paper dos Flashcards

1
Q

importance of maintaining glucose concentration

A

sufficient availability of respiratory substrate, stops water potential causing cells to burst or shrivel

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2
Q

role of negative feedback

A

restores systems to their original level

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3
Q

what creates a greater degree of control in feedback systems?

A

having separate systems to control different departures from the original state

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4
Q

how to explain action of hormones w blood glucode

A

‘activating enzymes involved in the conversion of…’

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5
Q

second messenger- what hormones trigger it and what enzyme does this activate

A

glucagon and adrenaline

adenylate cyclase

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6
Q

body parts involved in osmoregulation

A

hypothalamus and posterior pituitary gland

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7
Q

where is glucose reabsorbed in the kidney?

A

proximal convoluted tubule

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8
Q

process of glucose reabsorbtion

A

products such as glucose and amino acids are reabsorbed via co-transport with sodium ions through podocytes

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9
Q

which limbs of the loop of henle are permeable to what?

A

ascending- ions only

descending- water, ions also move in

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10
Q

net atp production from 1 krebs cycle

A

1 molecule

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11
Q

where do the electrons in the electron transfer chain come from?

A

reduced coenzymes

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12
Q

light-dependent reaction (5)

A
  • 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
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13
Q

gpp definition

A

chemical energy store in plant biomass in a given area or volume

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14
Q

npp definition

A

chemical energy store in plant biomass after respiratory losses to the environment have been taken into account

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15
Q

net production of consumers

A

chemical store of ingested food - (faeces and urine + respiratory losses)
n = i - (f+r)

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16
Q

example unit of productivity

A

kJ ha-1 yr-1

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17
Q

nitrogen fixation

A

atmospheric nitrogen > ammonium ions, or other ammonium-containing products

18
Q

nitrification

A

ammonium > nitrate via nitrite

19
Q

denitrification

A

nitrate > atmospheric nitrogen

20
Q

ammonification

A

breakdown of ammonium-containing products into ammonium ions

21
Q

why is leaching bad

A

nitrates in water can cause problems with oxygen transport in babies, linked with increased risk of stomach cancer

22
Q

eutrophication

A
  • 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
23
Q

why is eutrophication bad

A

populations of anaerobic organisms rise, and decompose the dead material, releasing more nitrates/other toxic material so water is bad

24
Q

process that inhibit transcription

A

increased methylation

decreased acetylation

25
what is epigenetics?
heritable changes in gene function, without changes to the base sequence of dna
26
action of oestrogen
- easily diffuses through phospholipid bilayer - binds with the receptor on a transcription factor - dna binding site on transcription factor changes shape, now complementary to dna - enters through nuclear pore and stimulates transcription of the gene
27
acetylation on transcription
- decreased makes the histones more positive - so more attracted to phosphate groups on dna - less accessible to transcription factors
28
methylation on transcription
- increased prevents binding of transcription factors | - induces deacetylation of histones
29
where do sirnas come from?
double stranded rna bound to an enzyme
30
what are schwann cells?
myelin-containing cells that provide electrical insulation/general protection
31
where is myelin?
in the cell membranes of schwann cells
32
open at resting potential
k+ channels, net movement of na+ out of pump
33
when do na+ channels close?
when +40mv potential has been established
34
what causes hyper-polarisation?
outward transport of k+ through the channels that are able to close
35
repolarisation
closable k+ channels shut, resting potential restored
36
name for the node of ranvier thing
saltatory conduction
37
greater axon diameter
increases speed of conductance due to less ion leakage
38
types of summation
spatial- multiple neurones | temporal- high frequency of neurotransmitter release from one neurone
39
3 purposes of the refractory period
one direction only discrete impulses limits number of action potentials
40
action of an inhibitory synapse
- neurotransmitter causes chloride ion channels to open - cl- move in, also triggers k+ channels to open, so they move out - membrane potential drops - this hyperpolarisation makes it less likely that an action potential will be triggered