Chapter 13 - Energy And Ecosystems Flashcards
What are ecosystems
The abundance and distribution of organisms which are controlled by biotic and abiotic factors
They are dynamic
What is meant by population
All of the organisms of a single species in a habitat
What is a community
All of the organisms of all species in a habitat
What is a habitat
The place where an organisms lives
What is a niche
The role of a species in an ecosystem
What is a trophic level
A stage of the food chain
Eg producer, primary consumer, secondary consumer
What is meant by biotic and abiotic factors
Living and non living
Eg competition and temperature
What is meant by gross primary production (GPP)
The total amount of energy made by producers, per unit area per unit time
What is meant by respiratory loss (R)
The energy used by organisms for respiration
Eg active transport, movement (muscle contraction), heat
What is meant by net primary productivity NPP
The amount of chemical energy a producer stores as energy per unit area per unit time
This is therefore the total amount of energy available to the next trophic level
What is the formula to work out net primary productivity
GPP - R
How do you calculate energy transfer efficiency
Net production/total energy ingested x 100
How do you work out net production
Total energy ingested - (respiratory loss + Excretion)
What percentage of energy is passed from sunlight to producer, producer to primary consumer and primary consumer to secondary consumer
Roughly 2%, 10%, 10-15%
Why is little energy passed from sunlight to producer
- Light can be reflected off leaf
- Can be reflected off a non-photosynthetic region eg bark
- Lost as heat energy
- Could be wrong wavelength
Why is little energy passed from producer to primary consumer
- Respiratory loss as plant uses energy for metabolic processes eg active transport
- Lost as heat energy
- Not all of the plant is eaten
- Some that is eaten is not digested
Why is little energy passed from primary consumer to secondary consumer
- Respiratory loss as primary consumer uses energy for metabolism eg muscle contraction
- Lost as heat
- Not all of primary consumer is eaten
- Not all of primary consumer eaten is digested
How can energy transfer efficiency be increased in plants/crops
- Use of fertilisers you prevent growth being limited by lack of nutrients
- Artificially select organisms with a high yield of what you want
- Reduce competition so that the plant has more energy to create biomass (eg herbicides to kill weeds)
How can energy transfer efficiency be increased in animals/livestock
- Reduce respiratory loss by restricting movement and keeping warm in winter
- Slaughter animals whilst still growing
- Keep predators away
- Controlled diet so that higher percentage of food is digested
What are the 2 ways that biomass can be measured
Dry biomass
Mass of carbon
How can dry biomass be measured
- A sample of biomass is warmed until it’s mass remains constant (all water evaporated)
- Temperature must not be too high to avoid burning
- Units = Kg m^2
How can mass of carbon be measured
- Organisms are made from organic compounds (which contain carbon)
- So mass of carbon is a good indicator for biomass
- Carbon is usually about 50% of dry biomass
- Units Kg m^2 per year
Per year because some organisms, eg deciduous trees change biomass when leaves drop
How can the energy stored in biomass be calculated
Calorimetry
What is the process of calorimetry
- Burn a sample of biomass completely
- Heat a known volume of water
- Measure the temperature change of water
- Calculate energy released
Draw and describe the nitrogen cycle
In folder
Draw and explain the phosphorus cycle
In folder
How do microorganisms play a vital role in recycling nutrients such as nitrogen and phosphorus
They break down large organic compounds into small inorganic and soluble compounds that can be absorbed by producers
What are saprobiants
A type of decomposed that digest their food by saprobiontic nutrition
What is meant by saprobiontic nutrition
Digestion of dead organic matter by extracellular enzymes, products can then be absorbed
What are mycorrhizae
Fungi that grow in mutualistic relationship with plant roots
What are the benefits to a plant of mycorrhizae
- Increase SA of roots so increase absorption of water and minerals
What is the benefit to fungi of being Mycorrhizae
Exchange of organic compounds eg sucrose from plants
Why do fertilisers have to be used for crops
- Crops are harvested so nitrogen and phosphorus are removed from their cycles
- Soil becomes depleted of these
- Have to add fertiliser to replace these
How can too much fertiliser be harmful
Change in water potential to more negative so harder for plants to absorb water
What is meant by a natural fertiliser
Something the contains nitrogen and phosphorus in organic compounds
What are the benefits of using natural fertilisers
- Aerate soil
- Contain a wider range of elements eg magnesium
- Consumes less energy
What are drawbacks of using natural fertilisers
- Need to be broken down by saprobiants
- Therefore slower release of nitrogen and phosphate ions
What are artificial fertilisers
Inorganic chemical compounds that counts nitrogen and phosphorus ions
What is meant by leaching
When soluble compounds are washed off land by rain
This is more common in artificial fertilisers as they are water soluble
Describe the process of eutrophication
- Nitrates/phosphate ions leach into fresh water
- Algal bloom
- Blocks out light
- Plants can’t photosynthesise
- Saprobiants break down dead matter
- Respire aerobically so use oxygen
- Fish and other organisms die
