exam Q's Flashcards
give three features of a climax community
-stable community (same species present over a long time)
-populations are stable around carrying capacity
-abiotic factors are constant over time
describe and explain the process of succession
-colonisation by pioneer species
-pioneer species change the environment e.g form soil
-environment becomes less hostile for new species
-this increases biodiversity
-eventually a climax community is formed
suggest one limitation of using a transect to collect data
transect may avoid certain areas
suggest why the mark-release recapture method may produce unreliable results in large nature reserves
-less chance of recapturing animals
-unlikely that animals will distribute themselves evenly
explain what is meant by succession
-change in a community over time
-due to change in the environment/ abiotic factors
explain why ecologist measured percentage cover of the algae rather than frequency
-too many plants to count
state three conditions that must be present in order for speciation to occur
-mutation / genetic diversity
-natural / directional , selection
-idea that environment / selection pressure , is different from the ‘other’ population
-time
suggest one biotic factor that might effect the distribution of buttercups
-predation/ herbivory
-competition
choose and describe sampling techniques that would show how the distribution and abundance of native and introduced grasses change across two zones
-lay tape measure in line across zones
-across salt spray and rain to watered zone
-use a quadrat
-place quadrat systematically/ at regular intervals
-use a key
-to indentify species present
-estimate percentage cover
-repeated sampling over time
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what word is used to describe the study of the interactions between organisms and their environment
ecology
what is an ecosystem
a physical area that includes all the organisms present and their interactions with each other and with the physical environment
state and describe two types of ecological interaction that can occur between different species in a habitat and examples of species
- competition e.g between a red and grey squirrel
2.predator-prey e.g rabbit and a fox
outline how the percentage efficiency of energy transfer between producers and herbivores can be estimated
-(primary consumer energy / producer energy) x100
-producer sample collected
-sample of herbivores collected
-measure dry mass
-use of calorimeter
explain the sequence of the nitrogen cycle including products, reactants and oxi/red
1) nitrogen fixation= Nitrogen gas (N2) and hydrogen ions -> ammonia (NH3) REDUCTION
2) nitrification= ammonium ions (NH4^+) into nitrites (NO2^-) OXIDATION
3) Denitrification= nitrites into nitrogen gas REDUCTION
explain the advantages of farmers growing legumes
-contain nitrogen fixing/ rhizobium bacteria
-nitrogen required for nitrogen compounds
-reduced need for fertiliser
explain how nitrogen-containing compounds are returned to the soil
-fungi/ bacteria
-break down organic material
-by extracellular enzymes
-ammonification
describe the differences between a pioneer community and climax community
-pioneers arrive before climax
-pioneer community usually has lower biodiversity
-pioneer community has lower biomass
-pioneer community is less stable
describe the difference between conservation and preservation
conservation involves active management of ecosystem, preservation leaves ecosystem undisturbed
the remaining population of D.sumatrensis are all small and are scattered in isolated areas. these are factors that might speed up the extinction of the species, suggest why
-more vulnerable to poachers/ predators
-hard to find a mate
-less likely to cope with environmental changes
-small gene pool / genetic bottleneck
explain why it is sometimes necessary to conserve a plant species outside of its natural habitat (ex situ)
-allows protection from herbivores/ grazing/ competing species
-protection from disease
-breeding ex situ can maintain genetic diversity
-population in natural habitat is very low
-natural habitat lost due to human activity e.g deforestation, overgrazing
Beavers are considered a keystone species, explain why they are a keystone species?
-have significant effect on ecosystem
-many other species rely on activity of beavers
increasing habitat diversity may lead to an increase in species diversity and genetic diversity, explain why species diversity and genetic diversity may be increased as a result of the beavers’ activity
-species diversity will rise as more species live in the new habitats
-genetic diversity will increase as species have a wider range of conditions in which to live
suggest and explain why the % of biomass transferred between heather and grouse is smaller than the % of biomass transferred between grouse and hen harrier (heather is a plant with a woody stem)
-heather is less easily digested
-because of cellulose cell walls/ lignin in (woody parts)
describe the similarities between the nitrogen cycle and carbon cycle
-both include inorganic gases CO2 and N2
-both C and N fixed into organic compounds= both form proteins and nucleic acids
-animals obtain C and N by feeding on plants
-microorganism return element to atmosphere CO2 released during decomposition N2 by denitrifying bacteria
-incorporated into plants then animals
-decomposing microorganisms
-break down organic macromolecules in living things
