Energy transfers Flashcards
trophic level
the position an organism occurs within an energy transfer
producers
-start of the food chain
-autotrophic meaning they make their own foods
-build up organic compounds from simple molecules needed for growth
-photosynthetic organisms build up complex organic compounds in the process of photosynthesis
Consumers
-heterotrophic
-rely on external source of organic compounds
-animals are consumers
saprobionts
-heterotrophic/saprotrophic
break down complex organic compounds in dead organisms
-eg. bacteria and fungi
how saprobionts break down complex organic compounds
- secrete extracellular enzymes
-hydrolyse organic material on outside of organism
-absorb the hydrolysed monomer across cell membrane
how many trophic levels in a food web
there are usually only 4-5 trophic levels in a food web as energy is lost each trophic level
biomass
total mass of organic material in a specific area at a given time.
fresh mass
-living
-easy to assess
-variable water content
-unreliable due to varying water content
-variable food indigested
dry mass
-dead
-difficult to assess
-small sample size
-may not be representative
-unreliable as unethical to collect large samples
-gm-2
-situational as only valid at that moment in time standing crop as may fluctuate
calculating energy in biomass
-calorimetry
-dry biomass is combusted with a sealed chamber
-chamber is surrounded by a water bath and heat energy released causes a temperature rise in the water
-using the known specific heat capacity of water and the volume of water and temp rise we can calculate energy released
energy released equation
q=mc(change in t)
q/1000 = x
x/n = energy released
how much sun energy is trapped in photosynthesis
only 1-3% of sun energy is trapped in photosynthesis
energy loses from sun
-some of the light is reflected
-some light may be absorbed by gases/water vapour in the atmosphere
-some of the light is the wrong wavelength
-some light does not strike chlorophyll
Gross primary production (GPP)
-light energy converted into organic molecules
-eg cellulose/starch
Net primary production (NPP)
GPP-R
r=respiratory losses
energy losses in food chain
-large amounts of the plant/animal may be indigestible
-lost from the animal as faeces.
-not all of the plant/animal may be eaten
-some energy is lost in excretion such as energy lost in urine
-energy lost in respiration and as heat to the environment
net production of consumers can be calculated as
N= I - (F+R)
N= net production
I= chemical energy store
F= energy lost in faeces and urine
R= energy lost in respiration
percentage efficiency
percentage efficiency= energy available after transfer/energy available before transfer x100
Suggest how you could determine the dry mass of a sample of plant material
-heat at 100 to evaporate water
-weigh and heat and record then repeat until no further change in mass
What is the advantage of using dry mass and not fresh mass to compare the yield of plants?
-water content is variable;
-will not affect dry mass
Domestic livestock
-domestic livestock to increase productivity by reducing energy losses
-more energy is transferred into new tissue
energy conversion rates is increased by
-restricting movement SO less respiratory loss due to less muscle contraction
-keeping warm SO reduced heat loss from body
-feeding nutritious foods SO optimum foods for growth
-food sources which are easier to digest reducing energy lost in egestion
-selective breeding animals which are more efficient at converting energy into new tissue which are genetically selected for high productivity
-slaughtered before reaching adulthood where least amount of respiration so more energy transferred to biomass
monoculture definition
one particular crop grown over very large areas
monoculture disadvantages
-very easy for disease to spread
-easy for insects to travel from plant to plant
-can e affected in a short space of time
-dramatically reduce biodiversity through loss of niches and a reduction in a variety of food sources
chemical pesticides definition
general term given to chemicals used in the control of pests
nutrient cycle
organic compounds in producers –> organic compounds in primary consumers –> organic compounds in secondary consumers –> decomposers –> organic compounds in producers
the nitrogen cycle
nitrogen fixation –> nitrification –> assimilation –> ammonification
nitrogen fixation
nitrogen fixing bacteria
found in root nodules in legumes
turn nitrogen gas to ammonia
nitrification
nitrifying bacteria
turns ammonia to nitrites to nitrates
assimilation
nitrates are absorbed into plants by active transport through root hair cells
plants use N for amino acids/DNA allows the plant to grow and reproduce
consumers eat the plants and hydrolase proteins into amino acids assimilated into new tissue
primary consumers eaten by secondary consumers
denitrifying bacteria
nitrates converted to N2 gas by denitrifying bacteria
only occurs in waterlogged anaerobic conditions
ammonification
sabrobiants secrete extracellular enzymes through exocytosis
used to hydrolyse N containing polymers into monomers which can be absorbed and release ammonia into the soil
Describe how the action of microorganisms in the soil produces a source of nitrates for crop plants (5)
- amino acids converted into ammonium
- By saprobionts
- Ammonium into nitrite
- Nitrite into nitrate
- By nitrifying bacteria
- Nitrogen gas to ammonium
- By nitrogen-fixing bacteria in soil
How could a farmer make farmland more fertile
-fertiliser
-legumes
-aerate the soil
-drain the soil
Phosphorus containing molecules
ATP
Phospholipids
Nucleic acids
Erosion
once the rock has been weakened and broken up by weathering it is ready for erosion
erosion happens when rocks and sediment are picked up and moved to another place by ice,water or wind or chemical erosion
deposition
sediments, soil and rocks are added to a landform or land mass
Phosphorous cycle
- phospholipids, RNA and DNA from dead organisms into phosphate ions
- decomposed by saprobionts
- phosphate ions are also found in waste and remains eg. guano, bones and shells
- phosphate ions are transported by streams,rivers and lake
- form sedimentary rock
- weathering and erosion of rocks help phosphate ions dissolve into oceans and lakes
- phosphates become available for absorption by plants via active transport to incorporate into biomass
fertilisers
ions lost in soil need to be replaced
fertilisers can do this
organic- manure
inorganic- manufactured ,man made powders or pellets
Leaching
inorganic fertilisers result in more ions applied to soil then plant uptake
leads to leaching, ions dissolve in soil water and are washed from the soil into streams, rivers and lakes
eutrophication
nitrates washed away into water
high conc of ions cause rapid growth of algae
algae block light and less light penetrate water
less photosynthesis
algae die
aquatic plants die
increase population of saprobionts
respiration rate increases
O2 conc in water decreases
O2 levels drop resulting in death of aerobic organisms
increase in anaerobic respiration leads to release of toxins
Mycorrhizae
fungi have a symbiotic relationship between fungi and plants
mycelium
thin hair like structures
increase the surface area for the fungi to fix nitrogen gas, absorb water and nutrients. In return the plant provides the fungus with carbohydrates (sucrose) formed in photosynthesis
