Revision Notes for Prelim Biology
REVISION NOTES FOR PRELIM BIOLOGY:
[ A LOCAL ECOSYSTEM ]
~ Ecosystems: “any area that contains living organisms interacting with each other and their environment. In a balanced ecosystem, there is a flow of energy through it and recycling of some materials”
Inputs and Outputs of Ecosystems include:
- the energy flow through the ecosystem; energy from the sun flows one way through, with heat loss at each trophic level
- the input and recycling of inorganic and organic material (matter)
- the movement of animals in and out of the habitat
Processes of an Ecosystem include:
- feeding interactions of members of the same species
- Interactions between members of different species
- And recycling of matter
The Boundaries of an Ecosystem:
- are defined by the physical and chemical features of the environment. A particular ecosystem can be described by considering:
- the organisms present
- the physical and chemical features of the abiotic environment
- where the ecosystem is found
+ METHODS OF ESTIMATING POPULATION NUMBERS:
1. Transects ~ a cross-section through an area. It is used to record the type and number of species present. It is useful for recording the relationship between a species and the abiotic factors in the area. Transects can only be used on animals that move very slowly or not at all, this method being most suitable to finding the population of trees and other flora.
2. Random quadrats ~ hoopie thingies. These can only be used for organisms that move very slowly or not at all, good for estimating the population of smaller organisms that do not move very far at all from original position.
3. Capture-Recapture ~ one of the most common methods of estimating population numbers. This method involves tagging or marking a sample of the population and then releasing it. The proportion of marked animals in subsequent recaptured samples gives a reasonable estimate of the population.
number of animals tagged x number recaptured
[ A LOCAL ECOSYSTEM ]
~ Ecosystems: “any area that contains living organisms interacting with each other and their environment. In a balanced ecosystem, there is a flow of energy through it and recycling of some materials”
Inputs and Outputs of Ecosystems include:
- the energy flow through the ecosystem; energy from the sun flows one way through, with heat loss at each trophic level
- the input and recycling of inorganic and organic material (matter)
- the movement of animals in and out of the habitat
Processes of an Ecosystem include:
- feeding interactions of members of the same species
- Interactions between members of different species
- And recycling of matter
The Boundaries of an Ecosystem:
- are defined by the physical and chemical features of the environment. A particular ecosystem can be described by considering:
- the organisms present
- the physical and chemical features of the abiotic environment
- where the ecosystem is found
+ METHODS OF ESTIMATING POPULATION NUMBERS:
1. Transects ~ a cross-section through an area. It is used to record the type and number of species present. It is useful for recording the relationship between a species and the abiotic factors in the area. Transects can only be used on animals that move very slowly or not at all, this method being most suitable to finding the population of trees and other flora.
2. Random quadrats ~ hoopie thingies. These can only be used for organisms that move very slowly or not at all, good for estimating the population of smaller organisms that do not move very far at all from original position.
3. Capture-Recapture ~ one of the most common methods of estimating population numbers. This method involves tagging or marking a sample of the population and then releasing it. The proportion of marked animals in subsequent recaptured samples gives a reasonable estimate of the population.
number of animals tagged x number recaptured