4.1 Flashcards
what is ecology?
the study of relationships between living organisms & between organisms & their environment
what is the definition of species?
a group of organisms that can interbreed to produce fertile offspring
- if species are not closely related, it is often impossible for them to breed
- f 2 species do not live in the same ecosystem → reproductively isolated
What is the definition for population?
a group of organisms of the same species that are living in the same area at the same time
what is the definition of community?
a group of populations that are living & interacting w eachother in the same area
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what are all species dependent on?
all species are dependent on interactions w members of other species for survival
what are the type of heterotrophs?
- consumers
- detritivore
- saprotrophs
what is the method of nutrition for heterotrophs?
heterotrophs obtain their organic molecules from other organisms
how do detritivore obtain nutrients?
obtains nutrients by consuming non-living organic organic sources e.g→ humus & detritus
- internally digest
examples of detritivores
dung beetles, earthworms, woodlice & crabs
how do saprotrophs obtain nutrients?
- live on or in non-living organic matter
- not consumers because they do not ingest food→ unlike most heterotrophs
- digestion is external as enzymes are secreted
- referred to as decomposers bc they facilitate the breakdown of organic material
- e.g of saprotrophs → bacteria & fungi
- externally digest → digest/break down debris around them
What are consumers?
- heterotrophs that ingest other organisms to obtain their organic molecules
What are the classes of consumers?
- herbivores
- omnivores
- carnivores
- scavengers
what can eat herbivores?
primary consumers
what does positive association mean?
species found in the same habitat
what does negative association mean?
species occur separately in differing habitats
what does no association mean
species occur as frequently apart together
Habitat:
The environment in which a species normally lives, or the location of a living organism
reproductive isolation
Organisms that live in different regions (i.e. different populations) are reproductively isolated & unlikely to interbreed, however are classified as the same species if interbreeding is functionally possible
- reproductive isolation occurs when barriers prevent two populations from interbreeding
- > keeping their gene pools separate
gene pool
a collection of different genes, both expressed and not expressed, present in a population of a particular species
-includes alleles
how do different gene pools within a species prevent the different species from interbreeding?
Different species may have different genes that are active in development; therefore, it may not be possible to develop a viable offspring with two different sets of directions.
what is interbreeding
breeding with another of a different race or species.
what does a gene pool consist of?
all the genes and their different alleles, present in an interbreeding population
how to organisms obtain chemical energy?
- Organisms that make their own carbon compounds from carbon dioxide and other simple substances – autotrophic
- Organisms that obtain their carbon compounds from other organisms
what is an ecosystem?
A community and its abiotic environment
Mixotrophs
Certain unicellular organisms may on occasion use both forms of nutrition, depending on resource availability
Euglena gracilis possess chlorophyll for photosynthesis (autotrophic) but may also feed on detritus (heterotrophic)
Autotrophs obtain inorganic nutrients from the abiotic environment
Most autotrophs derive the energy for this process from sunlight (via photosynthesis)
Some may derive the needed energy from the oxidation of inorganic chemicals (chemosynthesis)
Autotrophs obtain the simple inorganic substances required for this process from the abiotic environment
These nutrients – including carbon, nitrogen, hydrogen, oxygen and phosphorus – are obtained from the air, water and soil
herbivores
feed principally on plant matter (e.g. cows, sheep, rabbits)
carnivores
consumers that feed principally on animal matter (e.g. crocodiles, wolves, tigers)
omnivores
consumers that have a principle diet composed of both plant and animal matter (e.g. pandas, humans)
scavengers
type of consumer that principally feed on dead and decaying carcasses rather than hunting live prey
Examples of scavengers include hyenas, vultures and carrion birds (such as crows)
What is Detritus?
dead, particulate organic matter – such as decaying organic material and fecal matter
What is humus?
term given specifically to the decaying leaf litter intermixed within the topsoil
What are saprotrophs commonly referred to as?
decomposers
- facilitate the breakdown of dead organic materia
examples of saprotrophs
bacteria and fungi
what does nutrient refer to?
the material required by an organism, and include elements such as carbon, nitrogen and phosphorus
what do species that can interbreed produce?
a fertile offspring
do communities involve microbes and plants?
yes
What can quadrant sampling be used for?
- estimation of population density/size
- measuring the distribution of a species
How are quadrants used
- they are placed repeatedly in a sample area to provide a reliable estimate
- they can be placed systematically to measure changing distribution
- they can be placed randomly to estimate population density
- both random & sampling methods are used to avoid bias in the selection sample
what is the limitation of quadrant sampling?
