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Biology Y13 > Nutrient, Nitrogen, phosphorus cycle > Flashcards

Nutrient, Nitrogen, phosphorus cycle Flashcards

1
Q

What is the carbon cycle

A

Carbon is taken out of the atmosphere in the form of carbon dioxide by plants and algae during photosynthesis (the carbon is used to make glucose, which can be turned into carbohydrates, fats and proteins – biomass – within plants and algae)
This carbon is passed on to animals (and microorganisms) when they feed on plants and algae
It is returned to the atmosphere in the form of carbon dioxide, during respiration by plants, animals and microorganisms (that release CO2 during decomposition)
If animals and plants die in conditions where decomposing microorganisms are not present, the carbon in their bodies can be converted, over millions of years and significant pressure, into fossil fuels
When wood or fossil fuels are burned (a process is known as combustion), the carbon within them combines with oxygen and carbon dioxide is released into the atmosphere

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2
Q

What is the nutrient cycle?

A

the continuous movement of nutrients from the environment, through living organisms, and back to the environment. The cycles involve the transformation of these nutrients from one form to another as they are taken up, used, and released by different organisms.

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3
Q

Describe the nutrient cycle? Draw a diagram to show this..

A

Simple inorganic molecules:
e.g. carbon dioxide, phosphate ions and nitrogen are assimilated (or fixed) from the environment.
Complex organic molecules:
E.g. carbohydrates, proteins, nucleic acids and lipids. These organic molecules pass through the food chains and Eventually return to the environment as simple inorganic molecules by saprobionts (decomposers)

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4
Q

What are the two main types of saproboints?

A

bacteria and fungi

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5
Q

what are scavengers?

A

first to feed on dead animals

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6
Q

What are detrivores?

A

invertebrates which feed on partly broken down dead matter (DETRITUS). Most are unable to digest cellulose.

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7
Q

What are saprobionts?

A

organisms which secrete enzymes outside their bodies then absorb the products of digestion

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8
Q

what is decomposition?

A

Decomposition is the breakdown of dead organic material (or waste material) into simpler compounds by saprobiotic micro-organisms e.g. Bacteria/fungi (known as saprobionts, formerly saprophytes).

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9
Q

what is saprobiotic nutrition?

A

Saprobiotic nutrition is how decomposers e.g. Rhizopus or Mucor (bread moulds) obtain their energy.

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10
Q

what do these saprobiotic organisms do?

A

They detect the composition of surrounding
dead organic material and activate the genes that make the correct digestive enzyme.

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11
Q

What is hyphae?

A

secrete digestive enzymes, which hydrolyse the substrates. digested products can then be absorbed and used for respiration

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12
Q

what is extracellular digestion?

A

They release hydrolytic enzymes, which break down complex organic molecules. (extracellular digestion). The digested
products (e.g.??) can then be absorbed and used for respiration.

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13
Q

what is Mycorrhizae?

A

Means ‘fungus-root’ - Mutualistic, threads grow in and around the roots.

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14
Q

what is the role of Mycorrhizae?

A

they increase the SA may be more efficient at absorbing minerals (some plant roots couldn’t get phosphate ions without it)

Fungus gets sugars from the plant, plant benefits from enhanced absorption of water and minerals

when they absorb minerals, water potential decreases, so water follows by osmosis

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15
Q

Why is nutrient recycling in a natural
ecosystem vital for plant growth?

A

Nutrient recycling is vital because there is only a limited supply of nutrients and so
they must be recycled, otherwise they would all become locked up in biological
material.

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16
Q

Describe how the method of digestion used by saprobionts results in some nutrients being made available to plant roots.

A

Saprobionts hydrolyse biological molecules by secreting enzymes into their surrounding environment. Some of the products of hydrolysis are then absorbed by the saprobionts, but many remain in their surroundings and may then be absorbed by other organisms.

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17
Q

The Nitrogen cycle

A
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18
Q

What is the nitrogen cycle?

A

The nitrogen cycle demonstrates the movement of nitrogen from the atmosphere into the soil, where is it utilised by bacteria and plants.

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19
Q

what is the importance of the nitrogen cycle?

