Population size And Ecosystems Flashcards
What is a ecosystem
A characteristic community of interdependent species interacting with the abiotic components of their habitat
What is a community
Interacting populations of two or more species in the same habitat at a particular time
What is ecology
The study of interrelationships between organisms and abiotic and bitotic environment
What is a population
Interbreeding group of organisms of the same species occupying a particular habitat
Abiotic environment
Non living parts of the environment e.g. Temperature and ph
Bitotic conditions
Living factors e.g Predation or disease
What is niche
The role and position a species has in its environment including all interactions with biotic and abiotic factors of the ip environments
What various factors cause fluctuations in population size
Emigration movement of individuals out of a particular area
Immigration movement of individuals into a particular area.
Population size will increase when immigration is greater than emigration
Death rate - and birth rate -reproductive capacity of a particular organism population size will increase when birth rates are greater than death rates
Explain graph showing changes in population growth
- Lag phase - no increase but a period of slow growth intense metabolic activity e.g enzyme synthesis waiting for organism to become sexually mature
- Exponential phase -exponential increase in population no limiting factors. More individual produce for reproduction and cells divide so there’s a constant rate of pop doubling in bacteria
- Stationary - birth rate and death rate are equal. Reached carrying capacity (never a straight line because there’s a constant fluctuation in response to environmental changes, carrying capacity can increase when there is more food resources )
- Death rate becomes higher the birth rate or production of individuals.
What is carrying capacity
Maximum no of individual ps that a environment can support or maintain the population fluctuates around this
What is intraspecific and inter specific competition
Intra - competition between individuals of same species
Inter competition between individuals of different species
What factors increase population
Good water and food supplies Plenty of space Ability to resist disease and avoid predation High productive rate Favourable light Stable biotic conditions
What factors decrease population
Competition indadequate supply of food and water
Not enough space
e.g accumulation of toxic waste
Inability to resist parasitism and predation
Lowe reproductive rate
Too little or too much light
Unstable abiotic conditions
What are density dependant factors and density inderoendant factors
Tend to slow down population growth, it’s effect increases as the population increases e.g accumulation of toxic waste, depletion of food and disease
Cause a population size to crash and its effect doesn’t depend on pours toon e.g natural disaster
