B4: Community level systems Flashcards
what are ecosystems
- dynamic systems consisting of communities of interacting living organisms and their physical environment
what is a community
- all the organisms within the ecosystem - diff species living together in an area at a particular time
what is a population
- all the organisms of a single species living in one area at a particular time
what is a predator
- an animal which hunts + kills other animals
what is an adaptation
- a feature which allows an organism to live successfully in its environment
what is a prey
- an animal that is hunted + killed by other animals
what is biotic
- the living organisms in an area and their interactions
what is abiotic
- the non-living factors in an area
what is mutualism
- a relationship where both organisms receive some benefit
what is parasitism
- a relationship where only one of the organism gains and the other suffers
what is predation
- a relationship where one organism eats another organism
> the population sizes affect each other
what is competition
- two or more organisms requiring the same source
- plants + animals have to compete for resources if materials are limited
> may result in weaker competitors dying or leaving that area (weaker plant species often die)
ecosystems can be ____ or ____
- terrestrial
> tundra, hot dessert, rainforest - aquatic
> freshwater, coral reef, ocean
what are the two factors that affect an ecosystem
- biotoic factors
- abiotic factors
what are the biotic factors that affect ecosystems
- competition - for food, water, shelter, partners, light, CO2, minerals
- disease
- food chains
> predators - food availability
- human activity
what are the abiotic factors that affect ecosystem
- light intensity
- temperature
- moisture levels
- soil pH
how does light intensity affect communities
- light needed for photosynthesis
- greater light availability, greater success of plant
- plant evolve to grow successfully in diff light intensities
> e.g. areas of low light, plants often have larger leaves
how does temperature affect communities
- temp has greatest effect on enzyme controlling metabolic reactions
- plants develop quicker in warmer temps as their metabolisms will be faster
how does moisture level affect communities
- for most animals + plants lack of water leads to death
> water is main component of blood plasma
> plants wilt with less water as water is used to keep cells turgid which makes plants upright
> water needed for photosynthesis
how does soil pH affect communities
- pH of soil affects biological activity in soil + availability of certain minerals
- some plants grow better in acidic soil (pH < 7)
> rhododendrons + ferns - others grow better in alkaline soils (pH > 7> cucumber + cauliflower
how can you measure light intensity (equipment)
- light meter
> lux (units)
how can you measure availability of moisture (equipment)
- humidity sensor
> % (units)
how can you measure pH (equipment)
- pH probe
> no units
how can you measure temperature (equipment)
- thermometer
> degrees Celsius
what is interdependence
- how different organisms depend on each other in a community
what are the interactions between organisms known as
- ecological relationships
what are the 3 main types of ecological relationships
- predation - relationship where predator feeds on prey
- mutualism - both organisms gain from relationship
- parasitism - only one organism (parasite) gains from relationship
why do animals need to eat
- to get energy
what does the chemical energy from food allow us to do
- to do respiration to make our cells work + keep our bodies warm
what is a producer
- on organism that can make its own food (nutrients) by photosynthesis
what is a consumer
- an organism that can’t make its own food
> they have to eat other organisms to gain energy - all animals are consumers
what is a decomposer
- an organisms that gets its energy from feeding on dead or decaying material
how is energy transferred between organisms - producers
- energy from sun transferred by light to chlorophyll in cell of producer
- here CO2 + water react producing glucose which stores energy within its chemical bonds
- glucose then converted into carbs, proteins + fats, which are used as energy stores, growth + repair
- as an organism grows it increases its biomass
what is biomass
- the dry mass of material in living organisms
why is dry mass used for biomass
- because wet mass varies as amount of water in organism varies
> requires organism to be killed + dried in a kiln
how is energy transferred between organisms - consumers
- consumers eat producers
