term 2 Flashcards
Classification
Classification is the process of sorting a variety of different things into manageable groups.
The study of biological classification is called taxonomy or systematics.
A universally accepted system of classification is important as it allows scientists to identify a species based on shared characteristics.
Artificial Classification
Artificial classification sorts organisms into groups based on similar identifiable characteristics.
Organisms are organised into groups based on a limited number of similar characteristics (e.g. the presence of wings or an exoskeleton).
Dichotomous Keys
Keys are used in biology to categorise and identify organisms.
A dichotomous key is a series of statements consisting of two choices that describe the characteristics of unidentified organisms.
Natural Classification
Natural classification organises species into groups organisms that share characteristics that have been inherited from a common ancestor (called homologous characteristics)
A natural classification system considers the degree of evolutionary relationship among organisms.
Hierarchical Classification
Organisms are grouped into hierarchical categories;
Domain, Kingdom, Phylum, Class, Order, Family, Genus and Species.
(do kids prefer candy over fried green spinach).
Kingdoms – Fungi
Fungi are eukaryotic heterotrophs.
Some species grow as single cells; but most are multicellular.
Fungal cell walls contain chitin but not cellulose.
Fungi do not carry out photosynthesis.
Kingdoms – Protista (Protists)
Protists are eukaryotes.
Most protists are unicellular.
The kingdom of protists consists of all eukaryotes that are not plants, animals or fungi - sometimes referred to as the ’leftovers’.
Both autotrophic and heterotrophic protists exist.
Phylum
Kingdoms are further subdivided into phyla (singular: phylum).
All members of a phylum have a common ancestor and similar anatomical features.
Class
Each phylum consists of one or more classes.
Organisms in a phylum are subdivided further into classes based on similar anatomical features.
Order
A class of organisms can be further sub-categorised into orders. Members of an order have more specific characteristics than members of a class.
Family
Orders are sub-categorised into families of closely related organisms.
Members of one family have very similar anatomical features and behavioural characteristics.
Genus
A genus (plural: genera) is a highly specific grouping of species that are very closely related. Two or more species that share unique anatomical structures or behavioural characteristics are considered to be closely related and are placed together in a genus.
Species
A species is the most specific ranking in the taxonomic hierarchy.
Members of one species can interbreed and produce fertile offspring.
Occasionally organisms of different closely-related species can reproduce; however they don’t produce fertile offspring. E.g. a Liger or a Mule.
DNA and the Organism
The DNA found within an organism’s cells makes up its genetic structure and forms structures called chromosomes.
Chromosomes contain genes that code for all of the characteristics of an organism.
Each organism has different genes that code for characteristics to help it survive in its environment.
Adaptations
An adaptation is a characteristic or feature of an organism that will assist the organism to survive in its particular environment.
Why Adapt?
Organisms compete for resources including food and mates.
Organisms that acquire a stable and adequate source of resources have a greater chance of survival and reproduction.
Individuals that are better adapted to their environment are more likely to succeed in obtaining these resources and are more likely to survive and reproduce.
Types of Adaptations
Behavioural Adaptations
Physiological/Functional Adaptations
Structural Adaptations
Animals Behavioural Adaptations
Learning Communication Migration to new habitats Hunting behaviours Huddling Courtship displays and reproductive strategies The formation of symbiotic relationships Altering times the organism is active (nocturnal).
Plants Behavioural Adaptations
The ability to grow without soil (Air plants) and obtain water and nutrients from the surface on which they grow.
Use of removable appendages (tumbleweeds) to relocate to areas that have more suitable conditions.
The ability to climb up other trees to obtain more sunlight for growth.
Animal Physiological Adaptations
The use of hormones and electrochemical signals to generate the desired response.
The synthesis of chemical compounds used to defend an organism from predators and attack/kill prey.
Snakes release venom to kill their prey, skunks and some beetles release foul-smelling substances when attacked by a predator.
Plant Physiological Adaptations
Opening stomata at night instead of during the day.
Photosynthetic cells contain enzymes that convert CO2 into a storage molecule in the vacuole overnight.
The molecule can then be broken down and the CO2 used when light is present.
Animal Structural Adaptations
Hair in ears and eyelashes – prevent debris getting into ears and eyes.
Fur or hair – to prevent heat loss
Wings – to allow for flight (usually)
Strong beaks – to provide the ability to break seeds, etc.
Presence of large ears – to increase surface area to make it easier for animals to cool down.
Streamlined shape – to reduce resistance from air or water when moving/swimming.
