What is Biology? Bio. 100 Tri-County Tec. College Pendleton, S. C.

Biology The Science of Life Best defined as the “scientific study of life Two critical important questions that divide our society: (1) When does life begin, and (2) When does life end?

Characteristics of Life Living things can and do: Metabolize Maintain homeostasis Respond to stimuli (irritability) Grow and reproduce Adapt and evolve

Cell Theory The cell is the structural and functional unit of life All living things are composed of one or more cells Cells can only come from preexisting cells

Types of Cells Prokaryotic cells do not have a nucleus or membrane-bound organelles Not as complex, sophisticated, nor as large as eukaryotic cells Eukaryotic cells have a nucleus and membrane-bound organelles Subdivided by membranes into compartments

The Three Domains It has been proposed to divide all living things into one of three domains: Archaea More closely related to Eukarya Bacteria Eukarya Contains all the eukaryotes

Five Kingdom Scheme Monera (Prokaryotae) Contains all the prokaryotes Protista Estes defines as the “swing’ kingdom Fungi Plantae Animalia

The Unifying Theme of Biology Evolution is the unifying theme of biology “change through time” Descent with modification Descent (life’s unity) and modification (diversity) Mechanism is natural selection Environment selects most suited traits

What is Science? A process that involves testing possible solutions to a problem or understanding an event in nature. The process that science uses is known as the scientific method What is the scientific method?

The Scientific Method a way of getting information an organized way of questioning involves rigorous testing of a proposed solution One aspect of the scientific method is observation.

Observations the use of our senses to record an event examples of observation the leaves on that tree are different from the others of the same kind of tree I urinate a lot when I drink coffee. Observations are followed by forming a hypothesis and testing it.

Hypotheses A hypothesis is a statement that provides a possible answer to a question or an explanation for an observation. Example-- Chemical A will kill weeds. To test this hypothesis, we set up experiments and controls.

Experiments and Controls Experiment recreation of an event in a way that enables a scientist to support or reject a hypothesis. experimental group and a control group Experimental group all members receive the experimental treatment Control group do not receive the experimental treatment

Definitions, continued Placebo is typically an nonmedicated substance given to the control group NCTR studies time Blind study: The participants do NOT know if they are in the control or experimental group Double-blind study: Participants and researcher(s) do NOT know which group is experimental and which is control

Testing our Hypothesis Hypothesis: chemical A will kill weeds Select two plots of soil with miscellaneous weeds growing on them. Treat one plot with chemical A Experimental Plot Treat another plot with water Control Plot

Plot A treated with Chemical A is the experimental plot. Plot B treated with water becomes the control plot.

Testing, ctd. Allow two weeks to elapse. Count the number of living weed plants on Plot A and Plot B. Keep careful records of the appearance of the plots such as when signs of dying begin to develop. What do you expect to see?

Plot A Plot B

Conclusions Chemical A will kill weeds under conditions of this study. Our hypothesis is supported by the experiment. One experiment is usually not enough to support a hypothesis.

Medicine and the Sci. Method When you go to a physician, he or she collects data through the process of physical examination, lab. tests, and other means. The physician then formulates two hypotheses-- a diagnosis of your ailment a course of treatment to help you get better

Medicine, ctd. You, the patient, then carries out the experiment by following whatever treatment protocol is prescribed If you get well the hypothesis is supported. If you don’t get well the hypothesis is not supported and the physician formulates another hypothesis.

Theories and Laws Theory a hypothesis that has been supported by years of repeated experimentation and evidence gathering. “Germ Theory of Disease” Law a widely accepted theory a constant fact of nature Law of Biogenesis

Two Mindsets of Science Inductive reasoning is generalization that summarizes many concurrent observations Specific to the general Hypothesis driven (Deductive) asks questions and seeks explanations General to specific Takes form of prediction(s) “if…then” logic

Believe it or Not Peppered moths data Spider mimic experiments DDT; antibiotics; HIV Time for an Estesism