Unit 2- Section 1 variation Flashcards
What are the causes of intraspecific variation?
Genetic factors, environmental factors or both
What are the two types of variation?
Interspecific- the variation that exists between different species. For example, horse vary from ducks etc
Intraspecific- the differences that occur within a species. For example, the number of eyes on a peacocks feather or the length of a giraffes neck
What are the genetic factors of intraspecific variation?
All the members of a species have the same genes, that is what makes them the same species. Individuals within a species can have different variations of genes called alleles. The alleles an organism have make up it’s GENOTYPE. Different genotype a result in the variation in PHENOTYPES, the characteristics displayed by an organism,
Describe the environmental factors that cause intraspecific variation
The appearance (phenotype) of an individual is also affected by the environment
How can genes and the environment affect intraspecific variation?
Variation is often a combination of genetic and environmental factors. All individuals may have the benefit information for a particular characteristic but environmental factors may affect the expression of this characteristic
How are twins used to draw conclusions about the causes of variation?
Studies of identical twins are extremely useful when trying to determine what’s due to environmental factors and what’s due to genetic factors. Because twins are genetically identical so any differences in phenotype must be entirely due to environmental factors, if a characteristic is very similar in identical twins,genetics probably plays a more important role but if a characteristic is different between the twins the environment must have had a larger impact
Why are population samples taken?
For most species it would be too time consuming and impossible to catch all of the individuals in the group so therefore population samples are taken
What is random sampling and why is it used?
Because a sample population is taken a correct conclusion needs to be taken so therefore to make sure the sample is not biased it should be random, for example, if you were looking at plant species in a field you could pick ransom sample sites by dividing the field into a grid and using a random number generator to select coordinates
How can 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 does the mean value tell you?
The average of the values collected in a sample. It can be used to tell if there is variation between samples
With a normal distribution curve, the mean is the centre of the bell. So either side is symmetrical
What does the 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.
If the normal distribution curve is tall and slim the standard deviation is small
If the normal distribution curve is fat and wide then the standard deviation is large
