4.1 & 4.2 Flashcards
what is the difference between an autotroph and a heterotroph?
autotroph = obtains food by producing organic compounds from inorganic compounds
heterotrophs = obtains food by consuming other organisms
what are the 3 types of heterotroph?
- consumers
- detritivore
- saprotroph
what is the difference between a consumer, a saprotroph and a detritivore?
consumer; obtains nutrients by digesting other organisms
saprotroph; obtains nutrients from dead organisms via external digestion
detritivore; obtains nutrients from detritus via internal digestion
what is a chi-squared test?
a test that calculates the association between species viewed in quadrant sampling
what is the formula for chi-squared?
x^2 = Σ (observed value - expected value)^2/ expected value
what is the formula for degree of freedom in a child-squared test?
dof = number of groups tested - 1
what is the formula for expected frequency in a chi-squared test?
expected frequency = (row total x column total)/ grand total
what is the difference between the abiotic and biotic components of an environment?
abiotic factors = non-living things
biotic factors = living things
define species
can interbreed to produce fertile offsprings
define population
same species living in the same area at the same time
define community
multiple populations living in the same area at the same time
define ecosystem
the interaction of a community with its abiotic environment
what are the 3 types of species present in a community
- autotrophic
- heterotrophic
- mixotrophic
what is a common method used for autotrophs to obtain energy (make food)
photosynthesis
what are the 3 types of autotrophs?
- plants
- algae
- cyanobacteria
define mixotrophs
species that can carry out both heterotrophic and autotrophic nutritions
e.g. venus fly trap
what is speciation?
if members of species are isolated, either geographically or behaviourally, they diverge to become 2 different species
what is nutrient cycling?
recycling of nutrients and minerals
this includes
- carbon
- hydrogen
- oxygen
- nitrogen
- phosphorus
for an ecosystem to be fully sustainable, ^ these nutrients must be continually available
what are mesocosms and what does it require?
an artificial mini ecosystem to investigate the effects of factors on ecosystem sustainability
- light source
- water
- air
- autotroph, to produce organic compounds and uptake nutrients and minerals
- a saprotroph or a detritivore, to decompose waste material and dead organisms, returning nutrients and minerals to the ground
what are the 2 representations of feeding networks?
- food webs
- food chains
what is always at the bottom of the food chain?
the producer, an autotroph
e.g. grass
where does the arrow in a food chain point to the direction of?
the direction of energy transfer
e.g.
grass —> beetle —> salmon —> bear
what is each stage of the food chain known as?
a tropic level
why is it so common that most communities only have a maximum of 3 - 4 trophies levels?
due to the inefficient nature of energy transfer
loss of energy in the ecosystem
- sunlight (light energy) is brought into the ecosystem whilst the process of heat loss occurs
list the 4 main ways of energy loss
- respiration; therefore losing heat energy to the environment
- uneaten parts e.g. roots of plants
- undigested parts e.g. hair or cellulose
- death of organisms; dead before consumption can occur, their energy pass on
only x% of energy within one trophic level moves to the next trophic level due to energy loss
10%
- this percentage is very low since
- its organisms convert chemical energy into useful kinetic and heat energy
- the KE and heat energy cannot convert back to chemical energy therefore its lost
what is the units measured in for the pyramid of energy?
kJ m^-2 yr^-1
width proportional to energy present within the trophic level
define biomass
the total mass of group of organisms
what is the use of a quadrat?
used to view the relationship between 2 different organisms within a given area
describe the step by step process of using the quadrat
- select an area and divide it into a numbered grid 0f 1m x 1m squares
- use a random number generator to randomly select study areas
- select 2 study organisms
- create a null hypothesis and an alternative hypothesis
- place a quadrat and note which organisms are present in the selected study areas
- create a table to show the presents and or absents of the 2 chosen study species (noting the observed frequencies)
- calculate the row and column total
- calculate the grand total
- calculate the expected frequencies; f(e) = (row total x column total)/ grand total
10 determine the value of chi-squared - find the degrees of freedom
- compare chi-squared value to the critical chi-squared table
- if the chi-squared number is greater than 3.841, then the results are significant and there is a statistical difference between the 2 chosen study organisms, vice versa
how does energy flow in a food chain?
from organisms to organisms
outline the role of an autotroph within an ecosystem (3)
- autotrophs make their own carbon compounds from CO2
- autotrophs are often producers
- start the food chain so they are vital to the ecosystem
- they constitute most plants within an ecosystem
using 4 named organisms, outline the meaning of the term food chain (3)
- grass —> beetle —> salmon —> bear
- a food chain is a diagram that links organisms together that consume on one another
- starts with a producer, autotroph
outline the meaning of the term food chain (2)
- a food chain is a diagram that links organisms together that consumes on one another
- starts with a producer/ autotroph
describe how mesocosms can be used to investigate the sustainability of ecosystems (6)
- mesocosms are small experimental ecosystems
- they can be terrestrial or aquatic
- factors can be removed or added to investigate their effects
- can be sealed to investigate which are sustainable over the long term
- possible harm to organisms should be considered
- careful selection of organisms is required for balance
- oxygen supply must be balanced
what are the 3 requirements for a sustainable ecosystem? (3)
- energy; sunlight as this where producers source their energy from and producers are the foundation of every food web in every ecosystem
- nutrients; decomposers guarantee the availability of inorganic nutrients through recycling
- waster removal; bacteria serve to breakdown and sometimes detoxify harmful waste material
how do saprotrophs feed? (4)
- saprotrophs are heterotrophs that
- obtain organic nutrients from dead organisms and waste material via
- external digestion that occurs when they secrete
- enzymes
outline the use, transfer and efficiency of energy within an ecosystem (8)
energy is used for
- growth and repair
- respiration
- feeding and reproduction
- energy is transferred form one trophic level to the next
- lots of energy is lost from producers to primary consumers
- only 10% of energy is transferred from one organism to the next
energy is lost in
- incomplete digestion
- uneaten food
- energy transfer through an ecosystem is inefficient
why is heat generated by living organisms lost from the ecosystem? (2)
- heat is transferred from warmer to cooler bodies
- at each transfer heat is lost to the abiotic environment
what is the function of ATP? (4)
- ATP is used to fuel various cellular functions
- it is a universal energy currency of the cell
- it is used for endocytosis and exocytosis
- nerve transmission
- growth and repair
- movement
- light emission
