Flashcards in Genetic information, variation and relationships between organisms - 3.4.7 Investigating diversity Deck (29)
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?
Shows 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 varies very little)
If the standard deviations of the 2 sets of data collected overlaps what can be concluded?
no difference in the 2 sets of data, its not significant - due to chance
the differences between individuals
variation is caused by
genetics and the environment (or both)
Variation 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 studying variation - can you study the whole population?
NO - take a sample
When you sample to study variation, how should you go about collecting the sample?
Taking samples at random ensures...
results are not biased
results are representative
When studying variation between 2 populations, what would you calculate?
When plotting variation data, what type of graph do you get?
normal distribution curve
The highest point on a normal distribution curve (that is symmetrical) is ..
the mean value
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 a statistical test (the right one!)
When carrying out a statistical test what do you have to formulate first?
a null hypothesis
When comparing means of samples what statistical test would you do?
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?
When drawing conclusions from statistical tests what words should you include in it?
significant or not
What level of probability to Biologists refer too?
5% / 0.05
If your calculate value in your tests is GREATER than the critical value in the table (at the 5% level), what can you conclude?
results are significant
less than a 5% probability that the differences are due to chance
If your calculate value in your tests is LESS than the critical value in the table (at the 5% level), what can you conclude?
difference in the mean values are significant
greater than a 5% probability the difference is due to chance
if the P value is less than 0.02 what can you conclude
difference between mean values are significant
less than 2% probability that the difference
is due to chance
removal of hedgerows reduced diversity of birds - why?
1. Removes species/types of plant/insect;
2. Fewer food sources;
3. Fewer habitats/niches;
How should a person collect and process data to investigate if there is a difference is size of seeds produced by a particular tree in 2 different areas?
1. randomly sample seeds from both areas
2. large sample size to ensure representative (reliable mean)
3. measure mass of seed as indicator of size
4. calculate mean and standard deviation
5. T test carried out
6. determine if there is a significant difference between the means of the two samples