. Ca2+
b. K+
c. glucose
d. water
e. Cl-
e
