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Nutrient cycle > nutrient cycles > Flashcards

nutrient cycles Flashcards

1
Q

what is denitrification?

A

the loss of nitrates from the soil under anerobc conditions

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2
Q

what happens in the process of denitrification?

A

nitrates are converted into nitrogen gas

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3
Q

what carries out denitrification?

A

denitrifying bacteria

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4
Q

describe an organic molecule

A

large, complex molecules that all contain the element carbon

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5
Q

describe an inorganic molecule

A

simple, small molecules and tend to be found in the abiotic

phase.

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6
Q

Name two nucleic acids

A

DNA & RNA

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7
Q

Name two other organic compounds which always contain nitrogen

A

Amino acids / proteins / ATP / ADP

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8
Q

What does inert ’ mean?

A

unreactive

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9
Q

how much nitrogen makes up the earths atmosphere?

A

80%

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10
Q

Why will lack of nitrogen lead to stunted growth?

A

Organism is unable to make proteins which are needed for growth

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11
Q

name the 5 main stages in the nitrogen cycle

A
  1. Nitrogen fixation
  2. Nitrification
  3. Denitrification
  4. Nitrogen flow through food webs
  5. Ammonification (during decomposition
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12
Q

describe nitrogen fixation

A

This is a process by which
nitrogen gas is converted into a nitrogen containing
compound that is more useful to organisms.

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13
Q

what carries out nitrification?

A

nitrifying bacteria

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14
Q

how does nitrogen fixing bacteria work?

A

They convert the nitrogen into ammonia using a reduction reaction catalysed by the enzyme
nitrogenase

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15
Q

where can nitrogen fixing bacteria be found?

A
  • Some of these bacteria live in special swellings on the roots (known as root nodules of plants called legumes .
  • free living in the soil
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16
Q

describe the mutually beneficial relationship

between the bacteria and the plant is an example of

A

The bacterium receives water and sugars

from the plant and in return supplies the plant with ammonia.

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17
Q

Name some types of legumes

A

Clover, soy beans, pea plants

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18
Q

when the ammonia is dissolved in water in the soil. what is produced?

A

ammonium ions

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19
Q

what carries out nitrification?

A

nitrifying bacteria

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20
Q

what do nitrifying bacteria do?

A

transform ammonium ions into nitrates.

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21
Q

why are nitrifying bacteria described as autotrophs?

A

when they transform ammonium ions into nitrates, it releases energy which they use for the synthesis of organic molecules such as carbohydrates. For this reason, these

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22
Q

Green plants are also called autotrophs. What is the difference between green plants and nitrifying bacteria autotrophs?

A
  • Green plants use light energy to synthesise organic matter(= PHOTOautotrophs)
  • Some bacteria oxidise chemical compounds (e.g. nitrites) to release energy they need to synthesise organic matter (= CHEMOautotrophs
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23
Q

describe the two stages of nitrification

A
  1. The oxidation of ammonium ions to nitrite by nitrifying bacteria
  2. The oxidation of nitrites to nitrates by nitrifying bacteria
24
Q

describe the two stages of nitrification

A
  1. The oxidation of ammonium ions to nitrite by nitrifying bacteria
  2. The oxidation of nitrites to nitrates by nitrifying bacteria
25
Q

how do plants take up nitrogen from the soil in the form of nitrates?

A

through their roots by active transport

26
Q

what are sabrobiotic microorganisms and how do they cause decay?

A

Fungi/bacteria that perform extracellular digestion. They secrete enzymes on to the
detritus so the nitrogen-containing compounds (e.g. DNA/proteins/urea) are digested
externally. They absorb some of the products of digestion and use them, but some
(e.g. ammonia) are released into the environment

27
Q

name the process that converts nitrogen into ammonia

A

nitrogen fixation

28
Q

name the process that converts ammonium ions into nitrates and then into nitrites

A

nitrification

29
Q

name the process when nitrates are converted into nitrogen gas

A

denitrification

30
Q

describe the role of nitrogen fixing bacteria

A

reduce nitrogen gas to ammonia/ ammonium ions

31
Q

describe the role of sabrobiotic bacteria

A

decompose dead/waste material by extracellular digestion

-convert nitrogen containing organic molecules into ammonia

32
Q

describe the role of nitrifying bacteria

A

oxidise ammonia to nitrates

oxidise nitrates to nitrites

33
Q

describe the role of denitrifying bacteria

A

concert nitrates in the soil to nitrogen gas in the atmosphere
the bacteria work in anaerobic conditions

34
Q

how can crop rotation involving legumes increase crop yield

A

Nitrogen-fixing bacteria in the clover convert nitrogen gas to ammonia. The clover uses the N in ammonia to make proteins etc. When left to decay, saprobiotic bacteria will convert the proteins in dead clover to ammonia, and nitrifying bacteria will convert it to nitrates.
different crops grown after the legumes will then absorb different nutrients from different soil depths (due to different requirements and different root lengths).
Different crops will have different pest species. Those from the previous year’s crop are unlikely to affect the new crop

35
Q

where can the phosphate element be found?

