(SL) Unit 4: Ecology; Topic 4.1 Species, Communities, and Ecosystems Flashcards
Flashcard Main Resource: https://ib.bioninja.com.au/standard-level/topic-4-ecology/41-species-communities-and/
A species is…
a group of organisms that can potentially interbreed to produce fertile, viable offspring
Members of a single species are unable to…
produce fertile, viable offspring with members from a different species
When two different species do produce offspring by cross-breeding…
these hybrids are reproductively sterile (e.g. liger, mule)
A population is…
a group of organisms of the same species that are living in the same area at the same time
Organisms that live in different regions (i.e. different populations) are…
reproductively isolated and unlikely to interbreed, however are classified as the same species if interbreeding is functionally possible
A Community is…
A group of populations living together and interacting with each other within a given area
A habitat is..
The environment in which a species normally lives, or the location of a living organism
An ecosystem is…
A community and its abiotic environment (i.e. habitat)
What is an abiotic environment?
a non-living part of an ecosystem that shapes its environment
Ecology is…
The study of the relationship between living organisms, or between living organisms and their environment
What are the 2 methods of nutrition for species?
autotrophic or heterotrophic
What is an autotrophic mode of nutrition?
Autotrophic nutrition is the type of nutrition where organisms synthesize their own food.
Because autotrophs synthesise their own organic molecules they are commonly referred to as…
producers
Where do autotrophs synthesize its own organic molecules from?
simple inorganic substances (e.g. CO2, nitrates)
Energy for the synthesis process in autotrophs is derived from…
sunlight (photosynthesis) or via the oxidation of inorganic molecules (chemosynthesis)
What is a heterotrophic mode of nutrition?
Heterotrophic nutrition is the mode of nutrition where the organism is unable to prepare its food and hence, depends upon plants or other organisms for nutrition.
Heterotrophs obtain organic molecules from…
other organisms (either living / recently killed or their non-living remains and detritus)
Because heterotrophs cannot produce their own organic molecules and obtain them from other sources, they are called…
Consumers
What is a mixotrophic mode of nutrition?
Mixotrophy is the mode of nutrition whereby an organism has the ability to gain carbon and/or nutrients by using two functionally different processes: photosynthesis and the uptake from organic matter. (Autotrophs and Heterotrophs)
for example; Euglena gracilis possess chlorophyll for photosynthesis (autotrophic) but may also feed on detritus (heterotrophic)
Certain unicellular organisms may on occasion use both forms of nutrition, depending on…
resource availability
Autotrophs produce their own organic molecules using…
either light energy or energy derived from the oxidation of chemicals
Autotrophs obtain the simple inorganic substances required for the process of obtaining their own organic molecules from…
the abiotic environment
the nutrients collected from the abiotic environment for the process include…
carbon, nitrogen, hydrogen, oxygen and phosphorus
where are those nutrients are obtained from?
the air, water and soil
Heterotrophs also may obtain some simple inorganic substances from the environment but principally obtain their carbon and nitrogen from the organic molecules produced by…
autotrophs
Heterotrophs obtain organic molecules from…
other organisms via one of three methods
What are the 3 methods of Heterotrophs obtaining organic molecules?
Consumers
Detritivores
Saprotrophs
How do consumers obtain organic molecules?
they ingest organic molecules from living or recently killed organisms
How do detritivores obtain organic molecules?
they ingest organic molecules found in the non-living remnants of organisms (e.g. detritus, humus)
How do saprotrophs obtain organic molecules?
release digestive enzymes and then absorb the external products of digestion (decomposers)
What are consumers?
they are heterotrophs that feed on living organisms by ingestion
What are examples of consumers?
Herbivores , Carnivores and Omnivores
What are herbivores?
Herbivores are consumers that feed principally on plant matter (e.g. cows, sheep, rabbits)
What are carnivores?
Carnivores are consumers that feed principally on animal matter (e.g. crocodiles, wolves, tigers)
What are omnivores?
Omnivores are consumers that have a principle diet composed of both plant and animal matter (e.g. pandas, humans)
What are scavengers?
Scavengers are a type of consumer that principally feed on dead and decaying carcasses rather than hunting live prey
What are some examples of scavengers?
Hyenas, vultures, and carrion birds (such as crows))
What are detritivores?
Detritivores are a type of heterotroph that obtains nutrients from non-living organic sources, such as detritus and humus
What is detritus?
Detritus is dead, particulate organic matter – such as decaying organic material and fecal matter
What is humus?
Humus is the term given specifically to the decaying leaf litter intermixed within the topsoil
What are some examples of detritivores?
Dung beetles, earthworms, woodlice, snails and crabs
What are saprotrophs?
Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion
Saprotrophs live on (or in)…
non-living organic matter, they secrete digestive enzymes into it and absorb the products of digestion
Unlike other types of heterotrophs, saprotrophs do not ingest food but use … to facilitate external digestion
enzymatic secretion
What is enzymatic secretion?
it is digestive enzymes secreted by different exocrine glands
Because saprotrophs facilitate the breakdown of dead organic material, they are commonly referred to as…
decomposers
What are examples of saprotrophs?
bacteria and fungi
The supply of inorganic nutrients is maintained by…
nutrient cycling
Nutrients refer to the material required by an organism, and include elements such as…
carbon, nitrogen and phosphorus
The supply of inorganic nutrients on Earth is finit, this means that?
new elements cannot simply be created and so are in limited supply, hence 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 what for autotrophs?
the continual supply of raw materials
Ecosystems have the potential to be what over long periods of time?
sustainable
Ecosystems describe the interaction between…
biotic components (i.e. communities) and abiotic components (i.e. habitat)
What are the three main components required for sustainability in an ecosystem?
Energy availability, Nutrient availability, and Recycling of wastes
How is energy availability a main component for sustainability in an ecosystem?
light from the sun provides the initial energy source for almost all communities
How is nutrient availability a main component for sustainability in an ecosystem?
saprotrophic decomposers ensure the constant recycling of inorganic nutrients within an environment
How is recycling of waste a main component of sustainability in an ecosystem?
certain bacteria can detoxify harmful waste byproducts (e.g. denitrifying bacteria such as Nitrosomonas)
What is a mesocosm?
Mesocosms are enclosed environments that allow a small part of a natural environment to be observed under controlled conditions
What is a terrarium?
A terrarium is a small transparent container (e.g. glass or plastic) in which selected plants (or animals) are kept and observed
What are the 3 main steps to making a Self-Sustaining Terrarium?
Building a verdant foundation, Selecting the right plants
, and Maintaining appropriate conditions
How do you build a verdant foundation?
Add a bottom layer of pebbles, gravel or sand – this layer exists for drainage (smaller vessels require thinner rock layers)
Add a second thin layer of activated charcoal – this will prevent mold and help to aerate the soil
Spread a thin cover of sphagnum moss (or use an organic coffee filter) to create a barrier between the lower layers and soil
The final layer is the pre-moistened growing medium (i.e. potting mix)
How do you select the right plants?
Ideally, choose plants that are both slow growing and thrive in a bit of humidity (e.g. most ferns, club moss, etc.)
Inspect the plant thoroughly for any signs of disease or insects before introducing to the terrarium
How do you maintain appropriate conditions?
Ensure the terrarium is placed in a location that provides a continuous source of light
Locate the terrarium in a place that does not experience fluctuating temperature conditions (i.e. avoid direct sunlight)
Do not initially over-water the plants – once the right humidity is established, a terrarium can go months without watering
Occasional pruning may be required – however, as level of soil nutrients decrease, plant growth should slow down
What is the chi-square test?
A chi-square test is a statistical test used to compare observed results with expected results.
What is the purpose of the chi-squared test?
The purpose of this test is to determine if a difference between observed data and expected data is due to chance, or if it is due to a relationship between the variables you are studying.
The presence of two species within a given environment will be dependent upon…
potential interactions between them
If two species are typically found within the same habitat, they show a…
positive association
Species that show a positive association include those that exhibit…
predator-prey or symbiotic relationships
If two species tend not to occur within the same habitat, they show a…
negative association
Species will typically show a negative association if there is…
competition for the same resources
What is competitive exclusion?
it is where one species may utilise the resources more efficiently, precluding survival of the other species
What is resource partitioning?
it is where both species may alter their use of the environment to avoid direct competition
If two species do not interact…
there will be no association between them and their distribution will be independent of one another
The presence of two species within a given environment can be determined using…
quadrat sampling
How do you establish population densities?
By using a quadrat is which is a rectangular frame of known dimensions
Using a quadrant how is the population density established?
- Quadrats are placed inside a defined area in either a random arrangement or according to a design (e.g. belted transect)
- The number of individuals of a given species is either counted or estimated via percentage coverage
-The sampling process is repeated many times in order to gain a representative data set
Is quadrat sampling is an effective method for counting motile organisms?
No
What is quadrant sampling then used for?
it is used for counting plants and sessile animals
In each quadrat what is identified?
the presence or absence of each species
A chi-squared test can be applied to data generated from quadrat sampling to determine…
if there is a statistically significant association between the distribution of two species
What are the 5 steps to complete a chi-squared?
1) Identify hypotheses (null versus alternative)
2) Construct a table of frequencies (observed versus expected)
3) Apply the chi-squared formula
4) Determine the degree of freedom (df)
5) Identify the p value (should be <0.05)
