chapter 6 Flashcards
(23 cards)
what is diffusion?
random movement of molecules, ions, atoms from area of high concentration area of low concentration using kinetic energy.
more collisions in high concentration
how are molucules spread?
random collisions spread molecules down concentration gradient.
what substances diffuse into cell?
O2, CO2, urea, steroids, sodium, ions, potassium ions, fatty acids and glycerol
What substances diffuse in and out of cell?
Gases, food molecules, waste products
what is the function of the plasma membrane?
Regulates the passage of molecules into and out of cell
what is a differentially plasma membrane?
glucose and amino acids through carrier proteins
must combine with and ion (Na+) or a molecule to transport across membrane
what is a permeable plasma membrane?
CO2, O2, glycerol (lipid) ad alcohol pass freely through
cell always use O2 -> concentration lower inside
what are the factors influencing rate of diffusion?
surface area
temp
concentration gradient
diffusion distance
what is the importance of gaseous diffusion?
- CO2 used for photosynthesis from air into leaves through stomata, lower concentration inside
- O2 diffuses out leaf through stomata
- Flowering plants attract bees -> scent move from leaves into air
- alveolar membrane in lungs O2 diffuses across membrane into blood, CO2 across to alveoli
energy for diffusion?
- spontaneous, does not require energy
- MIA above 0, kinetic energy
- small amount kinetic energy involved
- source of energy comes from random movement of molecules
what is the importance of diffusion?
helps obtain rquirements
gets rid of waste products
help carry out gas exchange
what is the importance of solute diffusion?
products of digestion absorbed from ileum by diffusion
amino acids and glucose
what is a simple solution?
2 or more substances mixed together
What is the difference between solute and solvent?
solute: to be dissolved
solvent: one doing dissolving
what is water potential?
relative tendency of water molecules 2 move
hypotonic solution?
- less dissolved substances, more water
- lots free water molecules, high water potential
- dilute water
- cell in hypotonic, water move in
isotonic solution?
- solution with same water potential
- 2 solutions with same water molecules and same concentration of solutiions
- cell: same concentration and outside
hypertonic solution?
- more dissolved substances, less water
- less free molecules, low water potential
- strong solution
- salt water
- cell in hypertonic solution, water moves out of coll through osmosis
osmosis?
movement of water molecule from high water potential to low water potential through selectively permeable membrane down water potential gradient
turgar pressure?
pressure from fluid within cell pushing against cell wall -> maintained by osmosis
what causes wilting of plant?
loses too much water, plasmolyses plant becomes flaccid. cell membrane not pressed tightly against cell wall
active transport?
movement of particles through cell membrane form high concentration to low concentration against concentration gradient using energy from respiration
what is absorbed by root hairs?
Magnesium
phosphate
nitrates
