Energy and Ecosystems Flashcards

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1
Q

Define Population

A

all the organisms of one species in a habitat

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2
Q

Define community

A

all the different organisms of all species living in a habitat at a particular time

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3
Q

Define habitat

A

the place where an organism lives

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4
Q

Define niche

A

the role of a species in an ecosystem

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5
Q

Define trophic level

A

a stage of the food chain

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6
Q

What is productivity

A

the amount of energy transferred between trophic levels

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7
Q

What is gross primary production

A

The total amount of energy made by a producer KJm-2yr-2

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8
Q

What is respiratory loss

A

energy used in respiration

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9
Q

What is nett primary production

A

The amount of chemical energy the producer stores as biomass

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10
Q

How do we calculate net production?

A

N = I (R+F) where I is total energy ingested

R is respiratory loss, and F is energy lost via faeces/urine

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11
Q

Why is the efficiency of energy transfer between the sun and a plant very low? (approx. 2%)

A
  • wrong WL of light
  • light hits non photosynthetic region eg) bark
  • light reflected
  • lost as heat
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12
Q

Why is the efficiency of energy transfer between the plant and a consumer low? (approx. 10%)

A
  • respiratory loss
  • lost as heat
  • not all plant is eaten
  • some not digested
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13
Q

Why is the efficiency of energy transfer between the consumer and a secondary consumer low? (approx. 10 -15%)

A
  • respiratory loss
  • primary consumer uses energy for metabolism
  • not all is eaten
  • faeces
  • lost as heat
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14
Q

Why might energy transfer be low?

A
  • old animal - less energy into biomass
  • herbivores - more faeces
  • homiotherms/ endotherms (warm blooded)
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15
Q

How can farmers increase energy transfer efficiency within plant crops?

A
  • reduce competition (herbicide/ insecticide)

- fertilisers - eg) nitrates

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16
Q

How can a farmer increase yield with animals?

A
  • restrict movement - reduce respiratory loss
  • keep warm
  • slaughter the animal whilst it is still young
  • control diet so a higher % of food is digested
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17
Q

what technique to increase yield can be applied to both animals and plants?

A

selective breeding

18
Q

How can we measure an organisms dry biomass?

A

warm sample on a scale until mass remains constant (water has been removed)

19
Q

when measuring biomass why is the temperature kept below 80 degrees Celsius?

A

to avoid combustion CO2 = biomass

20
Q

Why do we use dry biomass to compare samples?

A

amount of water varies eg) cucumber and potato

dry biomass is more representative

21
Q

What are the units for biomass?

A

Kgm-2

22
Q

How else can we compare organisms?

A

mass of carbon

23
Q

What are the units for mass of carbon?

A

kgm-2yr-1

24
Q

Why don’t we use mass of carbon as much as dry biomass?

A

hard to measure

25
Q

How can we use calorimetry to estimate the energy stored in dried biomass?

A

burn substance completely
to heat a known volume of water
measure the temperature change and calculate the energy released

26
Q

describe the 6 stages of the nitrogen cycle

A

1) Ammonium ions —> nitr1tes by nitrification
2) nitrites —–> nitrate (late) by nitrification
3) denitrification in anaerobic conditions to nitrogen gas in atmosphere (unreactive)
4) nitrates to plants or nitrogen fixation of nitrogen in the atmosphere by leguminous plants
5) saprobiotic nutrition of animals and plants by decomposers
6) Ammonification of decomposer = back at 1

27
Q

what are the 2 ways phosphate ions are returned to the soil in the phosphorous cycle?

A

weathering and erosion of rocks

saprobiotic nutrition

28
Q

What is the role of microorganisms in the recycling of nutrients?

A

break down large organic compounds into small inorganic compounds (often soluble so they can be absorbed by plants)

29
Q

What is a saprobiont?

A

digests food using extracellular enzymes by saprobiotic nutrition

30
Q

Define Saprobiotic nutrition

A

digestion of organic matter by extracellular enzymes

31
Q

What are Mycorrizhae?

A

fungi that grow in a mutualistic relationship with plant roots

32
Q

how do plants benefit from the mycorrhizae?

A

increased SA of roots increases absorbtion of water and minerals

33
Q

how do mycorrhizae benefit from the relationship with plants?

A

exchange of organic substances eg) sucrose

34
Q

What is a natural fertiliser?

A

contain nitrogen and phosphorous in organic compounds eg)compost

35
Q

What are the disadvantages of natural fertilisers?

A

still need to be broken down by saprobionts so slower release of phosphate ions and nitrates

36
Q

what are the advantages of natural fertilisers?

A

aerates soil - decreases anaerobic denitrification
wider range of elements
less leaching
uses less energy

37
Q

what is the impact of farming/use of fertiliser?

A

removes N and P from cycle so soil becomes depleted
fertiliser is added
too much fertiliser can alter the water potential (more negative) making it harder for the plants to absorb water by osmosis

38
Q

what is artificial fertiliser?

A

inorganic chemical compounds that contain nitrogen and phosphorous

39
Q

what is leaching?

A

when soluble compounds are washed off the land by rain - more common in artificial fertilisers as they are soluble

40
Q

Describe the 7 steps of eutrophication

A

1) nitrates/ phosphate ions are leached into fresh water
2) Algal bloom
3) blocks out light
4) plants below surface cannot photosynthesise so die
5) saprobionts break down dead plants
6) saprobionts respire anaerobically and use up O2
7) fish and other organisms die