Plant Structural Adaptations
Thick bark – to store water and reduce water loss when water is scarce.
Thick, waxy cuticle on leaves and stomata on un– to prevent water loss through evapotranspiration.
Large, flat leaves – to increase surface area to absorb light.
Leaves or flowers forming cups, pitchers or traps to catch insects – provides them with nutrients they can’t obtain from their natural environment.
Vertically hanging leaves – reduces the amount of time the surface of leaves are in direct sunlight to reduce evapotranspiration.
Ecosystems
Ecosystems are defined by their biotic and abiotic components and the interactions between elements of these components.
An ecosystem is a community of interacting populations and their physical environment. These include:
Biotic Factors: the living components of the ecosystem
Abiotic Factors: the nonliving components of the ecosystem
Biotic Factors
Producers (e.g. plants)
Consumers (e.g. animals)
Decomposers (e.g. bacteria)
Competitors/Pathogens
Producers (e.g. plants)
Autotrophs that convert inorganic materials into organic materials using sunlight or chemical energy.
Consumers (e.g. animals)
Heterotrophs that obtain organic materials and energy through the consumption of other living things.
Decomposers (e.g. bacteria)
Heterotrophs that break down (decompose) dead or decaying organisms
Competitors/Pathogens
Organisms that compete for the same resources or infect an organism preventing their ability to reproduce and survive.
Abiotic Factors
Sunlight Water Atmospheric and Dissolved Gases Temperature Soil Fire
Zonation
Zonation is a spatial change in the distribution of species.
Species occupy a habitat within an ecosystem and are adapted to survive and reproduce in that ecosystem.
Species rarely leave their habitat unless the environmental conditions change.
Occurs more frequently in locations where environmental conditions vary greatly over short distances.
Zonation in Mountains
Air temperature decreases with altitude → fewer organisms survive near the apex.
Humidity decreases with altitude → less rain near the apex.
Soils near the base of the mountain are richer → facilitate more plant growth.
Zonation in Intertidal Zones
Water movement along the coast creates multiple zones.
Water presence varies depending on tides and swell → some areas dry out while others remain submerged.
Light intensity decreases as water depth increases → fewer plants are able to survive further into the ocean.
Stratification
Stratification is a term used to describe the composition and arrangement of the vertical layers (strata) of a community.
Vegetation can be classified into strata by their different layers.
Each different strata is a vertical section of the vegetation zone of the ecosystem.
Ecological Niche and Keystone Species
Each ecosystem is defined by many and various abiotic and biotic environmental components.
The populations of organisms that make up an ecosystem are ones that are able to tolerate or benefit from the effect of the ecosystems’ environmental components.
What is a Niche?
The way a population of organisms functions in an ecosystem is called its ecological niche.
Representing the niche of different species
One way to represent how much niche overlap exists between different species is to draw a niche overlap graph.
If the zone of overlap is small, there is relatively little competition between the species. This means the species will likely co-exist in the ecosystem.
If the zone of overlap is large, the species will compete for resources.
If Niches Overlap
Overlap occurs when two species compete for the same resource. This is referred to as interspecific competition.
When two species compete for the same resource, one species will outcompete the other and:
The niche of the more successful competitor will increase
The niche of the less successful competitor will decrease.
If two species occupy the same niche, one will outcompete the other resulting in one species disappearing from the ecosystem.
Fundamental vs. Realised Niche
The theoretical area a population can occupy and the physical area it does occupy can vary significantly.
The amount of an ecological niche that is occupied by one species is dependent on the competition from other species.
Very rarely is the fundamental niche of an organism the same as its realised niche.
The Fundamental Niche
The largest niche that the organisms could occupy in the absence of competition from other species.
A description of the role that species could play in a community in the absence of competition.
The Realised Niche
The actual niche that the organisms occupy in the presence of competition and other interactions with species.
A description of the role that species actually plays in the community.
Ecosystem Stability
Ecosystems will only persist if they can capture, transform and transfer energy and cycle essential nutrients and chemical elements effectively.
What is a Keystone?
The keystone is the most important stone of the arch even though all other stones are needed.
The presence of the keystone ensures the arch’s stability is maintained.
Keystone Species in Ecosystems
Each ecosystem has at least one keystone species that underpins ecosystem function.
Keystone species play essential roles in an ecosystem.
The other species are not able to survive without the keystone species.
A habitat is changed dramatically when a keystone species is removed.
Removing Keystone Species
Removing the keystone species affects the ability of the species above and below it on the food web to survive and reproduce.
