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
