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AL. AQA Biology > energy flow > Flashcards

energy flow Flashcards

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1
Q

biomass

A

the dry mass of organic molecules

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2
Q

productivity

A

rate of biomass accumulation

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3
Q

units if productivity

A

kg/km2/year

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4
Q

net productivity of consumers

A

NP = I - (E+R)

net productivity = ingested - (egestion + respiratory losses)

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5
Q

net productivity of producers

A

NPP = GPP - R

net primary productivity = rate of photosynthesis - respiratory losses

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6
Q

% of light energy which becomes chemical energy in producers

A

2%

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7
Q

% chemical energy in producers which becomes chemical energy in primary consumers

A

10%

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8
Q

% chemical energy in primary consumers which becomes chemical energy in secondary consumers

A

20%

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9
Q

why is percentage of chemical energy lost between trophic levels so high

A
  • not all of previous trophic level is consumed or didgested
  • energy lost in undigestible food (eg. feaces)
  • respiratory losses of energy
  • excretion - CO2/urea
  • some of organism cannot be consumed
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10
Q

why is percentage of chemical energy lost between sun and producers so high

A
  • not all wavelengths of light are absorbed by pigments - some reflected
  • some light reflected by clouds
  • not all light hits chlorophyll
  • limiting factors affect rate of photosynthesis
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11
Q

how to increase productivity of producers (5)

A
  • sewing density
  • controlling pests
  • fertilisers
  • genetically modifying / selected breeding
  • control limiting factors eg. temp, light + CO2
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12
Q

how to increase productivity of consumers (non-producers) (8)

A
  • restricting movement - limiting respiratory losses
  • keep warm - limit heat lost to environment
  • vaccination - reduce disease
  • more digestible food
  • selective breeding
  • hormones/steroids
  • more nutrient rich food
  • early slaughter - when feed:gain ratio is at its highest
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13
Q

percentage efficiency

A

energy available after transfer / energy available before transfer x 100

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14
Q

advantages of artificial fertilisers

A
  • faster response

- specific to a crop

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15
Q

disadvantages of artificial fertilisers

A
  • expensive (although less machinery needed)

- soluble - lead to leaching

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16
Q

advantages of natural fertilisers

A
  • free/cheap - eg. manure
  • increases soil stability
  • organic
  • increases drainage - decrease water-logging
17
Q

disadvantages of natural fertilisers

A
  • slower acting - as decomposition needed
18
Q

environmental consequences of overuse of fertilisers (2)

A
  • loss of biodiversity - extra N spreads to neighbouring environments, favouring fast-growing plants ie. weeds which outcompete other species
  • eutrophication
19
Q

detritus

A

dead organic matter

20
Q

saprobiotic bacteria

A

decomposers

21
Q

ammonification

A

converting nitrogen ion in detritus to ammonium ions in the soil

22
Q

nitrification

A

taking ammonium ions and

23
Q

producers

A

photosynthetic organisms which make organic substances using light energy, H2O and CO2 + mineral ions

24
Q

consumers

A

organisms which obtain energy by feeding on other organisms (p. s. t. )

25
Q

food chain

A

feeding relationship where producers are eaten by consumers - each stage is a TROPHIC LEVEL
- diagram shows energy flow through ecosystem

26
Q

how to estimate energy store in dry mass

  • method
  • units of results
A

CALORIMETRY -
bomb calorimetry - sample of dry material weighed and burnt in exc. O2 in sealed chamber - energy given out heats water and temp rises
- calculate energy change in kJ/Kg

27
Q

d. Gross primary product (GPP)

A

total quantity of chemical energy in plant biomass in a given area/volume

28
Q

Net primary productivity (NPP)

A

chemical energy store after taking respiratory losses into account

29
Q

summary of nitrogen cycle:

A

1) AMMONIFICATION - saprobiotic bacteria make ammonia from dead organisms and waste -> ions into soil
2) NITRIFICATION - nitrifying bacteria make NO3- ions by oxidation reactions of ammonium ions -> nitrite ions -> nitrate ions
3) NITROGEN FIXATION - nitrogen gas - > nitrogen containing compounds - by: 1 - free living nitrogen fixing bacteria (make ammonia and release nitrogen rich compounds when they die and decay)
2 - mutualistic nitrogen fixing bacteria in nodules of plant roots - obtain carbs from plants and releases amino acids to plants
4) DENITRIFICATION - [less O2 = less aerobic nitrifying and nitrogen-fixing bacteria. more anaerobic denitrifying bacteria] - convert nitrates to gaseous N2 gas

30
Q

how to combat denitrification

A

keep soils well aerated and drained

31
Q

stores of phosphorus

A

mineral rock

32
Q

stores of nitrogen

A

gases in atmosphere

33
Q

eutrophication process

A
  • lakes and rivers, [N] = limiting factors
  • [N] ↑ = algae +plant pop. ↑
  • algal bloom at surface, reducing light intensities for plants at lower depths (= limiting factor)
  • plants die - broken down by saprobiotic bacteria - releasing CO2 by aerobic respiration
  • [O] ↓ = limiting reactant
  • fish and aerobic organisms die (broken down)
  • anaerobic pop ↑ more dead material to break down - releasing products such as nitrates and Hydrogen sulfates, making water putrid
34
Q

effects of nitrogen (neg.)

A
  • leaching - down by rainwater out of reach of plants and into groundwater supplies - leading to health effects eg stomach cancers
  • reduced species diversity as high [N] favours fast growing plants - increased interspecific competition
35
Q

uses of phosphorus (3)

A
  • ATP
  • Phospholipids
  • DNA
36
Q

uses of nitrogen (2)

A
  • nucleic acid synthesis
  • ATP
  • amino acids

AL. AQA Biology (18 decks)

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