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biology > Energy And Ecosystems > Flashcards

Energy And Ecosystems Flashcards

1
Q

Define producers

A

Photosynthetic organisms who manufacture organic substances

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2
Q

Define consumers

A

Organisms that gain energy from consuming other organisms

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3
Q

Define saprobionts

A

Decompose waste and remains of dead organisms

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4
Q

What is the difference between food chains and webs

A

Food chains show one organism at each trophic level

Food webs show complex interrelations of many food webs

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5
Q

Pros and cons of food webs

A

Show more realistic consumption as organisms will have more than one food source

Can get very complex

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6
Q

Define trophic level

A

Stages of food chain

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7
Q

What do arrows in food chains depict

A

Transfer of energy along chain

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8
Q

Define biomass

A

Mass of living material

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9
Q

Why is dry material used not fresh

A

Fresh will vary due to water availability

Dry is more accurate

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10
Q

What are the cons of using dry mass

A

Have to kill organisms so only small sample obtained which is not representative

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11
Q

What are the units for biomass

A

Grams per metre squared

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12
Q

Describe. How to use a calorimeter

A

Weigh the sample and place in cup in chamber

Ignite using ignition wires

Record initial temp

Heat from combustion heats water

Record max temp

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13
Q

What temp is used for calculating dry biomass, why

A

100

Water evaporates and biomass doesn’t burn

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14
Q

When does all the energy in an ecosystem originate and end up

A

From the sun

Ends up are heat energy

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15
Q

What is the major difference between the transfer of energy and nutrients in an ecosystem

A

Nutrients can be recycled

Energy cannot

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16
Q

Why is only 1% of the sun’s energy transferred by plants

A

Rays reflected back into space via clouds and dust

Not all wavelengths used in Photosynthesis

Other factors are limiting (co2)

Light may not land on a chlorophyll

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17
Q

How and why can net primary production be used to compare ecosystems

A

Allow comparison between efficiency of energy storage

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18
Q

Define net primary production

A

The rate at which plants store energy

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19
Q

Define the gross primary production

A

The energy converted into biomass

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20
Q

Why is there a low percentage of energy between trophic levels

A

Not all of organism is consumed
Some parts can’t be consumed
Energy lost via excretion and movement
Heat energy lost via Respiration

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21
Q

Why is there a higher percentage energy transfer between 2 and 3 trophic levels

A

Carnivores use more of there food than herbivores

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22
Q

In what instances is energy transfer lower

A

Older animals
Mammals (heat lost to maintain temp)
Primary consumers

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23
Q

What are the results of inefficient energy transfer

A

Food chains have few trophic levels

Total biomass at higher trophic levels is less

Less energy available for higher trophic levels

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24
Q

Why do organisms require nitrogen

A

Amino acid, protein and nucleic acid synthesis

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25
Q

What form of nitrogen do plants absorb

A

Nitrate ions

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26
Q

How are nitrates absorbed by plants

A

Active transport

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27
Q

Why do nitrates need regular replenishment

A

They are leached (because soluble) and used up

28
Q

What are the processes in the nitrogen cycle

A

Nitrogen fixing

Ammonification

Nitrification

Denitrification

29
Q

Describe nitrogen fixing

A

Nitrogen gas from atmosphere converted into ammonia

30
Q

In what ways can nitrogen be fixed

A

Atmospheric (lightning)
Industrially
Biologically

31
Q

What types of nitrogen fixing bacteria are there

A

Free living and mutualistic

32
Q

Describe how mutualistic nitrogen fixing bacteria interact with plants

A

Assimilate ammonia into Amino acids and exchanged for carbohydrates

33
Q

Describe how nitrogen fixing bacteria work

A

Reduce nitrogen to ammonia

Aerobic Respiration

34
Q

Describe the process of Ammonification

A

Saprobionts convert ammonia to ammonium ions

35
Q

From what does Ammonification take place

A

Waste and dead material

Urea
Protein
Nucleic acids
Vitamins

36
Q

Describe Nitrification

A

Conversion of ammonium ions to nitrite ions then nitrate ions by aerobic bacteria

37
Q

Describe nitrifying bacteria

A

Chemotrophs= use chemical to produce food not light

Aerobic

38
Q

Describe Denitrification

A

Conversion of nitrate ions into nitrogen gas by anaerobic denitrifying batería

39
Q

Describe denitrifying bacteria

A

Anaerobic

Use nitrate ions instead of oxygen.

