A2 AQA Biology Unit 4 Ecology, Populations, Nitrogen cycle, carbon cycle

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What is the definition of ecology?
The study of how living organisms interact with each other and their environment
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What is the definition of interact, in relation to ecology?
The relationship an organism has with its physical surroundings and with individuals of the same or different species
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What is the definition of biosphere?
The land, vegetation, air and water surrounding the earth that support life
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What is the definition of environment?
All the conditions that surround an organism
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What is the definition of an abiotic factor?
Physical or non-living things in the environment (e.g. light, air temperature, water)
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What is the definition of a biotic factor?
Living things within an environment (predators, food supply, disease, mico-organisms, competition)
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What is the definition of an ecosystem?
The living organisms and the abiotic factors that affect them
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What is the definition of population?
A group of organism of the same speices that can interbreed (e.g. Same habitat or same species)
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What is the definition of community?
A group of organism of different species
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What is the definition of habitat?
Places where a community of organisms live
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What is the definition of microhabitat?
A smaller habitat, can make up a habitat (e.g a pond bed)
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What is the definition of an ecological niche?
The role an organism plays in its environment (Only one organism occupying one niche)
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Why do we use quadrats to only measure a sample?
It would be time-consuming to measure the extra populations
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What feature of the smaple would enure your data is reliable?
A large sample number and random sampling
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What feature of tthe sample would ensure your data is valid?
Appropriate level of accuracy
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What is a quadrat?
A clearly defined area, usually a frame
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What is the difference between a point quadrat and a frame quadrat?
With a point quadrat, long pins are dropped through holes along a horizontal bar. The species the pin touches are recorded. However a frame quadrat, there is a frame often sub-divided into smaller squares and the species abundance is recorded
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How does the size of the quadrat affect its use?
The size of the quadrat to use depends on the size of the species being counted and their distribution
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How does the number of quadrats affect its use?
The larger the smaple size, the more reliable the results but also the more time-consuming it is to gather data. Although more quadrats mean a big enough sample to be representative of the whole population.
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How does the position of each quadrat within the study area affect its use?
Random smapling is needed to ensure there is no bias in the data
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When is it more appropriate to use systematic sampling rather than random sampling?
When there are changes in abundance and distribution of species, where some sort of transition occurs e.g. changes from light to shaded areas
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What is a line transect?
A tape is laid across the sample area and any species that touch the tape recorded
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What is a belt transect?
A tape is laid accross the sample area and quadrats are set down at regular intervals along the tape. Species within the quadrat are recorded.
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What is abundance (in relation to ecology)?
Number of individuals of species within a given area
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How is frequency used as measure of abundance?
If a species is present in quadrats or not e.g. a species present in 15/30 quadrats has a frequency of 50%.
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Commment on the effectiveness of using frequency as a measure of abundance
This is a quick method which is useful for species were it difficult to count (e.g. blades of grass). However it doesnt give information about species density
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How is percentage cover used as measure of abundance?
Estimate the area covered by a particular species
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Commment on the effectiveness of using percentage cover as a measure of abundance
useful where a species is abundant or difficult to count, less useful where plants are in abundance
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How is population density used as measure of abundance?
plants or species per metre squared
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Commment on the effectiveness of using population density as a measure of abundance
accurate and repeatable, but not when time consuming when species is abundant
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What are the ethical issues to fieldwork?
Risk to habitat such as destroying habitat, disturbing animals esp. when breeding or nesting, collecting speciemens that could be endangered
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When would it be appropriate to use a chi squared test to interpret your data?
When the investigation involves counting numbers of individuals in particular categories (e.g.effect of light intensity on number of bubbles produced by water weed)
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When would it be appropriate to use spearman's rank correlation to interpret data?
When the investigation involves taking measurements, and looking for associations between different measurements from the same sample (e.g. investigation into height and weight of human population)
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When would it be appropriate to use standard error & 95% confidence limits?
When the investigation involves taking measurements, and looking for differences between different measurements of different samples (e.g. comparison of No. of people suffering from asthma in rural and urban areas)
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Why do we need to do a statistical test?
To measure the probability that the results obtained were due to chance (random) variation
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Describe the techniques of mark-release-recapture
Set the traps and catch the animals, count the No. in the sample then mark them. Release the marked animals. Set traps again and capture the 2nd sample. Count the No. of marked animals in the 2nd sample
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Whats is the formula for working out the population size?
Total No. in population=(No. of animals caught marked and released X No. in 2nd sample) / (No.marked in 2nd sample)
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What assumptions are made with mark-release-recapture
No births or deaths, no migration/immigration, none eaten. mark doesnt come off, they have moved around since released
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How does temperature (an abiotic factor) effect animals?
Homeostasis, enzymic activity may increase/decrease, affects metabolic rate in cold blooded animals