A

There is 78% nitrogen in the air, however plants and animals can not obtain the nitrogen through gas exchange, and so obtains it through the nitrogen cycle.

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20
Q

What is nitrogen?

A

nitrogen is an inert gas, contains a triple bond and is really hard to break these bonds

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21
Q

What is needed to convert nitrogen gas into nitrogen containing compounds?

A

microorganisms so plants and animals can absorb them

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22
Q

Which biological molecules contain Nitrogen?

A

proteins - AA, ATP, nucleic acids, such as DNA, RNA

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23
Q

What are the four/five key stages in the Nitrogen cycle?

A
  1. Saprobiotic nutrition + microbes
  2. Ammonification
  3. Nitrification
  4. Nitrogen fixation
  5. Denitrification
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24
Q

What is Nitrogen Fixation?

A

Where Nitrogen gas from the atmosphere is converted into Nitrogen containing compounds (soluble form)

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25
Q

What are the 3 ways nitrogen can be fixed?

A
  1. Lightning
  2. free living Nitrogen fixing bacteria naturally occuring in the soil or water.
  3. mutualistic Nitrogen fixing bacteria in the nodules on roots of legumes (peas, beans, clover).
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26
Q

where is energy supplied from to split nitrogen molecules?

A

from oxidation of organic molecules found in the soil, the organic molecules may be from the plant or as a product from the bacteria’s own photosynthesis

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27
Q

how is nitrogen fixed through lightning?

A

The high temperature of a lightning bolt can break the bonds of atmospheric nitrogen molecules. Free nitrogen atoms in the air bond with oxygen in the air to create nitrogen oxides, which dissolve in moisture to form nitrates

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28
Q

Why is bacterial present in leguminous roots able to fix nitrogen?

A

the root nodules, contain mutualistic bacteria that is able to convert nitrogen into ammonia and then into nitrites to nitrates (via nitrification). however not all plants have root nodules

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29
Q

which Mutualistic bacteria is able to convert N2 in atmosphere into Ammonia?

A

Azotabacter bacteria

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30
Q

what is the relationship described as?

A

symbiotic - both bacteria and plants are gaining benefit from co-existing together

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31
Q

how can nitrogen be fixed by free-living bacteria?

A

free-living nitrogen fixing bacteria is naturally occurring in soil, which is able to react with the nitrogen in the air and convert it into ammonium

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32
Q

give the name of a free-living nitrogen fixing bacteria?

A

Rhizobium

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33
Q

In order for plants to absorb the ammonia what needs to happen?

A

Nitrification - so plants can absorb

34
Q

What is nitrification?

A

the process in which ammonium compounds are converted into nitrites and nitrates
NH4+ —-> NO2- —–> NO3-

35
Q

What is nitrification carried out by?

A

nitrifying bacteria which are chemotrophic bacteria that obtain their energy from oxidising ammonium ions

36
Q

what process is nitrification?

A

Nitrification is an oxidation reaction, so converting ammonium ions into nitrate + nitrites is oxidation and so denitrification will be reduction.

37
Q

what type of nitrifying bacteria coverts ammonium ions into nitrites?

A

nitrosomonous (bacteria)

38
Q

where does energy from nitrification come from, and what else is this energy used for?

A

Bacteria get energy from nitrification rather than respiration, then use the energy for chemosynthesis (synthesise own organic
compounds)

39
Q

what type of nitrifying bacteria converts nitrites into nitrates?

A

nitrobacter (bacteria)

40
Q

in order for nitrifying bacteria to oxidise ammonium into nitrites + nitrates, what does it need?

A

oxygen - so will need aerated soil

41
Q

how do plants get nitrates? By which process? To make?

A

Through absorption and assimilation. nitrates, could be dissolved in the water within the soil and are able to be absorbed into the plant by active transport , then they’re assimilated into cells - so used to create Amino acids, ATP + DNA

42
Q

how does waterlogged soil affect how the nitrifying bacteria?

A

no oxygen can get in - so an insufficient supply of oxygen - will be under anaerobic conditions - denitrification will occur - so nitrates are converted back into N2 gas

43
Q

what are the nitrates made into when absorbed into the plant?