- when organism respires, energy stored in food is transferred to production of ATP
- organism grows + biomass increases
what are food chains
- charts showing the flow of energy from one organism to the other
> shows what an organism eats
what is a trophic level
- each step in a a food chain
- the position of an organism in food chain
what is always on the first trophic level
- producers
what are the 5 tropic levels
- producer
- primary consumer
- secondary consumer
- tertiary consumer
- quaternary consumer
what is a food web
- series of interconnected food chains showing energy flow through part of an ecosystem
why are food webs needed
- food chain are too simple and show only ne organism eating one
- in most communities animals eat more than one type of organisms + can be eaten by more than one
- to show this, food webs are illustrated
what is a pyramid of number
- a chart showing the number of organisms at each tropic level
- inverted pyramid
what is a pyramid of biomass
- just like pyramid of numbers with each tropic level on top of each other BUT
- pyramid of biomass takes into the mass of each organism
why is pyramid of biomass more accurate than pyramid of numbers
- takes into account the number + size of organisms present
why is biomass lost between different trophic levels
- biomass is lost in waste
- biomass is used to carry out respiration
what are some of the ways that biomass is lost
- in waste: undigested material in faeces, excess protein in urine, inedible parts
- biomass used in respiration: resp produces ATP; muscles use ATP for movement - also used to maintain constant body temp
- egestion: some parts of organism can’t be eaten - hair + teeth - so removed in faeces
- excretion: waste products produced by body are lost through excretion > e.g. urea lost in urine
how do you calculate the efficiency of biomass transfer
- efficiency of biomass transfer = biomass available after transfer / biomass available before transfer x 100
= after / before x 100
how does the efficiency of biomass transfers affect the number of trophic levels in a biomass pyramid
- the less efficient the transfers, the fewer trophic levels + the fewer organisms in higher trophic levels
what is a primary consumer
- an organism that feeds on producers
what is a secondary consumer
- an organism that feeds on primary consumers
what do plants compete for
- light
- water
- CO2
- minerals
- space
what do animals compete for
- food
- water
- breeding partners
- space (territory)
- shelter
what are decomposers
- microorganisms (bacteria + fungi) that break down/decay dead organisms + waste materials
what is decomposition
- process by which dead organisms + waste material are broken down by decomposers
what happens through decomposition
- decomposers use nutrients to live + grow
- excess nutrients are released back into the environment for recycling
what are saprophytes
- organisms that feed on dead material
what are detritivores
- small animals
what is the role of detritivores in decomposition
- they speed up decomposition by breaking organic material into smaller pieces
> this creates a larger surface area for decomposers to work on
how do decomposers release nutrients
- bacteria + fungi release enzymes on the dead remains
- the enzymes digest the dead matter and make it soluble
- the soluble products are absorbed by the bacteria / fungus (for growth + as an energy store)
> many of the bacteria + fungi will be eaten by other organism, resulting in the nutrients being passed on
> some of the nutrients are released directly into the soil or the environment
what factors affect the rate of decomposition
- temperature
- moisture
- oxygen levels - aerobic conditions
how does temperature affect the rate of decomposition
- most decomposers work best in warm conditions (rate highest at 50 degrees Celsius)
> this is because decomposers contain enzymes which work best at higher temps - low temps: rate of decomposition slow - enzyme controlled reactions are reduced
- higher temps: enzyme becomes denatured + decomposition stops (often results in death of microorganism)
how does moist environments affect the rate of decomposition
- decomposers need water for survival
- if not enough water is available, the reaction slows down or is prevented
> rate of decomposition inc in moist conditions
how does aerobic conditions affect the rate of decomposition
- oxygen needed for decomposers to respire
> rate of decomposition inc with more oxygen - anaerobic conditions will prevent most forms of decomposition as decomposers can’t survive in this condition
