topic 4 - Ecology Flashcards
Define Species.
Species:
A group of organisms that can interbreed and produce fertile, viable offspring
Define population.
Population:
Group of organisms of the same species, living in the same area at the same time
Define Community.
Community:
A group of different populations living together and interacting in a given area
Define Habitat.
Habitat:
The environment in which a species lives or the normal location of an organism
Define Ecosystem.
Ecosystem:
A community and also its environment (all biotic and abiotic factors)
True or False?
Living organisms can obtain chemical energy by one of two methods of nutrition (a few species can use both methods)
True
Living organisms can obtain chemical energy by one of two methods of nutrition (a few species can use both methods). One of these species is Autotrophs. What are autotrophs?
Autotrophs synthesise organic molecules from inorganic nutrients within the environment, using energy from either:
• Light (photoautotrophs)
• Oxidation reactions (chemoautotophs)
Living organisms can obtain chemical energy by one of two methods of nutrition (a few species can use both methods). Heterotrophs are one these species. What are heterotrophs?
Heterotrophs obtain their organic molecules from other organisms via a variety of feeding methods and food sources
• Consumers ingest other living organisms
• Detritivores ingest detritus (decomposing matter and faeces)
• Saprotrophs externally digest dead organisms (decomposers)
True or False?
Autotrophs are commonly referred to as producers, as they are responsible for the production of organic molecules
• Heterotrophs could not survive without autotrophs
True
Nutrients are materials required by organisms for survival
The supply of inorganic nutrients within the environment is finite and therefore must be constantly recycled. How do autotrophs do this?
Autotrophs convert inorganic nutrients into organic molecules (i.e. they are producers)
Nutrients are materials required by organisms for survival
The supply of inorganic nutrients within the environment is finite and therefore must be constantly recycled. How do heterotrophs do this?
Heterotrophs ingest organic molecules and may release inorganic byproducts (e.g. carbon dioxide)
Nutrients are materials required by organisms for survival
The supply of inorganic nutrients within the environment is finite and therefore must be constantly recycled. How do saprotrophs do this?
Saprotrophs break down the nutrients in dead organisms and return them to the soil (i.e. they are decomposers) by external digestion (use of enzymatic secretion)
Ecosystems have the potential to be sustainable over long periods of time, however this requires three conditions. What are these 3 conditions? Give an example for each condition.
Energy availability (e.g. light source)
• Nutrient availability (e.g. decomposers)
• Waste recycling (e.g. detoxifying bacteria)
What are mesocosms?
Mesocosms are enclosed environments with controlled conditions (e.g. terrariums)
• They can be used to study sustainability
The presence of species in a habitat may be dependent on the interactions between them (either positive or negative).
What does a positive association suggest? Give an example.
If species are always found in the same habitat, this suggests a positive association.
Example:
Predator / prey relationships
OR
Symbiotic interaction (mutualism, commensalism, parasitism
The presence of species in a habitat may be dependent on the interactions between them (either positive or negative). What does a negative association suggest? Give an example.
If species do not share the same habitat, this suggests there is a negative association (such as):
• Competition (niche partitioning or competitive exclusion)
What is Quadrat Sampling? How does it work?
The presence of a species in a given area can be determined via quadrat sampling (to assess sessile/non-motile species)
How does it work?
Rectangular frame placed in an area (+ repeat sampling) • Speciesnumberswithintheframearecounted/estimated
What is a chi-squared test conducted?
A chi-squared test can be applied to quadrat sampling data to determine if there is a statistically significant association between the distribution of two species
How do you conduct a chi-squared test?
Step 1: Identify Expected Frequencies
Expected frequency = (Row total × Column total) ÷ Grand total
a) hypothesis: Null Hypothesis (H0) – There is no association (i.e. distribution is random) Alternative Hypothesis (H1) – There is an association (positive or negative)
b) construct table
compares expected frequencies v.s. observed values (present, absent. total)
Step 2: Apply the Chi-Squared Formula
a) calculate: x^2 = sum of (O-E)^2/E
b) find df = (#of rows -1) multiplied by (#of columns -1)
Step 3: Determine Significance
a) significance is based on p-value p<0.05 = significant
b) state conclusion based on hypothesis
Define Ecology.
