Measurements and Variation Flashcards
What is interspecific variation?
Variation between organisms of a different species
What is intraspecific variation?
The variation between organisms of the same species,
How can we ensure sampling isn’t biased?
To carry out random sampling.
➣Divide the area into a grid of numbered lines
➣Using random numbers from a table or pc generator, obtain a series of coordinates
➣Take samples at the intersection of each pair of coordinates
Why is using a large sample size better? What is used to evaluate the effect of chance on data?
It’s more representative and reduces the chance on the sampling process. The larger the sample size, the smaller the probability that chance will influence the results and the more representative the sample will be.
Statistical tests analyse the data collected to determine the extent chance may have influenced data
What are the causes of variation?
Genetic factors and environmental factors, or a combo of both
What are the genetic factors in variation?
Gene mutations, crossing over, and independent segregation of chromosomes
Characteristics mainly influenced by genetic factors with little environmental influence are?
Controlled by one or two genes, expressed as distinct phenotypes with no intermediates (tongue roller or non-roller), are represented as distinct groups on a bar or pie graph.
What are the environmental factors in variation?
➣Light, water and nutrient availability in plants. Diet, temperature could affect characteristics in animals
What characteristics are significantly influenced by the environment?
➣Controlled by many genes (polygenic)
➣Have no separate categories or types, but a range of intermediates between the 2 extremes
➣Produce a normal distribution curve when plotted on a graph
How is there variation between and within species?
➣Different species have different genies, causing variation between species
➣Individuals within a species have the same genes, but different alleles, causing variation within a species
What must you use to study variation?
A sample, which models the whole population as it’s too time consuming/ impossible to catch a whole group
Why is a mean necessary in samples?
It provides an average and can be used if there’s variation between samples and includes values either side of the mean, creating a bell-shaped graph, a normal distribution which is symmetrical with the mean
What does standard deviation tell you about a sample?
Tells you how much the values in a single sample vary. A measure of the spread of values about the mean. A large standard deviation indicates the values vary a lot, a small means most of the data is around the mean and doesn’t vary much.
What do error bars show?
If they overlap, they show there is no significant difference between the results. If they don’t overlap. it indicates a large significant difference. The longer the bar, the larger the SD.
