6.3.1 Ecosystems

define ecosystem

an area where biotic organisms and abiotic environmental factors interact forming a relatively self-sustaining system driven by energy flows and nutrient cycles

define niche

the role of an organism within an ecosystem, only one species can occupy a specific niche

what is the name for the role of an organism in an ecosystem

niche

what are the types of nutrition

autotrophic- photoautotrophic and chemoautotrophic, and heterotrophic- holozoic and saprotrophic

define autotrophic nutrition

a process of obtaining carbon from carbon dioxide

define heterotrophic

a process of obtaining carbon from breakdown of organic compounds

what is the name for the process of obtaining carbon from breakdown of organic compounds

heterotrophic nutrition

what is the name for the process of obtaining carbon from carbon dioxide

autotrophic nutrition

define photoautotrophic

a process of obtaining carbon from carbon dioxide using energy from light

what is the name for the process of obtaining carbon from carbon dioxide using energy from light

photoautotrophic nutrition

define chemoautotrophic

a process of obtaining carbon from carbon dioxide using energy from chemical reactions, starts food chains where there is no sunlight

what is the name for the process of obtaining carbon from carbon dioxide using energy from chemical reactions, starts food chains where there is no sunlight

chemoautotrophic nutrition

define holozoic

a process of obtaining carbon by ingestion and internal digestion of organic compounds

what is the name for the process of obtaining carbon by ingestion and internal digestion of organic compounds

holozoic nutrition

define saprotrophic

a process of heterotrophic extracellular digestion involved in the processing of decayed organic matter

what is the name for the process of heterotrophic extracellular digestion involved in the processing of decayed organic matter

saprotrophic nutrition

define detritivores

organisms that shed detritus, ingest it and digest it internally (holozoic nutrition), they precede decomposers in the process of decomposition

define decomposers

a saprotrophic microorganism that breaks down dead organic matter to simpler organic or inorganic material

what is the difference between detritivores and decomposers

detritivores precede decomposers in the process of decomposition, detritivores use holozoic nutrition and decomposers use saprotrophic nutrition

define hummus

dead organic matter in the soil

what is the name for the dead organic matter in the soil

hummus

define biomass

the total quantity of dry mass in an organism, commonly measured for a trophic level or a population/community inhabiting a certain region

what is the name for the total quantity of dry mass in an organism, commonly measured for a trophic level or a population/community inhabiting a certain region

biomass

define dynamic

a word to describe the change in distribution and abundance of species in an ecosystem over time

what are the features of an ecosystem

• different in size

• dynamic

• biotic factors

• abiotic factors

what are the types of change in an ecosystem

cyclic change, directional change, erratic/unpredictable change

what is cyclic change in an ecosystem

repeat in a rhythm e.g. tides, seasons

what is directional change in an ecosystem

gradual change in one direction that lasts longer than the lifetime of organisms e.g. erosion of coastline

examples of different size ecosystems

rock pool, playing field, large tree

what are examples of erratic change in an ecosystem

hurricane, lightening, tsunami, forest fires

what are examples of biotic factors affecting ecosystems

• food chains/webs

• decomposition

• predator-prey relationships

• competition

• cooperation

• providing a habitat

• disease- pathogens and parasites

what are the steps of a food chain called

trophic levels

what are the trophic levels

1- producer, 2- primary consumer, 3- secondary consumer, 4- tertiary consumer

what are the types of food chain

grazing food chains, detrital/decomposer food chain

what are decomposer food chains

involve decomposition, allows nutrient cycling

what is the role of producers

all organisms depend on producers for energy and biomass, energy enters the ecosystem through producers

what do producers depend on

the activity of decomposing microorganisms for most of their supply of inorganic ions e.g. nitrates, phosphates, magnesium

what are decomposers

microorganisms e.g. bacteria, fungi, that digest dead organic matter by external secretion of enzymes to then absorb the productions- saprotrophic nutrition

what does the saprotrophic nutrition of decomposers allow for

this type of nutrition releases all nutrients into the soil including minerals, taken up by producers, mineral recycling is dependent on decomposer activity

what is the nutrient cycle

• organic substances containing element taken up by producers

• primary consumers take in organic substances containing element

• higher consumers take in organic substances containing element (grazing food chain)

• death excretion and egestion of wastes and other loss of organic substances enters decomposer food chain

• decomposers break down organic substances containing element

• release of soluble nutrients so inorganic substances in reservoirs or sinks e.g. soil, water or rocks contain element

what are predator-prey relationships

part of a food chain, numbers of each, affect the other cyclically

what are the types of competition

intraspecific- between members of the same species, interspecific- between members of different species

what are the types of cooperation in an ecosystem

intraspecific- between members of the same species e.g. social insects, interspecific- between members of different species

what are the types of interspecific cooperation

mutualism e.g. coral and algae, commensalism- when one species gains and the other is neutral e.g. barnacles on whales

what are the abiotic factors that affect ecosystems

climatic factors, topographic factors, edaphic factors

what are climatic factors

wind speed, precipitation, temperature, wave action, light intensity

what are topographic factors

altitude, gradient, shape of land, aspect (direction land is facing)

what are edaphic factors

soil nutrients- features of the soil, river bed

what does an abiotic factor need to be

measurable

what are the types of measurement between trophic levels in an ecosystem

pyramid of numbers, pyramid of biomass, energy transfer in ecosystems

what is a pyramid of numbers as a way of measuring trophic levels

to show the relative numbers of individuals at each trophic level

what is a pyramid of biomass as a way of measuring trophic levels

to show the relative amount of biomass at each trophic level

how is biomass measured

dry in an oven at 80’C, weigh sample until it remains at a constant mass to know all the water is removed

