MCB 2010C MCB 2010C EXAM 2 FSW 2024|2025 Micr obiology EXAM @Q uestion And Answer (CORRECT ANSWER) Salt and sugars work to preserve foods by creating a Lower osmotic pressure A depletion of nutrients A hypotonic environment A hypertonic environment A hypertonic environment Salt and sugars work to preserve foods by creating a hypertonic envi ronment, which dehydrates microbial cells and inhibits their growth. Water has an unequal distribution of charges and is called a(n) a)nonpolar molecule. b)polar molecule. c)hydrophobic molecule. d)org anic molecule. b)polar molecule : think of the north and south pole, opposite partial charges within a water molecule (partial positive hydrogen and partial negative oxygen) wrong answers: nonpolar molecule= no partial charges because the electrons are evenly distributed hydrophobic molecule= water -fearing organic molecule contains carbon and hydrogen MCB 2010C In a dehydration synthesis reaction, a)a larger molecule is broken down into smaller parts. b)old bonds are broken and new bonds are formed. c)neither the reactants nor end products are stable. d)atoms, ions, or molecules are combined to form a larger molecule. d)atoms, ions, or molecules are combined to form a larger molecule. Dehydration synthesis is the process of building larg er molecules (synthesizing) and in the process you dehydrate the molecules forming a chemical bond and water. A-OH + H -B = A -B + H2O The building of complex organic molecules from simpler ones is called a)catabolism. b)anabolism. c)photosynthesis. d)ox idation. b)anabolism. Anabolism is the process of using smaller molecules to build larger ones. In this process chemical bonds are formed through dehydration synthesis and energy is used. An example is photosynthesis. Catabolism is the process of breakin g larger molecules down into smaller ones. In this process chemical bonds are broken through hydrolysis or decomposition releasing energy. An example is cellular respiration. MCB 2010C Oxidation reduction reactions are due to the removal and subsequent gain of elec trons from an atom or molecule. What happens to enzyme activity at temperatures above optimum but before denaturation? a)Enzyme activity stays the same. b)Enzyme activity decreases. c)Enzyme activity increases. b)Enzyme activity decreases. Enzyme a ctivity increases with temperature until the optimum temperature is reached. After the optimum temperature the enzyme activity will decrease and too far past the optimum temperature the enzyme will denature. When every enzyme's active site is reacting with a substrate, it is called __________. a)saturation b)competitive inhibition c)denaturation d)noncompetitive inhibition a) saturation MCB 2010C Saturation is when every enzyme's active site is reacting with a substrate. In a graph the line for enzyme activity w ill plateau or level off flat. Competitive and noncompetitive inhibition interfere with the enzyme at either the active or allosteric site, respectively. Denaturation is when the 3 -D shape of an enzyme falls apart. Inhibitors that fill the enzyme's ac tive site and compete with the normal substrate are a)noncompetitive. b)allosteric. c)competitive. d)conformational. c)competitive. Competitive inhibitors are called such because they compete with the enzyme’s substrate by interacting with and blocking th e active site. Non -competitive or allosteric inhibitors bind to the alternate (allosteric) site which causes a change in shape (conformational change) of the active site so the enzyme cannot interact with its substrate. A molecule that undergoes reduct ion a)becomes phosphorylated. b)loses a hydrogen atom. c)gains one or more electrons. d)loses one or more electrons.
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