Biology Internal Assessment
IB Biology – Internal Assessment: Measuring Population Size
A population is defined as a group of individuals of the same species, occupying a particular area at the same time. In all studies of quantitative ecology, it is essential to be able to estimate the number of organisms within a given area of ground or volume of water or air. In most cases, this is equivalent to estimating the population size; the methods employed are determined by the size and mode of life of organisms involved and also the size of the area under investigation. For species living in uniform and accessible habitats, given their sizes are large enough, the population can be estimated by marking and recapture methods, or by using square grids of known areas. In some cases, when one is dealing with relatively small areas, it is possible to isolate the entire population and take a complete census.
Although the methods of estimation are different, their outlying principles are simple and can be demonstrated in laboratory by using simple apparatuses.
Design
Experiment I
Question: Capture-recapture Method for Estimating Population Size
Hypothesis: Population size can be estimated by capture-recapture method
Materials: Big bowl, beans, quick drying marker, small spoon
Procedure:
1. Filled the Petri dish with 500 beans. 2. 52 rice grains were taken out by random and marked with the marker. They were allowed to dry. 3. The marked beans were returned to the Petri dish and mixed thoroughly together with the unmarked beans. Here, all the beans represented individuals in a population, whereas the marked beans represented the first captured and then released individuals. 4. A sampled of beans was removed by using a small spoon. The numbers of marked and unmarked beans were counted and recorded. 5. Step 4 was repeated 9 times and the results were averaged and tabulated below.
Diagram of Setup
Data Collection and Processing
Raw data table:
Table 1: Number of marked
A population is defined as a group of individuals of the same species, occupying a particular area at the same time. In all studies of quantitative ecology, it is essential to be able to estimate the number of organisms within a given area of ground or volume of water or air. In most cases, this is equivalent to estimating the population size; the methods employed are determined by the size and mode of life of organisms involved and also the size of the area under investigation. For species living in uniform and accessible habitats, given their sizes are large enough, the population can be estimated by marking and recapture methods, or by using square grids of known areas. In some cases, when one is dealing with relatively small areas, it is possible to isolate the entire population and take a complete census.
Although the methods of estimation are different, their outlying principles are simple and can be demonstrated in laboratory by using simple apparatuses.
Design
Experiment I
Question: Capture-recapture Method for Estimating Population Size
Hypothesis: Population size can be estimated by capture-recapture method
Materials: Big bowl, beans, quick drying marker, small spoon
Procedure:
1. Filled the Petri dish with 500 beans. 2. 52 rice grains were taken out by random and marked with the marker. They were allowed to dry. 3. The marked beans were returned to the Petri dish and mixed thoroughly together with the unmarked beans. Here, all the beans represented individuals in a population, whereas the marked beans represented the first captured and then released individuals. 4. A sampled of beans was removed by using a small spoon. The numbers of marked and unmarked beans were counted and recorded. 5. Step 4 was repeated 9 times and the results were averaged and tabulated below.
Diagram of Setup
Data Collection and Processing
Raw data table:
Table 1: Number of marked