The study of the relationship between living organisms, or between living organisms and their environment
True or False?
Autotrophs obtain inorganic nutrients from the abiotic environment
TRUE
Autotrophs obtain inorganic nutrients from the abiotic environment
True or False?
Consumers are heterotrophs that feed on living organisms by ingestion. Heterotrophs obtain organic molecules from other organisms via different feeding mechanisms and different food sources.
TRUE
Define scavengers.
Opportunistic animal that feeds on dead or decaying matter rather than hurting live prey
Define Detritivores. Give an example.
Detritivores are heterotroph that obtains organic nutrients from non-living organic sources, such as detritus (dead, particulate organic matter) and humus (decaying leaf litter intermixed w/ soil) via internal digestion
The supply of inorganic nutrients is maintained by nutrient cycling. Describe this nutrient cycles of recycling chemical elements is in terms of autotrophs, heterotrophs and saprotrophs.
Chemical elements are constantly recycled after they are used:
Autotrophs obtain inorganic nutrients from the air, water and soil and convert them into organic compounds
Heterotrophs ingest these organic compounds and use them for growth and respiration, releasing inorganic byproducts
When organisms die, saprotrophs decompose the remains and free inorganic materials into the soil
The return of inorganic nutrients to the soil ensures the continual supply of raw materials for the autotrophs
What is an ecological niche?
An ecological niche describes the functional position and role of an organism within its environment
What are the components that an ecological niche is composed of?
The habitat in which the organism lives
The activity patterns of the organism (e.g. periods of time during which it is active)
The resources it obtains from the environment (e.g. food source, territorial boundaries, etc.)
The interactions that occur with other species in the region (e.g. competition / predator-prey relationships)
What is niche differentiation?
Niche differentiation describes the way by which competing species use the environment differently in order to exist
If two species with identical niches compete, two distinct outcomes are possible. Describe them.
Competitive exclusion: One species will use the resources more efficiently and drive the other species to local extinction
Resource partitioning: Two species will alter their use of the niche to avoid direct competition, allowing for co-existence
What is the energy source for almost all communities? How does some producers derive this energy?
Light is the initial energy source for almost all communities • Some producers derive energy from chemical processes
How is light energy converted into chemical energy (i.e. organic compounds)?
Light energy is converted into chemical energy (i.e. organic compounds) via the process of photosynthesis
True or False?
Energy Transfer
Heterotrophs obtain their chemical energy by feeding
• The energy stored in organic molecules is released via cellular respiration (in heterotrophs and autotrophs)
TRUE
What does an organism’s trophic level refer to? Identify the organisms for trophic levels 1-4?
An organism’s trophic level refers to the position it occupies within a feeding sequence
1 = producer 2 = primary consumer 3 = secondary consumer 4 = tertiary consumer
Define food chains.
Food Chains
Food chains show linear feeding patterns between the species in a community
• Arrows indicate the direction of energy flow
producer –> primary consumer –> secondary consumer –> tertiary consumer
Define Food webs
Food webs show interrelated feeding patterns
• Most species have multiple food sources and hence will
occupy multiple trophic levels
Define pyramids of Energy.
Pyramids of energy are representations of the amount of energy available at each trophic level
• Measured in energy units per area per time (kJ m2 year–1)
Pyramids of energy can never be inverted and their levels should differ by a factor of ~10
• Because energy transformations are ~10% efficient
True or False
Not all the stored energy is transferred upon feeding – most of the energy released via cell respiration is lost as heat.
Organisms can then convert heat into other energy forms.
FALSE
ENERGY LOSS
Not all the stored energy is transferred upon feeding – most of the energy released via cell respiration is lost as heat
• Organisms CANNOT convert heat into other energy forms
and hence the heat is lost from the ecosystem
TRUE OR FALSE?