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How does temperature (an abiotic factor) effect plants?
Evappouration of water/freezing of water, transpiration, increase/decrease in photosynthesis, stomatal activity
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How does light (an abiotic factor) effect animals?
Affects when they can get food (e.g plants), migration and hibernation
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How does light (an abiotic factor) effect plants?
Photosynthesis (light dependant reaction), therefore affects growth (flowering or fruiting), stomatal opening
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How does water (an abiotic factor) effect animals?
Hydration, too much water/not enough water (e.g. camels store water),salinity (saltiness)
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How does water (an abiotic factor) effect plants?
Transpiration, cohesion tension theory, pH, photosynthesis, salinity (saltiness)
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How do air and water currents (abiotic factor) affect animals?
If they drown, pollinations affect, therefore food supply
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How do air and water currents (abiotic factors) affect plants?
Transpiration, pollination and seed dispersal
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How does humidity (abiotic factor) affect animals?
Heat loss
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How does humidity (abiotic factor) affect plants?
Transpiration, heat loss
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What are the three things population increase/decrease depends on?
Birth rate, death rate and migration (immigration/emigration)
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What is the formula for population growth?
Population growth= (births + immigration) - (deaths + emigration)
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What is the formula for percentage population growth rate (in a given period)?
=[ (population change during) / (populaiton at start) ] X 100
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What are some factors affecting birth rates?
cultral and religeous pressure, political factors (china one child policy), medical care, economic, age profile, social pressures
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What are some factors affecting death rates?
War, food supply life expectancy at birth, natural disasters, political factors, economic, safe drinking water and sanitation, medical care
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What is conservation?
The management of Earth's natural resources in such a way that maximum use can be made of them in the future
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What are the ethical reasons it is important to conserve habitats?
We should protect living things who have veen on earth a lot longre than we have
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What are the economic reasons it is important to conserve habitats?
Maintains gene polls which may have some potensially useful genes, producing is greater in natural ecosystems
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What are the cultural and aesthetic reasons it is important to conserve habitats?
The are great variety of natural ecosystems enriches the lives and improves creativity
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How does science improve conservation?
Fencing areas to conserve new plants or animals, traps for squirrals, deer census
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What is succession?
The process by which communities colonize an ecosystem and then are replaced over time by other communities. Includes change in structure and species of community
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What is the difference between primary and secondary succession?
in primary succcession the starting point is a bare ecosystem (e.g. volcanic erruption or land slide), whereas secondary succession stars from bare existing soil (e.g. after fire, flood or rhuman intervention)
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What is deflected succession?
SUccession doesnt reach climax community as humans intervenes preventing it occuring
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What are seres?
The stages involved in succession when particular communities that dominate are known as seres
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What is a climax community?
The final stage of succession (No further change)
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What makes a good pioneer species?
A species that is able to establish itself in an area where nothing is growing, or in an area that has been devestated by fire, flood, etc. They can; enrich soil, provide nutrients for animals. produce many spores (seeds) quickly, harsh environments
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What are the 5 carbon stores?
All organisms, fossil fuels, air (atmospheric carbon), soil (organic matter in the soil), rocks/oceans
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What is organic carbon?
In living or dead organisms,so can be used again
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What is inorganic carbon?
In a form that you cannot use it, e.g. atmospheric carbon
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What is eutrophication?
An increase in the rate of supply of organic matter in an ecosystem
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What is nitrogen fixation?
The process by which nitrogen gas is converted into nitrogen-containing compounds, ammonia (NH3), ammonium ions (NH4+)
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What is denitrification?
The conversion of nitrate ions (NO3-) back into nitrogen gas (N2) by anaerobic denitrifying bacteria in the soil (occurs in water-logged soil)
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What is ammonification?
The productiion of ammonia from organic ammonium containing compounds (urea and protein, nucleic acid and vitamins (found in faecesand dead organisms))
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What is nitrification?
conversions of ammonium ions to nitrite ions to nitrate ions
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What is deamination?
removal of an amino group (-NH2) and an hydrogen atom, these combine to form ammonia
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What is eutrophication?
The process of fresh water being enriched by nutrients (especially nitrates and phosphates)
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What is leeching?
increase of growth of algae in water, which meand the bacteria decompose dead algae and use up oxygen in the water, reulting in the deaths of fish and vertebrates that need oxygenated water
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What is the definition of interact, in relation to ecology?

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The relationship an organism has with its physical surroundings and with individuals of the same or different species

Card 3

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What is the definition of biosphere?

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Card 4

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What is the definition of environment?

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Card 5

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What is the definition of an abiotic factor?

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Comments

Rebecca

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Great for just before the exam, thanks :) but I don't think some of the answers are in enough detail eg 9) what is the definition of community? In the exam to get all the marks you have to say 'all the individuals of all the different species in an area' to get the marks. 

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