5B - energy transfer and nutrient cycles Flashcards
What is an ecosystem
This is all the organisms living in a particular area and all the abiotic conditions
What is a producer
An organism that makes its own food
What do plants use and create in photosynthesis
Use energy and co2 to make glucose and other sugars
What is biomass and what is it made up of?
- The mass of living material/Chemical energy stored in the plant
- Biological molecules made from glucose eg cellulose
What can biomass be measured in terms of :
- The mass of carbon that an organism contains
- The dry mass of its tissue per unit area
How do you measure dry mass
- Sample of organism is dried
- Weighed at regular intervals
- Once mass becomes constant all water has been removed
- Scale up result to give biomass of the total pop
How you you estimate the amount of chemical energy stored in biomass
- CALORIMETRY
1. Burn dry biomass
2. Energy released is used to heat a known volume of water
3. Change in temp of water is used to calculate the chemical energy of dry biomass
What is energy measured in
Joules
KiloJoules
What is GPP
Gross primary production is the total amount of chemical energy converted from light energy by plants in a given area
What is R?
This is respiratory loss and is the amount of of GPP lost to the environment as heat when plants respire
What is NPP
Net primary production is the remaining chemical energy for growth and reproduction
How do you work out primary production
NPP = GPP - R
What are the units for primary production?
It is expressed as a rate (total amount of chemical energy in a given area in a given time)
- Kjha^-1yr^-1
- kjm^2yr^-1
How is chemical energy lost
- Not all food is eaten to energy not taken in
- Some are indigestible so lost as faeces
- Respiration
- Urine
What is the Net production?
The energy that is left after all this is stored in the consumers biomass
How do you calculate net production
N = I - (F+R)
N = net production
I = chemical energy in ingested food
F = Chemical energy lost in faeces and urine
R = Energy lost through respiration
How do you calculate efficiency of energy transfer
% efficiency of energy transfer = net production of trophic level / net production of previous trophic level x 100
When does energy transfer become more efficient
When you move up the food chain as producers contain more indigestible matter than consumers
What is a trophic level?
The stages in a food chain
What are the two ways to increase efficiency?
Simplifying food webs
Reducing respiratory losses
How does simplifying food webs increase efficiency
Using pests to reduce the amount of energy available for crops so less for humans
This gets rid of food chains that dont involve humans so energy losses reduced and NPP of crop increases
How does reducing respiratory loss increase efficiency
- Restrict movement of animals movement can increase rate of respiration
-Keep animals warm so less energy lost by generating body heat
What are the 2 things that saprobionts do ?
- Feed on the remains of dead plants and animals and their waste products breaking them down so chemical elements can be recycled
- Secrete enzymes and digest food externally - EXTRACELLULAR DIGESTION so organic molecules are broken into inorganic ions
What is saprobiotic nutrition
Obtaining nutrients from dead organic matter and animal waste using extracellular digestion
What is a symbiotic relationship
Two species live closely together and one or both species depend on each other for survival
What is a Mycorrhizae
A type of fungi that forms a symbiotic relationship with the roots of a plants
- fungi made up of long thin strands known as Hyphae which connect to the plants roots increasing the SA so they can absorb ions
- Hyphae also increase water uptake in turn the fungi obtain organic compounds such as glucose
What contains nitrogen
Proteins, Nucleic Acids, Dna, RNA
What are the basic stages of the nitrogen cycle
- Nitrogen Fixation
- Ammonification
- Nitrification
- Denitrification
What is the first stage of the nitrogen cycle in detail?
Nitrogen fixation
1. Bacteria ( Rhizobium) turn nitrogen into ammonia which goes to form ammonium ions in solution that can be used by plants
2. The Rhizobium are found inside root nodules of leguminous plants forming a mutualistic relationship
How does the bacteria form a mutualistic relationship
The bacteria provide the plant with nitrogen compounds and the plant provides them with carbohydrates
What is the second stage of the nitrogen cycle in detail
Ammonification
1. nitrogen compounds from dead organisms are turned into ammonia by saprobionts forming ammonium ions
2. Animal waste such as urine and faeces also contain nitrogen compounds which are turned into ammonium ions
What is the 3rd stage of the nitrogen cycle in detail
Nitrification
1. Ammonium ions in the soil are changed into nitrogen compounds that can be used by plants –> NITRATES
2. It is first changed into NITRITES and other nitrifying bacteria turn it into NITRATES
What is the 4th stage of the nitrogen cycle in detail
Denitrification
- Nitrates in soil are converted into nitrogen gas by denitrifying bacteria
- Happens under anaerobic conditions by using nitrates in soil to carry out resp
What compounds contain phosphorus
Phospholipids
Dna
Atp
Where is phosphorus found
Rocks
Dissolved in oceans in the form of phosphate ions
What is the stages of the phosphorus cycle
- Phosphate ions released into soil by weathering
- Phosphate ions taken into plants through roots and mycorihizzae increase rate
- Ions transferred through food chain
- Saprobionts break down the organic compounds when plants and animals die releasing phosphate ions into the soil
- Phosphate ions released from urine and faeces
- Weathering of rocks are releases phosphate ions into seas, lakes and rivers which is taken up by aquatic producers such as algae
- Waste produced by sea birds is known as Guano and contains phosphate ions therefore used as a natural fertiliser
How are nutrients lost
Harvesting of crops
Animals removed from land
What are the different types of fertilisers
Artificial - inorganic and contain pure chemicals as powder or pellets
Natural - organic and include manure, composted veg, crop residue
What is the environmental issue with Fertilisers
Leaching - water soluble compounds in the soil are washed away into ponds and rivers leading to eutrophication
What is Eutrophication
- Mineral ions leached from fertilised fields stimulate rapid growth of algae
- The algae block lights reaching surface below
- The plants die as unable to photosynthesise
- Bacteria feed on dead matter reducing o2 conc by carrying out aerobic resp
- Aquatic organisms die as not enough dissolved oxygen