Only ~10% of energy is transferred from one trophic level to the next (90% is lost as heat or is unconsumed)
• These energy losses restrict the length of food chains
and limit the biomass of higher trophic levels
TRUE
Only ~10% of energy is transferred from one trophic level to the next (90% is lost as heat or is unconsumed)
• These energy losses restrict the length of food chains
and limit the biomass of higher trophic levels
Energy losses between trophic levels restrict _______________
Fill in the blank.
Energy losses between trophic levels restrict the length of food chains and the biomass of higher trophic levels
Defin biomass.
Biomass is the total mass of a group of organisms – consisting of the carbon compounds contained in the cells and tissues
Construct a diagram of the carbon cycle
Look at bioninja
How is carbon exchanged? Describe one of these forms?
Atmospheric gases – mainly carbon dioxide (CO2), but also methane (CH4)
Oceanic carbonates – including bicarbonates dissolved in the water and calcium carbonate in corals and shells
As organic materials – including the carbohydrates, lipids and proteins found in all living things
As non-living remains – such as detritus and fossil fuels
How does the carbon cycle relate to autotrophs, heterotrophs and cell respiration.
Autotrophs convert atmospheric carbon dioxide into organic compounds via the process of photosynthesis
• Equation (balanced): 6CO2 + 6H2O → C6H12O6 + 6O2
Heterotrophs obtain organic compounds via feeding
The breakdown of organic compounds via cell respiration (to produce ATP) releases carbon dioxide as a by-product
• Equation (balanced): C6H12O6 + 6O2 → 6CO2 + 6H2O
In aerobic conditions, saprotrophic bacteria will _________________
In aerobic conditions, saprotrophic bacteria will break down organic material and return it to the soil (i.e. decomposition)
In anaerobic conditions, decomposition is prevented as ___________________
• Anaerobic respiration will produce ____________
In anaerobic conditions, decomposition is prevented as the saprotrophic bacteria cannot function effectively
• Anaerobic respiration will produce organic acids (⬇ ph)
What is Peat/ Coal?
- Organic matter that is not fully decomposed in anoxic or acidic soils will become peat
- When peat is compressed under layers of sediment, heat and pressure remove moisture to transform it into coal
Describe the relation of marine organisms and oil and natural gas.
When marine organisms are buried under sediment on the ocean floor, compaction and anaerobic conditions transform the organic matter into oil and natural gas
Describe a combustion reaction in relation to hydrocarbons.
Hydrocarbons undergo combustion in the presence of O2
• The reaction is exergonic and CO2 and H2O is produced
The energy produced by combustion reactions is typically used to power industrial processes
• The combustion of fossil fuels is responsible for a
significant increase in atmospheric CO2 concentrations
What are the sources of hydrocarbons?
Fossilised organic matter (i.e. coal, oil and gas)
Biomass (e.g. bioethanol and biofuels
In aquatic ecosystems, carbon dioxide may ________________
In aquatic ecosystems, carbon dioxide may remain dissolved in water or alternatively form hydrogen carbonate ions
True or false?
Animals may combine the carbonate ions with calcium to form hard shells (e.g. mollusca) and exoskeletons (e.g. coral)
Carbonate ions may also interact with rock and sediment to form limestone
TRUE
Methane (CH4) is produced from organic compounds by ___________
Methane (CH4) is produced from organic compounds by methanogenic archaeans
Methane (CH4) is produced from organic compounds by methanogenic archaeans. What does this methane production require?: Where can it commonly be found?
This requires anaerobic conditions (commonly found in wetlands, marine sediments or digestive tract of ruminants)
Methane diffuses into___________________________
• In the air, methane is _________________
Methane diffuses into the air or forms deposits underground
• In the air, methane is oxidised to form CO2 and H2O
True or False?
Animals such as reef-building corals and mollusca have hard parts that are composed of calcium carbonate and can become fossilised in limestone
What are carbon fluxes?
Carbon fluxes describe the rate of exchange of carbon between the various carbon sinks / reservoirs
What are the 4 main carbon sinks?
lithosphere (earth crust), hydrosphere (oceans), atmosphere (air), biosphere (organisms)
The rate at which carbon is exchanged between these reservoirs depends on the conversion processes involved. How does work in relation to photosynthesis, respiration, decomposition, gaseous dissolution, lithification, combustion?
