Ch 2 - Movement of Substances Flashcards
Diffusion, Osmosis, Active Transport
Definition of diffusion
Diffusion is the net movement of particles moving from a region of a higher concentration to a region of lower concentration, down a concentration gradient.
Definition of concentration gradient?
Concentration gradient is the difference in concentration between 2 regions
During diffusion, do the particles diffuse evenly?
Yes
Relation between Concentration gradient and rate of diffusion?
the steeper the concentration gradient, the faster the rate of diffusion
What happens when there are more than 1 liquid dissolved in the same liquid?
the dissolved particles of one substance will diffuse independantly of the others
Factors that affect the rate of diffusion?
- concentration gradient
- diffusion distance
- surface area-to-volume ratio
Definition of diffusion distance?
it is the distance through whicha substance diffuses
Relation between diffusion distance and rate of diffusion?
the longer the diffusion distance, the longer the time taken for the substane to diffuse, and hence, the rate of diffusion is lower
how is a human lung adapted for a higher rate of diffusion?
the lung cells are only 1cm thick, shortening the diffusion distance. this allows carbon dioxide to diffuse out faster and oxygen to diffuse into the the red blood cell faster
how is a root hair cell adapted for a higher rate of diffsion?
the diffusion distance is short, allowing for oxygen to diffuse into the root hair cell faster
Why are cells small?
cells need to moxe oxygen, nutrients and waste materials across their cell fast enough to stay alive
Relation between the suraface area-to-volume ratio and rate of substances moving in and out of a cell?
The greater the SATV ratio, the higher the rate at which the substances move in and out of the cell
Why does a cell’s growth come to a stop when iit reaches its optimum size?
As the cell grows larger, the rate of oxygen and food intake slows down. Thus it is not beneficial fro a cells to grow too big.
Definition of osmosis?
Osmosis the net movement of water molecules moving from a region of higher concentration to a region of lower concentration, through a partially permeable membrane
What are the factors that affect the rate of diffusion?
- water potential gradient
- distance which water molecules need to move over
- SATV ratio
What happens to a cell in a solution with the same water potential?
the cytoplasm will not change in their chape or size. the movement of water molecules is the same in both directions. hence there is no net movement.
What does turgor help with?
Turgor maintains the shape of soft tissues in plants.
Definiton of active transport?
Sctivve transport is the process in which energy is used to move the particles of a substance across a membrane against its concentration gradient, from a region where the particlelsareof lower concentration to a region where they are of higher concentration
Is energy from respiration required for diffusion?
no
is energy from respiration required for active transport?
yes
why is energy needed for active transport?
thhe particles are moving against the concentration gradient
is a cell membrane required for diffusion?
not required
which type(s) of substance(s) need(s) a cell membrane?
osmosis and active transport
Where doees active transport take place? Why there?
It only takes place in living cells as living cells respire
