A2 Biology Progress Test 1
- Created by: AbbieLouise28
- Created on: 22-09-15 10:06
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- A2 Biology progress test 1
- nerves
- resting potential
- sodium-potassium pumps active
- this is against concentration gradient
- ATP required
- this is against concentration gradient
- 3 Na+ moved out for every 2K+ moved in
- membrane does allow some to leak through
- leakier to K+ than Na+
- more positive on the outside than inside
- creates a positive charge on outside
- difference in charge creates the resting potential
- -70mV
- sodium-potassium pumps active
- structure
- part after cell body is the axon
- part before cell body is the dendron
- myelin
- made up of Schwann cells
- mostly lipid with some proteins
- gaps known as nodes of Ranvier
- allows for salutatory conduction
- increased speed
- action potential jumps between nodes of Ranvier
- allows for salutatory conduction
- 1/3 are myelinated
- made up of Schwann cells
- action potential
- membranes of neurones also have other protein channels as well as the ion pumps
- some of these are voltage-gated
- they open and close depending on the potential difference across the membrane
- at resting potential they are closed
- some channels are caused to open and close depending on stimuli
- 1-the Na+ ions can now flow back into the cell
- can do this as an electrical gradient is set up
- resting potential is now removed
- no overall charge
- membrane is depolarised
- no overall charge
- 1-the Na+ ions can now flow back into the cell
- some of these are voltage-gated
- all-or-nothing law
- either an action potential is generated or not no matter how big stimuli is
- frequency of action potentials tells us the difference between a strong or soft touch
- membranes of neurones also have other protein channels as well as the ion pumps
- synapses
- gap is called synaptic cleft
- impulse crosses the synapse
- action potential arrives at the membrane of the presynaptic neurone
- transmitter substance is released into cleft and diffuses across it
- happens via exocytosis
- presynaptic neurone has many vesicles containing the neurotransmitter
- Ca2+ channels open causing vesicles to move
- plasma membrane of postsynaptic neurone has receptor proteins
- neurotransmitters are complementary to this and bind with the receptors
- this allows Na+ ions to rush into the postsynaptic neurone, depolarising the membrane to start the AP
- transmitter substance is released into cleft and diffuses across it
- action potential arrives at the membrane of the presynaptic neurone
- resting potential
- Hormones
- endocrine
- endocrine system transmits info from one cell or organ to another
- travel in blood plasma
- go to target cells
- gland produces and secretes the hormones
- travel in blood plasma
- endocrine system transmits info from one cell or organ to another
- exocrine
- secrete substances into a duct
- carried to another part of the body
- secrete substances into a duct
- 1st and 2nd messengers
- affect target cells by attaching to a specific receptor molecule
- this sets into action a series of events within the cell
- affect target cells by attaching to a specific receptor molecule
- endocrine
- energy flow
- abiotic factors involve non-living parts of the environment
- biotic factors involve other living organisms
- trophic level is the level at which an organism is in the food chain
- most energy is wasted and transferred elsewhere, will not move to the next organism
- can be lost due to
- unedible parts
- primary will use the energy in bodily functions
- the primary used up the energy in movement
- the primary loses energy on excretion
- less than 10% energy transfer when mammal eats mammal
- energy lost as heat to maintain body temp.
- we can manipulate energy levels from producer to consumer by
- harvesting animal before adulthood
- treat with steroids
- selective breeding
- treat with antibiotics
- maintain constant temp.
- limit movement
- supply food
- can be lost due to
- most energy is wasted and transferred elsewhere, will not move to the next organism
- nitrogen cycle
- geochemical
- lightning
- breaks down n=-n to form nitrates
- add nitrates to soil to improve fertility
- haber process
- makes ammonium ions to improve fertility of soils
- volcanic activity
- releases vast quantities of energy to break n=-n
- ocean currents
- dead organic matter cant decompose
- currents may lift the matter to be exploited in shallow water
- dead organic matter cant decompose
- lightning
- biological
- nitrogen fixation
- bacteria in root nodules of lugumes
- risobium
- bacteria is anaerobic so the root nodule becomes anaerobic as the enzyme releases leghaemoglobin to take up o2
- nostoc is free-living nitrogen fixing bacteria in the soil
- use ammonium ions
- bacteria in root nodules of lugumes
- denitrifying bacteria
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- nitrogen fixation
- geochemical
- succession
- primary succession
- development of a community from bare ground
- pioneer community
- algae and lichens begin to live on the bare rock
- the erosion of rock and build up of dead and rotting organisms produces soil for mosses and ferns to grow
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- pioneer community
- development of a community from bare ground
- primary succession
- nerves
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