4 (a-d) - Ecology and the environment Flashcards
What is a population?
A population is defined as a group of organisms of the same species living in the same place at the same time
What is interdependence?
- Within a community, each species depends on other species for food, shelter, pollination, seed dispersal etc
- If one species is removed it can affect the whole community
What is a community?
Groups of populations living and interacting with each other in an area
What is a habitat?
- A habitat is the place where an organism lives
- E.g. badgers, deer, oak trees and ants are all species that would live in a woodland habitat
What is an ecosystem?
An ecosystem is defined as all the biotic factors and all the abiotic factors that interact within an area at one time
What is a biotic factor?
Biotic factors includes all the living components such as plants and animals
What is an abiotic factor?
Abiotic factors includes all the non-living components such as light intensity, mineral ions, water availability
Do ecosystems vary in size?
Ecosystems can vary greatly in size and scale
- A small ecosystem might be a garden pond
- A large ecosystem might be the whole of Antarctica
What is a quadrat?
Rectangular frames of known dimensions that can be used to establish population densities by counting and identifying organisms within frame
What are quadrats commonly used for?
Plants species are commonly studied using quadrats to estimate the abundance
How can you used quadrats to measure the abundance of a species?
- The number of an individual species: the total number of individuals of a single species (eg. buttercups) is recorded
- Species richness: the total number of different species (but not the number of individuals of each species) is recorded
- Percentage cover: the approximate percentage of the quadrat area in which an individual species is found is recorded (this method is used when it is difficult to count individuals of the plant species being recorded eg. grass or moss
How do you estimate the size of a population?
- Place quadrat randomly within sampling area
- Count the number of members of the same species within the quadrat
- Repeat this numerous times within sampling area using the same size quadrat
- Repeat the process in another area to compare results
What is the Equation to Calculate the Approximate Population Size of an Organism?
Population size = (Total area / sample area) x total number of organisms
How is abundance of a species abundance influenced (biotic factors)?
Species abundance is likely to be influenced by biotic factors such as:
- Competition
- Predator-prey relationships
- Interactions with other organisms within the food chain or food web
How is abundance of a species abundance influenced (abiotic)?
The abundance will also be influenced by abiotic factors such as:
- Light intensity
- Mineral availability
- Water availability
- pH
- Temperature
- Salinity
