movement into and out of cells- (topic 3) Flashcards
diffusion
the net movement of particles from a
region of their higher concentration to a region of their lower concentration (i.e. down a concentration gradient), as a result of their random movement.
where does the energy from diffusion come from
energy for diffusion comes from the kinetic
energy of random movement of molecules and ions
how do susbtances move into and out of cells
diffusion partially
examples of diffusion in organsims
movement of: co2 and o2, glucose and other food molecules into and out of blood, co2 and o2 in alveoli in lungs, water glucose urea and ions in glomerolous and nephron of kidney
how does temp affect rate of diffusion
if temperature increases, more ke is given to molecules, moving faster, therefore rate of diffusion increases
how does surface area affect rate of diffusion
larger surface area, The rate of diffusion increases for the folded cell as there is a larger surface area over which diffusion can occur
how does concentration affect rate of diffusion
The rate of diffusion increases as the concentration gradient increases. Particles are constantly moving but there is faster net movement of particles from an area of high concentration to where their concentration is lower as a result of their random movement.
how does distance affect rate of diffusion
the thicker the distance molecules must travel, the smaller the rate of diffusion
what is the role of water in organsim
water is a solvent, meaning many reactants first dissolve in it, it is needed for, digestion, excretion and transport
what is osmosis
osmosis the diffusion of water molecules across a partially permeable memebane. In osmosis, water moves through a partially permeable membrane. This means that water can move into and out of cells by osmosis
how to investigate osmosis using dialysis tube
The dialysis tubing blocks larger molecules such as sucrose from passing through it while allowing smaller molecules such as water to pass through. therefore shows how partially permeable membrane works during osmosis
how are plants supported?
plants are supported by the pressure of water inside the cells pressing outwards on the cell wall
turgid cell?
a turgid cell is one with high tugor pressure, meaning water has movmed into the cell via osmosis and helps support plant. However if tugor pressure is too high, meaning there is more solvent that solute the cell becomes hypotonic, and because of excess water might even burst.
hypertonic cell?
there is more solute than solvent, meaning water is lacking, meaning tugor pressure is low. Hence, cytoplasm and vacuole shrink and cytoplasm might even pull away from cell wall, called plasmolysis, plant will probably die.
isotonic cell?
cell with perfect balance between solvent and solute, healthy cell.
