BSC2011L Final Exam Study Guide A t test is a statistical examination of two population means A two sample t test examines whether two samples are different and is commonly used when the variances of two normal distributions are unknown and when an experiment uses a small sample size o Includes mean variance and sample size NOT Median A null hypothesis will be the scenario of no relationship between two sets of data or that there is no difference between two sets of data The p value refers to the probability that a difference between two groups is due to chance o If a p value is less than 05 then the data supports your hypothesis o If the value is greater than 05 then the date disproves your hypothesis Chi Square Test allows us to compare observed frequencies to expected frequencies count data o Uses categorical data o Why not a t test A t test doesn t use categorical data for the dependent variable it uses continuous and looks for differences between two groups using means variance A scientific method is a formal way of asking and answering questions Experiment a test of a hypothesis o A scientific test in which the researcher can control and alter the value of the independent variable Hypothesis a proposed explanation for a phenomenon o A specific prediction that can be tested Science advances by disproving incorrect hypotheses it s much easier to disprove a Science is the investigation of rational concepts that can be tested using observation and hypothesis experimentation o Not science Art evaluated by aesthetics what appeals to senses and emotions Philosophy investigation is by reasoned argument ex ethics metaphysics the nature of being Religion investigation is by meditation and reflection Pseudoscience any practice that claims to be science but does not fit the definition Accurate measurements that are close to the truth or the actual value o Accuracy how close measurements are to the true value Precise measurements that are consistent or repeatable but may or may not be close o Precision how closely repeated measurements of the same thing are to one to the truth another in value Random error reproducibility error data spread out Systematic error Bias consistently off target in the same direction data samples of the population the shape of our data Independent vs dependent variables Variation in the independent variable is presumed to be the cause of variation in the dependent variable o Independent variable is what is changed and controlled A measured factor that is presumed to have an effect on another variable o Dependent variable changes based on the independent variable A measured factor that is measured as the outcome of a study Descriptive statistics describe our data but don t allow you to infer anything about your Statistics Allows you to infer a conclusion about the population as a whole from The histogram can show us how common a particular size is in a sample and shows us Probability assaying the probability something happened by chance Mean average Range max min Median the middle number in a data set arranged from least to greatest take the average Mode the number that appears most frequently in a data set may have more than one Bilateral symmetry having a body that has a single plane of symmetry down the Differentiation the developmental process of cells becoming phenotypically and if there are 2 middles midline of an animal functionally mature o Stem cells are undifferentiated cells that can become a wide variety of other cell types through differentiation Once differentiated cells can generally not changed other cell types Isometry Changes and proportion with changes in size that lead to organisms or structures with the same shape e g if you double the length of the year of the cat and the width of the ear also doubles that is an isometric change Planaria Small mostly freshwater flat worms in the phylum Platyhelminthes They are structurally simple bilaterally symmetrical animals with great regenerative abilities Locus the physical location of a gene on a chromosome Allele a particular version of a gene For example in Drosophila there are Scarlet and wild type of alleles at the scarlet locus Homologous Chromosomes homologs Chromosomes with the same loci but not always the same alleles copies of each locus Diploid having two of each homolog chromosomes occurring in pairs having two Gamete A haploid reproductive cell sperm or egg Genotype the combination of alleles in an individual either at a single locus or multiple Phenotype traits or characteristics of an organism Haploid having one set of chromosomes one of each homolog only one copy of each loci locus Heterozygous having two different alleles at a locus Homozygous having two copies of the same allele at a locus Meiosis the process of a diploid cell undergoing two rounds of cell division to produce for haploid daughter cells o In animals meiosis produces gametes sperm and eggs Allometry Gene Expression the production of a gene product o The control of gene expression such that different genes are expressed in different cells and areas of the body is the principle method of control of development Sex linked vs Autosome Sex linked is carried on the sex chromosomes either X or Y while an autosomal is carried on any other chromosome Phenotype vs Genotype phenotype is generally the trait you can see and genotype is Dominant vs Recessive The stronger allele is dominant and the weaker allele that is the genetic makeup behind it masked is recessive Model Systems Punnett Squares Allele Frequency The proportion of total number of copies of a gene in a population that are of one particular allele Node Branching point in phylogeny where one species splits into two Phylogeny diagram depicting evolutionary history of a group of organisms Sister Taxa two taxa which share a most recent common ancestor that is not shared by any other taxa in the tree Taxon named group of organisms Species or collection of species Heritable Phenotypic Variation The variability in phenotypes that exists in a population o Organisms vary greatly within species When this phenotypic variation has a genetic component biological evolution can occur o Without phenotypic variation there would be no evolution by natural selection Variability refers to the extent to which these data points differ from each other o There are four commonly used measures of variability range mean variance and standard deviation Standard deviation the square root of
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