A

Phospholipids, Nucleic Acids (DNA and RNA), ATP, ADP, NADPH

36
Q

describe the role of saprobionets

A

Saprobionts decompose dead animals / plants / algae/ waste materials using
extracellular digestion

37
Q

explain the phosphorus cycle

A

-Saprobionts decompose dead animals / plants / algae/ waste materials using
extracellular digestion
-Saprobionts absorb the products of digestion and release phosphate ions into soils, lakes, rivers and oceans where they dissolve.
-some of these phosphate ions are absorbed by plants and algae and are used to form organic biological molecules used in growth, such as phospholipids, ATP and nucleic acids.
-The phosphate ions are then passed to the animals that feed on the plants and algae. The phosphate-containing organic compounds are digested then
absorbed and assimilated.

38
Q

what does the word Mycorrhizae mean ?

A

fungus root

39
Q

why does mycorrhizae help increase growth?

A

it Increases growth beacuse the presence of fungus which, due to their large surface area, allow a more efficient absorption of water and the minerals that are
essential for growth (and are often the limiting factors in plant growth )

40
Q

give examples of mutualistic relationship

A
  • legumes and nitorgen fixing bacteria

- lichens (a fungus and an algae)

41
Q

what ions are needed to produce proteins?

A

nitrites

42
Q

what ions are needed to produce nucleuic acids?

A

Nitrates and phosphates

43
Q

what ions are needed to produce ATP?

A

Phosphates (and nitrates)

44
Q

what ions are needed to produce phospholipids ?

A

Phosphates

45
Q

what do natural fertilisers consist of?

A

orgainic plant or animal matter, containing complex orgainc compounds

46
Q

what do articfical fertilisers consost of?

A

concentrated mineral ions in an in orgain, soluble ready to use form

47
Q

give the advantages of artifical fertiliser

A
  • nutrients in concentrated form can be applied in smaller amounts (cost effective)
  • nutrients relesed rapidly into soil
  • clean chemicals that lack odur
48
Q

give the disadvantages of artifical fertiliser

A
  • readily leached from soil so u can damage ecosystems of ponds and lakes
  • rick of fertiliser spray spreading to ther areas
  • expensive to buy/ maufacteur
49
Q

give the advantages of natural fertiliser

A
  • slow release of nutrients
  • adds humus to soil improves structure and drainage
  • nutrients not readily leeched
  • useful, cheap mean disposable of farm waste
50
Q

give the disadvantages of natural fertiliser

A
  • may be difficult to spread
  • minerals only released slowly
  • unknown concentration of nutrients
51
Q

why may crop yeild fall when there is too much fertiliser?

A

higher concentration of ions may reduce water potential of the soil plants may loose water through their roots via osmosis

52
Q

describe the process of leeching

A

the process by which nutrients are removed from the soil

53
Q

why does leeching occur?

A

inorganic fertilisers are very soluble in water

-so rain water dissolves them and washes them out of the soil

54
Q

describe eutrophication

A
  • rapid algal growth
  • a dnese layer of algal forms on the surface of the water, absorbing light and preventing it from penatrating to lower depths, so plants below the surface cannot photosynthesise and therefore die
  • increased competition between algea results in death of algae too
  • When the algae and plants die, they are decomposed by bacteria and other saprobiotic organisms, whose populations suddenly increase.
  • The increase in aerobic respiration by bacteria uses up oxygen.
  • The dissolved oxygen in the water becomes depleted, causing many species of invertebrates and fish to die
55
Q

pollution of a river with sewage can also cause eutrophication explain how?

A

the orgainic material in sewage is fed upon by bacteria, which will respire areobically, using up the oxygen in the river
If detergents are present, these contain phosphates which will encourage algal growth.

56
Q

why does adding fertilisers reduce species diversity?

A

they increase the growthof species such as nettles and grasses .
these rapidly growing species outcompete many other species, which die as a result

57
Q

what do the different species compete for?

A
  • light
  • minerals
  • water

Nutrient cycle (1 decks)

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