Topic 2: energy for life

if data has low accuracy it means

the data is not close to the true value

in bacteria population growth curve, what occurs in death phase

• reproduction rate is lower than death

• due to there being not enough nutrients or toxins building up

key steps to random sampling

• use 2 tape measures to divide the sampling area into a numbered grid

• select random X and Y coordinates using a random number generator

• place the quadrant and coordinate and collect data

• repeat 10x and calculate a mean

4 sections of a population growth curve for bacteria

lag phase, log phase, stationary phase and death phase

what happens in log phase of animal population growth curve

birth rate is significantly higher than death rate as population is growing exponentially

how can the reliability of data you’ve collected be improved

collect more data and calculate a mean

what happens in lag phase of bacteria population growth curve

• reproduction rate is slightly higher than death rate

• due to DNA replication, organelle replication, protein synthesis, obtaining nutrients, respiration

key steps to systematic sampling

• run a transect across the area of study

• every 1m place a quadrant

• measure the species frequency of each species

• measure an abiotic factor at each interval

random sampling may be used when

sampling an area that is uniform eg a field

stationary phase of animal population growth curve

• population size fluctuates around the carrying capacity

• when above carrying capacity, there is more competition and less reproduction so population size decreases

• when beneath carrying capacity, there is less competition and more reproduction so population size then increases

how can reliability be measured

calculating the standard deviation of the data

stationary phase of bacteria population growth curve

reproduction rate is equal to death rate due to limit of nutrients or space

if data has high reliability then

data doesn’t vary much around the mean

low standard deviation means

data doesn’t vary greatly around the mean so high reliability

explain why population growth curves look difference for bacteria and animals

bacteria are in closed systems whereas animals are in open systems

lag phase of animal population growth curve

birth rate is slightly higher than the death rate due to individuals waiting for sexual maturity, individuals finding a mate and gestation

why would systematic sampling be used

when sampling an area that isn’t uniform

population size increases due to

increase in reproduction (bacteria)/ births (animals), increase in immigration (individuals joining the population)

density independent factor

abiotic factor that could increase the death rate and they have the same effect on any population size

carrying capacity

maximum number of animals in a population that can be maintained in a habitat, can change if there are environmental changes

community

organisms of all the different species that live in a particular area

ecosystem

system of interacting biotic and abiotic factors within an environment

ecology

study of relationships of organisms to one another and to their physical surroundings

niche

an organisms role in the environment , including thee abiotic and biotic factors required for its survival

abiotic

ecological factor that makes up part of the non biological environment of the organism (eg pH or sunlight)

inter-specific competition

competittion between organisms of different species

prredation

killing of one living organisms by another for food

intra-specific competition

competition between organisms of same species

habitiat

place where an organism lives

population

group of interbreeding organisms of ONE species in a habitat

biotic

an ecological factor that makes up part of the living environment of an organism eg competition

systematic sampling

• used to investigate an environmental gradient (change across a habitat)

• often uses a transect- quadrats place along transect at regular intervals

immigration

movement of individuals into a population of the same species

equilibrium species

species that control their population by competition rather than reproduction and dispersal

birth rate

reproductive capacity o a population, the number of new individuals derived from reproduction per unit time

environmental resistance

environmental factors that slow down population growth

carrying capacity

maximum number aroundd which a population fluctuates in a given environment

abundance

number of individuals in a species in a given time

saprobionts

micro-organisms that obtain inorganic molecules from the dead or decaying remains of other organisms

predator-prey cycles

ways in which population sizes of predators and prey are interlinked and dependent on one another

trophic levels

feeding level determined by the number of times the energy has ben transferred between the sun and successive organisms

how are ammonium compounds converted to nitrate ions

• nitrification

• ammonium compounds converted to nitrite ions using nitrosomanos bacteria

• nitrite ions are converted to nitrate ions using nitrobacter bacteria

explain why ploughing increases the concentration of nitrate and ammonia in the soil

• nitrogen fixing bacteria and nitrification require aerobic conditions

• ploughing increases oxygen content of soil

• so there is an increased rate of nitrogen fixing and nitrification

explain why lichen are a common pioneer species in succession

• spores are deposited by wind/ animals

• lichen releases enzymes that erode the rock and produce the first layer of soil

name the processes that add carbon dioxide to the atmosphere

• respiration: from plants, animals, decomposers

• combustion: of fossil fuels created from dead organic matter from plants and animals

process that removes carbon dioxide from the atmosphere

photosynthesis

final stage of succession

climax community

succession

change in the species found in a community over time

primary succession

succession of an environment where nothing has grown before

locations where primary succession may occur

bare rock and sand dunes

2 forms of nitrogen that an be absorbed by plants

ammonia (NH3) and nitrate ions (NO3-)

explain why mosses are a common species in the second seral stage of succession

have no vascular system and therefore do not require a thick layer of soil

explain how nitrogen in the air is converted to ammonium compounds

• nitrogen is converted to ammonium compounds in nitrogen fixing

• azotobacter bacteria are required for this process

relationships between rhizobium bacteria and legume plants described as mutualistic

