Year 13 - Energy transfers Flashcards
(15 cards)
Describe the reasons for low efficiency of energy transfer through ecosystems
- Some light is reflected
- Some light is not the appropriate wavelength so not abosrbed
- Some light misses chloroplasts
- Energy lost as heat loss from respiration
- Energy lost by faeces as food is not digested
- Excretion of urea
Describe how intensive rearing of domestic livestock increases net production
Slaughtered when still growing so more energy transferred to biomass tissue
Fed on controlled diet so higher proportion of food digested and not lost in faeces
Movement restricted so less heat lost from respiration
Kept warm inside so less heat loss to maintain body temperature
Genetically selected for higher productivity.
Describe the action of microorganisms in the nitrogen cycle
- Mycorrhizae, in legumes root nodules and soil, facilitate the active uptake of nitrate ions and water into plants
- Plants use nitrates to synthesise N containing polymers such as DNA and polypeptides
- Plants die, or plants eaten and then animals die
Ammonification during decomposition - Saprobionts convert protein, amino acids, DNA into ammonia
Nitrification - Nitrifying bacteria oxidise ammonia into nitrite and then into nitrate
Nitrogen Fixation - Nitrogen-fixing bacteria reduce nitrogen gas to ammonia
Denitrification - Denitrifying bacteria convert nitrates to N2 gas when in anaerobic conditions such as waterlogged soil.
Describe the phosphorus cycle whilst highlighting the role of microorganisms
- Saprobionts decompose dead organisms and excreta
- phosphate ions from phospholipids, DNA and RNA
- Phosphate ions from waste and remains (guano, bones and shells)
- Phosphate ions transported by streams, river lakes and oceans
- Form sedimentary rock
- Weathering and erosion of rock helps phosphate ions dissolve in oceans, lakes and soils.
- Phosphates become available for absorption by plants through active transport and incorporated into biomass.
- Mycorrhizae, in fungi and root systems, facilitate the active uptake of ions and water into plants
Describe the mutualistic relationship of mycorrhizae and plants
Mycorrhizae benefit plants by:
- Increasing the total surface area of the plants root
- Increasing the absorption of water
- Increasing the absorption of mineral ions e.g. phosphates and nitrates
Describe and explain the environmental impact of using fertilisers (/describe leaching and eutrophication)
- Reduced species diversity as plants adapted to high nitrate concentrations outcompete other species.
- Excess nitrate and phosphate (and other) ions are not taken up by the plants and leads to leaching.
- High concentrations of ions cause rapid growth of algae causing an algal bloom.
- Algae block light from penetrating water causing less photosynthesis
- Plants and algae die.
- Saprobionts decompose by secreting enzymes onto dead tissue for extracellular digestion.
- Increase respiration rate reducing oxygen concentration available to other aquatic life.
- Animals increase anaerobic respiration leading to release of toxins and death.
Describe why succession eventually causes GPP/NPP to decrease
NPP = GPP – respiratory losses
NPP decrease due to GPP decrease.
GPP decrease caused by large trees reducing sunlight to ground.
This reduces photosynthesis in plants beneath
This reduces production of organic molecules therefore less organic biomass.
Additionally, reduction in biodiversity due to more competition for light in shaded areas.
In ecosystems, what do plants use to synthesise organic compounds?
Aquatic/atmospheric CO2
How do plants use sugars synthesised in plants?
Most for respiratory substrates, some for new biological molecules to form the biomass of plants
Explain how increase in named biomass can be taken as a measurement of NPP
Represents dry mass/mass of carbon
Define GPP
Chemical energy store in plant biomass per area/volume
Define R
respiratory losses to the environment
Define NPP
chemical energy store in biomass after respiratory losses to the environment
Define net production of consumers
N = I – (F + R)
State appropriate Gross productivity units
Unit of energy, per area, per year. E.g. KJ per m2 per year
