Investigating Variation Flashcards
What can variation be caused by
Genes, the environment, or both
What is variation
Variation is the differences that exists between individuals. Theres variation between species and within species
What can variation be caused by
Variation can be caused by genetic factors. Different species have different genes, which causes variation between species
Individuals of the same species have the same genes, but different alleles (versions of genes)
Thus causes variation within a species
What can variation within a species also be caused by
Differences in the environment, e.g. climate, food, lifestyle.
What is most variation within a species caused by
A combination of genetic and environmental factors.
E.g. genes determine how tall an organism can grow, but nutrient availability affects how tall the organism actually grows
What must you do to a population to study variation
Sample it
When investigating variation what do you usually only look at
You usually only look at a sample of the population, not the whole thing. For most species it would be too time-consuming or impossible to catch all the individuals in the group. So samples are used as models for the whole population
Must the sample be specific or random
The sample has to be random because sample data will be used to draw conclusions about the whole population, it’s important that it accurately represents the whole population and that any patterns observed are tested to make sure they’re not due to chance .
How do you make sure the sample isn’t biased,
It should be random, for example if you were looking at plant species in a field you could pick random sample sites by dividing the field into a grid and using a random number generator to select coordinates
How do you ensure any variation observed in the sample isn’t just due to chance
Analyse the results statistically. This allows you to be more confident that the results are true and therefore will reflect what’s going on in the whole population.
What is the equation to find out the mean (average) samples collected in a sample
Total of all the values in your data
Mean. —————————————————-
The number of values in your data
What can the mean be used to tell
If there is variation between samples
What does standard deviation tell you
How much the values in a single sample vary
It’s a measure of the spread of values about the mean
