paper dos Flashcards
importance of maintaining glucose concentration
sufficient availability of respiratory substrate, stops water potential causing cells to burst or shrivel
role of negative feedback
restores systems to their original level
what creates a greater degree of control in feedback systems?
having separate systems to control different departures from the original state
how to explain action of hormones w blood glucode
‘activating enzymes involved in the conversion of…’
second messenger- what hormones trigger it and what enzyme does this activate
glucagon and adrenaline
adenylate cyclase
body parts involved in osmoregulation
hypothalamus and posterior pituitary gland
where is glucose reabsorbed in the kidney?
proximal convoluted tubule
process of glucose reabsorbtion
products such as glucose and amino acids are reabsorbed via co-transport with sodium ions through podocytes
which limbs of the loop of henle are permeable to what?
ascending- ions only
descending- water, ions also move in
net atp production from 1 krebs cycle
1 molecule
where do the electrons in the electron transfer chain come from?
reduced coenzymes
light-dependent reaction (5)
- chlorophyll absorbs light- it is photoionised
- some energy from photoionisation is conserved in the production of atp and nadph
- some atp is also produced from chemiosmosis, using energy from the electron transfer chain
- h+ are pumped into the thylakoid and catalyse atp synthase by moving out
- photolysis of water produces protons, electrons (which enter the etc) and oxygen
gpp definition
chemical energy store in plant biomass in a given area or volume
npp definition
chemical energy store in plant biomass after respiratory losses to the environment have been taken into account
net production of consumers
chemical store of ingested food - (faeces and urine + respiratory losses)
n = i - (f+r)
example unit of productivity
kJ ha-1 yr-1
nitrogen fixation
atmospheric nitrogen > ammonium ions, or other ammonium-containing products
nitrification
ammonium > nitrate via nitrite
denitrification
nitrate > atmospheric nitrogen
ammonification
breakdown of ammonium-containing products into ammonium ions
why is leaching bad
nitrates in water can cause problems with oxygen transport in babies, linked with increased risk of stomach cancer
eutrophication
- algal growth as nutrient availability no longer limiting, causing algal blooms
- less light at lower depths
- light becomes the limiting factor for plants and algae lower down
- dead plants and algae allow more growth of saprobiontic bacteria
- the bacteria use up the oxygen
- fish and other aerobic organisms die
why is eutrophication bad
populations of anaerobic organisms rise, and decompose the dead material, releasing more nitrates/other toxic material so water is bad
process that inhibit transcription
increased methylation
decreased acetylation