- large & mobile animals cannot be effectively sampled
what is quadrant sampling most suited for?
- plants
- small/slow moving animals
null hypothesis
there is no significant difference between the distribution of the 2 species (i.e the distribution is random)
alternate hypothesis
there is a significant difference between the distribution species (i.e species are associated)
what are nutrients?
elements required by an organism for growth & metabolism (e.g carbon, nitrogen & phosphorus)
what is the purpose of nutrient cycling?
- supply of nutrients is limited & therefore ecosystems constantly recycle the nutrients between organisms
Why are ecosystems relatively sustainable?
most flows of energy & nutrients in an ecosystem are between members of the biotic community
relatively few flows of energy & nutrients enter of leave from surrounding ecosystems
- therefore ecosystems to a large extent are self-contained & hence self-sustaining
to remain sustainable, an ecosystem requires:
- continuous energy availability, e.g sunlight
- nutrient cycling, e.g saprotrophs are essential for continuous provision of nutrients to producers
- recycling waste, e.g certain wastes are toxic, decomposing bacteria breaks down toxic waste
What are mesocosms?
biological systems that contains the abiotic & biotic features of an ecosystem, but are restricted in size and/or under controlled conditions
- they are a type of experimental setup
The restriction on mesocosms make them useful for what?
- restriction make them useful for scientific investigations where the uncontrolled nature of a natural ecosystem makes it difficult to collect meaningful data
hybrid
the offspring of 2 similar but different species
if chi squared value is larger than the degrees of freedom…….
the results are statistically significant
- the observed results are different from what is expected
- in terms of species, they aren’t found together if there is a significant difference between the results
What is the ecological role of saprotrophic bacteria?
To digest dead organic matter and release nutrients from it.
what is an ecosystem
a community which consists of all the biotic factors such as plants and animals in an area, functioning together with all of the physical or abiotic factors of the environment
Humus
decaying leaf matter mixed w soil
What do herbivores feed on?
producers
Nutrient cycling
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.
Main requirements for sustainability of an ecosystem
- energy availability
- nutrient availability
- recycling of wastes
species that show a positive association
include those that exhibit predator-prey or symbiotic relationships
How can the presence of 2 species in an environment be determined?
quadrant sampling
what are 2 ways quadrant sampling can be used?
- population density
2. distribution of a species
Levels of an ecosystem (smallest to largest)
species, population, community, ecosystem, biome, biosphere
mutualism
a type of relationship where both organisms benefit
commensalism
a type of symbiotic relationship where one organism benefits & the other is unaffected
parasitism
a type of symbiotic relationship where one organism is benefitted and the other is harmed
photoautotrophic
All green plants, and some bacteria, are photoautotrophic – they use sunlight as a source of energy
trophic level 1
producer
trophic level 2
primary consumer
trophic level 3
secondary consumer
trophic level 4
tertiary consumer
what does a food chain show
the linear feeding relationships between species in a community
what do the arrows in a food chain represent?
the transfer of energy and matter as one organism is eaten by another (arrows point in the direction of energy flow)
how is the energy stored in organic molecules released
can be released by cell respiration to produce ATP
Not all energy stored in organic molecules is transferred via heterotrophic feeding?
- Being excreted as part of the organism’s faeces
- Remaining unconsumed as the uneaten portions of the food
The chemical energy produced by an organism can be converted into a number of forms, including:
Kinetic energy (e.g. during muscular contractions) Electrical energy (e.g. during the transmission of nerve impulses) Light energy (e.g. producing bioluminescence)
All of these reactions are exothermic and release thermal energy (heat) as a by-product
Living organisms cannot turn this heat into other forms of usable energy
This heat energy is released from the organism and is lost from the ecosystem (unlike nutrients, which are recycled)
Hence ecosystems require a continuous influx of energy from an external source (such as the sun)
Biomass
the total mass of a group of organisms – consisting of the carbon compounds contained in the cells and tissues
what is a pyramid of energy
a graphical representation of the amount of energy at each trophic level of a food chain (expressed in units of energy per era of time)
what is the carbon cycle?
a biogeochemical cycle whereby carbon is exchanged between the different spheres of the Earth
what are the 4 spheres?
atmosphere (air), lithosphere (ground), hydrosphere (water / oceans) and biosphere (living things)