• both benefit from the relationship

• rhizobium bacteria produce ammonia for the plant

• legume plants produce glucose in photosynthesis and give some glucose to rhizobium bacteria

overuse of fertilisers can cause what to occur in nearby rivers

eutrophication

why do animals require nitrogen

produce proteins and nucleic acids

secondary succession

succession of an environment that has been cleared

what form of nitrogen is found in the air

N2

carbon footprint

amount of carbon dioxide equivalent a person/ product/ service produces in a year

which type of competition is more extreme

intraspecific competition as the individuals are all in the same niche so competing for exactly the same resources

reasons why secondary succession is a quicker process than primary succession

already soil containing seeds and nutrients

denitrification

nitrate ions in the soil are converted to N2 in the air, this requirred psedomonas bacteria which are found in waterlogged soil

name for different phases of succession

seral stages or seres

apart from ploughing, describe 3 ways that thee concentration of nitrate and ammonia in the soil can be increased

1. fertilisers which increase the nitrogen content of the soil

2. drainage as less water logged soil so there is a decrease in denitrification

3. plant legumes eg clover and beans so there will be more nitrogen fixing via rhizobium

why do plants require nitrogen

to produce chlorophyll, proteins and amino acids

disadvantage of adding fertilisers or drainage to the soil

can decrease biodiversity as som plant species thrive in damp or poor nutrient soil

why is lichen a common pioneer species in succession

• spores deposited by wind/ animals

• lichen releases enzymes that rode the rock and produce the first layer of soil

2 forms of nitrogen that can be absorbed by plants

ammonia (NH3) and nitrate ions (NO3-)

what happens to soil thickness and nutrient content of the soil during succession

• soil thickness and nutrient content of the soil increases

• because as more organisms colonise the land, they also die and decay so the organic matter enters the soil

pioneer species

first species to colonise the land

eutrophication

• fertilisers are used on fields and dissolve in rainwater which drains into water ways eg rivers

• it promotes aquatic plants to grow but also algae to grow leading to algal blood

• algae covers the surface of the water blocking the lights from aquatic plants which cannot photosynthesis an so die

• this decreases the O2 in the water

• decomposer population increases so more oxygen is used by this population

• less oxygen is available for aquatic animals leading to their death

how nitrogen in the air is converted to ammonia

nitrogen fixing using rhizobium only found in root nodules of legume plant

food web

• graphical model showing the interconnecting food chains in an ecological community

• shows the feeding relationships of organisms in an ecosystem

GPP

rate of production of chemical energy in organic chemicals by photosynthesis (KJ m-2 yr-1)

NPP

• rate of production of biomass by photosynthesis which is (potentially) available to heterotrophs

• NPP= GPP - product respiration

equation for photosynthetic efficiency (PE)

quantity of light energy incorporated into the product/ quantity of energy falling on the plant X 100

why is only a small amount of the light energy falling on a plant absorbed

• wrong wavelength

• reflected

• transmitted straight through the leaf

pyramid of biomass

graphical representation showing the relative amounts of biomass at each trophic level in an ecosystem

saprobionts/ saprotrophs/ decomposers

organisms that feed on dead and decaying material by secreting hydrolytic enzymes and absorbing their products

trophic level

• feeding level in a food chains, web or ecological pyramid

• level 1 in occupied by producers, level 2 primary consumers and so on

• normally decomposers occupy the last trophic level

pyramid of biomass

• biomasses at each trophic level allows easy comparison they are usually measured kg m-2

• difficult to make measurements

• include material which is hard for consumers to digest eg wood bone therefore energy in these structures not transferred directly to next trophic level

• organisms lifespan not included- if organism short lived its biomass may only be available to the next trophic level for a short period of time

often population growth curves are plotted on a log scale, why is that

to accommodate the very small and very large values also described as a large range

describe why not all of the light energy that hits a plant is absorbed

• some will reflect of the way cuticle

• some will not hit a chloroplast and will be transmitted

• some will not be the correct wavelength and will be transmitted

NPP

GPP- respiration

gross primary productivity

rate of glucose production by photosynthesis per meter squared per year

why are the number of trophic levels limited

energy is lost at each energy level so eventually there is not enough left to sustain another level

reasons why energy is lost from a carnivore in a food chain

• faeces: mainly undigested bone and fur that is passed to decomposers

• urine: removes excess amino acids this is passed to decomposers

• respiration: used for metabolism and movement, some is lost as heat

reasons why energy is lost from a herbivore in a food chain

• faeces: mainly undigested cellulose that is passed to decomposers

• urine: remove excess amino acids, this is passed to decomposers

• respiration: used for metabolism and movement, some of this is lost as heat

net primary productivity

plant biomass that is available to the herbivore, so does not include the energy used in respiration

what does SSSI mean

site of special scientific interest

types of international cooperation that could conserve a species

• banning activities eg whaling

• banning trade eg not exporting ivory

• custom checks eg to check for invasive species

solutions to deforestation

protected areas, replanting of native species, coppicing and pollarding

conservation methods that could prevent a species from becoming extinct

• protective status

• international cooperation

• breeding programmes in zoos and botanical gardens

• sperm and seed banks

• ecotourism and education

• reintroduction programmes

reasons why a species may become extinct

• destroying habitats

• polluting habitats

• introducing a new species

• growing monocultures

• using land for building

• harvesting unsustainably

impacts of deforestation

• succession less likely to occur

• climate change

• destruction of habitats

difference between exctinction and endangered

extinction is a total loss of species whereas endangered is a species at risk of extinction

reasons why deforestation is occurring

• source of timber for firewood and building

• to clear land for agriculture: either plants (crops) or animals (livestock)

types of protective status that can be given to an area

nature reserve or sssi

if critical value is lower than correlation coefficient you calculated, what should you conclude

• reject null hypothesis

• statistically significant correlation

• less than 5% probability results are due to chance

how can reliability be measured

calculate standard deviation