A

made into biological molecules such as proteins, DNA, RNA, ATP

44
Q

How do animals get nitrates/ nitrogen?

A

animals eat the plants, and will also absorb the nitrates + assimilate biological molecules such as DNA, proteins

45
Q

what happens when animals eat the plants?

A

they produce waste (faeces) which will contain ammonia - as well as when they decompose. - ammonification

46
Q

what happens when plants and animals die?

A

AMMONIFICATION - the proteins, DNA, ATP that is made within them can be broken down by saprobiotic microorganisms back into ammonia.

47
Q

what can the saprobiotic microorganisms do to the proteins, amino acids, DNA or even detritus (waste or debris)?
Results in two processes

A

stage 1 - can digest, break down the proteins into amino acids (nitrogen containing compounds) using extracellular protease enzymes - (also into ammonia- ammonification)
stage 2 - removal of the amino group from the amino acids using a deaminase enzymes - deamination

48
Q

What is Denitrification?

A

is the process in which nitrates are converted back into atmospheric nitrogen gas. NO3- ——> N2

49
Q

What type of bacteria is denitrification carried out by?

A

anaerobic denitrifying bacteria uses nitrates as electron acceptors in respiration to produce nitrogen gas

50
Q

when does denitrification occur?

A

in conditions with no oxygen so tends to take place in waterlogged soil

51
Q

how can farmers prevent denitrification?

A

plow the soil to aerate the soil using a garden fork to make sure there is oxygen

52
Q

Phosphorus cycle

A
53
Q

what is the phosphorus cycle?

A

The phosphorus cycle shows how phosphorus is recycled in ecosystems and explores the role of mycorrhizae in facilitating the uptake of water + inorganic ions by plants.

54
Q

what is phosphorus needed for to make?

A
  • Phospholipids (phosphate group)
  • ATP (phosphate ion)
  • Nucleotides -> DNA/RNA (phosphate ion)
55
Q

what are mycorrhizae?

A

fungal associations between plant roots and beneficial fungi

56
Q

why are mycorrhizae beneficial for plant growth?

A
  1. the fungi increase the surface area for water and mineral absorption
  2. the mycorrhizae acts like a sponge so holds water and minerals around the roots
  3. this makes plants more drought resistant and able to take up more inorganic ions
57
Q

so overall what is their part in nutrient cycles?

A

improving the uptake of relatively scarce ions, such as phosphate ions - act mutalistically

58
Q

Draw a diagram of the phosphorus cycle

A
59
Q

describe the phosphorus cycle, including all the stages

A
  1. Phosphate ions in sedimentary rocks are released into oceans, rivers and soil b weathering
  2. Phosphate ions are taken into the plants through the roots by active transport. Mycorrhizae increase the rate at which phosphorus can be assimilated
  3. Animals will then eat, absorb and digest the plants, and then also assimilate these phosphate ions into their biological molecules such as phospholipids, DNA
  4. Phosphate ions are lost from animals through waste products via excretion
  5. Guano - waste products by birds is rich in phosphate ions, and returns phosphate ions back to the soil.
  6. when plats and animals die, saprobionts are involved in breaking down organic compounds, releasing phosphate ions into the soil for the assimilation of plants. these microorganisms also release the phosphate ions from urine and faeces
  7. some phosphate ions remain in the shells/bones of animals and so go through a slow break down of phosphates and release into oceans and rivers. some of this will go towards creating phosphorus in rocks called deposition.
  8. And through sedimentation, the build up of phosphate ions and sediment in oceans and rivers build up creating sedimentary rocks (over thousands of years)
60
Q

Fertilisers And Eutrophication

A
61
Q

Why do we need fertilisers?

A

Fertilisers are added to the soil to replace the lost nitrates and phosphate ions when plants are harvested and removed from nutrient cycles as crops.

62
Q

when we remove crops…?
Also when we remove animals..?

A
  • they can no longer can die and decompose, and return the mineral ions/nutrients they contain back to the soil
  • when animals are removed from land, they used to eat grass + plants from and take in their nutrients, phosphates and nitrates are also lost, the urine, faeces and dead matter is not returned to the same area of land.
63
Q

So farmers use fertilisers to..?

