unit 2 section 3 hw
b
In the lab, you use a special balloon that is permeable to water but not sucrose to make an "artificial cell." The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water. The solution in the balloon is __________ relative to the solution of the beaker. a. isotonic b. hypotonic c. hypertonic
b
In the lab, you use a special balloon that is permeable to water but not sucrose to make an "artificial cell." the balloon is filled with a solution of 20% sucrose and 80% water an is immersed in a beaker containing a solution of 40% sucrose and 60% water. Which of the following will occur? a. sucrose will leave the balloon b. water will leave the balloon c. sucrose will enter the balloon d. water will enter the balloon
a
a plant cell in a hypotonic solution a. becomes turgid because of an inflow of water b. bursts because of an inflow of water c. shrivels because of an outflow of water d. wilts because of an outflow of water
hypertonic
a plant cell placed in a(n) __________ solution will lose water and plasmolyze.
isotonic
a plant cell surrounded by a(n)_________ solution will be flaccid (limp).
hypotonic
an animal cell is placed in a(n)__________ solution will gain water, swell and possibly burst.
c
diffusion does not require the cell to expend ATP. therefore, diffusion is considered a type of a. endocytosis b. active transport c. passive transport d. exocytosis
d
facilitated diffusion across a biological membrane requires______ and moves a substance________ its concentration gradient a. energy and transport proteins; down b. transport proteins; against c. energy and transport proteins; against d. transport proteins; down
d
fluidity of an animal cell plasma membrane is enhanced by________. a. polyunsaturated triglycerides b. saturated phospholipids c. saturated triglycerides d. cholesterol molecules
a
how do fatty acids travel through a cell membrane? a. carrier proteins b. endocytosis c. diffusion d. active transport
b
membrane phospholipids a. have hydrophilic tails that face outward and are exposed to water b. are able to drift about in the plasma membrane c. have hydrophobic heads that face the center of the membrane and are shielded from water d. remain fluid because they are tightly packed against one another
a
most of the functions of a cell membrane, including transport and enzymatic function, are performed by a. proteins b. phospholipids c. glycolipids d. cholesterol
b
osmosis can be defined as a. the diffusion of a solute b. the diffusion of water c. the diffusion of nonpolar molecules d. active transport
b
plasma membranes are selectively permeable. this means that a. glucose cannot enter the cell b. the plasma membrane allows some substances to enter or leave a cell more easily than others c. anything can pass into or out of a cell as long as the membrane is intact and the cell is healthy d. plasma membranes must be very thick
c
some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment a. is hypertonic to the protozan b. is isotonic to the protozan c. is hypotonic to the protozan d. contains a higher concentration of solutes than the protazoan
a
the cholesterol associated with animal cell membranes a. helps to keep phospholipids from being too close to one another b. is an abnormally resulting from a diet in cholesterol c. helps solidify the membranes when the room temperature is below freezing d. is attached to membrane proteins and extends into the watery environment surrounding the cell
a
the fluid mosaic model describes the plasma membrane as consisting of a. diverse proteins embedded in a phospholipid bilayer b. a phospholipid bilayer with embedded carbohydrates c. two layers of phosphlipids with cholesterol sandwiched between them d. carbohydrates and phospholipids that can drift in the membrane
hypotonic
the ideal osmotic environment for a plant cell is a(n) _______________ environment.
isotonic
the ideal osmotic environment for an animal cell is a(n) __________ environment.
a
the plasma membrane is selectively permeable. which of the following can pass freely through the membrane with no assistance? a. oxygen and carbon dioxide b. starch and cellulose c. glucose and lactose d. sodium and hydrogen ions
a
the process of a white blood cell engulfing a bacterium is a. phagocytosis b. osmosis c. exocytosis d. receptor-mediated endocytosis
a
thee molecules responsible for membrane transport are a. proteins b. carbohydrates c. steroids d. phospholipids
hypertonic
there is a net diffusion of water out of an animal cell when it is placed in a(n) __________ solution.
d
what controls the net direction of molecules, such as oxygen, involved in passive transport? a. the type of cell to or from which the oxygen molecule is moving b. the size of the oxygen molecule c. the amount of energy available to transport oxygen d. the direction of the oxygen concentration gradient
b
when two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane and osmosis is allowed to take place, the water will a. exhibit an equal movement in both directions across the membrane b. exhibit a net movement to the side with lower free water concentration c. exhibit a net movement to the side with lower solute concentration d. exhibit a net movement to the side with higher free water concentration
b
which of the following processes can move a solute against its concentration gradient? a. osmosis b. active transport c. facilitated diffusion d. passive transport
c
which of the following regarding membrane protein function is false? a. membrane proteins form junctions between cells b. membrane proteins serve as enzymes c. membrane proteins produce phospholipds d. membrane proteins act as receptors to molecules like hormones
a
which of the following statements regarding active transport is false? a. active transport is driven by the concentration gradient b. active transport uses ATP as an energy source c. active transport can move a solute against its concentration gradient d. active transport requires the cell to expend energy
d
which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer? a. CO2 b. a small, nonpolar molecule such as butane c. O2 d. Na+
a
which statement best describes phagocytosis? a. a cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole b. a receptor on the plasma membrane binds to a molecule, and the cell engulfs both the receptor and the molecule c. small droplets of extracellular fluid and all the dissolved solutes enter the cell by this process d. cells use this process to export products such as insulin or thyroxine
