POPULATION SIZE AND ECOSYSTEMS Flashcards
(32 cards)
What are the 4 factors affect in population size
Birth rate
Death rate
Immigration
Emigration
Define abiotic factors
Non living factors in a organism
Define niche
An organisms role within the ecosystem
Define carrying capacity
Maximum population size an ecosystem can support
Define ecosystem
A community of non living components of an environment
Define community
All populations of different species in the same area at the same time
4 examples of abiotic factors
Temperature, pH, light intensity, carbon dioxide levels
How are plants and animals developed to adopt to abiotic factors
Through natural selection
Define intraspecific competition
When members of the same species compete for the same resources
Explain required practical for population size (quadrats)
- Place 2 tape measures at right angles to create a gridded area to take samples from
- Use random number generator to generate coordinates to take samples from
- Place quadrat on coordinates and calculate abundance of the species
- Repeat at least 30 times
Explain belt transect practical
- Tape measure placed through a non uniform ecosystem eg Rocky beach
- Quadrat placed at intervals along transect to measure the impact of changes in the environment
Describe mark - release - recapture
- Animals are trapped and marked with a substance that is non toxic, weather resistant and not impacted by predication or reproduction
- Released and left to distribute themselves in the population
- Recaptured a few days later and 2nd sample is taken and this is repeated
Define succession
A change in the ecological community over time
Describe steps of primary succession
- A pioneer species colonises bare rock or sand 2. Pioneer species are adapted to survive harsh abiotic conditions. They can change abiotic factors to become less harsh through their death and decomposition
- Moss and other plants can now survive due to the nutrients in soil and less harsh abiotic conditions. They release more nutrients to soil when they die
- This continues and larger plants can survive and further change environment
Define species
An organism that can interbreed and produce fertile offspring
What is secondary succession
Succession is disrupted and plants are destroyed
What are the 4 stages of the nitrogen cycle
Nitrification
Ammonification
Denitrification
Nitrogen fixation
What happens in nitrification
Ammonium ions —— nitrite (nitrosomonas) —— nitrate (nitrobacter)
What are the 2 bacteria’s in nitrification
Nitrosomonas
Nitrobacter
What happens in ammonificaion
Nitrite/Nitrate —— ammonium ions (decomposes) —— ammonia
What happens in denitrification
Nitrate —— nitrogen gas (pseudonomas)
What is the bacteria called in denitrification
Pseudonomas
What happens in nitrogen fixation
Nitrogen gas + hydrogen gas —— ammonia (rhizobium + azobacter)
What are the 2 bacteria’s in nitrogen fixation
Azobacter
Rhizobium
