3.4.7 Investigating Diversity Flashcards
Comparing the base sequences of a gene provides more information than comparing the amino acid sequence for which the gene codes. Explain why
Different base triplets code for the same amino acids
What does standard deviation show?
The spread of data about the mean
What can be said about the data collected if the standard deviation is large?
Less reliable
Data varies a lot
What can be said about the data collected if the standard deviation is small
More reliable
Data more consistent
If the standard deviations of the 2 sets of data collected overlaps, what can be concluded
No difference in the 2 sets of data
It’s not significant - due to chance
Variation is…
The differences between individuals
Variation is caused by
Genetics and the environment
Variations between organisms of the same species is due to…
Differences in their alleles (and the environment)
Variation between organisms of different species is due to…
Different genes (and the environment)
When you sample to study variation, how should you go about collecting the sample and why
Randomly
Results are not biased
Results are representative
When plotting variation data, what type of graph do you get?
Normal distribution curve
The highest point on normal distribution curve (that is symmetical) is…
The mean value
When studying variation between 2 populations, what would you need to calculate?
Mean
Standard deviation
If the standard deviation of the 2 sets of data DO NOT overlap, what can you conclude from the data
There is a difference between the data collected.
It is likely significant and not due to chance
What could you do to data collected if you wanted to determine if data collected was significant or not?
Carry out the right statistical test
When carrying a statistical test, what do you have to formulate first?
A null hypothesis
When comparing means of samples, what statistical test would you do?
T test
When comparing observed and expected data, what test would you perform?
Chi squared test
When looking for a correlation between two variables, what test would you do?
Spearman’s rank
When drawing conclusions from statistical tests, what words should you include?
Significant or not
Chance
Probability
What level of probability do Biologists refer to?
5% / 0.05
If your calculated value in your tests is GREATER than the critical value in the table (at the 5% level), what can you conclude?
REJECT NULL HYPOTHESIS
Results are significant
Less than 5% probability that the differences are due to chance
If your calculated value in your tests is LESS than the critical value in the table (at 5% level), what can you conclude?
ACCEPT NULL HYPOTHESIS
Differences in the mean values are significant
Results are not significant
Greater than a 5% probability that the differences is due to chance
If the P value is less than 0.02, what can you conclude?
REJECT NULL HYPOTHESIS
Differences between mean values are significant
Less than 2% probability that the difference is due to chance
Removal of hedgerows reduced diversity of birds. Why?
- Removes species / types of plants/ insects
- Fewer food sources
- Fewer habitats / niches
Define species richness
Number of different species in a community / habitat
How should a person collect and process data to investigate if there is a difference in size of seeds produced by a particular tree in 2 different areas?
- Randomly sample seeds from both areas
- Large sample to ensure representative (reliable mean)
- Measure mass of seed as indicator of size
- Calculate mean and standard deviation
- T test carried out
- Determine if there is a significant difference between the means of the two samples
