Chapter 7

Question 1

amiphipathic molecule

Answer 1

both water loving (hydrophillic) and water fearing (hydrophobic) regions

Question 2

fluid mosaic model

Answer 2

membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids

Question 3

integral proteins

Answer 3

penetrate the hydrophobic interior of the lipid bilayer

Question 4

transmembrane proteins

Answer 4

spam the membrane

Question 5

peripheral proteins

Answer 5

not embedded in the lipid bilayer at all; loosely bound to the surface of the membrane

Question 6

selective permeability

Answer 6

allows some substances to cross more easily than others

Question 7

diffusion

Answer 7

the movement of particles of any substance so that they spread out into the available space

Question 8

concentration gradient

Answer 8

region along which the density of a chemical substance increases or decreases

Question 9

passive transport

Answer 9

diffusion of a substance across a biological membrane

Question 10

osmosis

Answer 10

diffusion of free water across a selectively permeable membrane, whether artificial or cellular

Question 11

tonicity

Answer 11

the ability of a surrounding solution to cause a cell to gain or lose water

Question 12

isotonic

Answer 12

iso (same; no net movement of water across the plasma membrane

Question 13

hypertonic

Answer 13

hyper (more water)

Question 14

hypotonic

Answer 14

hypo (less water)

Question 15

osmoregulation

Answer 15

the control of solute concentrations and water balance

Question 16

turgid

Answer 16

very firm

Question 17

flaccid

Answer 17

limp

Question 18

plasmolysis

Answer 18

as the plant cell shrivels, its plasma membrane pulls away from the cell wall at multiple places (can lead to plant death)

Question 19

facilitated diffusion

Answer 19

molecules and ions blocked by the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane

Question 20

electrochemical gradient

Answer 20

combinations of forces acting on an ion

Question 21

cotransport

Answer 21

a transport protein can couple the down hill diffusion of the solute to the uphill transport of a second substance against its own concentration gradient

Question 22

endocytosis

Answer 22

cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane