20.2 Environmental management and the Nitrogen cycle Flashcards

1
Q

what is the use of a food chain?

A

to illustrate the transfer of energy between organisms within an ecosystem

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2
Q

what is an ecosystem?

A

the biotic and abiotic components of a specific area, and their interactions

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3
Q

what is a community?

A

the organisms within an ecosystem

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4
Q

what is a producer?

A

an autotrophic organism that converts light energy to chemical energy

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5
Q

what are primary consumers?

A

organisms that gain their organic molecules and chemical energy from the consumption of producers

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6
Q

what are secondary consumers?

A

carnivores/omnivores that eat primary consumers

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7
Q

what are tertiary consumers?

A

carnivores/omnivores that eat secondary consumers

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8
Q

what is a trophic level?

A

the level at which consumer eats in a food chain

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9
Q

what is the unit of energy used in energy flows?

A

MJ m-2 yr-1

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10
Q

give some examples of energy loss

A

movement

reproduction

reflected

excretion

growth

respiration

digestion

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11
Q

what is an ectotherm?

A

an animal that relies on external sources of heat for thermoregulation

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12
Q

how is energy transfer calculated?

A

(E available after transfer / E available before transfer) x 100

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13
Q

what is the Malthusian crisis?

A

the population in an area grows to exceed its food supply

resulting in mass starvation

and population decrease

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14
Q

what is overfishing?

A

over-exploitation where fish stocks are reduced to below acceptable levels

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15
Q

what is sustainable fishing?

A

removing a controlled number from the natural population, allowing the remainder to reproduce and replenish ∴ no significant reduction in adult population

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16
Q

what are four factors affecting fish populations?

A

food availability

diseases and parasites

level of predation

intensity of fishing

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17
Q

give an example of some strategies used to reduce overfishing

A

catch quotas

minimum catchable size

fishing effort limits

no-take zones

closed seasons

protected individuals

population seeding

18
Q

what four factors should be considered in aquaculture?

A

feed

stock

location

breed

19
Q

how does light affect marine productivity?

A

cannot penetrate deep water ∴ autotrophs only found in shallow water

turbid water can reduced penetrable depth

20
Q

how do nutrients affect marine productivity?

A

autotrophs absorb nutrients directly from water

productivity maintained only when nutrients are constantly arriving (e.g. mouth of river)

rarely reach open ocean

21
Q

give an example of a ruminant organism

A

cattle

sheep

goats

22
Q

what are the features of the ruminant’s digestive system?

A

contains micro-organisms that produce cellulase

cellulase hydrolyses cellulose and other complex carbs into mono- and di-saccharides

other bacteria converts these into fatty acids

23
Q

outline the role of the rumen in digestion

A

(anaerobic)

bacteria hydrolyse cellulose to B. glucose

sugars fermented to organic acids and absorbed

produces CO(2), H(2)O and CH(4)

bacteria produce proteins from ammonium salts and saliva of ruminant

24
Q

outline the role of the reticulum in digestion

A

fermented grass passes into reticulum

formed into cud - regurgitated, ground and swallowed

25
outline the role of the omasum in digestion
very muscular walls - squeezes water out for reabsorption
26
outline the role of the abomasum in digestion
'normal' digestion secretion of proteases and HCl
27
why is eructation required?
release of pressure from stomach
28
what is a farm?
an ecosystem manipulated by humans to increase productivity based on biotic and abiotic factors
29
what is the definition of productivity?
the amount of E available at one trophic level for a defined area over a defined period of time
30
what units is productivity measured in?
KJ m-2 yr-1
31
what is gross primary productivity (GPP)?
the rate that producers convert light E into CPE
32
what is net primary productivity (NPP)? how is it calculated?
the E available for transfer after a plant uses some for respiration NPP = GPP - respiration
33
outline the abiotic factors that affect productivity and how they can be manipulated to increase it
light - ensuring constant optimal light intensity and duration temperature - ensuring constant warmth water - irrigation or GM to reduce drought resistance nutrients - rotating crops with nitrogen-fixing plants
34
outline the biotic factors that affect productivity and how they can be manipulated to increase it
pests - pesticides competition - herbicides disease - fungicides
35
what is secondary productivity?
the rate at which animals convert chemical energy in the plants they consume into their own biomass
36
what are the techniques used to increase the efficiency of energy transfer?
antibiotics limiting movement maintaining constant temperature selective breeding harvesting animals before adulthood treatment with steroids
37
what is the main benefit and criticism of techniques that increase efficiency of energy transfer?
+ more efficient food production - at general expense of animal welfare
38
what is eutrophication?
the enrichment of a water body with nutrients, usually with an excess amount of nutrients, inducing growth of plants and algae and resulting in oxygen depletion of the water body
39
what is spray drift?
when herbicides and pesticides kill a non-target species
40
outline the benefits of conservation
medical use food/agriculture ecotourism prevention of natural disasters home to indigenous populations removes CO(2) from atmosphere ∴ reduces climate change