Human Impacts on Ecosystems
Human Activities
Activities such as agriculture, forestry, fishing, urbanisation and manufacturing all have an effect on the biodiversity of ecosystems.
Human Impacts on Ecosystems
Key threats to the ecosystem and species diversity as a result of human activities include: Habitat fragmentation Climate change Introduced species/pathogens Agriculture (cropping and grazing)
Habitat Fragmentation
Habitat fragmentation occurs when natural forests are broken up into smaller, isolated patches due to habitat destruction.
Importance of Natural Habitats
Natural forests are rich in biodiversity and contribute to the preservation of species.
They provide essential habitats for many endangered flora and fauna.
Why maintain natural vegetation?
It is vital to maintain natural vegetation:
To provide a range of habitats to help maintain species diversity.
To provide vegetation with deep roots which maintain water table levels and help prevent salinity.
To help maintain and protect the soil from erosion.
To absorb carbon dioxide and produce oxygen.
To help maintain regional rainfall patterns.
To help reduce weed and feral animals.
Climate Change
Global warming is leading to climate change and changes in physical biological systems worldwide.
Australia has warmed by approximately 1°C since records began.
Higher carbon dioxide concentrations cause increasing temperatures, altered rainfall patterns, rising sea levels and acidification of oceans impacting on habitats, ecosystems and species.
Global Temperature and CO2
Greenhouse gases are those whose presence in the atmosphere causes an increase in the Earth’s temperature.
Ocean Temperatures and pH
Global warming and Climate Change impact oceans by:
- Rising sea levels
- Rising water temperatures
There is evidence that as oceans warm, organisms will relocate to cooler waters
- Oceans become more acidified
Occurs when excess CO2 dissolves into the water, lowering the pH and impacts upon shell-forming species and the navigation of fish
Introduced Species and Pathogens
An introduced species is any species that has been brought to an area in which it is not usually found either intentionally or accidentally.
Introduced pathogens are ‘disease-causing organisms or microbes’ that are not commonly found in the ecosystem.
Indicator Species
Indicator species are those that:
Identify changes in the abiotic or biotic components of their ecosystem.
Have behaviours and distributions that environmental scientists can use as evidence to show the effect changes are having on ecosystems and biodiversity.
Five impacts
Extinction Climate change Deforestation Acid rain Desertification Pollution And more.
Energy Transfers and Nutrient Cycles
All living organisms require nutrients and energy to survive.
Matter vs. Energy
Nutrients that are required for the organism to survive are also known as ‘matter.’ Examples include Carbon and Nitrogen.
Matter takes up space.
Energy is required for organisms to be able to move, synthesise important molecules, maintain a stable internal environment, fight disease and reproduce.
Energy moves matter
Energy Origins
The sun is the primary source of energy for most ecosystems.
Provides a source of radiant electromagnetic energy.
Transforming Energy
The producers within a community are the basis of life on Earth.
Producers trap the energy from external sources (e.g. the sun) and transform it into chemical energy during either photosynthesis or chemosynthesis to create organic molecules.
These newly created organic compounds that contain the newly made chemical energy within their bonds are stored within the organism for later use.
Transferring Energy
The chemical energy stored within the producers can then be transferred to other organisms within the ecosystem.
Consumers obtain matter and energy by consuming other organisms.
When one organism is consumed by another it passes on its matter and energy.
Food Chains
A food chain is a diagram showing the organisms that feed on each other.
The arrows show the transfer of energy and food materials from the organism being consumed to the consumer.
All food chains start with a primary producer.
Food Webs
Within a community there are numerous food chains.
Food Webs are formed from all of the connected food chains in a community.
One organism may be in many chains
Arrows indicate the direction of energy flow
Energy Flows
Energy does not cycle through ecosystems like matter does.
Energy flows continuously through the ecosystem, between organisms as food.
Energy for primary producers comes from the sun (or geothermal vents for some deep sea communities).
Ecological efficiency is a measure of the percentage of energy that is transferred from one trophic level to the next.
Most of the energy consumed by an organism doesn’t move onto the next trophic level – it’s not available to the next organism.
Primary consumers only obtain 10% of the available energy from producers.
Secondary and tertiary consumers transfer approx. 10-20% of the energy available to them onto the next trophic level.
The ‘loss’ of energy is due to:
The organism needs to build and repair body cells.
The energy being used for movement and processes such as generating heat to keep warm.
Heat being released from the organism into the environment.
Ecological Pyramids of Energy
‘Pyramids’ can be used to illustrate energy losses along a food chain at each trophic level.
Often it is useful to show the energy that is stored at each trophic level.