how to calculate the efficiency of biomass transfer between trophic levels

=quantity of biomass transferred/total quantity of biomass available *100

what does the equation quantity of biomass transferred/total quantity of biomass available *100 represent

efficiency of biomass transfer

what does productivity mean

the rate at which energy transfers between trophic levels in an ecosystem

what is the word for the rate at which energy transfers between trophic levels in an ecosystem

productivity

what is productivity measured in

kJ m^-2 yr^-1 for land or kJ m^-3yr^-1 for an aquatic food chain (using years allows seasons to be taken into account)

what is the rate at which energy enters the food chain through producers called

primary productivity

what is primary productivity

the rate at which energy enters the food chain through producers

what are the levels of primary productivity

gross primary productivity (GPP) and net primary productivity (NPP)

what is gross primary productivity

the rate at which the solar energy absorbed by the plant is converted to chemical energy through photosynthesis

what is the name for the rate at which the solar energy absorbed by the plant is converted to chemical energy through photosynthesis

gross primary productivity

what is the normal GPP value and why

around 2%, a lot of the light energy, mainly green light, is reflected so not absorbed, doesn’t hit chloroplasts, of the energy absorbed, much is lost through respiration and evaporation of water

what is net primary productivity

the energy stored in the biomass of producers, different to GPP as energy is lost in respiration

what is the name for the energy stored in the biomass of producers

net primary productivity

how to calculate NPP

GPP-respiration

what is secondary productivity

when herbivores and carnivores consume food, energy and biomass is transferred along the food chain

how is energy and energy in biomass lost at each trophic level

respiration, death, excreta (urine), egesta (faeces)

what are the types of energy lost that are available to decomposers

death, excreta (urine) and egesta (faeces)

what is the name for the energy that is incorporated into the biomass of the animal

secondary production

what is secondary production

the energy that is incorporated into the biomass of the animal

what limits the length of food chains

at each step energy-containing materials are transferred, but not all the energy from one trophic level transfers to the next

what is the impact of not all the energy from one trophic level transferring to the next

limits the length of food chains

why is a lot of food consumed by herbivores lost as faeces

the cellulose in plant cell walls is hard to digest

what are the ways farmers can maximise energy flow in primary or secondary production

• maximise energy input

• maximise growth

• control disease

• control grazing/predation

• reduce interspecific competition

• reduce energy loss

how can you maximise energy input in producers and primary consumers

producers: optimum planting distances between crops, provide light on overcast days, seed early in the season, primary consumers: provide good quality feed

how can you maximise growth in producers and primary consumers

producers: provide water (irrigation) or fertilisers containing NPKS, carbon dioxide enriched greenhouses, selective breeding for fast growth, crop rotation with legumes, primary consumers: selective breeding for fast growth, kill just before adulthood, provide food supplements e.g. vitamins and minerals

how can you control disease with producers and primary consumers

producers: sow disease-resistant GM crops, spray fungicides/herbicides, primary consumers: antibiotics and vaccines

how can you control grazing/predation in producers and primary consumers

producers: pest-resistant GM crops, fencing to exclude grazers, use pesticides, primary consumers: control predators such as foxes and wolves, keep animals in shed protected from predators

how can you reduce interspecific competition in producers and primary consumers

producers: ploughing and herbicides kill weeds, primary consumers: control competitors

how can you reduce energy loss in producers and primary consumers

producers: breed plants that maximise energy storage in edible products e.g. seeds, tubers, primary consumers: keep animals in warm environments, restrict movement to reduce energy lost to respiration

what is the carbon cycle

carbon containing compounds in plants → carbon containing compounds in herbivores → carbon containing compounds in carnivores → carbon containing compounds in dead remains and excretory products → carbon containing compounds in decomposers → carbon atoms in carbon dioxide in the atmosphere from respiration

why do carbon levels have peaks and troughs

different seasons- in summer more plants so more photosynthesis, in winter increased fuel combustion

what is the general nitrogen cycle

plant biomass → animal biomass → NH4+ → nitrite ions NO2- → nitrate ions NO3- → plant biomass/ N2 gas in atmosphere → plant biomass/ NH4+

what happens in the transfer of nitrogen between plant biomass and animal biomass

holozoic nutrition, plant protein hydrolysed to plant amino acids, absorption of amino acids by animals, amino acids go through a condensation reaction to form animal protein

what connects plants to ammonium ions in the nitrogen cycle

death

what happens in the transfer of nitrogen between animal biomass and ammonium ions

ammonification by decomposers, death, egesta or excreta

what is ammonification

decomposers convert nitrogen-containing molecules in dead organisms, faeces and urine into ammonium compounds

what is nitrification

where ammonium compounds in the soil are converted to nitrogen-containing molecules that can be used by plants by nitrifying/chemosynthetic bacteria

what are the stages of nitrification

NH4+ → nitrite ions NO^-2 → nitrate ions NO^-3

what bacteria converts ammonium ions into nitrite ions in nitrification

nitrosomonas

what does nitrosomonas do

converts ammonium ions into nitrite ions in nitrification

what converts nitrite ions to nitrate ions in nitrification

nitrobacter

what does nitrobacter do

converts nitrite ions to nitrate ions in nitrification

what is the name for the process of converting ammonium ions to nitrite and then nitrate ions

nitrification

what is denitrification

denitrifying bacteria convert nitrate ions back into nitrogen gas

in what form does nitrogen enter plants and why

nitrate ions as they are highly soluble

how are nitrate ions converted back into nitrogen gas in the atmosphere

by denitrifying bacteria in anaerobic conditions e.g. water-logged soil, use nitrate instead of oxygen as a source of energy for respiration

when does denitrification take place

in anaerobic conditions e.g. water-logged soil