Photosynthesis – removes carbon dioxide from the atmosphere and fixes it in producers as organic compounds
Respiration – releases carbon dioxide into the atmosphere when organic compounds are digested in living organisms
Decomposition – releases carbon products into the air or sediment when organic matter is recycled after death of an organism
Gaseous dissolution – the exchange of carbon gases between the ocean and atmosphere
Lithification – the compaction of carbon-containing sediments into fossils and rocks within the Earth’s crust (e.g. limestone)
Combustion – releases carbon gases when organic hydrocarbons (coal, oil and gas) are burned as a fuel source
True or False?
It is possible to directly measure the size of the carbon sinks or the fluxes between them – instead estimates are made
FALSE
It is not possible to directly measure the size of the carbon sinks or the fluxes between them – instead estimates are made
Describe the nitrogen cycle.
The majority of the Earth’s atmosphere is composed on nitrogen gas (N2 = ~79%) however it is chemically inert in this form
Atmospheric nitrogen must be chemically processed by nitrogen-fixing bacteria in order to be used by plants
Plants absorb nitrogen from the soil as nitrite ions, nitrate ions or ammonium, while animals consume these products from plants
When organisms die, nitrogen is in an organic form (proteins) and must be converted back into inorganic form (ammonification)
Nitrogen in the soil is converted back into inert nitrogen gas by denitrifying bacteria
What are biofuels?
Biofuels are liquid fuels that are produced from the structural components (biomass) and waste of plant and animal matter
- renewable
- may include industrial waste as reagents
How does ocean acidification happen?
The oceans are a major carbon sink (i.e. stores CO2 from the atmosphere)
Some of the CO2 remains dissolved, but most of it is chemically converted
CO2 is converted into carbonic acid, which dissociates to release H+ ions
How does ocean acidification impact marine life?This conversion impacts marine organisms (such as coral) in a number of ways:
• It increases ocean acidity, which can stress coral survival (⬆ H+ = ⬇ pH)
• It lowers carbonate levels, which is required for shells and exoskeletons
• These conditions can cause coral to expel mutualistic algae (coral bleaching)
What are greenhouse gases? What impact do they have?
Greenhouse gases include carbon dioxide, water vapor, methane & nitrogen oxides
• Their impact depends on their concentration and ability to absorb IR radiation
• Water vapor and carbon dioxide are the most significant greenhouse gases
What is the greenhouse effect?
The greenhouse effect is a natural process that increases average temperatures:
• Incoming radiation from the sun includes short-wave ultraviolet (UV) radiation
• This radiation may be emitted by the Earth as long-wave infrared (IR) radiation
• Greenhouse gases absorb and re-emit this infrared radiation as heat
Fill in the blank.
Carbon fluxes describe _________________
Give an example.
Carbon fluxes describe the amount of carbon transferred between various carbon pools (e.g. lithosphere → atmosphere)
Carbon dioxide concentrations are increasing within the atmosphere due to a number of human-induced activities. What are they?
- Industrial practices (i.e. combustion of fossil fuels)
- Deforestation (less CO2 transferred to the biosphere)
- Agriculture (land clearing and methane production)
There is a positive correlation between rising CO2 levels (since industrial revolution) and average global temperature. Why is this relationship shown?
As global temperatures and climate patterns are influenced by greenhouse gases, increasing CO2 concentrations may be causing global climate change (enhanced greenhouse effect)
Describe 3 main points made during the climate change debate.
Is current climate change natural? Claim: Historical data show temperature cycles Counter: Past changes were not as abrupt Ocean levels are rising, pH decreasing
Are greenhouse gases the cause? Claim: Changes could be caused by sunspots Counter: Climate changes don’t match sun activity CO2 levels are highest ever recorded
Are climate models reliable? Claim: Models may make varying predictions Counter: All the climate models are predicting a temperature increase by 2100 (~2–6oC)