40
Q

Describe denitrifying bacteria

A

Anaerobic

Use nitrate ions instead of oxygen.

41
Q

How can to productivity of soils be improved other than fertilisers

A

Aerate soils= more oxygen= more nitrification= more nitrate ions

More DOM= more Ammonification

42
Q

What forms of nitrogen can plants use

A

Ammonia

Nitrate ions

43
Q

Describe how saprobionts work

A

Secrete enzymes for extracellular digestion

Macro molecules hydrolysed to micromolecules which diffuse into bacteria

Aerobic Respiration

44
Q

In what form is phosphorus found in the phosphorus cycle

A

Phosphate ions

45
Q

What are the differences between the phosphorus and nitrogen cycle

A

Phosphorus is never gaseous

Nitrogen is fast

Phosphorus can be found in skeletons and shells

Phosphorus is released from rocks via Weathering

46
Q

What is phosphorus used for

A

DNA
Phospholipids
ATP

47
Q

Describe the phosphorus cycle

A

Phosphates in rock are released due to Weathering and erosion

Phosphate ions are in the sea and rivers

Absorbed by plants and move along food chain

Waste and dead material contain phosphates which are broken down by saprobionts

Phosphates released into rivers where they sediment to form rocks

48
Q

Describe the nitrogen cycle

A

Nitrogen gas is converted into ammonia by nitrogen fixing bacteria

Ammonia is absorbed by plants and passed along food chain

Waste and dead matter contain ammonia compounds which are converted into ammonium ions via saprobionts

Ammonium ions converted into nitrite and then nitrate ions by nitrifying bacteria

Nitrates absorbed by plants

Denitrifying bacteria convert nitrates into nitrogen gas

49
Q

What microbe is involved in the phosphorus cycle

A

Mycorrhizae fungi

50
Q

Describe the interaction between the micorrhzae and plants

A

Fungi grows in and around plant tissue

Highly specific to species
Coevolution

Increase surface area for absorption of water and mineral ions

Act like sponge so plant is drought resistant

Exchange mineral ions for carbohydrates

51
Q

What type of organism are micorrhzae

A

Saprobionts

52
Q

Why do we need fertilisers

A

Intense farming disrupts nutrient cycles depleting soils of nutrients

Biomass removed so no decomposition

Increases productivity

53
Q

What needs to be ensured for fertilisers to have maximum effect

A

Applied at right time and right amount

54
Q

What types of fertilizers are there

A

Natural and artificial

55
Q

What are artificial fertilizers made of

A

NPK

mined from rock deposits

56
Q

What are the benefits of artificial fertilizers

A

Immediate source of mineral ions

Guaranteed composition

More concentrated= less needed= cheaper (transport and supply) and less damage done by machines

Clean and convenient

57
Q

What are the cons of artificial fertilizers

A

Leaching and eutrophication

Mining causes damage

58
Q

What are natural fertilisers made of

A

Dead matter and waste

Bone meal
Urea
Manure
Compost

59
Q

What are the pros of using natural fertilisers

A

Lasts longer
Longer release
May contain important trace elements
Improve soil structure (reduced erosion and better at holding water)

60
Q

How do fertilizers increase crop yield

A

Provide vital mineral ions

Converted into Amino acids, lipids and DNA

Larger biomass= Larger leaves

Large SA for Photosynthesis= more carbohydrates = taller

61
Q

What are the environmental effects of fertilisers

A

Reduced species diversity

Leaching

Eutrophication

62
Q

How do fertilizers lead to reduced species diversity

A

High N conc favours grasses and nettles which outcompete other species

63
Q

Describe leaching

A

Rainwater dissolves nitrate ions

Carries them far down into soil

Roots are unable to reach ions

Found in rivers and lakes and drinking water

64
Q

Why is leaching bad

A

Nitrates end up in drinking water

Can cause stomach cancer

Prevent efficient oxygen transport in babies

Eutrophication

65
Q

Describe how eutrophication occurs an dits effects

A

Nitrates are usually limiting factor in lakes

N conc increases, no longer limiting so algal bloom

Light doesn’t reach lake floor

Photosynthesising plants lower down die

Less oxygen produced

Decomposition increases so more saprobionts

Oxygen is limiting for aerobic organisms

Aerobic organisms die so less competition between aerobic and anaerobic organisms

More decomposition so more nitrates and toxic substances (hydrogen sulphide) = putrid water

biology (28 decks)

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