mastering biology : chapter 5

pinocytosis is one form of ___ , the movement of large materials into a cell by an infolding of the plasma membrane.

endocytosis

the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. this describes the process of a. endocytosis b. diffusion c. passive transport d. active transport e. exocytosis

(a) - in endocytosis, the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell -

why can't cells get as large as golf balls? a. a cell that large would not have enough surface area to use in exchanging materials. b. a cell that large would not have enough energy inside it to run. c. a cell that large would collapse under its own weight. d. a cell that large would be too hypertonic to prevent swelling. e. a cell that large wouldn't have enough volume to conduct chemical reactions.

(a) - the larger the cell, the more nutrients it needs to pull in and the more waste in needs to expel. the volume outgrows the available surface area quickly -

a molecule moves down its concentration gradient using a transport protein in the plasma membrane. this is an example of a. active transport b. facilitated diffusion c. diffusion d. exocytosis e. endocytosis

(b) - in facilitated diffusion, molecules use transport protein to move across the plasma membrane. there is a net movement of molecules down the concentration gradient -- that is, there is a net movement of molecules from where they are more concentrated to where they are less concentrated -

the sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. this is an example of a. passive transport b. diffusion c. active transport d. exocytosis e. facilitated diffusion

(c) - the sodium-potassium pump moves ions across the plasma membrane against their concentration gradients. this requires energy and is an example of active transport -

what name is given to the process by which water crosses a selectively permeable membrane? a. phagocytosis b. passive transport c. diffusion d. osmosis e. pinocytosis

(d) - osmosis is the passive transport of water -

in active transport, a. molecules move across the plasma membrane by crossing the lipid bilayer directly, rather than by using a transport protein. b. the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. c. no energy input is required from the cell. d. a vesicle inside the cell fuses with the plasma membrane and releases its contents outside the cell. e. molecules move across the plasma membrane against their concentration gradient.

(e) - molecules move against their concentration gradient in active transport -

water crosses the plasma membrane a. through cotransport b. through active transport c. against its concentration gradient d. using a process that requires energy from the cell e. through facilitated diffusion or diffusion

(e) - water can cross the plasma membrane through the process of facilitated diffusion. however, water molecules can also cross the lipid bilayer directly -

diffusion

a form of passive transport. molecules move across the plasma membrane by crossing the lipid bilayer.

facilitated diffusion

a form of passive transport. molecules move across the plasma membrane using a transport protein.

exocytosis

a vesicle inside the cell fuses with the plasma membrane and releases its contents outside the cell.

___ is the movement of materials out of a cell through the fusion of a transport vesicle with the plasma membrane.

exocytosis

a(n) ___ solution has higher concentration of dissolved particles that an adjacent solution.

hypertonic

a(n) ___ solution has lower concentration of dissolved particles that an adjacent solution.

hypotonic

a(n) ___ solution has the same concentration of dissolved particles as an adjacent solution.

isotonic

___ is the movement of large materials into a cell by wrapping extensions of the plasma membrane around the material and engulfing it by fusing the extensions together.

phagocytosis

active transport

requires energy from the cell. molecules move against their concentration gradient.

endocytosis

the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell.

embedded within the phospholipid bilayer surrounding a cell are ___ , which regulate the movement of hydrophilic molecules from one side of the plasma membrane to the other.

transport proteins