Energy & Ecosystems Flashcards
What is an ecosystem?
All the community living in a specific area + all the non- living factors of it’s environment
What is a community?
Groups of different organisms which live + interact in a particular place at the same time
What are biotic factors with examples?
Living factors e.g. predators, amount of plants, diseases
What are abiotic factors with examples?
Non- living factors e.g. light levels, temperature, pH of soil
What is an environment?
The surroundings of an organism including physical + chemical environment with which it comes into contact
What is a niche?
Each species particular role in their habitat
What is the suns role in the ecosystem?
The Sun is the source of all energy in ecosystems with photosynthetic organisms using this to produce their own food
Why is only 1-3% of the suns energy transferred to producers?
- Most energy is absorbed by the atmosphere
- Chlorophyll cannot absorb green and only absorbs red/blue
- Not all light falls on leaf/chloroplast some light lands on stems
- Energy lost during respiration
What is the producers role in the ecosystem?
Plants are autotrophs which make their own food. They provide energy to herbivores/primary consumers. This is where carbon starts in our food chain so the more productivity through photosynthesis = more biomass across trophic levels.
What is the role of consumers in an ecosystem?
It will consume producers to pass on energy through the food chain and will be consumed by other carnivores/2’ + 3’ consumers
Why is only 10% of energy passed along the food chain?
• Uneaten parts e.g. the bones, stem/roots of plant.
• Decay of dead material e.g. bacteria may decay some material.
• Excretion and egestion e.g. energy is lost in faeces
• Exothermic reactions e.g. heat lost in respiration.
What is GPP?
Gross primary productivity. This is the chemical energy store in the plant in a given area/ volume = all the energy entering due to photosynthesis
What is NPP for plants and animals?
Net primary production is the GPP with consideration to loss of energy through respiration.
For plants: NPP= GPP- R
For animals: N= I - (F+R)
Formula to calculate % efficiency of energy transfer through trophic levels
Percentage efficiency = energy after/ energy before *100
What is biomass with units?
Total mass of dry tissue or carbon measured of a given area. Biomass is what will be passed onto the next organism.
For an area: gm-2
For a volume: gm-3
How can the energy in a biomass be estimated?
Remove all the water from the sample so it is dry mass. You now have the mass of the carbon which you can use through bomb calorimetry.
What are the 4 parts of the nitrogen cycle?
Ammonification: make ammonium ions
Nitrification: make nitrite ions -> nitrate ions
Nitrogen fixation: make nitrogen containing compounds
Denitrification: make N2 gas
Describe ammonification
Saprobionts decompose organic matter ( faeces + dead organisms- urea, proteins, nucleic acid) to make ammonia which dissolves in water in soil to make ammonium ions
Describe nitrification
Nitrifying bacteria in soil oxidize ammonium ions -> nitrite ions-> oxidized to nitrate ions
Describe nitrogen fixation
Nitrogen fixing bacteria on legume nodules + free in soil reduce N2 gas to ammonia to produce aminos
Describe denitrification
Anaerobic denitrifying bacteria in waterlogged soil with less O2 convert nitrates -> N2 gas
Why can N2 gas not be used by plants directly from the air?
N2 has very stable tripe covalent bonds that are hard to break and absorb
How can farmers raise productivity?
Keep soil light with plowed air spaces and good drainage. Nitrifying bacteria need O2 to oxidize. If waterlogged= Anaerobic denitrifying bacteria form and less NB/NFB= less nitrogen for plants so must be good soil to reduce DNB
Why is nitrogen important to the ecosystem?
Plant uptake to make aminos, NAD/NADP, nucleic acid
Positive effects of nitrogen containing fertilizer
It is an essential component for plant growth = increase in gross productivity = higher yield for cheaper
Negative effects of nitrogen containing fertilizer
Reduced species diversity: nitrogen favors some plant= rapid growth out compete = death of other plant
Leaching: can cause watercourse pollution
Eutrophication: fertilizer into water course
What is leaching?
Nitrates dissolved in rainwater go deep into soil beyond root reach. Run off into water streams -> freshwater lakes
Harmful if drunk and causes eutrophication
What is eutrophication?
1) Nitrate level no longer a limiting factor so aquatic plants increase
2) Algal bloom forms = prevents light reaching bottom = plants die
3) Dead plants + Saprobionts = less O2 level so fish die
4) Less aerobics organisms = increase in anaerobic organisms = toxic waste and putrid water
What are the 5 parts of the phosphorus cycle?
Weathering
Runoff
Assimilation
Decomposition
Uplift
Describe weathering + runoff
Phosphate is released from sedimentary rock and then and as a result of weathering = leaching into water and soil
Describe assimilation
Uptake of phosphate ions by plants and algae
Describe decomposition
Saprobionts break down phosphorus ions in dead animals /waste in the soil
Describe uplift
Sedimentary layers from the ocean are bought to land over many years
Explain the phosphate cycle
- Dissolved ions in bodies of water and soil are absorbed by plants
- Passed onto animals that consume plants
- Either excreted back into bodies of water or excreted/decomposed as guano, bones. and shells
- Some waste and remains erode back into the bodies of water and some go through deposition = forming phosphate in rocks
- Rocks erode into bodies of water
- Bodies of water form phosphate in rocks via sedimentation over many years
Role of mycorrhizae in nutrient cycles
Mutualistic relationship
- Increase surface area for water/mineral absorption
- Act as a sponge to hold water/mineral ions around the plant’s root
- Makes plant drought resistant + able to uptake scarce ions
Pros/Cons of natural fertilizers
PROS:
- Cheaper/manure free if you own farm animals
CONS:
- Cannot control proportions of minerals added
Pros/Cons of artificial fertilizers
PROS:
- Exact proportion of minerals
- Inorganic ions = more water-soluble = dissolve into soil = easier for plants to absorb
CONS:
- High solubility = rain can wash away = leaching
