Energy and ecosystems A2 Flashcards

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1
Q

what happens to the majority of the sun’s energy when not used in making organic matter

A

it is reflected, the wrong wavelength, light misses the chlorophyll molecule used in respiration of producer

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2
Q

equation of net productivity

A

net productivity = gross productivity - respiratory losses

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3
Q

how is energy lost between trophic levels

A

in respiration
as heat
in excretory products
movement

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4
Q

what’s the maximum number of trophic levels most food chains have

A

5

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5
Q

units for energy flow

A

kJm^-2 year

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6
Q

what is the unit for biomass

A

gm^-3

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7
Q

define biomass

A

the total mass of living material in a specific area at a given time

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8
Q

pros and cons of dry biomass

A

overcomes the problem of varying volumes of water in an organism but you must kill organism to find this

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9
Q

how do you remove water from a sample of biomass

A

recording mass and heating until a constant mass is recorded

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10
Q

what shape are pyramids of numbers and why

A

any shape because it doesn’t account for size of organism

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11
Q

cons of pyramids of numbers

A

there’s often so many individuals it’s hard to show on a scale
doesn’t show seasonal differences

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12
Q

why is conversion of food to biomass lower in colder temperatures

A

lose more heat
more respiration
more energy used in respiration

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13
Q

equation for energy transfer (% efficiency)

A

energy available after transfer/energy available before transfer

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14
Q

what is the purpose of an agricultural ecosystem

A

to improve productivity

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15
Q

how is an ecosystem prevented form reaching natural climax community

A

decrease species diversity

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16
Q

methods to improve productivity

A
adding fertilisers
using pesticides
using greenhouses/irrigation systems
ploughing
covering crops with nets
intensive farming
selective breeding
17
Q

why use greenhouses/irrigation system

A

to remove limiting factors of photosynthesis

18
Q

why use nets to cover crops

A

to protect from birds

19
Q

why plough

A

improve drainage and increase O2 for saprobionts in nitrogen cycle

20
Q

how do factory farms intensively farm animals

A

restrict movement
keep warm
no predators
feeding controlled

21
Q

why do factory farms restrict movement of their animals

A

less energy being used for muscle contraction and more on growth

22
Q

why do factory farms keep warm

A

less energy spent keeping warm and more for growing

23
Q

how to estimate energy store in biomass

A

calorimetry

24
Q

define biomass

A

formed from the biological molecules of plants

can be measured in terms of carbon or dry mass of tissue, per given area, per time