Nitrogen/phosphate Cycles + Energy Transfers Flashcards
Define Biomass
Mass of carbon (organic compounds)
Suggest what you should do to ensure all water is removed from a tissue/sample
Regularly weigh and reheat until mass is constant
Define Gross Primary Productivity (GPP)
Chemical energy store in plant biomass, in a given area or volume
Define Net Primary Productivity (NPP)
Chemical energy stores in plant biomass after respiratory losses have been taken into account
NPP is available for new plant growth and reproduction or available for other trophic levels in the ecosystem, such as herbivores and sacrobionts
Define Net production of consumers
N= I- (F+R)
I represents the chemical energy store in ingested food
F represents the chemical energy lost to the environment in faeces and urine
R represents the respiratory losses to the environment
What are the units for biomass?
kJ ha-1 year-1
The percentage of the light energy trapped by the producers is very low. Give three reasons why
1) Reflected/absorbed by water vapour
2)Reflected from wrong wavelength
3) Does not strike chlorophyll
In natural ecosystems, most of the light falling on producers is not used in photosynthesis
Suggest reasons why
1) Light energy is not absorbed
2) Light is the wrong wavelength
3) Light misses chlorophyll
The biomass of primary consumers is less than the biomass of producers. Explain why
1) Loss of energy
2) In respiration
3) In excretion/urine
4) In indigestible parts
Describe how and explain why the efficency of energy transfer is different at different stages in the transfer?
1) Some light energy fails to strike
2) Efficiency of photosynthesis in plants is low
3) Respiratory loss/faeces
4) Loss as heat
5) Efficiency is lower in older animals
6) Carnivores consume, digest & assimilate more of their food than herbivores
Explain how the intensive rearing of domestic livestock increases net productivity
1) Slaughtered when still growing so more energy transferred to biomass
2) Fed on a controlled diet so a higher proportion of digested food absorbed
3) Movement restricted so less energy used
4) Kept inside so less heat loss
5) Genetically selected for high productivity
Describe the role of saprobionts in the nitrogen cycle
1) Secrete enzymes to decompose proteins/DNA/RNA
2) Producing ammonia/ammonium lons:
Explain how carbon-containing compounds present in the pine leaves that fall from the trees are absorbed and used for growth by saprobionts/fungi that live in the soil
1) Extracellular digestion
2) By secretion of hydrolytic/digestive enzymes
3) Absorption of digested/soluble products
4) Synthesis of structural compounds
5) Respiration provides energy for the growth of saprobionts
What are saprobionts?
1) Fungi/Bacteria that secrete extracelluar enzymes to digest large insoluble organic matter
2) Absorb monomers for assimilation/ respiration
Nitrogen compounds in the plants are made available for the main crop after ploughing in spring. Describe the role of microorganisms in this process
1) Proteins/amino acids broken down
2) Ammonification (release of ammonium compounds)
3) By saprobionts
4) Conversion to nitrates via nitrites
5) By nitrifying bacteria
6) Nitrates absorbed into roots via active transport
The scientists used units of ug g-1 for the concentration of ammonia in soil
Suggest why, in this investigation, the scientists used these units
1) ug because very little ammonia in the soil
2) ug because avoids use of lots of decimal places
Give two examples of biological molecules containing nitrogen that would be removed when a crop is harvested
Amino acids and DNA
Describe why phosphates are needed by a growing plant
Production of DNA, RNA, NADP, and phospholipids in cell membranes
Describe how a lack of phosphates in the soil surrounding a plant can affect its growth
Potential essay link
1) Required to make ATP so less energy for growth;
2) Required to make nucleotides, so less DNA for cell division
3) Required to make RuBP/NADP, so less CO2 reduced into sugar,
4) Required to make phospholipids for membranes
Outline the advantages of having Mycorrhizae growth near plants
Essay link
1) Mycorrhizae help plants to defend themselves, causing an increase in crop yield
2) Mycorrhizae help plants to take up nitrates/phosphates, causing an increase in crop yield
You are given samples of water from three different rivers.
Describe how you would obtain a quantitative measurement of their cloudiness
1) Use of colorimeter
2) Measure the absorbance
3) To standardise method, use same volume of water/filter/shake the sample
Describe the process of eutrophication
1) Nitrates/Phosphates/Ammonium ions flushed into the waterway (leaching)
2) Increased algal bloom
3) Light blocked out
4) Submerged aquatic plants are unable to photosynthesise and die
5) Increase in saprobionts so increases rate of aerobic respiration
6) Saprobionts die due to lack of oxygen (anoxic conditions)
7) Increase in anaerobic microorganisms that produce toxins
NPP= ?
NPP= GPP - R
