Biology Wischusen Essay

Observation Must be observable Generalization or model We are always looking more better models are are more accurate Prediction or Hypothesis Testing Someone else must be able to do your experiment or test What is the outcome of this process? A continuation tot the Scientific New discoveries and advances Terminology

Hypothesis-an educated answer to a well framed question; “an explanation on trial”; an untested theory of a phenomena Theory-supported and proven/tested hypothesis Law-widely accepted theory proved many times over We are going to begin by using the reductionism approach Reducing down to its fundamental parts Start small and put the pieces together Whilst approach (opposite):looking at something as a whole first Scales of Nature Atomic: smallest (IOWA-8 meters) Community/Ecosystem: largest (IOWA meters) Atoms: smallest unit of matter separated by normal chemical means; smallest unit of n element that retains all of the elements properties; an atom is composed of many smaller particles.

Proton Positively charged Located in the nucleus Weighs 1 Dalton Neutron No charge Electron Negatively charged Located in the electron cloud Weighs less than 1 Dalton Element Substance that cannot be broken down into other substances by chemical reactions Organisms are composed of roughly 1 1 elements 92 elements are natural 20-25% of elements are essential (an organism needs them to live) Trace elements are required only in minute quantities Boor Model This model has electrons moving in orbital or shells around the nucleus Electrons rye to always be in the lowest orbital or energy shell (closest to the nucleus) Lowest level: K Next level: L The outer most shell is called the valence shell Valence and valence electrons are different Valence electrons: electrons on the outermost shell Valence: number of electrons needed to be gained or lost in order to fill the outer shell What determines solubility? “Like dissolves like” “Like” in terms of polarity Polar dissolves polar and vice versa What determines polarity?

How many bonds are made determines polarity The type of bond determines polarity Isotope Different atomic forms of the same element They can be light or heavy Same number of protons but different number of neutron Energy The capacity to do work Chemical Bonds: form when atoms gain or lose electrons/share electrons and are a result of an electrical attraction Strong Ionic Bonds Form when atoms completely gain or lose electrons Strongest bonds when dry Usually a metal and a non-metal A non-sharing of electrons Covalent Bonds A sharing of electrons Strongest bonds in water Equally shared�pure and non-polar Not equally shared�polar (one atom is pulling the electrons more than the other one) Weak Not involved in making a substance Hold atoms together

Cause interactions between molecules A bond which the result of very weak electrical attractions between atoms bearing partial electrical charges are Weak attractions between atoms on different molecular or different parts of a large molecule Hydrogen is partially positive Oxygen is partially negative Water is polar covalent One atom involved must be hydrogen Very, very weak Occur between molecules that are polar covalent to ionic Partial bonds Water The only common substance to exist in the natural environment in all 3 physical stages Cells are 70-90% water water bonded together