What is causing deformities in Pacific tree frogs In some of the ponds flatworm parasites trematodes were present If the parasites are causing deformities frogs with deformities should have more parasites than frogs without They found a positive correlation between Parasites and deformities But they can t say that the flatworms caused the deformities A well designed experiment includes Experimental group s and control s many samples individuals in each group Replication Why do we need a control group All living organisms change over time Organisms grow reproduce and die Cells change in size and structure The concentration of molecules increase and decrease Eliminate environmental errors Without a control we cannot determine if the changes would have happened regardless of the treatment Johnson et al If the parasites are causing deformities then the treatments with higher parasite numbers will lead to increased deformities Johnson et al s conclusion Data supports the hypothesis that Ribeiroia but not Alaria infection causes deformities in this tree frog population The scientific method 1 3 OBSERVE Observation Exploration of the natural world ASK Causal question Ask how and why SUGGEST Hypothesis Testable explanation The scientific method 4 6 Predict Compare Answer The scientific method Observation Causal question Hypothesis Prediction Results Conclusion Hypothetic deductive model Like induction the hypothetic deductive method begins with an individual observation The observation can be predicted by many hypotheses each of which provides additional predictions The predictions are then tested one by one and alternative hypotheses are eliminated until only one remains Scientists using this method never confirm hypotheses they only reject them or fail to reject them Theory What defines life RHEM R It can reproduce H It can maintain a relatively constant internal environment at disequilibrium with the wider environment homeostasis E It can evolve M It can manage its use of energy and matter metabolism All living organisms Consist of one or more cells Contain genetic information Use genetic information to reproduce themselves are genetically related and have evolved Acquire nutrients from their environment Can convert molecules into new biological molecules Regulate their internal environment Three domains of life on Earth based largely on molecular data Archaea Bacteria Eukarya How are organisms classified Taxonomy The taxonomic hierarchy Carl Linnaeus Domain Kingdom Phylum Class Order Family Genus Species Domain I Archaea Single celled organisms without a nucleus Prokaryotic Live in extreme environments hot salty acidic etc Domain II Bacteria Most common single celled prokaryotes Responsible for many human diseases Domain III Eukarya Any organism with nucleated cells eukaryotic May be unicellular or multicellular Eukarya kingdom I Protista Unicellular and simple multicellular eukaryotes Eukarya kingdom II Plantae Multicellular autotrophic eukaryotes Eukarya kingdom II Plantae Make their own food photosynthesis using chlorophylls a and b Eukarya kingdom II Plantae Have cell walls made of cellulose a polysaccharide Eukarya kingdom III Fungi mostly multicellular heterotrophic eukaryotes Eukaria kingdom IV Animalia Cells always lack cell walls Multicellular eukaryotes must ingest food heterotrophic Taxonomic classification of a tiger Species Population of similar Interbreeding individuals Panthera tigris Genus Groups of similar organisms that do not readily interbreed Panthera Leo onca pardus lion jaguar leopard The Biological Species Concept A species is a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups Evolution the process Genetic change in populations over time Evolution the basic theory Cumulative genetic changes produce new variants of organisms over time new taxa Increasing diversity of organisms Phylogenetic approach Begins with morphology and genomics how similar divergent Determines historical Relationships evolutionary framework Traces evolutionary Pathways common ancestors Mendel s Laws of Inheritance Law of segregation 1st law Independent assortment Inheritance of heredity The transmission of traits from one generation to the next Variation Offspring differ somewhat in appearance from parents and siblings How do we get gametes Meiosis S phase Stage of interphase when DNA replicates Homologous chromosome pairs possess the same genetic information but not identical DNA sequences Homologous chromosomes pair up during meiosis and have an important role here Heterozygous Two different alleles Homozygous 2 same alleles Phenotype The total physical appearance of the organism but it can also be things like blood type behavior and metabolic processes Genotype The genetic makeup of an organism Sources of genetic variation Independent assortment Random mating Crossing over Independent assortment 50 50 chance sister chromatids will end up on one side or another 8 million different assortments Crossing over homologous chromosomes exchange parts Gives additional recombinant chromosomes What is the mechanism of inheritance Genes Mendel Father of genetics Pea Plants Law of segregation Law 1 Alternate versions of gene alleles Law 2 One trait comes from mom and one from dad Law 3 Of alleles are different then the dominate genes will be used Law 4 Two alleles will then segregate during meiosis