osmosis, diffusion, active transport Flashcards
What are the factors making rate of diffusion faster
Thinner surface / smaller distance
Higher concentration gradient
Larger surface area
Higher temperature
What are the passive types of movement of particles
Osmosis, diffusion and facilitated diffusion
Definition of osmosis
Net movement of water particles from an area of low concentration to high concentration through a partially permeable membrane
What are the active types of movement of molecules
Active transport, Bulk transport, Endocytosis, Exocytosis
What is the value of the highest water potential
The water potential of pure/distilled water Is 0kpa kilopascales So solutions with a lower water potential have a negative value
What is water potential and what is it used for
It is the tendency of water molecules in a system to diffuse, Used to determine the net movement of water by osmosis by the difference in water potential
Equation of water potential
Pressure potential + solute potential
What is the trend of water potential as solute potential increases
The more solute added, the value for solute potential becomes more negative causing water potential to decrease also
Solute potential is 250 and pressure potential is 200 what is water potential
-50
-50 -10 -300 Which is the most dilute solution
-10
-50 -10 Which direction would water pass
high to low concentration so -10 to -50
What happened if insoluble molecules are in the solution
Insoluble molecules do not affect osmosis concentration
hypertonic hypotonic and isotonic
Hypertonic (higher water conc in the cell) - Water has moved out, cell becomes plasmolyzed (shrinks)
hypotonic (Higher water conc out of the cell) - Water has moved into the cell It becomes turgid and may burst
isotonic - The movement of water in is equal to movement of water out so same concentration inside and out So the cell stays flaccid
Why is it important to keep solute concentrations at the correct level in the body
To help prevent excess water loss and to help maintain correct fluid balance for necessary reactions for many body processes
What is an example of diffusion
Gas exchange Across respiratory surfaces like lungs
Fick’s law: Rate of diffusion is proportional to:
Surface area X concentration gradient % thickness of membrane
due to a flood There is now seawater on top of a plant, How would the plant be affected
Seawater has high salt concentration So low water concentration. Water from the plant undergoes osmosis from high to low concentration out of the plant. Therefore the plant cell shrinks and is plasmalised
What is the difference between simple and facilitated diffusion
In simple diffusion small non polar molecules eg co2 and lipid soluble substances easily pass through the bilayer
In facilitated diffusion polar and charged molecules such as carbohydrates, amino acids, nucleotides and ions pass through the membrane with the help of carrier or channel proteins
How do carrier proteins assist in moving large molecules in and out of the cell
A specific shaped molecule can bind to the carrier protein, change its shape and make the protein release the molecule onto the opposite side of the membrane
how do channel proteins assist in moving Small ions and polar molecules in and out of the cell
They open in response to the binding of a chemical messenger eg Ligand, allowing ions like na+ or cl- to pass through the membrane
State two changes to the structure of the cell membrane that would increase rate of diffusion of polar molecules
More channel and carrier proteins
Largest surface area and thinner membrane
Movement requires energy but diffusion requires none why is this
Diffusion does not require external energy sources but relies on kinetic energy from the natural random movement of particles
What is an example turgor of pressure
When a plant cell has lots of water (Is in a turgid state) the cell membrane is pushed against the cell wall
What is active transport
Movement of particles against a concentration gradient, requires energy in the form of ATP
Examples of processes that needs active transport
- Absorption of minerals by plant root hair cells
- uptake of glucose and amino acids in the small intestine
- excretion of hydrogen ions in urea by kidneys
- Exchange of sodium and potassium ions in neurons and muscle cells
what is bulk transport endocytosis
Transport of large substances into the cell
three types :
phagocytosis (solids) pinocytosis (liquids) and receptor mediated endocytosis
When is bulk transport used
when extremely large substances need to move through a cell membrane
what is bulk transport exocytosis and how does it happen
Transport of large substances out of the cell,
Vesicles fuse with the plasma membrane and release their contents out
What are the steps of bulk transport
Invagination of cell membrane surrounding the large molecules
Membrane folds until vesicle forms
Vesicle pinches off and moves into cytoplasm for further processing EG by lysosomes
Why is it important for plants to go through Active transport from the soil in an area of low concentration of minerals
Plants need mineral ions to survive,
as concentration is higher in the root hair cells they will diffuse out of root hair cells but energy is required to move mineral ions against the concentration gradient
Droplets of ink are dropped in water and start to spread why does this happen
They are moving from high concentration (the original droplet of ink) to low concentration (the surrounding water)
What happens when potato cells have a lower water potential than the solution
They gain water by osmosis causing vacuoles to swell and the cell content to be pushed against the cell wall making the cell turgid
What happens when potato cells have a higher water potential than the solution
The cells become flaccid so they will lose water by osmosis and they may become Plasmolyzed
What’s the difference between an animal cell and a plant cell in a hypotonic solution
Water moves into the cells by osmosis,
Animal cells could burst
plant cells vacuole and cytoplasm push against the cell wall but don’t burst
Why does a rate of oxygen consumption increase as rate of active transport increases
Active transport needs energy oxygen is used in aerobic respiration in the mitochondria to produce atp. this atp is used as energy to go against the concentration gradient So the more oxygen the more atp released so the more active transport can take place
what are the two ways water molecules can go through cell membrane
Simple diffusion or through aquaporin (channel protein)
why do plant cells not burst when left in pure water not burst when left in pure water
The cell wall made of cellular loose keeps them strong and prevents it from bursting
