Scientific Method Biology Coach Kirkpatrick

Introduction  Science: A way to investigate.  Biology: The study of life

Scientific Method A system of steps that scientists use to investigate questions. –Observations: Questioning, wandering or noticing something. –Hypothesis: Explanation that might be true— educated guess. IT MUST BE TESTABLE! –Prediction: What you expect to happen if the hypothesis is true. “If…then” statement. –Experiment: Planned and controlled procedure to test hypothesis.

Controlled experiment  Control group: Group that receives no experimental treatment.  Experimental group: Receives some type of experimental treatment. –Independent variable: The variable that changes or varies in an experiment. –Dependent variable: Variable that is measured in an experiment. What is observed in the end.

Scientific Method –Conclusions: Decisions about whether hypothesis was supported based on analysis of data. Many experiments may lead to a theory. Theory: Set of related hypotheses that have been tested over and over by many different scientists.

Energy  Ability to cause changes on matter.  Chemical reactions either use or give off energy.  Reactants  Products  Reactions in our bodies are critical.  Metabolism includes all chemical and physical reactions that occur to make energy available to an organism.  Homeostasis is our bodies ability to maintain a balance.

–Blood pressure –Body temperature –Blood sugar levels  Metabolism helps us maintain homeostasis.

Chemical Energy in the Body  Homeostasis and metabolism depends on the chemistry of the body.  pH is a measure of how acidic or basic a substance is.  The scale goes from 0-14 with 7 being neutral. Below 7 are acids, above is a base.  This balance is critical in the body. The stomach is very acidic while the intestines have a higher pH and blood is actually slightly basic.

Enzymes  Enzymes help chemical reactions take place.  These are proteins that help speed up chemical reactions (catalyst) by lowering activation energy—energy needed to start reactions.  They bond based on size and shape.  They end in –ase and if they don’t work properly it could result in death.

 Things that alter enzymes: –Enzymes can be denatured (structure gets broken down and they don’t do their job) by temperature or pH changes. –Temperature: Extreme temperatures cause enzymes to change shape and the can’t function –pH: Enzymes have a narrow pH range in which they are most effective and won’t work outside of that range. –Poisons denature enzymes leaving them unable to function resulting in death in many instances.

Chemistry  Matter is composed of atoms.  Atoms interact with one another to form compounds.  Electrons around the outside of atoms interact to form bonds.  Three types of bonding: –Ionic: When atoms gain or lose electrons to form compounds. Na +1 loses its one electron to Cl -1 which only needs one.

–Covalent: Atoms can share electrons so that each of their outer shells are full part of the time because the electrons are in constant motion. Ex: CH 4 & H 2 O. –Hydrogen: Weak bonds form between hydrogen and other atoms. Ex: bonds holding water molecules together.

Acids/Bases  Acid: Will form H + ions when dissolved in water.  Base: Will for OH - ions when dissolved in water.  pH: A measure of the amount of H + ions in solution. The scale goes from 0-14 with the low end of the scale being acidic and the high end being basic. 7 is neutral.