Unit 2 terms Flashcards
diffusion
the movement of particles from areas of high concentration to areas of low concentration
osmosis
diffusion applicable to particles of water
osmolarity
the combined concentration of all solutes in a solution
which particles diffuse easily
small, uncharged particles
which particles don’t diffuse easily
large, uncharged particles
charged particles (ions)
electrochemical gradient
combination of concentration and electric potential
electrochemical equilibrium
when charge and concentration are equal
isosmotic
osmolarities are equal
hyperosmotic
more concentrated
hyposmotic
less concentrated
water potential
tendency of water to move
hydrostatic pressure (pressure potential)
the “pushing” force on water due to more fluid occupying one region than another (pushes water out)
positive
osmotic pressure (solute potential)
the “pulling” force on water due to solutes present in the solution (pulls water in)
negative
water cohesion/adhesion (matrix potential)
tendency of water molecules to stick to each other and their environment (pulls water in)
simple diffusion
the movement of molecules through cell membranes without help from channels or pumps
cell membranes
phospholipid bilayer where the heads are hydrophilic/lipophobic and the tails are hydrophobic/lipophilic
simple diffusion
when particles can pass through the cell membrane easily
channel protein (permeation)
pore for particles to pass through the membrane
usually specialized for a certain particle
carrier protein (facilitated diffusion)
protein that “grabs” particles and undergoes a confirmation change that pulls the particle across the cell membrane
concentration gradient
a region of space over which the concentration of a substance changes
primary active transport
uses a cell’s energy (ATP) directly to move molecules across the cell membrane - against the gradient
secondary active transport (cotransport)
uses an electrochemical gradient – generated by active transport – as an energy source to move molecules against their gradient
does not directly require a chemical source of energy such as ATP
symporter
the protein during secondary active transport that moves molecules in the same direction
antiporter
the protein during secondary active transport that moves molecules in opposite directions
body size effects
surface area increases at a slower rate than volume; SA:V ratio decreases as size increases
* SA ɑ L^2
* V ɑ L^3
increased distance b/n surface and center
both reduce diffusion rate
Claude Bernard’s (French) contributions to physiology
cells are exposed to an internal environment that must be regulated
negative feedback loop
counteracts various properties to regulate homeostasis
signal
a deviation from the set point
*positive: above - yields negative response
cell wall
composed of cellulose, pectin, and lignin
*primary cell wall: more flexible due to pectin
*secondary cell wall: more rigid due to lignin
plasmodesmata
openings between adjacent plant cells
what parts of plant cells are unique to plants?
cell wall, central vacuoles, chloroplasts
root system
stores most of a plant’s energy underground
*goal is to maximize water intake - roots have large SA
*roots are thin and long and absorb with root hairs
root cap
layer of dead cells that allow roots to move through soil
shoot structure
supports leaves and flowers; transports materials
node
*root: the split between two parts of a stem
bud
*root: a place of new growth
modifications of shoots
asexual growth - wild strawberries
food - tubers
protection - thorns
leaf system
sunlight harvester
modifications of leaves
food - onions
water storage - succulents
tendrils
floral mimics
spines
traps - venus fly trap
2 type of plant development
growth and differentiation
meristems
location of plant growth (all plant growth occurs at meristems)
totipotent cells
produced by meristems; can differentiate into any type of cell
apical meristems (primary growth)
make plants longer at shoots or roots
lateral meristems (secondary growth)
make plants wider (internally or externally)
after cells form they _____
expand
cells expand by
loosening cell walls
creating turgor pressure