Cell membrane/ gas exchange in plants/ transport in plants Flashcards
what is simple diffusion
is from high to low concentration, it happens directly across a plasma membrane and molecules move down their concentration gradient
what is osmosis
molecule being moved is water, it occurs when movement of molecules is blocked by a selectively permeable membrane and water moves until solutions on either side of membrane reach equilibrium
what is facilitated diffusion
this process does not require energy, occurs when molecules move down their concentration gradient across membrane using help of transport proteins.
what is active trasnport?
is when molecules move from low to high concentration, against the concentration gradient, energy required is ATP!
describe a isotonic solution
solution has same concen as another solution, there is so net movement of water and cells stay the same
what is a hypertonic solution?
when the solution has a higher SOLUTE concen and water moves out of the cell, causing crenation and the cells will shrink
what is a hypotonic solution?
solution has lower solute concen causing water to move into the cell and then the cells will lyse and burst because they get so full.
do the three solutions( iso, hypo, etc) have diff effects on animals and plant cells?
plant cells do not respond the same in these solutions because after their plasma memebrane they have a hard cell wall.
what is passive transport?
process requires no energy includes diffusion, osmosis, facilitated diffusion and requires assistance of transport proteins.
what is active transport?
requires energy, and is the transport of smaller molecules against the concen gradient, it includes exo/endocytosis and bulk transport.
what is solute
in which molecules are dissolved in a solvent, in biology the solvent is always water.
what is a solution?
term used for the solute plus water mixed together.
what is a solute concentration?
the amount of solute in the solution.
what is exo and endocytosis?
exo- molecules moved thru vesicles, when the vesicle inside cell fuses with the plasma membrane and the vesicle contents are then again released into the cell.
endo-when the plasma membrane folds in and surrounds molecule for transport, then pinches off of plasma membrane and forms a vesicle inside the cell.
what is the structure of the plasma membrane?
composed of a bilayer of phospolipids. they have a hydrophilic head and hydrophobic tail. this membrane is selectively permeable.
what are channel proteins
are tunnels thru the plasma membrane , which can allow molecules to go thru freely
what are carrier proteins
open and close to let ONLY certain molecules in and others are not allowed inside.
what is gas exchange
process of taking up gases from environment and into the cell then releasing the gases from the cell into the environment.
what are stomata
is flanked by two specialized cells called guard ells which chnage the shape when water moves in or out of them causing the stomata to open and close
what are guard cells
are bean shaped cells, become turgid when water enters, opening the stomata
and become flaccid when water exits, closing the stomata
explain gas exchange in leaves
leaves have many air spaces that allow contact between air and cells, and plant leaves maximize this because they have a large surface area to allow this to happen
how does gas exchange happen in roots
in soil, there are air pockets where the plant roots can exchange gases
difference between new and old roots in gas exchange
in new roots- there are roots hairs that allow surface area for gas exchange.
older roots- have branches so they can gas exchange thru the bark.
list some mechanisms of short distance transport
diffusion- used by vascular plants to transport c02 and 02 in and out the stomata
cytoplasmic streaming- when cellular components and chemicals are carried between cells and the plasmodesmata
what is transpiration
when water is constantly re-circulated thru vertebrate bodies via the circulatory system
describe the cohesion-tension model
when there is tension created by the evaporation of water so water gets pulled from xylem to nearby mesophyll cells
what is cohesion
the attraction between same substance molecules.
what is adhesion
the attraction between different substance molecules
describe root pressure
when transpiration is slow, water flows intot he xylem by osmosis and creates a positive pressure in the roots
