M A&P Membrane physiology
Which of the following best describes the difference between active and passive transport mechanisms?
Active mechanisms use energy to move solutes against their concentration gradients. Passive mechanism move solutes with their concentration gradients.
What is the basic difference between simple diffusion and facilitated diffusion across a cell membrane?
In facilitated diffusion, molecules only move with the aid of a protein in the membrane.
Which of the following is most likely to move through the cell membrane by facilitated diffusion?
Na+
Which of the following is not a passive process?
Na+/K+ pump
The hormone epinephrine (adrenaline) increases the pumping rate of the sodium-potassium exchange pump in skeletal muscles. How would you expect this to affect the concentration of Na+ and K+ in the muscle cytoplasm?
The Na+ concentration would decrease and the K+ concentration would increase.
If a person is severely dehydrated, their extracellular fluids will become hypertonic to the intracellular fluid. What do you predict will happen to the person's cells?
The cells will lose water and shrink.
Which of the following occurs during a single cycle of the sodium-potassium exchange pump?
Three Na+ ions are transported out of the cell.
Watch the video tutor about transport, and then answer the question. In the video clip, which movement process is depicted?
active transport
Which of the following is not required for osmosis to occur?
cellular energy
Carriers transport solutes across the plasma membrane by __________.
changing shape as the solutes bind, causing the solutes to move across the membrane
A vesicle fuses with the plasma membrane and releases its contents to the extracellular fluid. This statement describes _____.
exocytosis
Passive movement of a solute by a carrier protein is called __________.
facilitated diffusion
Some transport processes use transport proteins in the plasma membrane, but do not require ATP. This type of transport is known as _____.
facilitated diffusion
The majority of water molecules moving across plasma membranes by osmosis do so via a process that is most similar to ____.
facilitated diffusion
What concentration gradients are established and maintained by the sodium-potassium exchange pump?
high Na+ concentration in the extracellular fluid; high K+ concentration in the cytoplasm
Which of the following solutions contains the most solute?
hypertonic
In general, to maintain homeostasis the relationship between our intracellular and extracellular fluids should be which of the following?
isotonic to each other
A primary active transport process is one in which __________.
molecules move through transport proteins that have been activated by ATP
Which of the following best explains diffusion?
movement of molecules from an area of high concentration to an area of low concentration
What is the normal direction of calcium transport via the calcium pump?
out of the cell, against its concentration gradient
The sodium-potassium pump uses ATP to move sodium and potassium ions across the plasma membrane. This statement describes _____.
primary active transport
Which of the following is least likely to increase the rate of diffusion?
small concentration gradient
What is the energy source used by the calcium pump during its normal operation?
the hydrolysis of ATP
Which of the following conditions would cause (net) glucose to be transported into a cell via facilitated diffusion? Assume ATP is present inside the cell.
0.5 mM glucose in cytoplasm; 5 mM glucose in extracellular fluid
