20.2 Environmental management and the Nitrogen cycle Flashcards
what is the use of a food chain?
to illustrate the transfer of energy between organisms within an ecosystem
what is an ecosystem?
the biotic and abiotic components of a specific area, and their interactions
what is a community?
the organisms within an ecosystem
what is a producer?
an autotrophic organism that converts light energy to chemical energy
what are primary consumers?
organisms that gain their organic molecules and chemical energy from the consumption of producers
what are secondary consumers?
carnivores/omnivores that eat primary consumers
what are tertiary consumers?
carnivores/omnivores that eat secondary consumers
what is a trophic level?
the level at which consumer eats in a food chain
what is the unit of energy used in energy flows?
MJ m-2 yr-1
give some examples of energy loss
movement
reproduction
reflected
excretion
growth
respiration
digestion
what is an ectotherm?
an animal that relies on external sources of heat for thermoregulation
how is energy transfer calculated?
(E available after transfer / E available before transfer) x 100
what is the Malthusian crisis?
the population in an area grows to exceed its food supply
resulting in mass starvation
and population decrease
what is overfishing?
over-exploitation where fish stocks are reduced to below acceptable levels
what is sustainable fishing?
removing a controlled number from the natural population, allowing the remainder to reproduce and replenish ∴ no significant reduction in adult population
what are four factors affecting fish populations?
food availability
diseases and parasites
level of predation
intensity of fishing
give an example of some strategies used to reduce overfishing
catch quotas
minimum catchable size
fishing effort limits
no-take zones
closed seasons
protected individuals
population seeding
what four factors should be considered in aquaculture?
feed
stock
location
breed
how does light affect marine productivity?
cannot penetrate deep water ∴ autotrophs only found in shallow water
turbid water can reduced penetrable depth
how do nutrients affect marine productivity?
autotrophs absorb nutrients directly from water
productivity maintained only when nutrients are constantly arriving (e.g. mouth of river)
rarely reach open ocean
give an example of a ruminant organism
cattle
sheep
goats
what are the features of the ruminant’s digestive system?
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
outline the role of the rumen in digestion
(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
outline the role of the reticulum in digestion
fermented grass passes into reticulum
formed into cud - regurgitated, ground and swallowed
outline the role of the omasum in digestion
very muscular walls - squeezes water out for reabsorption
outline the role of the abomasum in digestion
‘normal’ digestion
secretion of proteases and HCl
why is eructation required?
release of pressure from stomach
what is a farm?
an ecosystem manipulated by humans to increase productivity based on biotic and abiotic factors
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
what units is productivity measured in?
KJ m-2 yr-1
what is gross primary productivity (GPP)?
the rate that producers convert light E into CPE
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
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
outline the biotic factors that affect productivity and how they can be manipulated to increase it
pests - pesticides
competition - herbicides
disease - fungicides
what is secondary productivity?
the rate at which animals convert chemical energy in the plants they consume into their own biomass
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
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
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
what is spray drift?
when herbicides and pesticides kill a non-target species
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
