4.1 Species, communities and ecosystems Flashcards
What is a species?
A group of organisms that can potentially interbreed to produce fertile viable offspring
What happens when two different species breed?
Normally unable to produce offspring. If they are produced they are usually infertile
What is a population?
A group of organisms of the same species that are living in the same area at the same time
What happens to organisms from the same species that live in different regions?
They are reproductively isolated and unlikely to interbreed but it is still functionally possible
What is a community?
A group of populations living together and interacting with each other within a given area
What is a habitat?
The environment where a species normally lives
or the location of a living organism
What is an ecosystem?
A community and its abiotic environment
What is ecology?
The study of the relationship between living organisms or between living organisms and their environment
What are the two ways living organisms can obtain chemical energy?
Autotrophs and heterotrophs
What is an autotroph?
Synthesises its own organic molecule from simple inorganic substances
How is energy for autotrophs derived?
Via sunlight or the oxidation of inorganic molecules
Why are autotrophs often referred to as producers?
Because they synthesise their own organic molecules
What are heterotrophs?
Obtains organic molecules from other organisms dead and alive
Why are heterotrophs called cinsumers?
As they cannot produce their own organic molecules and thus obtain it from other sources
What is it called when a unicellular organism can use both form of nutritions of heterotrophs and autotrophs?
Mixotrophs
How can species be classified in accordance to?
Their mode of nutrition
What are the three methods of heterotrophs?
Consumers
Detritivores
Saprotrophs
What do detritivores do?
Ingest nonliving organic molecules
What do saprotrophs do?
Release digestive enzymes and absorb the external products of digestion
What are the two ways autotrophs derive energy?
Photosynthesis and chemosynthesis
What is chemosynthesis?
Energy derived from the oxidation of inorganic chemicals
Where do autotrophs obtain their inorganic substances from?
The abiotic environment
Where are the nutrients autotrophs needed from?
Air, water and soil
What are herbivores?
Consumers that feed principally on plant matter
What are carnivores?
Consumers that feed principally on animal matter
What are omnivores?
Consumers that feed on both plant and animal matter
What are scavengers?
Type of consumer that principally feed on dead and decaying carcasses rather than hunting live prey
What is detritus?
Dead, particulate organic matter
What is humus?
The decaying leaf litter intermixed within the topsoil
Where do saprotrophs live?
In or on non living organic matter
Do saprotrophs ingest food?
No they do external digestion
What are nutrients?
Material required by an organism
What word is used to describe the supply of inorganic nutrients on earth?
Finite
Why are inorganic nutrients finite?
As new elements cannot simply be created and are in limited supply
What is the chain of nutrient cycling?
Autotrophs to Heterotrophs to Saprotrophs back to autotrophs
What does autotrophs convert inorganic nutrients into?
Organic compounds
What do heterotrophs use the organic compounds for?
Growth and respiration
What happens as heterotrophs use organic compounds?
Inorganic byproducts are released
What happens when an organism dies?
Saprotrophs decompose the remains and free inorganic materials into the soil
What does the return of inorganic nutrients to the soil ensure?
The continual supply of raw materials for the autotrophs
What do ecosystems describe?
The interaction between biotic and abiotic components
What are the three main components required for sustainability in an ecosystem?
Energy availability
Nutrient availability
Recycling of wastes
What is energy availability?
Light from the sun provides the initial energy source for almost all communities
What is nutrient availability?
Saprotrophic decomposers ensure the constant recycling of inorganic nutrients within an environment
What is the recycling of wastes?
Certain bacteria can detoxify harmful waste byproducts
What are mesocosms?
Enclosed environments that allow a small part of a natural environment to be observed under controlled conditions
What is a terrarium?
A small transparent container where plants or animals are kept and observed
What are the three main steps to create a self sustaining terrarium?
Building a verdant foundation
Selecting the right plants
Maintaining appropriate conditions
What will the presence of two species within a given environment be dependent on?
Potential interactions between them
If two species are typically found within the same habitat what will they show?
A positive association
If two species tend not to occur within the same habitat what will they show?
A negative association
When will species typically show negative association?
If there is competition for the same resources
What is competitive exclusion?
When one species utilises the resources more efficiently precluding survival of the other species
What is resource partitioning?
When both species may alter their use of the environment to avoid direct competition
What happens if two species do not interact?
There will be no association and their distribution is independent of each other
What is a way that the presence of two species in a given environment can be determined?
Using quadrat sampling
What is a quadrat?
A rectangular frame of known dimensions that is used to establish population densities
What are the two ways quadrats can be distrubuted?
Randomly or in a pattern
What are the two ways species can be counted?
Counted or estimated via percentage cover
What is quadrat sampling not an effective method for?
Motile organisms
What is a chi squared test?
A test to test the data to determine if there is a statistically significant association between the distribution of two species?
What are the five steps for completing a chi squared test?
- identify hypotheses
- construct a table of observed vs expected frequencies
3/ apply the chi square formuls - determine the degree of freedom
- identify the p value
What is a null hypothesis?
No significant difference
What is an alternative hypothesis?
There is a significant differences
How do you calculate expected frequencies?
(row total x column total) / grand total
What is the chi squared formula?
x2= sum of (O-E)2 / E
How do you calculate degrees of freedom?
df = (m-1)(n-1)
m = rows
n = columns
When is a value considered significant?
If there is less than a 5% probability
