Topic 4: Ecology Flashcards
Differentiate between abiotic and biotic factors
Abiotic are the non-living chemical and physical factors in an environment such as temperature, pH, humidity, wind, etc. Biotic factors are the living components of an environment which affect an ecosystem such as diseases, predation, competition, etc.
Define species
A group of organisms that can potentially interbreed to produce fertile viable offspring.
Define population
A group of organisms of the same species that are living in the same area at the same time
Define community
A group of populations living together and interacting with each other within a given area
Define habitat
The environment in which a species normally lives, or the location of a living organism.
Define ecosystem
A community and its abiotic environment
Define nutrient
A nutrient is a substance (found in food) used by an organism to survive, grow and reproduce. There are 6 major nutrients: carbohydrates, fats/lipids, proteins, vitamins, minerals, and water.
Distinguish between autotroph and heterotroph
Autotrophs synthesise their own organic molecules from simple inorganic substances/make their own food with energy derived from sunlight or oxidation of molecules. Heterotrophs obtain their organic molecules from other organisms.
Differentiate between the types of heterotrophs (consumer, detritivore, decomposer), with an example each
Consumer: ingest organic molecules from living or recently killed organisms such as mammals (e.g. wolves, bears, humans, etc.)
Detritivore: ingest organic molecules found in the non-living remnants of organisms (e.g. dung beetles, millipedes)
Decomposer: release digestive enzymes and then absorb the external products of digestion (e.g. saprotrophs)
Compare the fate of energy and nutrients within an ecosystem
Energy flows through an ecosystem and is lost – requires resupply from a constant energy source (e.g. sun)
Nutrients are finite and are recycled within a closed ecosystem
Outline the role of decomposers in maintaining nutrient supply
Decomposers release enzymes to externally break down organic material
This allows for inorganic compounds to be replenished within the environment (e.g. returned to the soil)
Define mesocosm
A mesocosm is an enclosed environment that allows a small part of the natural environment to be viewed under controlled conditions
Identify two methods of population sampling
Quadrats and transects
What is the formula for expected frequencies?
(Row total x Column total)/Grand total
What is the chi-square formula?
The sum of (O-E)^2/E
Identify a null hypothesis
There is no significant difference in the distribution of species (species are not associated)
Identify an alternative hypothesis
The is a significant difference in the distribution of species (species are associated)
If x^2 > 0.05, do we reject or accept null hypothesis
There is an insignificant difference meaning we accept null hypothesis
If x^2 < 0.05, do we reject or accept null hypothesis
There is a significant difference meaning we reject null hypothesis
Define trophic level
The position an organism occupies within a feeding sequences. Producers always occupy the first trophic level.
Differentiate between food chain and food web
A food chain only shows one or a linear feeding sequence while a food web is more complicated showing multiple food chains.
Distinguish between herbivores, carnivores, and omnivores
Herbivore: Feeds exclusively on plant matter
Carnivore: Feeds exclusively on animal matter
Omnivore: Feeds on both plant and animal matter
List three ways which energy may be lost from one trophic level to the next
As heat, converted into other form of energy, stored chemical energy remains unconsumed
Describe the flow of energy in ecosystems
Light energy (from the sun) is the initial energy source for almost all communities. It is converted into chemical energy (organic molecules) by producers / autotrophs via photosynthesis. The organic molecules are converted into a usable energy form (ATP) via cell respiration. Heterotrophs (consumers) ingest these organic compounds in order to undergo cell respiration. Energy transformations are only ~10% efficient, the majority of the energy is lost as heat
Identify the 6 processes involved in the carbon cycle
Photosynthesis, respiration, combustion, decomposition, feeding, and calcium carbonate
Write the balanced chemical equation for photosynthesis
6CO2 + 6H2O –> C6H12O6 + 6O2
Write the balanced chemical equation for cell respiration
C6H12O6 + 6O2 –> 6CO2 + 6H2O + ATP
Outline how carbon is stored in aquatic ecosystems
Some carbon dioxide in water stays as dissolved gas, however most reacts to form hydrogen carbonate ions. When the ions come to contact with rocks/sediments, they commonly form calcium carbonate (limestone). In animals, the calcium carbonate can be used to form hard exoskeletons (e.g. corals and shells).
Describe the production of methane by methanogens and its oxidation in the atmosphere
Methanogens produce methane from organic matter as a by-product of anaerobic respiration. The methane can either diffuse into the atmosphere or accumulate within the ground. Methane in the atmosphere is oxidised to carbon dioxide and water after ~12 years.
Outline the formation of peat/coal
In anaerobic conditions such as waterlogged soils, saprotrophs can only partially decompose organic matter. The remaining carbon-rich material stays within the soil and forms peat. When compressed under sediment, the high pressure and heat force out moisture and turn peat into coal.
Outline the formation of oil/natural gas
Oil and natural gas form as a result of the decay of marine organisms on the ocean floor. Sediments are deposited on top of the organic matter, creating anoxic conditions that prevent decomposition. The compacted and heated organic matter forms oil and gas, which accumulates within porous rocks.
Identify three human activities that can trigger carbon fluxes within the atmosphere
Combustion of fossil fuels, deforestation, and agricultural practices
Identify the most common greenhouse gas within the Earth’s atmosphere
Water vapour
List four other greenhouse gases
Carbon dioxide, methane, nitrogen oxides, fluorinated gases (e.g. CFCs)
Identify the two main factors that determine the impact of a greenhouse gas
Ability to absorb long-wave radiation and concentration within the atmosphere
Explain the relationship between greenhouse gases and the greenhouse effect
The greenhouse effect functions to trap heat within the atmosphere and prevent rapid temperature changes. Incoming radiation (from the sun) is shorter wave radiation (e.g. ultraviolet radiation and visible spectrum). The Earth’s surface absorbs this radiation and re-emits it at a longer wavelength (i.e. infrared radiation / heat). Greenhouse gases absorb and re-radiate the longer wave radiation and hence retain heat in the atmosphere. The higher the concentration of greenhouse gases in the atmosphere, the more heat is retained, hence global warming if there are too much greenhouse gases in the atmosphere.
List three climate conditions that are influenced by greenhouse hases
Global temperatures (increasing), weather conditions (more frequent extreme conditions), ocean currents (changes can cause longer El Nino events).
