osmosis

osmosis main points / summary

• movement of water - from area of low solute concentration to high solute concentration

• across a semi-permeable membrane - only water molecules can pass through

• passive process - meaning no energy required

• occurs in plants - e.g. water moving from oil into root cells

osmosis examples in animals

• red blood cells in water - water has a low solute concentration, meaning the water will move into the red blood cells via osmosis because the cells have a higher solute concentration, causing the blood cells to swell, become turgid, and possibly burst because they only have a cell membrane, not a cell wall

• kidneys (water reabsorption) - urine has a low solute concentration, meaning the water from the urine will move into the blood and be reabsorbed via osmosis because the blood has a higher solute concentration, allowing the body maintain its fluid balance, and prevent dehydration by conserving water

• animal cells in saltwater - salty solutions have a high solute concentration, meaning the water will move out of the cells via osmosis because the cells have a lower solute concentration, causing the cells to shrink and become flaccid

• cells in digestive system - water has a low solute concentration, meaning the water will move into the cells via osmosis because the cells have a higher solute concentration, causing the cells to become hydrated, and allowing them to function properly by absorbing the necessary nutrients

osmosis examples in plants

• root hair cells absorbing water - the soil has a lower concentration of solutes, meaning the water will move into the root hair cells via osmosis because the root hair cells have a higher concentration of solutes, helping the plant to take in the water it needs for photosynthesis and to stay hydrated

• water transport in xylem - water evaporates from the leaf surface through the stomata and to replace the water that is lost from this, the plant draws water from its roots via osmosis, helping with transpiration

• plant cells in water - water has a low solute concentration, meaning the water will move into the cells via osmosis because the cells have a higher solute concentration, causing the cells to swell, become turgid, and not burst because they have a cell wall which provides structure and prevents bursting