What is science An intellectual activity encompassing observation description experimentation and explanation of natural phenomena Why should we understand the way science works Scientific literacy a general fact based understand of the basics of science An adaptable process that can be done effectively in numerous ways o Interesting patterns cause and effect relationships o Based on observations a proposed explanation for observed What is biology The study of living things o The scientific method What is the scientific method What are its steps Observations Hypothesis phenomena Testable predictions Experiment Conclusions and revisions Retest conclusions Steps are self correcting What purpose do they serve and why The conclusions suggest new observations refinements increasingly precise What are hypotheses and predictions and how do they differ Must clearly establish mutually exclusive alternative explanations for a Must generate testable predictions Null hypothesis a hypothesis that states the lack of relationship between phenomenon two factors o Easier to disprove o Echinacea has no effect on the common cold Impossible to prove that a hypothesis is absolutely and permanently true What does it mean if your results don t match your predictions Helps us understand when we should change our minds revise hypothesis What is a scientific theory An explanatory hypothesis for natural phenomena that is exceptionally well A hypothesis that was withstood the test of time and is unlikely to be altered supported by the empirical data by any new evidence Already been repeatedly tested and nothing has contradicted it o Cell theory all organisms are composed of cells and all cells come from preexisting cells o The of evolution by natural selection species can change over time and all species are related to one another through common ancestry How do you set up a good experiment What do you need to include think about for an experiment to be valuable Controlling variables make experiments more powerful Treatment Experimental group group exposed to treatment Control group treated identically to experimental group but not exposed to the treatment change Variables characteristics of an experimental system that are subject to o Ex dosage of Echinacea measure of hair coarseness o Control variables describe the attempt to minimize any variables between a control group and an experiment group other than the treatment itself Thus any differences are due to the treatment Placebo effect phenomenon where people respond favorably to any treatment highlights the need for an appropriate control group Clever Hans phenomenon Blind experimental design the experimental subjects do not know which treatment they are receiving if any Double blind experimental design neither the experimental subjects or the experimenter know which treatment a subject is receiving Combines the blind double strategies in a randomized controlled double blind study Experiments must be repeatable for their conclusions to be considered valid and widely accepted Independent variable a measurable identify that is available at the start of the process and whose value can be changed as required Dependent variable one that is created by the process being observed and whose value cannot be controlled What are statistics A set of analytical and mathematical tools designed to help researchers gain understanding from the data they gather Positive correlation when one variable increases so does the other o Correlation is not causation Unifying themes of the study of life Hierarchical organization life is organized on many levels within individual organisms populations communities ecosystems biosphere The power of evolution evolution the change in genetic characteristics of individuals within populations over time accounts for the diversity of organisms but also explains the unity among them The chemical cellular and energetic foundations of life The genetics evolution and behavior of individuals The diversity of life and the unity underlying it Ecology the environment and the subtle and important links between organisms and the world Cells Chapter 3 What is a cell The most basic unit of any organism the smallest unit of life that can function independently and perform all the necessary functions of life including reproducing itself A 3d structure in which many of the essential chemical reactions of life take place o These reactions involve transporting raw meterials and fuel into the cell and exporting finished materials and waste products out of the cell o Nearly all cells contain DNA What is cell theory All living organisms are made up of one or more cells All cells arise from preexisting cells What are prokaryotes and eukaryotes Prokaryotes no nucleus DNA is in the cytoplasm Eukaryotic cell has a central control structure called the nucleus which contains the cells DNA How are they similar different than eukaryotes Prokaryotes are smaller evolutionarily older and structurally more simple o Plasma membrane encompasses the cell o Cytoplasm is the jelly like fluid inside the cell o Ribosomes proteins are made and scattered throughout the cytoplasm o Contains one or more circular loops or linear strands of DNA o Rigid cell wall protects and gives shape o Flagellum whip like projection that moves the cell through the o Pili thinner hair life projection that helps attach to surfaces tubes medium which it lives which DNA is exchanged o All bacteria are prokaryotes and arcaea o Prokaryotes are smaller evolutionarily older and structurally more simple than eukaryotes All plants and animals are eukaryotic and much larger o Nucleus membrane enclosed structure that contains linear strands of DNA o Organelles specialized structures in cytoplasm and enclosed separate within their own lipid membranes What is the plasma membrane and what is it made of A fluid mosaic of proteins lipids and carbohydrates Proteins found in the plasma membrane enable it to carry out most of its gatekeeping functions the proteins act as receptors that help molecules gain entry in and out of the cell catalyze reactions in conjunction with carbohydrates some plasma membrane proteins identify the cell to other cells cholesterol influences fluidity every cell in enclosed by a plasma membrane a two layered membrane that holds the contents of a cell in place and regulates what enters and leaves the cell Made of a phospholipid bilayer Transmembrane proteins penetrate right through the lipd