7.2 ecology Flashcards
(17 cards)
feeding relationships
connects different species in a community
represented by food chains
trophic levels—the position of an organism within a food chain
which group of organisms don’t fit neatly into a single trophic level?
decomposers: fungi and bacteria
secrete enzymes onto dead and decaying matter to digest it
absorb the soluble food molecules via diffusion and reutnr mineral ions to the soil
Biomass
produced by photosynthetic enzymes
biomass is a measure of the total mass of living material in each trophic level
wet vs dry biomass
dry biomeass: the organism has to die in order to remove all its water
wet biomass: water levels in living things very during the course of a day
how is biomass passed
passed along food chains trophic levels
herbivores eat plants and then carnivores eat the herbivores
pyramid: as you go up, the less biobass there is (biomass pyramids)
energy flow in food chains
producers are inefficient at transferry energy from light into new biomass—only about 1 % of the energy is transferred
food chains = inefficient, only 5-10% biomass consumed from the previous level being converted into new biomass becuase:
not all parts of the plant/animal are eaten, e.g. bones, shell, roots
not all parts of the organism can be digested so energy is lost as faeces
much of the enrgy is lost during cellular respiration, and some enerygy is lost in the form of heat
lost as urea/co2/water
predator prey relationships
producers are eaten by primary consumers, which are eaten be secondary consumers and then teriary consumers
cycles: look at cycle notes
measuring abundance and distribution: sampling
take a sample of the population/community
large sample size so that the sample is REPRESENTATIVE
needs to be RANDOM to remove any bias
quadrats
normally 0.25m2
number of organisms of each species in the quadrat is counted to give the frequency of each species—estimate percentage of the quadrat
standardis method to account for organisms that are only partially within the quadrat
quadrats can be used in 2 ways: estimating size of populations in an area (abundance)—RANDOM SAMPLING, investigating the change in distribution along a habitat—SYSTEMATIC SAMPLING
random sampling, rp9
compare population sizes in two areas
1) Grid the areas using two tape measures at right angles.
2) Use a calculator to generate a pair of random numbers. These two numbers represent the coordinates.
3) Place the 0.5m x 0.5m quadrat at the coordinate and count the number of organisms of each species (abundance) within the quadrat.
4) Repeat many times (at least 10 quadrats) to ensure sample is representative.
5) Calculate the mean abundance per quadrat. Then, multiply this by 4 to give the mean abundance per m?
6) An estimate can now be made of the abundance of your chosen species across the whole field by multiplying the mean abundance per m? by the total area of the field.
systematic sampling—rp9
distribution of one or more species differes along an environmental gradient: don’t randomly sample as you want to see if there is a correation with the change in abiotic factors, e.g. light intensity, soil moisture, nutrient content of the soil, wind speed
- lay a transect (tape measure) across the area
- place quadrats at regular intervals (1m)
- count the daisies (organisms) within each quadrat
- AND measure the abiotic factor, e.g. light intensity
5.plot a scatter graph and look for a correlation
Material cycling
materials such as minerla ions and water and elements e.g. O2, N2, C are constantly recycled through the environment
detritus feeders and decomposers play vital role in recycling of materials
carbon cycle
stored in air: CO2, plants: locked up in biological molecules, soil: microorganisms and bacteria, fossil fuels, animals: locked up in biological molecules
photosynthesis—green plants and algae take in CO2 from atmosphere and converts into biological molecules like glucose. then can be either passed back out to the atmosphere via respiration, or passed on to the animals that eat the plants
animals—respire to relase CO2
animals and plants when they die—organisms are decayed by microorganisms that live in the soil, which breaks them into smaller pieces until all the carbon has been released as carbon dioxide during microbial respiration (aerobic conditions)
if the animals and plants are decayed in anaerobic conditions, will be converted into FOSSIL FUELS
fossil fuels are burned by humans to produce CO2
water cycle
water from soil, oceans evaporates; also transpiration from plants (evaporation of water from leaves)
water vapour condenses into clouds
precipitation—ain, snow, sleet
then percolation: water filters through soil and porous rock; or flow into rivers; or taken up by plants
decomposition factors to speed up
warmth
high oxygen/oxygenated
moist
gardeners and farmers try to provide optimum conditions for rapid decay of waste biological material. the compost produced is used as a natural fertiliser for growing garden plants or crops
rp 10–investigate the effect of temp on the rate of decay of fresh milk by measuringng ph change
- label test tube with lipase. use pipette to place 5cm3 lipase solution into the test tube
- label another test tube milk and add five drops o the indicator cresol red to it. add 5cm3 milk and 7cm3 sodium carbonate solution to the milk test tube (purple solution, because it is alkali)
- place thermometer in test tube containing the milk. place both test tubes into a beaker of water at first chosen temperature (20C)
- wait until the temp of solutions is the same as the water in the beaker
- use a pipette to transfer 1cm3 of lipase solution to thee test tube containing milk and stir the solution and start the timer
(lipase will start to break down fat molecules in the milke which releases fatty acids, making the solution acidic, so cresol red will become yellow ) - when the solution turns yellow, stop timing and record the results
- repeat with range of dif temps
anaerobic decay
in anaerobic conditions, microorganisms produce methane gas—cheap source of fuel for cooking, heating, generating electrcity and powering vehicleds
biogas generators can be used to produce methane gas as a fuel
generator is buried under ground to maintain warm temperatures
some generators contain stirrer that runs on electricityt—good bc bacteria and waste material don’t settle at the bottom, but it’s bad becuase you use electricity to power the stirrer
