Bio 213 - Exam I – CFOQ Test Questions with Correct Answers

What are the first 2 tenets of the Cell theory and who proposed them? 1. All organisms are composed of one or more cells. 2. The cell is the structural unit of life. Proposed by Schleiden & Schwann in 1838 What is the third tenet of the Cell theory and who proposed it? 3. Cells can only arise by division from a preexisting cell. Proposed by Virchow in 1855 What theory did Pasteur's Experiment support and which theory did the experiment disprove? Supported: Germ theory - Omne vivum ex ovo (all life is from eggs) Disproved: Spontaneous Generation Describe Pasteur's Experiment Growing bacteria in 2 flasks, 1 with an open neck, 1 with a cursed S shaped neck. They are sterilized and then allowed to incubate. Bacteria grew in the open neck flask and did not in the S shaped flask. Free flowing air allowed bacteria to get back into the open neck flask while the S shape caught bacteria. Pasteurization "low" heat treatment food preservation. Kills a part of microorganisms in food. Nature of food does not change, preserves nutrient value of food. Sterilization Uses higher temperatures to extend shelf life by a few months. Another form o thermal processing and doesn't preserve as much nutrient value. Catabolic Breaking down Anabolic Building up Why does salt water freeze at lower temperatures then regular water? Salt water has to push the salt molecules away in order make crystalline structure Properties of Water Bond angle and covalent bonds make it a dipolar molecule High boiling point High specific heat Liquid at room temperature Lower density as solid (ice floats) Surface tension Are hydrogen bonds limited to water? No, it is extremely important in DNA, binding together the two strands with a Hydrogen and either an oxygen or nitrogen. Where in a cell might a hydrophobic interaction be needed? In the membrane, as it separates the external environment from the internal. These interactions are also essential in protein structure. Van der Waals Attractions A momentary attraction between molecules Avogadro's Number 6 x 10^23 Molarity M; 1 mol / 1 Liter Water Constant Kw = 1 x 10^-14 Acids Donate protons (H+ atoms); low pH numbers Bases Accept protons (H+ atoms); High pH numbers How much stronger of an acid is pH 4 than pH 6? 100X What is a buffers purpose? Resist change in pH when a small amount of acid or base is added What do buffers consist of? A mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. What defines a specific buffers pH range? its equilibrium dissociation constant. (some acids cling harder to H+ and can only be removed in more alkaline environments) Are cells buffered? Yes