ecology- 5b and 7c Flashcards
What is an ecosystem?
A community of living organisms and the non-living components of their environment interacting as a system.
What is a population?
All the organisms of one species in a particular area at a given time.
What is a community?
All the populations of different species living and interacting in a habitat at the same time.
What is a niche?
The role of a species in its ecosystem — includes its habitat, interactions, and how it uses resources.
What is the difference between biotic and abiotic factors?
Biotic = living factors (e.g. competition, predation)
Abiotic = non-living factors (e.g. temperature, light, pH)
What is succession?
The process by which ecosystems change and develop over time.
What is primary succession?
Succession that starts from bare rock or land with no soil or organisms.
What is secondary succession?
Succession on land where soil remains after a disturbance (e.g. fire, deforestation).
What is a pioneer species?
The first species to colonise an inhospitable area — often adapted to extreme conditions.
What happens during succession?
Pioneer species alter conditions
More species move in
Biodiversity increases
Eventually a climax community is reached
What is a climax community?
The stable final community at the end of succession, in equilibrium with the environment.
Why might succession be prevented or managed?
To maintain habitats or conserve species that would be lost in later stages of succession.
What is conservation?
Protecting ecosystems and biodiversity through management techniques (e.g. grazing, mowing).
What is a plagioclimax?
An artificial climax community resulting from human activity (e.g. regular burning or grazing).
What is intraspecific competition?
Competition between individuals of the same species.
What is interspecific competition?
Competition between individuals of different species.
What effect does competition have on population size?
Reduces it — if resources are limited, fewer individuals survive to reproduce.
What is predation?
Interaction where one organism (predator) kills and eats another (prey).
How does predation affect population sizes?
Causes cyclical changes — prey increase → predator increase → prey decrease → predator decrease
What is abundance?
The number of individuals of one species in a given area.
What is distribution?
How individuals of a species are spread out in an area.
What methods are used to investigate non-mobile species?
Quadrats and transects.
How do you investigate mobile species (e.g. insects)?
Use mark-release-recapture.
What is the mark-release-recapture method?
Capture a sample of animals
Mark them
Release them
Recapture a second sample
Use the formula to estimate population size.
What is the formula for mark-release-recapture?
Population size = no. marked in 2nd sample / (no. in 1st sample × no. in 2nd sample)
What assumptions must be met for mark-release-recapture to be valid?
No immigration/emigration
No births/deaths
Marking doesn’t affect survival
Enough time for mixing
Marked individuals still recognisable.
Where does energy in an ecosystem originate from?
The sun — captured by plants during photosynthesis.
What is a producer?
An organism that makes its own food (e.g. plants, algae).
What is a consumer?
An organism that eats other organisms (primary, secondary, tertiary, etc.).
What is biomass?
The mass of living material in an organism, usually measured as dry mass per given area.
What is the unit of biomass?
kg m⁻² (land) or kg m⁻³ (volume in water).
What is gross primary productivity (GPP)?
The total amount of chemical energy converted from light by producers in a given area.
What is net primary productivity (NPP)?
The energy remaining after respiration: NPP = GPP - R.
Why is energy transfer inefficient between trophic levels?
Not all eaten
Some indigestible
Lost as heat via respiration
Lost in waste (urine/faeces).
What is the typical efficiency between trophic levels?
Around 10%.
How can farming increase energy transfer efficiency?
Reduce movement
Control temperature
Antibiotics
Selective breeding
High-protein feed.
