Mr p bio 3 energy transfers Flashcards
what are trophic levels?
the levels organisms occupy in a food web
what are producers also known as and what do they do in terms of the food chain?
they are organisms start the food chain and are autotrophs so they build up organic compounds from simple molecules via photosynthesis
what are consumers known as?
heterotrophs
what do heterotrophs rely on?
an external source of organic compounds (have to take in organic compounds)
what do decomposers do?
break down complex organic compounds in dead organisms
what are decomposers also known as?
sacrobionts
what are 2 examples of sacrobiotic decomposers?
bacteria and fungi
what is a food web?
many food chains within a habitat linked together
what does a higher diversity mean?
the more complex the food web so that any one change in the food web will have less of an effect
what do food chains not give and what can be constructed to resolve this?
doesnt give quantitive information (like no. or organisms, amount of biomass or energy stored at each level. egological pyramids can be constructed
what are the three types of ecological pyramid
-number
-biomass
-energy
how are pyramids of number formatted?
bars are drawn which are proportional to the numbers of organisms present at eadch trophic level
disadvantages of using pyramids of number
size of an organism not taken into account and this results in inverted pyramids for some food chains
how are pyramids of biomass formatted?
more reliable than pyramids of no. and show the biomass at each trophic trophic level rather than the no. of organisms which overcomes the problem of size
why shouldnt fresh mass be used in pyramids of biomass?
-fresh mass can be measured but is measured but is unreliable as water content varies so important to use dry mass, half of which is approximately the mass of carbon in the organism
what is are the conditions required for measuring dry mass?
involves killing organsims so the samples tend to be small aand will also effect reliability
what is biomass/ dry mass measured in?
mass of its tissue per unit area per time e.g. kg m^2 yr
what does the pyramid of biomass not take into account?
only represents the situation at a given point in time doesnt take into account any changes at diff times of the year
why can biomass pyramid be inverted?
because biomass may fluctuate
what reasons is energy lost at each trophic level?
movement or digestion, heat, waste products, uneaten parts
what do energy pyramids show?
energy at each stage stage and energy lost at each stage
what is the advantage of energy pyramid?
most accurate
what is a disadvantage of energy pyramid?
hard to know how much energy is in everything
what does the producer bar on the energy pyramid represent?
light energy converted to chemical energy in photosynthesis
why is only 1-3% of the available sunlight comverted to chemical energy?
-some light reflected
-some light absorbed by atmosphere
-some light is wrong wavelength
-some light doesnt fall on chloroplasts and misses chlorophyll
what is the GPP?
gross primary production (energy which is converted to organic molecules
what is NPP?
Net primary production (the energy which is availabke to next trophic level)
how is NPP calculated?
NPP= GPP - R (R is respiratory loss)
how is lots of energy lost between producer and primary consumer?
large amount of plant may be indigestable so some NPP passes out as faeces
not all plant may be eaten
some energy lost as excretion
energy lost as heat during respiration
what is NP?
energy accumulated by producers and available to consumers
how is NP calculated?
NP= I- (F + R)
how do you calculate the efficiency of energy transfer?
(energy available after transfer/energy available before transfer) x100
what equipment can be used to find the chemical energy in an organism?
calorimeter
what is the process of using a calorimeter to find chemical energy in an organism?
-a sample of the organism is placed into the cup and ignited
-when burnt, energy released as heat energy
-temp change is measured
-larger the temp change, larger the amount of chem energy present
-use equation transferred equation
how do we make the results of using a calorimeter comparable?
calculate the energy transferred per gram
how can farmer increase efficiency of food chain?
-decrease size of food chain so less energy lost at each trophic level
-intensive rearing to ensure as much energy as possible converted to biomass (e.g. chickens kept indoors and kept warm) increases NP
-fertilisers (More minerals for growth)
-herbicides reduces comp for water, light and minerals so increases NPP
-insecticides increases GPP as higher SA of leaf to absorb light
negatives of pesticiides?
-pests may develo resistance
-may have harmful effects on animals or enviorenment
-costly as needs to be repeatedly re-applied
-not specific
after drying samples, how can you determine whether the drying removed all the water?
1.record mass and reheat
2.until constant mass recorded
explain how farming practices increase the productivity of agricultural crops
- fertilisers
- selective
