Answers for Chapter#2 Which of the following forms of energy is the stimulus for vision? chemical, electrical, mechanical, radiant. All of the following are examples of the four major elements contributing to body mass except hydrogen, carbon, nitrogen, sodium, oxygen. The mass number of an atom is equal to the number of protons it contains, the sum of its protons and neutrons, the sum of all of its subatomic particles, the average of the mass numbers of all of its isotopes. A deficiency in this element can be expected to reduce the hemoglobin content of blood: Fe, I, F, Ca, K. Which set of terms best describes a proton? negative charge, massless, in the orbital; positive charge, 1 amu, in the nucleus; uncharged, 1 amu, in the nucleus. The subatomic particles responsible for the chemical behavior of atoms are electrons, ions, neutrons, protons. In the body, carbohydrates are stored in the form of glycogen, starch, cholesterol, polypeptides. Which of the following does describe a mixture? properties of its components are retained, chemical bonds are formed, components can be separated physically, includes both heterogeneous and homogeneous examples. In a beaker of water, the water-water bonds can properly be called ionic bonds, polar covalent bonds, nonpolar covalent bonds, hydrogen bonds. When a pair of electrons is shared between two atoms, the bond formed is called a single covalent bond, a double covalent bond, a triple covalent bond, an ionic bond. Molecules formed when electrons are shared unequally are salts, polar molecules, nonpolar molecules. Which of the following covalently bonded molecules are polar? Identify each reaction as one of the following: a synthesis reaction, a decomposition reaction, an exchange ____ 2Hg + O2 S 2HgO _____ HCl + NaOH S NaCl + H2O Factors that accelerate the rate of chemical reactions include all but the presence of catalysts, increasing the temperature, increasing the particle size, increasing the concentration of the reactants. Which of the following molecules is an inorganic molecule? sucrose, cholesterol, collagen, sodium chloride. Water’s importance to living systems reflects its polarity and solvent properties, its high heat capacity, its high heat of vaporization, its chemical reactivity, all of these. Acids release hydroxyl ions when dissolved in water, are proton acceptors, cause the pH of a solution to rise, release protons when dissolved in water. A chemist, during the course of an analysis, runs across a chemical composed of carbon, hydrogen, and oxygen in the proportion 1:2:1 and having a six-sided molecular shape. It is probably a pentose, an amino acid, a fatty acid, a monosaccharide, a nucleic acid. A triglyceride consists of glycerol plus three fatty acids, a sugar-phosphate backbone to which two amino groups are attached, two to several hexoses, amino acids that have been thoroughly saturated with hydrogen. A chemical has an amine group and an organic acid group. It does not, however, have any peptide bonds. It is a monosaccharide, an amino acid, a protein, a fat. The lipid(s) used as the basis of vitamin D, sex hormones, and bile salts is/are triglycerides, cholesterol, phospholipids, prostaglandin. Enzymes are organic catalysts that alter the direction in which a chemical reaction proceeds, determine the nature of the products of a reaction, increase the speed of a chemical reaction, are essential raw materials for a chemical reaction that are converted into some of its products.