4.1 species, communities, and ecosystems Flashcards
define species
able to interbreed and produce fertile offspring
define population
same species that live in a particular area at the same time
define community
group of populations living and interacting in a particular area
define ecosystem
community + its abiotic envrionement (non living factors)
define biotic factors and abiotic factors
biotic: living creatures
abiotic: non living factors eg pH, salinity
organisms of the same species will be classified into the same ____
taxa
all members of a species share a common g____ p_____ and number of c_________ in their h_______ cells
gene pool
chromosomes
haploid
example for animals that can potentially interbreed to produce FERTILE offspring
lion vs tiger
- both 38 chromosomes (2n)
- offspring: liger
why are hybrid species often infertile
difference in chromosome numbers / odd number of chromosomes = cannot divide into 2 during meiosis
what are autotrophs
organisms that make organic molecules using abiotic environment (eg phototrophs/chemotrophs)
plants
what are heterotrophs
organisms obtain organic molecules from other organisms (cant prod their own food)
consumers
what are mixotrophs
organisms that use both autotrophic and heterotrophic modes of nutrition
eg. euglena gracilis – chlorophyll for psis + feeds on detritus
autotrophic or heterotrophic?
bacteria
protoctista
fungi
plantae
animalia
either
either
heterotrophic
mostly autotrophic
heterotrophic
what is ingestion
taking in of a substance into the body (consumers)
what are consumers
organisms that gain nutrients by feeding on other organisms thru ingestion / absorption
primary vs secondary vs tertiary consumers
pri: feed only on autotrophs aka herbivores
sec: feeds on pri consumers
ter: feeds on secondary consumers, not always exclusively
what are detritivores
heterotrophs BUT they obtain their organic nutrients from detritus (Waste/organic debris)
via internal digestion
importance of detrivores
improtant for recycling nutrients and returning them to the soil for autotrophs
what are saphotrophs
heterotrophs that obtain organic nutrients from DEAD ORGANISMS
- via external digestion
- secreting digestive enzymes into environment = breaks down org debris
eg fungi and bacteria
phototroph vs chemoautotroph
energy from sun vs energy from oxidation of chemicals
INGESTS organic matter which is
1. living or recently killed
2. non-living
- consumers
- detritivores
detrivores vs saprotrophs
INGESTS non living org matter
vs
SECRETS digestive enzymes, ABSORBING the products
whats symbiosis
‘living together’ – outcomes of interactions between populations
what is mutualism
BOTH organisms benefit
how is the relationship between spider crabs and algae mutualistic
algae live on crab backs = camoflague from predators
what is commensalism
one organism BENEFITS while the other in UNAFFECTED
what is parasitism
one organism BENEFITS and the other is HARMED
example of parasitism (mosquito and human)
mosquito depends on human blood for nutrition
causes itchy bites, spread of diseases like malaria
what is predator prey interaction
one organism hunts and feeds on another
what is nutrient cycling
the movement of organic molecules and minterals thru the food chain and back into the soil – can be taken up by plants
principle of nutrient cycles: energy cannot be _______
energy cannot be recycled! (one way flow)
whats part of the abiotic environment
rainfall, soil/water pH, temperature, humidity
what elements do organisms require
carbon sources
phosphorus and nitrogen – nucleic acids
sulfur – proteins
selenium – functioning of some enzymes
magnesium – bone formation
what is a mesocosm
experimental tool allowing control of the conditions in a small part of the natural environment
- can act as a model of a larger ecosystem
think a terrarium
what are mesocosms used for
evaluate how organisms/communities might react to environmental change (thru cangeing environemntal factors like temp)
advantages of a mesocosm 7
- treatments easily replicated
- effect of several factors can be tested
- food webs can be established
- direct and indirect effects can be studied
- contaimination influence can be evaluated
- constants can be controlled = see effect of one factor at a time
- sustainability of ecosystem can be tested
what does an aquatic mesocosm need
water circulation
what does a terrestrial mesocosm need
sufficient plant material to produce oxygen to support all life forms in the system
(use oxygen and co2 sensors)
when presented with. a quadrat, count the organism when…
more than half of it is inside the quadrat
what a quadrat used for
to establish population densities
what organisms is quadrat sampling used for!
plants and immobile organisms
(not effective for motile organisms)
whatis the chi squared test
a form of statistical analysis that determines how likely an observed distribuition is due to chance
what does the chi squared test test for
the null hypothesis that the variables are independent
what is the chi squared within ecology
to see if 2 populations are associated/dependent upon each other
what is the null hypothesis of the chi squared test
that there is no association between the two populations
how to calculate degrees of freedom
(no. of rows-1) x (no of columns-1)
how to calculate expected frequency for the chi squared test
expected frequency = (row total x column total) / grand total
steps to carrying out the chi square test 7
- draw table
- state null hypothesis and alternate hypothesis
- calculate expected frequency
- calculate chi-squared value
- identify degrees of freedom
- identify significance level (0.05)
- compare critical and calculated values
if p value is less than 0.05, the variables are? (chi squared test)
less than 0.05 = DEPENDENT!!!
when chi square is equal to or less than critical, the ______ hypothesis is accepted
NULL
4 limitations of chi squared test
- can only be used for categorical data
- data must be raw counts (no percentages etc)
- not valid if sample size is too small
- cannot tell you WHAT the association is, only if there IS one
