50 questions 2 pts per questions Curve: 1.5 or 1.25 off per wrong answer 96% with 2 wrong A 97% curved A 30% (15 out of 50) F 47.5% F Chapter 1 Life, hierarchy of complexity Atom Molecules Cells (simplest level of living complexity) Tissues Organs Systems Multicellular organisms Populations Community Ecosystem Biosphere What is science? What is natural science? Question/problem Hypothesis Theory Cell Theory Germ Theory Chapter 2 Atoms Protons + Neutrons 0 Electrons – Atomic number: # or protons; identifies the element that the atom is Hydrogen 1 proton; 0 neutrons; 1 electron Deuterium 1 proton; 1 neutron; 1 electron (isotope of hydrogen) Helium 2 protons; 2 neutron; 2 electrons (different chemical properties than H) 1) Covalent bond: shares electrons, occur if more stability results 2) Ionic bond: transfer of electrons, bond is based on electrical attraction 3) Hydrogen bond: attraction between polar molecules Polar molecules have an uneven distribution of electrons, have a + pole and a – pole Water is polar: It has surface tension (it sticks to itself, forms droplets, cohesive) It dissolves ionic compounds (salts), other polar molecules. Does not dissolve non-polar (e.g. oil) Water buffers temperature changes. Lot of heat needed to warm water, water must lose much heat to cool. Water absorbs much heat when it evaporates. Water is a good heat sink. Molecule: more than one atom bonded together Compound: more than one element bonded together Water has pH H20 H+ + OHWater disassociates Pure water [H+] and [OH-] are equal pH = 7 in pure water if more H+ than OH-, pH < 7, acidic if less H+ than OH-, pH > 7, basic pH 2 pOH 2 pH 7 pOH 7 HCl acid NaOH base Buffered solution resists changes in pH (either direction)