merensalsa bio chapter 5 5.1-5.9
the secretion of neurotransmitters out of the nerve cell, from small vesicles at the end of the axon, can be considered an example of ____
exocytocis.
which of the following statements is true diffusion?
it is a passive process.
the diffusion of water across a selective permeable membrane is called ___
osmosis.
LDLs enter cells by means of _____
receptor-mediated endocytosis.
which of the following enables a cell to pick up and concentrate a specific kind of molecule?
receptor-mediated endocytosis.
seawater is dangerous to drink because ______
sea water is hypertonic to your body tissues and drinking it will cause you to lose water by osmosis.
cells A and B are the same size and shape, but cell A is metabolically quite and cell B is actively consuming oxygen. oxygen will diffuse more quickly into cell ____ because ____
B--- the diffusion gradient there is steeper.
which statement best describes phagocytosis?
a cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole.
the concentration of solutes in a red blood cell is about 2%. sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immmersed in which of the following solutions?
a hypertonic sucrose solution
when in solution, a molecule that moves slowly across an artificial membrane moves rapidly across a plasma membrane. this occurs regardless of whether the concentration of this molecule is higher inside or outside the cell. using this information, which transport mechanism is most likely to be responsible for the movement of the molecule across a plasma membrane?
active transport
which of the following is a difference between active transport and facilitated diffusion?
active transport requires the expenditure of celullar energy, and facilitated diffusion does not.
which of the following statements about cell membrane transport is true?
active transport works with the assistance of proteins to move molecules from areas of low concentration to areas of high concentration.
green olives may be preserved in brine, which is a 20-30% salt solution. how does this method prevent contamination by microorganisms?
bacteria can't survive in a hypertonic solution because they lose water.
stability of an animal cell plasma membrane is enhanced by ___
cholesterol molecules.
the movement of atoms, ions, or molecules from a region of higher concentration to regions of lower concentration is called ____
diffusion.
a nursing infant is able to obtain disease fighting antibodies, which are large protein molecules, from its mother's milk. these molecules probably enter the cell lining the baby's digestive tract via ____
endocytosis.
which of these statements describes what occurs in facilitated diffusion?
facilitated diffusion of solutes occurs through protein pores in the membrane.
phospholipids are well suited to be the main structural components of membranes because they ___
form a selectively permeable structure.
when considering the formation of membranes, they ____
form spontaneously in aqueous environments.
phospholipids are well suited to serve as the major component of the plasma membrane because they ____
have a water soluble part and a water insoluble part.
if the volume of a cell increases when it is placed in a aqueous solution, that solution is said to be ____ to the cell
hypotonic.
which of the following statements is true about passive trabsport?
passive transport requires no expenditure of cellular energy.
how does passive transport functions?
passive transport transports molecules without the assistance of proteins from an area of high concentration to an area of lower concentration.
some liver cells ingest bacteria, a function probably accomplished by ____
phagocytosis.
which one of the following terms specifically refers to the intake of very large particles by cells?
phagocytosis.
which of these situations accurately represents osmoregulation in organisms?
plant cells need a hypotonic environment in order to stay turgid.
as shown below, proteins perform a number of functions within membraines. which of the following statements is true about membrane proteins?
proteins can bind other molecules, which may trigger specific cellular functions.
which of the following describes the general structure of a cell membrane?
proteins embedded in two layers of phospholipids.
the lipids in a cell membrane are arranged ___
so that the nonpolar parts of two lipids point toward each other.
the transport of molecules of a particular solute from inside an animal cell across the cell membrane to the extracellular fluid always requires energy when ____
the concentration of the solute is lower inside the cell than outside it.
the membrane is referred to as "fluid mosaic" structure. which of the following statements is true?
the fluid is phospholid, and the mosaic is protein.