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Nitrogen fixation by the haber process

- N2 + 3H2 NH3
- lots of energy
- in fertilisers

1

Denitrification

- denitrifying bacteria get energy from turning nitrate back to N2
- found in compost heaps and sewage plants

2

Nitrogen fixation

- the conversion of nitrogen from unreactive N2 to a more reactive form
- ie ammonia or nitrate ions

3

Nitrogen fixation by living organisms

- prokaryotes & archeans
- ie rhizobium in soil - mutualistic with roots of leguimous plants
- rhizobium colonises in root nodules
- N2 -> NH4+
- H+ from NADred
- ATP resp& photosynthesis
- anaerobic conditions from leghaemoglobin

4

Fixed nitrogen in plants

- rhizobium
- used to make amino acids
- moved and synthesised to make proteins
- others - N2 from soil active transport through root hairs
- Nitrate ions-> nitrite ions-> ammonia -> amino acids

5

Nitrogen in animals

- from diet (proteins + some nucleic acid)
- broken down in digestion to amino acids
- absorbed by and transported by blood
- waste deaminated in liver -> urea

6

Ammonification

- the production of ammonia

7

From living organisms to nitrogen in the soil

- bacteria and fungi break down dead organisms with protease
- some used some broken down to ammonia
- NH3-> nitrosomonas -> NO2 -> nitrobacteur -> NO3
- nitrifying bacteria
- require O2

8

Nitrogen fixation in the atmosphere

- energy from lightning = nitrogen oxides
- dissolved is soil from rain
- stormy countries contribute more

9

Studying succession

- sand dunes
- transects
- line transect (next to tape)
- belt transect (quadrats at intervals)
- Continuous transect- record whole length of tape
- interrupted transect - record at intervals

10

Succession stages

- pioneer species - abiotic factors
- they add nitrogen to the soil & produce humus, stabilise the soil and increase biodiversity
- other plants can then colonise- biotic factors

11

Pioneer plants

- the first living organism to colonise an area
- later outcompeted
- grow sparse, in low nitrate soils and have good disperal techniques
- alter the soil
- produce nutrients for decomposers

12

Seral stages

- the different communities present in succession

13

Climax community

- the final community of succession
- normally stable
- dont change much over time

14

Secondary succession

- if the area was disturbed
- if soil was already present

15

Primary succession

- if the original area had no soil
- and no living organisms present

16

Succession

- a directional change in a community over time

17

Maximising energy transfer in animals

- primary consumers - less trophic levels
- fertiliser - more energy in plant
- medicines to kill parasites - all energy in animal no lost to parasites
- indoors - controlled heat& movement

18

Maximising energy transfer in crops

- crops close together - more sunlight on leaves less on floor
- more H20 - isnt a limiting factor
- extra minerals ie fertiliser - not a limiting factor
- herbicides - specific to weeds

19

Monocultures

- grow a single variety of crop in an area
- all light energy for the plant
- herbicides - kill weeds
- pesticides - kill insects

20

Measuring energy transfer

- measure pop size
- calculate mean dry mass of an organism (killing and drying)
- calculate energy transfer per gram ( burning and calorimeter)
- calculate energy content

21

Net primary productivity

- the energy that is left as chemical energy after the plant has supplied its own needs by respiration

22

Gross primary productivity

- The total quantity of energy transferred by plants from sunlight into plant tissue

23

Productivity

- the rate at which plants turn light energy into chemical energy

24

Loss of chemical energy

- breaking down molecules in respiration- energy lost as heat
- ATP made used for activities
- not all energy from plants eaten
- not all the plant digested ie faeces
- energy lost as heat in digestion
- overall efficiency = about 10%

25

Loss of light energy

- sunlight missing leaves
- some wavelengths reflected
- some pass through and dont hit pigments
- only some wavelengths absorbed
- energy lost during photosynthesis

26

Decomposers

- feed on detrius

27

Detritus

- organic matter in dead organisms and wate material
- ie dead leaves/faeces/ urine

28

Food web

- the interrelationships between food chains

29

Trophic level

- the stages of a food chain at which an organism eats

30

Food chain

- the way in which energy flow from
producer to consumer
- may contain multiple consumers ie primary/secondary/tertiary

31

Consumer

- an organism that obtains its energy from organic compunds
- ie carbs, fats & proteins
- all animals and fungi - consume mainly plants

32

Producers

- an organism that transfers light/ inorganic energy into organic molecules ie carbs
- and supply the rest of the ecosystem

33

Abiotic factors

- non-living components of the enviroment
- ie temperature/light intensity/PH/wind speed/O2 conc/CO2 conc/ water availability/soil

34

Competition

- in which 2 organisms both require something which is in short supply

35

Parasitism

- one organism (the parasite) lives in close association with an organism of another species
- and does it harm

36

Mutualism

- a close relationship between 2 organisms where both benefit

37

Biotic factor

- factors that involve other living organisms
- ie feeding (on plants)/predation/competition/parasitism

38

Ecosystem

- relatively self contained system including all the living organisms and the enviroment interacting with each other