Life 102 Exam 1 CSU Arthun Questions and Answers Already Passed

Life 102 Exam 1 CSU Arthun Questions and Answers Already Passed At what organizational level is life's uniformity most evident? Most evident in cells At what organizational level is life diversity most evident? Most evident in organisms How do Atoms fill their Valence shell? Donate or accept electrons from another atom or two atoms can share an electron pair creating a covalent bond. What happens when an atom gains or loses an electron? It becomes ionic 96% of living mater is composed of which elements? Carbon, Nitrogen, Hydrogen, Oxygen (HONC) How can you distinguish one element from another? By the number of protons What are isotopes? Isotopes are the same element, with a different number of neutrons. How do isotopes differ? Based on their number of neutrons What is a covalent bond? A covalent bond is when two atoms share an electron pair What is the difference between a polar and non-polar covalent bond? Polar covalent bond electrons are not equally shared between the two atoms, non-polar are equally shared How do atoms share a pair of electrons? Through covalent bonds What effect does the sharing of a pair of electrons have on their valence shells? They can fill their valence shells How many electrons does it take to fill the valence shells of C, H, O, N Carbon-4 Nitrogen-3 Oxygen-2 Hydrogen-1 Why are hydrogen bonds important for biological molecules? Example of a biological molecule that contains hydrogen bonds They are important because due to them water has a high heat of vaporization, it will cause a high specific heat as we. It is also important for giving stabilization without permanent bonds. DNA is an example of a biological molecule containing hydrogen bonds What does mass conservation law state? Mass can be changed from one form to another but the overall mass does not change (number of molecules doesn't change) What does it mean when a reaction is reversible? Because its a reaction that can go from reactants to products or products to reactants. What is chemical equilibrium? When the rate of the forward reaction is equal to the rate of the reverse reaction. Why is water a polar molecule? Because it has a partial negative charge and a partial positive charge because the oxygen is partially negatively charged and hydrogen is partially positive. What type of bonds do water molecules form with each other? Hydrogen bonds What are the properties of water? Cohesion, surface tension, high specific heat, heat of vaporization. Cohesion high surface tension surface tension measure of how hard it is to stretch/break the surface of a liquid high specific heat the amount of energy it takes for temperature to raise 1 degree Heat of Vaporization amount of energy it takes to go from a liquid to a gas What is the density of water at various temperatures? Water is frozen at 4 degrees celsius Why does ice float? Because water molecules are more spread out when frozen (expand)