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Lecture 2 Review ProblemsKey

Lecture 2 Review ProblemsKey - Lecture 2 Review Problems 1...

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Unformatted text preview: Lecture 2 Review Problems 1. The most abundant molecule in the cell is a. a carbohydrate. b. a lipid. c. a nucleic acid. d. a protein. e. water. 2. All lipids are a. triglycerides. b. polar. c. hydrophilic. d. polymers of fatty acids. e. more soluble in nonpolar solvents than in water. 3. All carbohydrates a. are polymers. b. are simple sugars. c. consist of one or more simple sugars. d. are found in biological membranes. e. are more soluble in nonpolar solvents than in water. 4. Which of the following is not a carbohydrate? a. Glucose b. Starch c. Cellulose d. Hemoglobin e. Deoxyribose 5. All proteins a. are enzymes. b. consist of one or more polypeptide chains. c. are amino acids. d. have quaternary structures. e. are more soluble in nonpolar solvents than in water. 6. Which of the following statements about the primary structure of a protein is not true? a. It may be branched. b. It is held together by covalent bonds. c. It is unique to that protein. d. It determines the tertiary structure of the protein. e. It is the sequence of amino acids in the protein. 7. The amino acid leucine a. is found in all proteins. b. cannot form peptide linkages. c. has a hydrophobic side chain. d. has a hydrophilic side chain. e. is identical to the amino acid lysine. 8.Which of the following statements about condensation reactions is not true? a. Protein synthesis results from them. b. Polysaccharide synthesis results from them. c. They involve covalent bonds. d. They consume water as a reactant. e. Different condensation reactions produce different kinds of macromolecules. 9. The “building blocks” of polysaccharides are _______ and the blocks are covalently linked together by _______ bonds. a. glycerol and fatty acids; ester b. amino acids; peptide c. monosaccharides; glycosidic d. monosaccharides; ester e. disaccharides; glycosidic 10. A phospholipid differs from a triglyceride in that phospholipids a. are not derivatives of glycerol. b. are amphipathic. c. have both hydrophilic and hydrophobic parts. d. are used to store energy for the cell. e. do not contain fatty acids. 11. Which of the following statements about lipids is false? a. Lipids are a major component of the phospholipid bilayer. b. Lipids provide waterproofing for the surfaces of organisms. c. Steroid hormones are lipids. d. A number of vitamins are lipids. e. All of the above statements are true. 12. You have isolated an unidentified liquid from a sample of beans. You add the liquid to a beaker of water and shake vigorously. After a few minutes, the water and the other liquid separate into two layers. To which class of large biological molecules does the unknown liquid most likely belong? a. Carbohydrates b. Lipids c. Proteins d. Enzymes e. Nucleic acids 13. Starch and glycogen, which are both polysaccharides, differ in their functions in that starch is _______, whereas glycogen _______. a. the main component for plant structural support; is an energy source for animals b. a structural material found in plants and animals; forms external skeletons in animals c. the principle energy storage compound of plants; is the main energy storage of animals d. a temporary compound used to store glucose; is a highly stable compound that stores complex lipids e. is the main energy storage of animals; a temporary compound used to store glucose 14. A major component of RNA but not of DNA is: a. adenine. b. cytosine. c. guanine. d. thymine. e. uracil. 15. Compounds that contain a nitrogenous base, a sugar, and a phosphate group are called (a)_________Nucleotide________. Two purines found in DNA are (b)_________adenine_____ and ______________guanine____. A pyrimidines found in all DNA are (c)____thymidine_____________ and ____cytosine__________. In DNA, the base pair (d)_C__ ­__G_ is held together by three hydrogen bonds; the base pair (e)A___ ­_T__ has only two such bonds. 16. How do the different chemical properties of amino acid R groups contribute to the final threedimensional shape of the molecule? The size of the R group, the charge of the R group, and any special binding properties all contribute to the final orientation of a protein molecule. 17. Dietary guidelines encourage people to stay away from saturated fats. What is meant by the term “saturated fat”? Why is this type of fat of more concern than unsaturated fats in the diet? What is the structural difference between saturated and unsaturated fats? Saturated fats contain only single bonds and are “saturated” with hydrogen, which allows fat molecules to pack together densely. This characteristic is easily seen in that most saturated fats are solid at room temperature. Unsaturated fats contain double bonds that affect the shape of the molecule and are not “saturated” with hydrogen. This characteristic keeps them from packing together tightly, and they tend to be liquid at room temperature. Saturated fats are dangerous because of this “packing” ability. ...
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