Level 2 Biology: Osmosis Internal Flashcards
What does ‘hydrophobic’ mean?
water “hating”
What does ‘hydrophilic’ mean?
water “loving”
What is a phospholipid composed of?
Phosphate group and lipid
What is a ‘Bi-layer’
2 layers
What is a ‘Semi permeable membrane’?
It will only allow certain substances into and out of the cell
What can a phospholipid bilayer act as a barrier between?
A phospholipid bilayer can act as a barrier between two aqueous environments.
passive transport
Does not require energy. Movement of molecules across the cell membrane
Active transport
Requires energy (ATP)
Dependent on the permeability of the cell membrane there are 3 main kinds of passive transport. What are they?
1) Diffusion
2) Osmosis
3) Facilitated diffusion
Definition of Diffusion
Diffusion is the movement of molecules from an area of high concentration to one of low concentration. It uses no energy.
What are the 3 key points on ‘Concentration gradient’
1) For things to diffuse there must be a difference in concentration between two areas.
2) If not, the particles won’t be able to move to a lower concentration.
3) The bigger the difference in concentration the faster it will diffuse.
What does the ‘rate of diffusion’ depend on? (4 things)
1) The concentration gradient (bigger difference, the faster the diffusion).
2) Temperature (warmer=faster diffusion)
3) Particle size (Smaller=faster)
4) State of matter (gas=Faster diffusion)
What is ‘Facilitated diffusion’
Substances are helped across the membrane by carrier proteins. It still uses no energy but the proteins are specific to certain molecules.
How do cells absorb glucose?
Cells absorb glucose by facilitated diffusion. Insulin activates the transport proteins, if insulin is not there- can’t absorb glucose
What is the cell membrane impermeable to?
Most electrically charged molecules and large water soluble substances such as glucose and amino acids.
What do proteins embedded in the membrane contain?
Proteins embedded in the membrane contain channels that the large molecules diffuse through.
What are the similarities and differences between diffusion and facilitated diffusion?
Facilitated diffusion is the movement of larger molecules with the aid of protein channels. Diffusion is the movement of molecules form an areas of high concertation to one of low concentration. Both don’t require energy (passive)
What is Osmosis
Osmosis is the movement of water from an area of high concentration to one of low concentration (down the concentration gradient) across a semi permeable membrane.
What is the requirement for the concentration of water to be lower?
For the concentration of water to be lower means that it must have something else in it (sugar, salt, ions)
What is osmoregulation
The balancing of water inside an organism. Cells have to keep their water content balanced or else they either get too full or too empty of water.
In animals too much water makes the cell ______?
Pop
In animals too little water makes the cell ______?
Shrivel
What are the 3 states a cell can be in?
1) Hypertonic
2) Isotonic
3) Hypotonic
What is ‘Isotonic’
Isotonic means balanced. Outside cell and inside cell have same amount of water and solute as each other.
What is ‘Hypertonic’
The fluid outside cell has HIGH solute (less water). The fluid inside cell has LOWER solute (MORE water). Water comes out and tries to balance the water outside the cell=shrivelled cell (not enough water)
What is ‘Hypotonic’
The fluid outside cell has LOW solute (Higher water). The fluid inside cell has HIGHER solute (LESS water). Water goes in and tries to balance the water in the cell=Cell either pops or gets over full of water.
What are the 3 key points on ‘Tonicity’
In Isotonic solutions cells have no net loss or gain of water. Net loss of water due to osmosis in hypertonic solutions. Net gain of water due to osmosis in hypotonic solutions.
What will an animal cell do in hypertonic and hypotonic solutions
Shrivel or shrink in hypertonic solutions and expand or burst in hypotonic solutions.
What will plant cells do in hypertonic and hypotonic solutions
Plant cells become plasmolysed in hypertonic solutions-the cell membrane pulls away from the cell wall. Plant cells become firm in hypotonic solutions- hold their shape and are rigid or turgid.
What is Tonicity?
Tonicity is the measure of the water potential gradient of two solutions (solutions on either side of semi-permeable membrane)
What is water potential?
Water potential is a measure of the tendency of water molecules to move from one place to another. Water always moves from a region of higher water potential to one of lower water potential down the concentration gradient.
What is Active transport?
Active transport is the movement of molecules and ions through a cell membrane from a region of lower concentration to a region of higher concentration USING ENERGY from respiration.
What does Active transport require
Carrier proteins (each carrier protein being specific for a particular type of molecule or ion)
What also uses carrier proteins?
Facilitated diffusion
What is the difference between Facilitated diffusion and active transport despite them both using carrier proteins?
Active transport requires ENERGY
Why does active transport require ENERGY?
The energy is required to make carrier proteins change shape, allowing it to transfer the molecules or ions across the cell membrane. The energy required is provided by ATP produced during respiration.
What is an iron pump
This is where certain ions or molecules are pumped from one side of the cell membrane to the other. Usually different ions need to be present to make the other ion change sides.
What is the difference in two areas called in relation to diffusion?
The concentration gradient
What are the factors that affect the rate of diffusion?
Size, temperature and state
