BIO 202 Final Exam Material.pdf - Midterm 1 Chapter 2 The...

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Midterm 1 Chapter 2: The Chemical Context of Life Concept 2.1: Matter consists of chemical elements in pure form and in combinations called compounds * 92 naturally occurring elements * only about 20-25% are needed by organisms to survive and reproduce (essential elements) Concept 2.2: An element’s properties depend on the structure of its atoms * atomic number = tells the number of protons in an element (written as subscript on left of element’s symbol) * mass number = protons + neutrons (written as superscript on left of element’s symbol) * isotope = atoms that have more neutrons than neutral atoms * radioactive isotope = one in which the nucleus decays spontaneously, giving off particles and energy * radiometric dating = a process used to measure the ratio of different isotopes and calculate how many half-lives have passed since an organism was fossilized or a rock was formed * potential energy = the energy matter possesses because of its location or structure * matter has natural tendency to move toward the lowest possible state of potential energy * atoms with same number of electrons in their valence shells exhibit similar chemical behaviors * noble gases are inert, or chemically unreactive (due to full valence shells)
Concept 2.3: The formation and function of molecules depend on chemical bonding between atoms * covalent bonds, single/double/triple bonds, ionic bonds, hydrogen bonds * van der Waals interactions = individually weak interactions that occur only when atoms and molecules are very close together * molecular shape determines how biological molecules recognize and respond to one another with specificity Concept 2.4: Chemical reactions make and break chemical bonds * chemical equilibrium = in a chemical reaction, the state in which the rate of the forward reaction equals the rate of the reverse reaction so that the relative concentrations of the reactants and products do not change with time ______________________________________________________________________ Chapter 3: Water and Life Concept 3.1: Polar covalent bonds in water molecules result in hydrogen bonding * water has polar covalent bonds (oxygen region is partially negative and hydrogen region is partially positive) Concept 3.2: Four emergent properties of water contribute to Earth’s suitability for life * water has 4 emergent properties that contribute to Earth’s suitability for life = (1) cohesive behavior, (2) ability to moderate temperature, (3) expansion upon freezing, and (4) versatility as a solvent * cohesion = the linking together of like molecules, often by hydrogen bonding * adhesion = the clinging of one substance to another, such as water to plant cell walls by means of hydrogen bonding
* surface tension = a measure of how difficult it is to stretch or break the surface of a liquid * water can absorb or release a relatively large amount of heat with only a slight change in temperature * kinetic energy = the energy of motion (the faster a molecules move, the greater its kinetic energy) * thermal energy = kinetic energy due to the random motion of atoms molecules; energy in its most random form (direct relationship with volume) * temperature = a measure of energy that represents the average kinetic energy of the molecules in a body of matter, regardless of volume * heat = thermal energy in transfer from one body of matter to another * calorie (cal) = amount of heat it takes to raise the temperature of 1g of water by 1°C * kilocalorie (kcal) = quantity of heat required to raise the temperature of 1

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