## 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