> some decomposers will respire anaerobically but it transfers less energy, so decomposers will work more slowly
how do you calculate the rate of decay
- rate of decay (g/day) = change in mass (g) / time (day)
- rate = change in mass / time
what is nutrient cycling
- the process of material being passed between biotic + abiotic component of an ecosystem
describe the nutrient cycle
- plants get nutrients for growth from soil
- nutrients get passed onto animals when plant is eaten
- when plants + animals die, decomposers break down their bodies and this releases nutrients back into the environment
where does the nutrients released by dead animals + plants go
- many nutrients released into soil, for plants to absorb them
- some are released into the atmosphere
what materials are cycled in an ecosystem
- carbon
- nitrogen
- water
why is carbon important
- all living things contain carbon
> used to make: carbohydrates, fats, proteins and DNA - carbon present in atmosphere as CO2
> plants use CO2 during photosynthesis to produce sugars
> this can be converted to other molecules + can then be transferred to animals along food chain
what is the carbon cycle
- the process in which carbon is cycled through the atmosphere, the Earth, plants and animals
how is carbon removed from the atmosphere + passed on
- CO2 removed from environment during photosynthesis
> occurs in green plants, algae, phytoplankton
> CO2 + water —> glucose + oxygen - glucose simple sugar is converted to complex carbs
> allows plant to grow + develop - when animals eat plants, carbon from plant is transferred to animal - can be used to make fats + proteins
how is carbon released back into the atmosphere
- respiration: releases CO2
- decomposition: releases CO2
- burning fossil fuels: fossil fuels are a store of carbon - when burned CO2 released
> fossil fuels include: coal, oil, natural gas
what can the carbon from dead organisms also forms
- fossil fuels
- sedimentary rocks e.g. limestones
> these are long term carbon stores
why does the level of atmospheric CO2 vary
- photosynthesis only happens at daytime so CO2 is only removed then
- respiration is carried out by all living organisms at all times, so CO2 is released at a consistent rate
why has atmospheric CO2 concentration increased significantly in recent years
- mainly due to human activities
> combustion of fossil fuels
> deforestation - inc level of CO2 is contributing to global warming
why is nitrogen important
- nitrogen makes up nearly 80% of atmosphere
- nitrogen used to make amino acids (protein) + DNA + chlorophyll
- most organisms can’t take nitrogen from air, but use it when it’s in a compound form e.g. nitrate
how do plants take in nitrogen
- they take nitrogen through their roots as the mineral nitrate (nitrate dissolved in water so can be taken up)
- the nitrates are used to make proteins
how do animals get nitrogen
- animals eat plants
> they get their nitrogen as protein which they have to digest + assimilate
> protein then goes up food chain
what happens in the nitrogen cycle when organisms die
- waste material (uneaten pieces of plant, faeces, urine) gets broken down by decomposers
> and they get turned into ammonium ions in the soil
what happens to the ammonium ions in the nitrogen cycle
- ammonium is no use to living things
- a bacteria called nitrifying bacteria turns ammonium ions into nitrates for the plants
what is nitrogen-fixing bacteria
- a bacteria that converts nitrogen from the air into nitrate which is used in soil by plants to take up nitrogen
what is nitrifying bacteria
- bacteria which converts ammonium ions from waste / dead remains into nitrates for soil
what is denitrifying bacteria
- bacteria which converts nitrates in the soil back into nitrogen which gets releases into the atmosphere
how does nitrogen get into the soil in he first place
- nitrogen-fixing bacteria in soil
- nitrogen-fixing bacteria in root nodules (plant roots)
- nitrogen reacts with oxygen in air when high temps created by lightning - this dissolves in rainwater + soil gets nitrates from it
- nitrogen turned into ammonia in Haber process which is then used as fertilisers - fertilisers can be used to enrich soil with nitrates
how is water recycled in the water cycle
- sun makes water evaporate from land + sea + transpiration from plants
- water condenses as clouds
- water is returned through precipitation
what does the water cycle move
- water + nutrients through atmosphere, soil, rivers, lakes and oceans
how does the water cycle help
- it bring fresh water to people + animals + plants (organisms) all around the word
- transports nutrients to diff ecosystems