Energy is measured in joules (J)
The area of each rectangle represents the amount of energy present at each trophic level.
Biogeochemical Cycles
The main elements that make up tissues are carbon, oxygen, nitrogen, sulphur, phosphorous, potassium and calcium
These cycles involve interactions between the biotic and abiotic components of an ecosystem.
They utilise biological, geological and chemical processes and are thus termed biogeochemical cycles.
The Water Cycle
Water is one of the most precious resources on Earth and is an essential part of all living organisms.
Water is required for photosynthesis to occur.
Only 3% of water available to plants and animals is fresh (free of salt).
The water cycle describes the continuous movement of water between the different reservoirs and storage locations.
Processes of the Water Cycle
Evaporation: When heat causes water to change from a liquid to a gas.
Transpiration: When water evaporates through the leaves of plants (also called evapotranspiration).
Condensation: When water vapour cools to form a liquid again.
Precipitation: When water droplets are large enough to fall.
Rain, Hail, Snow, Sleet
Water molecules move between storage locations by a number of different processes:
Infiltration: When water infiltrates the ground and soils to collect underground in aquifers.
Run-off: When the ground is unable to absorb the water, it runs off down hill to create rivers, lakes and can run-off into the ocean.
Root Uptake: When plants absorb water from the soil through their roots.
The Carbon Cycle
Carbon is the key ingredient of all LIVING tissue (carbon-based life forms)
Biological processes such as photosynthesis, respiration and decomposition take up and release carbon.
Geochemical processes such as erosion and volcanic activity release carbon dioxide into the atmosphere and oceans.
Processes of The Carbon Cycle
Biological – photosynthesis, respiration and decomposition
Geochemical – erosion and volcanic activity
Mixed biogeochemical – burial and decomposition
Human activities – mining, cutting & burning forests, burning fossil fuels.
The Nitrogen Cycle
The element Nitrogen is vital for life – it is needed to make amino acids, proteins, chlorophyll, nucleic acids (DNA and RNA) and ATP in cells.
Molecular Nitrogen (N2) is abundant in the atmosphere, but is not in a form that can be used by most organisms.
Plants and animals can only obtain nitrogen in a fixed (water-soluble) form.
Molecular nitrogen is fixed by atmospheric events and bacteria that are found in soils.
Processes of the Nitrogen Cycle
Nitrogen Fixation
Nitrogen fixing bacteria are found in soils near roots.
They have enzymes that convert molecular nitrogen into ammonia (NH3) in soils.
Nitrification
Nitrifying bacteria convert toxic ammonia (NH3) into nitrates (NO3-) which is now ‘fixed’ nitrogen that is available to plants and animals.
Denitrification
Denitrifying bacteria convert nitrates back into molecular nitrogen
The Phosphorus Cycle
Phosphorus is an element essential in the production of nucleic acids (DNA and RNA), ATP and phospholipids (which are used to form cellular membranes).
Phosphorus is found in rocks, seawater and soils.
Phosphorous is released when the substances containing them are eroded by abiotic factors to form Phosphates
Some plants have a mutualistic relationship with mycorrhiza fungi that make phosphorus available to plants.
Plants absorb the phosphates and incorporate it into their tissues.
Animals consume plants and other animals to obtain phosphorus.
Human Interference - Water Cycle
Removing large quantities of water from rivers for irrigation (e.g. River Murray)
Releasing pollutants which enter waterways, either directly or indirectly
Deforestation where trees normally release water vapour into the atmosphere – decreases water available for precipitation
Increasing atmospheric temperatures increases the rate of evaporation.
Human Interference - Carbon Cycle
The burning of fossil fuels
Deforestation
These activities increase atmospheric carbon dioxide
Human Interference - Phosphorus Cycle
Run-off in fertilisers can cause overgrowth of some species and loss of biodiversity from the ecosystem.
Sewage, including household waste water, introduces high levels of phosphorus.
Use of fertilisers depletes stores of phosphate in the soils.
Human Interference - Nitrogen Cycle
Use of nitrogen-based fertilisers where excess run-off enters streams and waterways.
The burning of fossil fuels and use of fuel in combustion engines.
Agricultural practices, including the use of monocultures, involving nitrogen fixing crops.
Nitrogen fixation by human processes is increasing exponentially which can lead to uncontrolled plant growth
Ecological Succession:
Changing Ecosystems:
The location and composition of an ecosystem is influenced by its abiotic and biotic components and how they influence each other.
The abiotic and biotic components of an ecosystem change regularly.
These changes alter the make-up of the community and may alter the range over which is found.
