movement of molecules from an area of high concentration to an area of low concentration
question
Which of the following is most likely to move through the cell membrane by facilitated diffusion?
answer
Na+ Ions move easily through water, which is polar, but cannot pass directly through the lipid (nonpolar) part of the cell membrane.
question
What is the basic difference between simple diffusion and facilitated diffusion across a cell membrane?
answer
In facilitated diffusion, molecules only move with the aid of a protein in the membrane.
question
Which of the following is least likely to increase the rate of diffusion?
answer
small concentration gradient
question
Which of the following is not required for osmosis to occur?
answer
cellular energy
question
Which of the following solutions contains the most solute?
answer
hypertonic
"Hyper" means "high," so a hypertonic solution has a higher solute concentration than the solution to which it is being compared.
question
In general, to maintain homeostasis the relationship between our intracellular and extracellular fluids should be which of the following?
answer
isotonic to each other
In order to prevent the cells from either swelling or shrinking, the body fluids should be isotonic, meaning that they are at equilibrium.
question
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?
answer
The cells will lose water and shrink.
The hypertonic extracellular fluid will draw water out of the hypotonic intracellular fluid, so the cells will shrink. This is called crenulation.
question
A primary active transport process is one in which __________.
answer
molecules move through transport proteins that have been activated by ATP
question
Some transport processes use transport proteins in the plasma membrane, but do not require ATP. This type of transport is known as _____.
answer
facilitated diffusion
question
The majority of water molecules moving across plasma membranes by osmosis do so via a process that is most similar to ____.
answer
facilitated diffusion
question
The sodium-potassium pump uses ATP to move sodium and potassium ions across the plasma membrane. This statement describes _____.
answer
primary active transport
question
A vesicle fuses with the plasma membrane and releases its contents to the extracellular fluid. This statement describes _____.
answer
exocytosis
question
What happens when body cells are placed in a hypertonic solution?
answer
Water leaves the cells and the cells shrink.
question
What type of membrane junction allows ions to pass directly from the cytoplasm of one cell to the cytoplasm of the adjacent cell?
answer
gap junction
question
Which of these components add specialized functions to the plasma membrane?
answer
proteins
question
What part of the plasma membrane is hydrophobic?
answer
phospholipid tails
question
What process permits absorption of glucose into cells?
answer
facilitated diffusion
question
What transport process can create a concentration gradient for sodium across the plasma membrane?
answer
active transport
question
Which cell junctions prevent substances from passing between adjacent cells?
answer
tight junctions
question
What process does water use to move across the plasma membrane?
answer
osmosis
question
Type of active transport in which sodium and potassium are pumped across a membrane using ATP
answer
Solute pumping
question
Type of passive process in which water is moved through aquaporins
answer
osmosis
question
Type of passive process in which molecules move across the plasma membrane down a concentration gradient
answer
diffusion
question
Type of active process in which the cell engulfs extracellular substances by phagocytosis or pinocytosis
answer
Endocytosis
question
The phospholipid tails are ________, which make the plasma membrane impermeable to water.
answer
hydrophobic
question
The membrane connections that prevent the leaking of fluid between cells are called ________.
answer
tight junctions
question
The passive process that involves the movement of water through aquaporins is ________.
answer
osmosis
question
What assists the movement of substances by facilitated diffusion?
answer
protein carrier or channel
question
What is required for osmosis to occur?
answer
aquaporins
question
Passive processes that move substances across membranes ________.
answer
do not require ATP
question
By what endocytosis process do some white blood cells engulf bacteria?
answer
phagocytosis
question
What is required for diffusion to occur?
answer
concentration gradient
question
What are two types of endocytosis?
answer
phagocytosis and pinocytosis
question
A solution that contains fewer solutes than the cell is ________ to the cell.
answer
hypotonic
question
Which of the following substances must travel across a membrane via facilitated diffusion?
answer
glucose
question
Which of the following processes require the use of protein carrier molecules?
answer
facilitated diffusion and solute pumping
question
A cell is isotonic to the surrounding 4% dextrose solution. If the cell is moved to a 6% dextrose solution, then predict what will happen to the cell.
answer
The cell will shrink.
question
Which of the following is the main component of the cell membrane?
answer
phospholipids
question
Which of the following is a characteristic of the cell membrane?
answer
semipermeable
question
Which of the following is not a major function of proteins in the cell membrane?
answer
forming the entire glycocalyx
question
What part of a cell membrane is usually in contact with the interstitial fluid?
answer
phosphate heads of phospholipids
question
What is required for filtration to occur?
answer
pressure gradient
question
What separates the intracellular fluid from the extracellular fluid?
answer
plasma membrane
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