A

replace the lost minerals, so more energy from the ecosystem can be used for growth, increasing the efficiency of energy transfer

64
Q

What are the two types of fertilisers?

A

Natural (organic) and artificial (inorganic)

65
Q

What are natural fertilisers?

A

Natural fertilisers are organic material – which consist of dead and decaying plants and animals as well as animal wastes such as manure, slurry and bone meal

66
Q

what are Artificial fertilisers?

A

Artificial fertilisers are made up of inorganic matter which are mined from rocks and deposits and then converted into different forms and blended together to give the appropriate balance of minerals for a particular crop. (usually containing NPK)

67
Q

How do fertilisers increase productivity?

A

nitrogen + phosphorus is needed to make proteins, AA, DNA and chlorophyll which is needed for plant growth. without/ less will limit plant growth and so it’s addition increases productivity.

68
Q

why after a certain point, the addition of more fertilisers no longer improves the productivity of a crop?

A

some other factor is limiting photosynthesis. e.g light, co2, and only the addition of this factor will increase photosynthesis and hence productivity

69
Q

explain the consequences of the addition of too much fertiliser?

A
  • reduced species diversity - because nitrogen-rich soils favour the growth of grasses, nettles + other rapidly growing species.
  • species-rich Hay Meadows, only survive when nitrogen conc. in soil is low enough to allow other species to compete with the grasses
  • Leeching - leads to pollution of rivers, pond (watercourses
  • Eutrophication -
70
Q

What is Leeching?

A

leaching is the process by which excess water-soluble compounds in the soil are washed away by rain water or irrigation systems. They’re often washed away into nearby rivers and ponds. and can lead to eutrophication

71
Q

why is leeching less likely by natural fertilisers?

A

the nitrogen and phosphorus are still contained in organic molecules that need to be decomposed by microorganisms before they can be absorbed by plants. this means their release into the soil for uptake by plants is more controlled.

72
Q

why is the leeching of nitrogen more likely than phosphorus?

A

nitrates are more water-soluble than phosphates

73
Q

what is Eutrophication?

A

the process by which excess nutrients end up in freshwater lakes and rivers.

74
Q

Describe the process of eutrophication

A
  1. excess fertiliser/ mineral ions is leached from the soil causing algae to bloom
  2. large amounts of algae block the sunlight from reaching bottom dwelling plants
  3. plants end up dying from not being able to photosynthesise
  4. increased dead matter means saprobiontic bacteria feed on the dead plant matter, and so population of bacteria grows.
  5. these bacteria will then use the oxygen in the water in order to undergo aerobic respiration, reducing the oxygen concentration in the water
  6. Aerobic animals such as fish and other aquatic organisms die as there isn’t enough dissolved oxygen in the water.
  7. the anaerobic organism further decompose dead material, making water putrid
75
Q

what are the factors which affect eutrophication:

when is it more likely to happen?
when is it least likely to happen in?

A

more likely to occur in hot weather - because metabolic processes are speeded up due to increased enzyme activity

less likely to occur in moving water - because water is re-oxygenated continually and mineral ions are diluted rapidly

76
Q

Advantages of Natural fertilisers?

A

ADV:
- nutrients not readily leached from the soil
- add structure to the soil in the form of humus
- provides a useful means of disposing of animal/ farm waste
- provides a steady supply of nutrients to plants and contain both macro + micro nutrients

77
Q

Disadvantages of natural fertilisers?

A

DISADVANTAGES
- Offensive smells
- mineral release is slow
- unknown quantity of minerals
- may be difficult to spread and store

78
Q

Advantages of Artificial fertilisers?

A

ADVANTAGES
- easy to apply to fields
- nutrients in concentrated form and can therefore be applied in smaller amounts so cost effective
- clean chemicals that lack odor of organic manure
- nutrients released rapidly into the soil (more soluble)

79
Q

Disadvantage of Artificial fertilisers?

A

DISADVANTAGES:
- risk of fertiliser spray being spread to other areas
- expensive to manufacture and buy
- increased risk of eutrophication
- readily leached from soil

80
Q

DONE

A

Biology Y13 (13 decks)

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