B2 Flashcards
What is diffusion
- the net/ passive movement of particles from a region of high to low concentration
Factors increasing the rate of diffusion
- Short diffusion distance
- Steep concentration gradient
- Larger SA: V ratio
- Temperature
What is osmosis
- the diffusion of water/solvent molecules through a partially-permeable membrane following the concentration gradient
- passive movement
What is the concentration of water molecules called?
Water Potential
What is an isotonic solution
A solution that has the same solvent concentration inside and outside the cells
What is a hypotonic solution
A solution that has a higher water potential outside the cell
What is a hypertonic solution
A solution that has a lower water potential outside the cell
What happens when water leaves a PLANT CELL
- first the cell will become flaccid when the water leaves the cell then the cell will become plasmolyzed (the content of the cell collapses away from the cell wall)
- hypertonic solution
What happens when water enters a PLANT CELL
- first the plant cell will become turgid and the cell will have increased pressure
- hypotonic solution
What happens when solvent enters an ANIMAL CELL
- the solvent will fill up with water and then get too full and lyse (burst)
What happens when a solvent leaves an ANIMAL CELL
- solvent will leave the cell and the cell will have too little water
- The cell will crenate/crinkle
- hypertonic solution
What is Active Transport?
- the active movement of particles from low to high concentration using energy from respiration
How is active transport carried out?
- the molecules go against the concentration gradient
- carrier proteins in the cell membrane bind to a specific molecule
- They then use energy from ATP to turn and place the molecule in the cell then turn back and repeat the process
What is a carrier protein
- a protein in the cell membrane of a cell that binds to a specific molecule
- They use ATP from respiration to turn
Adaptations of cells that take part in active transport
- many mitochondria as more ATP is needed so more respiration will be done
Place where active transport takes place (plant)
- In the root hair cells
- Use active transport for mineral ions such as nitrates
- They use carrier proteins to get the nitrates for the leaves into the plant
Place where active transport takes place (animal)
- In the small intestine
- carbs are broken down into glucose
- half is diffused into the bloodstream, then concentration gradient is too steep for diffusion
- The other half is absorbed into blood via active transport
What is cell differentiation?
When cells differentiate they specilaise to perform a specififc function
Adaptations of Sperm Cell
- function of a sperm cell is to transfer genetic material from the male to the egg
- Flagellum - tail used for swimmining and propelling the sperm forward
- Lots of mitochondria because lots of energy is used in moving the sperm cell
- Acrosome, stores digestive enzymes which break down the outer layer of the egg cell
Adaptations of a Red Blood Cell
- No nucleus to carry more haemoglobin cells so more oxygen can be carried
- packed full of haemoglobin so most amount of oxygen can be carried
- Is in the shape of a bioconcave disk which increases SA”V ratio speeding up diffusion for carbon dixiode and oxygen
Adaptations of Palisade Cells
- specialised to carry out photosynthesis
- Found near leaf and are packed with chloroplasts
- Regular shaping to allow close packing within leaf maxinimsing absorption of sunlight
What is a stem cell
- A stem cell is an undifferentiated cell that can divide to produce a range of cell types
Where are embryonic stem cells found
- Embryonic stem cells are found in blastocysts which are one step after embryos
- They are totipotent and better than adult stem cells
Where are adult stem cells found
- Mainly found in the bone marrow
- can differentiate into less cells than embryonic stem cells
- Adult stem cells act as repair mechandism for the body
Advantages and Disadvatages of Animal Stem Cells
- Embryonic stem cells can be used for a wider variety of uses
- They are destroyed anyway so may as well be used
- However they cannot give consent
- They also have a right to life
Why does mitosis occur?
- to replace worn out cells
- to repair damaged tissue
- so the organism can increase in size/grow