BSC2011L Exam Review Science Doing science requires testing falsifiable hypothesis Science can only address hypotheses that I can prove are incorrect Not all science is hypothesis testing Describing the surface of Mars Measuring the relationship between the composition of a material and its flexibility Constructing a mathematical model to predict sea level rise Developing a new vaccine for the flu Science is the investigation of rational concepts that can be tested using observation and experimentation What is not science Art Philosophy Religion Pseudoscience any practice that claims to be science but does not fit the definition Alchemy Phrenology Belief that the topology of the skull indicates personality traits Quackery Promotion of unproven or fraudulent medical practices Measurements and Error Accurate measurements that are close to the truth or the actual value Precise measurements that are consistent or repeatable but may or may not be close to the truth Random error reproducibility error data spread out Systematic error Bias consistently off target in the same direction What type of error will these scenarios have Dice roll Loaded dice Scale that needs to be calibrated Dice roll random error Loaded dice systematic error random error is possible because you can still get different numbers on each roll just due to chance it will just be biased towards the loaded number Scale that needs to be calibrated systematic error Allows you to infer a conclusion about the population as a whole from Probability assaying the probability something happened by chance What does Statistics do in general Statistics samples of the population What is the basic principle behind Statistics Variation around a mean s2 x x 2 n 2 Calculating the variance around a mean quantifies the shape of the distribution Standard Deviation The standard deviation is a square root of the variance it can help you to see how variable your data are but it s in the same units you used for measuring s s2 Why do we do statistical analysis Descriptive statistics e g describe a set of data by their mean and SD Inferential statistics e g Hypothesis testing The use of inferential statistics allows biologists to make unbiased conclusions on a specific question using probability theory and algebra The t statistic is a ratio of the difference between the means and the variance Conclusion If p 0 05 we reject null hypothesis If p 0 05 we fail to reject the null hypothesis t 2 x1 x2 s2 s1 n1 n2 2 Type of data 1 Categorical 2 Ordinal discrete or continuous Why use the Chi Square Distribution Test allows us to compare observed frequencies to expected frequencies Uses categorical data T tests don t use categorical data and look for differences between two groups Ontogeny Development Resources energy are brought into an organism and are used in growth and development of tissue This process is complex Protein and nutrients in food are broken down and reconstructed to form new tissues Regeneration Regrowth of lost tissue Analogous to the process of development Cells must differentiate and re grow using the same mechanisms as development Model Systems Species studied extensively in order to under stand specific biology phenomenon Mouse Human Disease Guppy Natural Selection Fruitfly Genetics Planaria Regeneration Development Historical Perspective of Inheritance Offspring would look similar to parents Genetics What would happen if these offspring had offspring If traits were being blended then variation was being lost in each generation soon we d end up with populations of only blended individual who had very similar traits Descent with modification or Changes in allege frequencies Evolution Two themes Pattern What has happened Process How did it happen Forces of Evolution 1 Natural Selection 2 Genetic Drift 3 Gene Flow 4 Mutation Natural Selection Differential success in reproduction of different phenotypes resulting from the interaction of organisms with their environment Leads to adaptive evolution Sexual Selection Selection caused by differences among phenotypes in mating success Genetic Drift Process of evolution in which allele frequencies change due to random drift and chance events Genetic drift is a non adaptive process Gene Flow Process of evolution in which individuals migrate from one population to another resulting in changes in allele frequencies Mutation accidental changes in the DNA sequence of an organism These can be beneficial neutral or negative Evolution is NOT totally random Evolution is NOT always adaptive Evolution is NOT the survival of the fittest Evolution is NOT a march of progress Evolution is a theory BUT a scientific theory is a well sustained explanation of some aspect of the natural world It is supported by many laws and well supported hypotheses Phylogenies are created to examine evolutionary relationships between species Parsimony the tree w the fewest evolutionary events is best Homology traits that share common ancestry Analogy traits that share common function but NOT due to common ancestry result of convergence Convergent Evolution independent evolution of similar features in species of different lineages We may see this when two unrelated species live in a similar environment Divergent Evolution accumulation of differences between groups that can lead to a new species If on group moves to a new environment we may see them diverge from their source population Ecology is the study of interactions between organisms and their environment Includes Ecology Predator Prey dynamics Competition between among species Competition within a species Species distribution Interactions with between species and the abiotic habitat Plant insect interactions Holometabolous two distinct stages where there is complete metamorphosis Bean beetles Hemimetabolous nymph looks like miniature of adults think allometric scaling cockroach crickets
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