Energy Transfers Flashcards

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1
Q

Define biomass.

A
  • Mass of carbon (organic compounds)

- Dry mass of tissue per given area

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2
Q

Suggest what you should do to ensure all water is removed from a tissue sample.

A
  • Regularly weigh and Heat (less than 100 °C)

- Until mass is constant.

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3
Q

What is Gross Primary Productivity?

A

Chemical energy store in plant biomass, in a given area or volume. (Rate of photosynthesis).

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4
Q

What is Net Primary Production?

A
  • Chemical energy store in plant biomass after respiratory losses to the environment have been taken into account. NPP=GPP-R.
  • NPP is available for new plant growth and reproduction OR available for other trophic levels in the ecosystem, such as herbivores and saprobionts.
  • kJ ha–1 year–1 OR kJ km–2 year–1 OR kJ km–3 year–1
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5
Q

The percentage of the light energy trapped by the producers is very low. Give two reasons why.

A
  • Reflected/absorbed by water vapour
  • Reflected from producers/wrong wavelength
  • Transmitted/passes between chloroplasts/between plants/too few chloroplasts
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6
Q

The biomass of primary consumers is less than the biomass of producers. Explain why.

A
  • Loss of energy/heat/less energy to be passed on
  • In respiration
  • In excretion/urine/carbon dioxide
  • Inedible parts/indigestible parts/egestion/to decomposers
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7
Q

Describe how and explain why the efficiency of energy transfer is different at different stages in the transfer.

A
  • Some light energy fails to strike/is reflected/not of appropriate wavelength
  • Efficiency of photosynthesis in plants is low/approximately
  • 2% efficient
  • Respiratory loss/excretion/faeces/not eaten
  • Loss as heat
  • Efficiency of transfer to consumers greater than transfer to producers/approximately 10%
  • Efficiency lower in older animals/herbivores/primary consumers/warm blooded animals
  • Carnivores use more of their food than herbivores
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8
Q

Explain how the intensive rearing of domestic livestock increases net productivity.

A
  • Slaughtered when still growing/before maturity/while young so more energy transferred to biomass/tissue/production
  • Fed on concentrate/controlled diet/controlled conditions/so higher proportion of (digested) food absorbed/lower proportion lost in faeces/valid reason for addition
  • Movement restricted so less respiratory loss/less energy used
  • Kept inside/heating/shelter so less heat loss/no predators
  • Genetically selected for high productivity
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9
Q

Describe the need for plants to both photosynthesise AND respire.

A
  • In the dark no ATP production in photosynthesis
  • Some tissues unable to photosynthesise/produce ATP
  • ATP cannot be moved from cell to cell/stored
  • Plant uses more ATP than produced in photosynthesis
  • ATP for active transport
  • ATP for synthesis (of named substance)
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10
Q

The concentrations of carbon dioxide in the air at different heights above ground in a forest changes over a period of 24 hours. Use your knowledge of photosynthesis to describe these changes and explain why they occur.

A
  • High concentration of carbon dioxide linked with night/darkness
  • No photosynthesis in dark/night/light required for photosynthesis/light-dependent reaction
  • (In dark) plants (and other organisms) respire
  • In light net uptake of carbon dioxide by plants/plants use more carbon dioxide than they produce/rate of photosynthesis greater than rate of respiration
  • Decrease in carbon dioxide concentration with height
  • At ground level fewer leaves/less photosynthesising tissue/more animals/less light
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