Scientific Method

Biology

Coach Kirkpatrick

Introduction

Science: A way to investigate.

Biology: The study of life

Scientific MethodA 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: CH4 & H2O.

– 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.