AS-LEVEL AQA BIOLOGY NOTES
TOPIC 7: investigating diversity
Genetic diversity
Genetic diversity can be…
Investigating diversity/variation within a species:
Sampling is when a small, random group of individuals within a population is selected and studied carefully. You can then multiply up the numbers of individual species found to give an estimate for the entire habitat.
Sampling allows us to:
Mean
To find the mean of the data collected:
mean = xN
Where x = each value from the data set
And N = the total number of values
Standard deviation
The formula for finding the standard deviation for a set of data is:
s = (x-x)2n-1
Where n = sample size
And x= an individual value
And x = mean value
A low value indicates the data have a narrow range.
A high value indicates a larger range. This suggests lower reliability of the data.
The spread of the data = mean standard deviation
- DNA found in all living organisms
- Always provides the genetic code
- More similar the sequence the more closely related the species
Genetic diversity can be…
- Interspecies (between different species)
- Intraspecies (within the same species)
- Measured by…
- Base sequence of DNA or mRNA
- Amino acid sequence coded by DNA/mRNA
- Previously was measured by observable characteristics/features
- Modern technology allows direct genome sequencing for more accurate comparison between organisms
- Base sequence of DNA or mRNA
Investigating diversity/variation within a species:
Sampling is when a small, random group of individuals within a population is selected and studied carefully. You can then multiply up the numbers of individual species found to give an estimate for the entire habitat.
Sampling allows us to:
- Study any impacts on the environment (EIA)
- EIA is used to estimate effects of a planned development on the environment
- Depends on the size of the habitat and time
- Number of samples should be sufficient to give an accurate measure of the number of species in habitat and relative abundance
- If two areas are being compared, the same number of samples should be taken at each
- Samples must be randomly chosen
- This avoids bias/subjectivity
- You must estimate the size of the habitat and decide where to take samples
- This can be done by:
- Taking samples at regular distances
- Use random numbers to plot co-ordinates
- Select co-ordinates from a map and use GPS to find the exact location
- Taking samples at regular distances
Mean
To find the mean of the data collected:
mean = xN
Where x = each value from the data set
And N = the total number of values
Standard deviation
The formula for finding the standard deviation for a set of data is:
s = (x-x)2n-1
Where n = sample size
And x= an individual value
And x = mean value
A low value indicates the data have a narrow range.
A high value indicates a larger range. This suggests lower reliability of the data.
The spread of the data = mean standard deviation