M6 C23: ecosystems Flashcards
what are some examples of abiotic factors?
temperature
light
pH
water and humidity
how does temperature affect ecosystems?
Each species has a different optimum temperature
The further away from the optimum, the fewer can survive.
Ectothermic animals can grow faster (can’t control their own temp.)
how does light affect ecosystems?
Greater light intensity = greater rate of photosynthesis, more seeds produced, higher population, more animals can be supported
some may grow bigger leaves to absorb more light or develop pigments to require less light
how does pH affect ecosystems?
can break bond in enzymes used in reactions in metabolic reactions. slow rate of reactions, organisms less likely to survive
how does water and humidity affect ecosystems?
increased humidity means less water loss due to transpiration
water is scarce only species that are adapted to dry conditions will increase/maintain their population.
how does oxygen availability affect ecosystems?
aquatic ecosystems, it is beneficial to have fast flowing, cold water as it has high concs. of oxygen. Water-logged soil = less oxygen
how does soil factors affect ecosystems?
it provides the minerals needed for growth
water (for photosynthesis)
anchorage for the roots
what is clay soil?
Few air spaces, Retains water and flood easily
Eg. clay
what is sand soil?
Lots of large air spaces
Does not retain water
Eg. Sand
what are some examples of adaptations of organisms to abiotic factors?
otters have webbed feet – can walk on land and swim in water
whales have a thick blubber – keep warm in cold seas where food is plentiful
bears hibernate in winter – increase chance of survival as they conserve energy in coldest months
what are some examples of biotic factors?
competition
food
territory
breeding partners
what are some examples of adaptations of organisms to biotic factors?
monkeys use twigs to fish for termites – another source of food
scorpions dance dance before mating – ensures that they are the same species
Some bacteria produce antibiotics – kills other species of bacteria
what is a ecosystem?
Made up of all the living organisms that interact with one another in a defined area, and also the physical factors present in that region
what is the biosphere?
global sum of all ecosystems, representing the part of the Earth where life exists.
what is a producer?
Makes its own food, usually by photosynthesis.
what is a carnivore?
Eats only other animals.
what is a herbivore?
Eats only plants.
what is a omnivore?
Eats both animals and plants.
what is a primary consumer?
Eats producers. Usually a herbivore.
what is a secondary producer?
Eats primary consumer, usually a carnivore but could also be a herbivore.
what is a trophic level?
position or stage that an organism occupies in a food chain.
what is biomass?
mass of living material present in a particular place or in particular organisms. Energy stored within biomass can be passed along the food chain to different trophic levels.
how much biomass of each organism is passed onto the next trophic level?
Consumers at each trophic level convert at most 10% of the biomass in their food to their own organic tissue.
why is only 10% of biomass passed onto the next trophic level?
-not all parts of an animal can be digested
-Energy from cellular respiration is transferred by heating the surroundings
-used to provide energy for movement, growth, etc
-lost in urine and faeces
why are fewer trophic levels more efficient?
-Energy is lost at each trophic level
-Not all energy is passed to consumer as not all parts are digested
-Energy is lost through respiration, excretion, heat and movement
-The consumer loses up to 90% of the energy at each level / 10%passed on
what are methods of measuring biomass?
Mass of fresh material present- (easiest method but unreliable as mass of water varies greatly)
Dry mass - (most accurate but organisms have to be killed and put in an oven at 80°C to evaporate all the water)
what units are used to meassure biomass?
Areas of land - g/m-2 (grams per square metre)
Areas of water -g/m-3 (grams per cubic metre)
The energy available at each tropic level is measured in: KJm-2yr-1 (kilojoules per metre squared per year)
This allows for seasonal changes in photosynthesis and feeding patterns.
what is ecological efficencey?
The efficiency with which biomass or energy is transferred from one trophic level to the next.
how is the efficiency of producers affected?
- only convert 1-3% of the sunlight into chemical energy, therefore biomass.
-Not all solar energy available is used for photosynthesis 90% is reflected
-Limiting factors of photosynthesis (water availability/ CO2) - Some energy lost in photosynthetic reactions
what happens in the nitrogen cycle?
- Nitrogen gas is fixed into nitrate compounds by bacteria in root nodules or lightning
- Plants take in nitrates from soil to make protein for growth
- Nitrogen compounds (protein) passed along a food chain
- Decomposers (soil bacteria and fungi) convert protein and urea to ammonia
- Ammonia is converted to nitrates by nitrifying bacteria
- Nitrates are converted to nitrogen gas by denitrifying bacteria
why do we need the nitrogen cycle?
nitrogen-containing compounds exist on earth in finite amounts … no external source replenishing. Must be recycled!
what is decomposition?
Chemical process. Compound broken down into constituent molecules.
what are decomposers?
Organism that feeds on/breaks down dead matter.
Convert organic compounds into inorganic compounds.
They are saprotrophs
Examples: bacteria, fungi
what are detrivores?
Speed up decay process; feed on detritus (dead material)
Break dead matter down into smaller pieces. Increases SA for decomposers.
Examples: maggots, earthworms, woodlice
what happens in nitrogen fixation?
Nitrogen gas is converted into nitrogen containing compounds
Azotobacter and Rhizobium bacteria contain nitrogenase enzyme to convert nitrogen and hydrogen into ammonia.
what do Azotobacter (Free living bacteria ) do?
produce ammonia from nitrogen gas. Make amino acids. Release them when they die.
what do mutalistic bacteria do?
live in root nodules in peas and beans. Obtain carbohydrates from plant and plant gets amino acids from bacteria
what is ammonification?
Production of ammonia from organic compounds e.g. urea, proteins, nucleic acids.
Saprobionts microorganisms release ammonia into the soil.
what happens in nitrification 1?
Nitrifying bacteria oxidise ammonium compounds. (e.g. Nitrosomonas)
Ammonium ions are converted to nitrite ions (NO2-)
Oxidation reaction: aerated soil required
what happens in nitrification 2?
Nitrite ions converted to Nitrate Ions (NO3-)
This requires oxygen, too.
Nitrobacter bacteria do this
when does denitrification occur?
Occurs when soils become waterlogged – short of O2
what happens in denitrification?
Anaerobic bacteria carry this out
Soil nitrates converted to nitrogen in the atmosphere
Reduced nitrogen compounds available to plants – for land to be productive it must be kept well aerated.
