Energy and Ecosystems Flashcards
What is a key term to describe ecosystems and what is meant by it?
Dynamic - the abundance and distribution of organisms are controlled by biotic (living) and abiotic (non-living) factors.
What is meant by the term population?
All the organisms of a single species in a habitat.
What is meant by the term community?
All the organisms of all the species in a habitat.
What is meant by the term habitat?
The place where an organism lives.
What is meant by the term niche?
The role of a species in an ecosystem.
What is meant by the term trophic level?
Each stage of the food chain.
What is meant by Gross Primary Productivity (GPP)?
Total amount of energy made by producers (per unit area per unit time).
What are respiratory losses?
The energy used by organism for respiration.
What is net primary production?
The amount of chemical energy a producer store as biomass (per unit area per unit time).
What is the energy transfer efficiency between the sun and the producer?
Around 2%.
Why is the energy transfer efficiency so low between the sun and the producer?
- Wrong wavelength of light.
- Light strikes a non-photosynthetic region.
- Light reflected.
- Lost as heat.
What is the energy transfer efficiency between the producer and primary consumer?
Around 10%.
Why is the energy transfer efficiency between the producer and primary consumer low?
- Respiratory losses.
- Lost as heat.
- Not all the plant is eaten.
- Some food is not digested.
What is the energy transfer efficiency between the primary and secondary consumer?
Around 10.15%.
Why is the energy transfer efficiency between the primary and secondary consumer low?
- Respiratory losses.
- Lost as heat.
- Not all the animal is eaten.
- Some of the food not digested.
For what organisms is energy transfer efficiency especially low for?
- Old animals(stopped growing) - homeotherms/endotherms (warm blooded).
- Herbivores (more faeces).
How can we increase the efficiency of plant crops?
- Shorten food web (reduce competition so the plant has more energy to create biomass).
- Fertilisers (prevent growth being limited by lack of nutrients).
- Artificially select organism with a high yield.
What can be used to reduce competition for plants?
- Herbicides - kills weeds.
- Fungicides - Reduce fungal infections.
- insecticides - chemical control of pets.
How can we increase the efficiency of animals/livestock?
- Reduce respiratory loss (restrict movement and keep warm during winter).
- Slaughter animals while young.
- Keep predators away.
- Controlled diet.
- Artificially select organisms with a high yield.
How would you dry biomass before measuring it?
- A sample of biomass is warmed on a scale until the mass remains constant.
- Temperature must be low to avoid loss of biomass/CO2.
Why do we dry biomass before we measure it?
The amount of water in a sample can vary a lot so dry biomass gives a more representative sample.
Why is mass of carbon a good indicator of biomass?
- Organisms are made from organic compounds.
- Carbon is usually about 50% of the dry biomass.
What is calorimetry?
Used to estimate the amount of energy stored in dry biomass.
How do we calculate energy stored in biomass?
- Burn a sample of biomass completely.
- Heat a known volume of water.
- Measure the temperature change of water.
- Calculate energy released.
What is the nitrogen cycle?
Ammonium ions - (nitrification) -Nitrite - (Nitrification) - Nitrate - (denitrification) - Nitrogen gas - (nitrogen fixation) - Plants - (saprobiontic nutrition) - Decomposers - (Ammonification) - Ammonium ions.
What is the phosphorus cycle?
(PHOSPHORUS TRANSFERRED AT EACH STAGE).
- Plants are decomposed or eaten by animals.
- Animals produce faeces and eventually die - both are decomposed.
- Decomposers enter the soil.
- Weathering and erosion of rocks also enters soil.
- soil then enters lakes, rivers and oceans.
- water then used by plants and cycle starts all over again.
How do microorganisms play a vital role in recycling nutrients?
They breakdown large organic compounds into small inorganic (soluble) compounds. These can be stored by producers.
What are Saprobionts?
Type of decomposers that digest their food by saprobiontic nutrition.
What is saprobiontic nutrition?
Digestion of dead organic matter by extracellular enzymes. These products are absorbed.
What is Mycorrhizae?
A fungi that grow in a mutualistic relationship with plant roots.
What do natural fertilisers contain?
nitrogen and phosphorus in organic compounds.
What are benefits of natural fertilisers?
- Aerate soil.
- Less Leaching.
- Contain a wide range of elements.
- Consume less energy.
What are the negatives of natural fertilisers?
- Still need breaking down by saprobionts.
- Slow release of nitrogen and phosphorus.
What are artificial fertilisers?
Inorganic chemical compounds that contain nitrogen and phosphorus (water soluble).
What is leaching?
When soluble compounds are washed off land by rain.
When is leaching more common?
In artificial fertilisers.
What is eutrophication?
- Nitrate/phophorus ions leach into fresh water.
- Algal bloom.
- Blocks out the light.
- Plants can’t photosynthesise and therefore dies.
- Saprobionts breakdown dead plants.
- Respire anaerobically so use up oxygen.
- Fish, etc die.
What happens when you harvest crops/livestock?
- Removes nitrogen and phosphorus from their cycle.
- Soil becomes depleted.
- Add fertilisers to replace nitrogen and phosphorus (too much fertilisers can be harmful).
