Energy and Ecosystems (complete) Flashcards
Define:
- Biomass
- Producers
- Consumers
- Decomposers
- Biomass - the total mass of living material in a specific area at any given time.
- Producers - photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide and mineral ions.
- Consumers - organisms that obtain their energy by feeding on other organisms rather than using. light energy from the sun directly.
- Decomposers - (detrivores/saprobionts) group of organisms that break down the complex materials in dead organisms into simpler ones.
Why is not all of the sun’s available energy converted into organic matter in plants?
- ≥ 90% of the sun’s energy is reflected back into space by clouds or dust, or absorbed by the atmosphere.
- not all wavelengths of light can be absorbed and used for photosynthesis.
- a factor such as low CO2 levels may limit rate of photosynthesis.
Name 4 ways in which energy can be lost in food chains.
- some parts of the organism aren’t eaten.
- some parts are eaten but cannot be digested sour are lost in faeces.
- some of the energy is lost in excretory materials like urine.
- some energy losses occur as heat from respiration and directly from the body to the environment.
Define:
- Gross production
- Net production
- The total quantity of energy that the plants in a community covert to organic matter.
- The rate at which plants store energy.
Give the equation for calculating Net production in plants and consumers.
Plants: Net production = gross production - respiratory losses
Consumers: Net production = chemical energy consumed - (excretions + respiratory losses)
Why can the overall energy transfer between trophic levels only reach 4 or 5 levels?
- The overall energy transfer is insufficient so unable to support large enough breeding populations at higher trophic levels,
Name the four main stages of The Nitrogen Cycle.
1 - Ammonification - production of ammonia from organic nitrogen - containing compounds. Saprobionts feed on dead organisms, release ammonia, which forms ammonium ions in soil.
2 - Nitrification - conversion of ammonium ions to nitrate ions. Oxidation reaction so releases energy. 1st stage: oxidation of NH4+ to NO2-, 2nd stage: oxidation NO2- to NO3-.
3 - Nitrogen Fixation - nitrogen gas into nitrogen - containing compounds.
4 - DeNitrification - soils becomes waterlogged, anaerobic denitrifying bacteria, converts soil nitrates into gaseous nitrogen, lost in atmosphere.
Name the bacteria/micro-organisms found during in The Nitrogen Cycle, and their roles.
- Nitrogen Fixation - free-living nitrogen fixing bacteria/mutalistic nitrogen fixing bacteria.
- DeNitrification - anaerobic denitrifying bacteria.
- Nitrification - Nitrifying bacteria.
- Ammonification - Saprobiontic micro-organisms.
Why can gaseous nitrogen not be used by plants?
- Nitrogen gas is unreactive and not easily converted into other compounds. Most plants only take nitrogen up by active transport in the form of ammonia or nitrate ions.
What is the role of mycorrhizae fungi in nutrient cycles?
- Naturally occurring fungus found in soil.
- Form a symbiotic relationship with roots of trees and other plants.
- Increase surface area of roots for increases absorption of nutrients from the soil.
How do fertilisers increase productivity?
- they return the essential elements needed for growth/yield to the soil.
- (e.g:) nitrogen, phosphate and potassium.
What are the pros and cons of Inorganic fertilisers (artificial)
- They are very effective, but can have undesirable affects on the environment.
- The components are very soluble so can be washed away if its rains, and end up in local rivers and lakes, causing eutrophication.
- They can be very expensive, but don’t smell as much.
- Less bulky than organic fertilisers so easier to store
What are the pros and cons of Organic fertilisers.
- Cheaper to obtain from animals, but needed in larger amounts as not effective in small amounts.
- Can smell quite a bit.
- Are less soluble, so take longer to release the minerals but wont be washed away, and so will last longer.
- Improves soil structure by binding soil particles together and providing food for soil organisms.
Describe the stages of eutrophication.
- Leaching - rainwater dissolves any soluble nutrients in the soil and carriers them deep into the soil, away from the reach of the plant roots. they then find their way into water sources.
- Algal Bloom - as the nitrate concentration increases in the water source, they are no longer a limiting factor for growth, allowing algae to become densely populated on the surface of the water. This blocks the sun from reaching the lower level plants, so sun becomes a limiting factor for photosynthesis, so they die. This allows saprobiontic bacteria to grow as they can feed off th dead organisms, reducing oxygen in the water source as they require it.
- Anaerobic conditions - Oxygen is now a limiting factor for aerobic organisms, so they begin dying. Now there is less competition for anaerobic organisms, who grow in population, further decomposing dead material into toxic waste.
