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Biology 🌿 > productivity + cycles > Flashcards

productivity + cycles Flashcards

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1
Q

outline nitrogen cycle

A

nitrogen fixation
ammonification
nitrification
denitrification

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2
Q

nitrogen fixation

A

nitrogen converted to ammonia
by nitrogen fixing bacteria

nitrogen from atmosphere

bacteria found in root nodules of legumes
- mutualistic relationship
- provide plant with compounds, get carbohydrates from plant

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3
Q

ammonification

A

nitrogen compounds converted to ammonia
by saprobionts (decomposers)

nitrogen compounds from anima waste or dead organisms

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4
Q

nitrification

A

ammonium ions -> nitrites -> nitrates
by nitrifying bacteria

ammonium from soil

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5
Q

denitrification

A

nitrates converted to nitrogen gas
by denitrifying bacteria

happens in anaerobic conditions
by respiration of the bacteria

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6
Q

role of saprobionts

A

decomposers
break down remains of dead plants and animals and waste
allows chemical elements in the remains to be recycled

secrete enzymes and digest matter externally
then absorbs nutrients they need - extracellular digestion

organic molecules broken down into inorganic ions

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7
Q

what is saprobiontic nutrition?

A

obtaining nutrients from dead organic matter using extra cellular digestion

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8
Q

role of mycorrhizae

A

a symbiotic relation between fungi and roots of plants

  • fungi made of long thin strands, hyphae, which connect to plants roots
  • increase surface area of plants roots
  • helps plant absorb ions from soil
    eg phosphorus
  • increase uptake of water for plant
  • fungi get organic compounds from the plant
    eg glucose
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9
Q

outline phosphorus cycle

A
  1. phosphate ions in rocks released by weathering
  2. phosphate ions taken into plants through roots (rate increased by mycorrhizae)
  3. transferred through food chain
  4. phosphate ions lost from animals in waste products
  5. saprobionts release phosphate ions into soil by decomposition
    - breaking down dead plants, animals and waste

or
6. weathering also releases phosphate ions into water
7. taken up by aquatic producers, eg algae
8. passed along food chain to sea birds
9. phosphate ions returned to soil through guano

returned to producers or trapped in sediment again

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10
Q

outline eutrophication

A
  1. mineral ions leached from fertilised fields
  2. causes rapid growth of algae
  3. large amounts block sunlight
  4. plants die as they cant photosynthesise
  5. bacteria feed on bead plant matter
  6. increase in bacteria means less oxygen in water (respire aerobically)
  7. fish and species die as not enough oxygen
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11
Q

how does farming reduce nutrients in soil?

A

lost when plants harvested
- removed from area
- don’t die and decompose
- mineral ions not returned to soil

animals taken in phosphates and nitrites eating grass
- animals removed
- nutrients not returned in waste

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12
Q

why are fertilisers used?

A

to replace nutrients lost from soil

by harvesting and removing livestock
loses phosphates and nitrates

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13
Q

artificial fertilisers

A

inorganic
pure chemicals - ammonium nitrate

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14
Q

environmental impacts of fertilisers

A

leaching
eutrophication

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15
Q

natural fertilisers

A

organic matter
eg manure, composted vegetables, sewage
guano

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16
Q

outline leaching

A

mineral ions from fertilisers washed away (eg nitrate and phosphate)

happens as more fertiliser applied than a plant can use
- remain in soil water
more likely after heavy rainfall

inorganic ions in artificial more soluble - more likely to be leached

phosphates less soluble = leached less (than nitrates)

17
Q

what is biomass

A

the mass of living material
amount of chemical energy stored in an organism

in plants:
made up of biological molecules made from light energy into chemical energy in photosynthesis
(synthesised from CO2)

estimated using calorimetry

18
Q

gross primary production

A

chemical energy store in plant biomass in a given area

G primary productivity = given time (rate)

19
Q

respiratory loss

A

GPP energy lost as heat energy when plants respire

20
Q

net primary production

A

chemical energy store in plant biomass after respiratory losses in a given area

NPP = GPP - R

remaining chemical energy
available for:
- plant growth
- reproduction
- other trophic levels in ecosystem eg higher and decomposers

N primary productivity = per given time (rate)

21
Q

what is net production

A

energy stored in the biomass of consumers

get energy by digesting plants or animals that have eaten plants
not all energy transferred, lost by:
- respiration
- urine and faeces
- not all food eaten or digestible, eg bones

secondary productivity

22
Q

how is net production calculated?

A

N = I - (F + R)

N = net production
I = chemical energy in ingested food
F = chemical energy lost in faeces and urine
R = respiratory loss

23
Q

what is primary and secondary productivity measured in?

A

biomass in a given area in a given time

kJ ha-1 year-1

24
Q

how do farming practises increase efficiency of energy transfer (2)

A

simplifying food webs
- reduces energy lost

reducing respiratory losses
- reduces energy lost

both increase energy available for human consumption

25
Q

simplifying food webs

A

reduces energy lost to other organisms

getting rid of food chains not involving humans

  • increases NPP of plants
  • less energy lost to pests

done by pesticides + herbicides
kills weeds and pests to reduce competition

26
Q

how are respiratory losses reduced?

A

controlling conditions livestock live in
more energy available for there growth

reduce movement
keep indoors - less energy wasted maintaining temperature

more energy maintained (losses reduced) - more energy available for humans

but unethical for livestock to reduce movement

27
Q

ways nitrogen is introduced into soils

A

animal waste
nitrogen fixation (by nitrogen fixing bacteria)
artificial fertilisers
decay of organic matter by saprobionts (ammonification)

28
Q

ways phosphorus is introduced into soils/water

A

weathering of sedimentary rock
minerals in fertilisers
decomposition of animal waste

29
Q

what is a tropic level?

A

position of an organism in a food chain

net primary production available to those higher in tropic levels
and decomposers in soil

30
Q

production vs productivity

A

production = mass per area

productivity = mass per area per TIME
rate of production

31
Q

calorimetry

A

used to estimate biomass

burn matter in calorimeter
used to heat known volume of water
temperature change measured

32
Q

use of nitrogen in organisms

A

proteins and nucleic acids

33
Q

use of phosphorus in organisms

A

phospholipids and nucleic acids

34
Q

efficiency of energy transfer (%)

A

I - (F + R) = NP

(NP divided by I) x 100

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