Module 6.3.1 - Ecosystems Flashcards
What is an ecosystem?
All living organisms that interact with one another in defined area and also the physical factors present in that region, abiotic and biotic factors of an area
What are example abiotic factors?
- temperature
- light
- pH
water and humidity - oxygen availability
- soil factors
How does light affect an ecosystem?
Greater light intensity = greater rate of photosynthesis, more seeds, increase population, more animals can be supported
How does temperature affect an ecosystem?
- each species has own optimum temp
- further away from optimum, fewer can survive
- ectothermic animals can grow faster
How does pH affect an ecosystem?
- high pH will denature enzymes so substrate cant bind
- species have own optimum pH to survive
How does water and humidity affect an ecosystem?
- only species adapted to dry conditions will increase population
- increase humidity affect transpiration rates
How does oxygen availability affect an ecosystem?
- aquatic ecosystems benefit from fast flowing, cold water as has more concentration of oxygen
- waterlogged soil = less oxygen
How does edaphic(soil) factors affect an ecosystem?
- soil provides minerals needed for growth, water for photosynthesis and anchorage for roots
- different types of soil retain different things
What are the 3 types of soil and what are their properties?
Sandy soil: 0-10% clay, 0-10% silt, 80-1005 sand, more air spaces, doesnt retain water as much
Clay soil: 50-100% clay, 0-45% silt, 0-45% sand, fewer air spaces, retains water
Loam soil: 10-30% clay, 30-50% silt, 25-50% sand, ideal amount for farming
What are examples of biotic factors?
- territory
- food
- competition
- breeding partners
What is a producer?
- makes biomass
- start of food chain
- autotrophic
What is a carnivore?
eats other organisms/meat
What is a herbivore?
eats plants
What is an omnivore?
eat all kinds of biomass
What is a primary consumer?
- eats producers
- typically herbivores
What is a secondary consumer?
- consume primary consumers
- typically omnivores and carnivores
What is a trophic level?
Where an organism is within the food chain
What does a pyramid of numbers and pyramid of biomass do?
Pyramid of numbers - how many organisms support each other
Pyramids of biomass - amount of energy/biomass organisms have
What is biomass?
Mass of living material present in particular place or in particular organisms
How do you measure biomass?
Biomass in each organism x number of organisms in trophic level
What are the 2 ways to measure biomass?
Mass of fresh material present - easiest, unreliable as mass of water varies greatly
Dry mass - more accurate, organisms are killed and put in an oven at 80 degrees, evaporates water
What are the units for areas of land and water?
Land - g/m^2
Water - g/m^3
What is ecological efficiency?
Efficiency with which biomass or energy transferred from 1 trophic level to the next
What is the efficiency of producers?
- can only convert 1-3% of sunlight into chemical energy
- energy is lost in photosynthetic reactions
Why is the nitrogen cycle necessary?
- energy from the sun is limitless
- energy from sun is the source for nearly all ecosystems
- is finite so must be recycled
What are the 6 main parts of the nitrogen cycle?
- decomposition
- nitrogen fixation
- ammonification
- nitrification 1
- nitrification 2
- denitrification
How can you calculate net production?
Net production = gross production - respiratory losses
What is decomposition?
A chemical process of compounds being broken down into constituent molecules
What do decomposers and detritivores do?
Decomposers - feed on/break down dead matter, convert organic compounds into inorganic compounds, saprophytic
Detritivores -speed up decaying process, feed on dead material, break down dead matter onto small pieces which increases SA for decomposers
What is nitrogen fixation?
Nitrogen gas -> nitrogen containing compounds
what is Azotobacter and mutualistic bacteria?
Azotobacter/Rhizobium - free living, make amino acids, release them when they die, contain nitrogenase enzyme to convert nitrogen and hydrogen into ammonia
Mutualistic bacteria - live in root nodules in peas and beans, obtain carbohydrates from plants and it gets amino acids from bacteria
What is ammonification?
The production of ammonia from organic compounds (e.g. urea, proteins, nucleic acids)
- saprophytic microorganisms release ammonia into soil
What happens during nitrogen 1?
- nitrifying bacteria oxidise ammonium compounds
- ammonium ions > nitrite ions (NO2-)
- oxidation reaction, aerated soil required
What happens during nitrogen 2?
- nitrite ions > nitrate ions (NO3-)
- requires oxygen
- nitrobacteria do this
What is denitrification?
Occurs when soil becomes waterlogged
- O2 shortage
- anaerobic bacteria carry out denitrification as don’t need O2
- reduced nitrogen compounds available to plants
