PracticeQuestions_Chapter02 - Chapter 2 Sample Questions 1...

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Unformatted text preview: Chapter 2. Sample Questions 1. An element may have more than a one isotope. Isotopes have different atomic weights, but exhibit the same chemical behavior. Carbon-14 is an unstable isotope of carbon that decays very slowly. Compared to the common, stable carbon-12 isotope, carbon-14 has two additional ______________. A. electrons B. neutrons C. protons D. ions E. orbitals 2. Which of the following elements is least abundant in living organisms? A. sulfur B. carbon C. oxygen D. nitrogen E. hydrogen 3. For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below. Not all words or phrases will be used; each word or phrase should be used only once. Whereas ionic bonds form a(n) __________________, covalent bonds between atoms form a(n) __________________. These covalent bonds have a characteristic bond __________________ and become stronger and more rigid when two electrons are shared in a(n) __________________. Equal sharing of electrons yields a(n) __________________ covalent bond. If one atom participating in the bond has a stronger affinity for the electron, this produces a partial negative charge on one atom and a partial positive charge on the other. These __________________ covalent bonds should not be confused with the weaker __________________ bonds that are critical for the three-dimensional structure of biological molecules and for interactions between these molecules. charge covalent double bond ionic length molecule noncovalent nonpolar polar salt single bond weight 4. Which of the following(s) is/are Not true for covalent bond? A. It takes about 2~5 kcal to break a mole of covalent bonds. B. Shapes of atomic orbitals altered when forming covalent bonds. C. Shared electrons in the covalent bonds stay closer to more electronegative nucleus (atom) D. Covalent bonds form because atoms are most stable when their valence shell is completely filled. E. Hydrogen can make up to 2 covalent bonds with other atoms. 5. With of the following(s) are/is Not true for noncovalent bond? A. Noncovalent bonds are attractive force. B. Noncovalent bonds can form and break easily. C. Noncovalent bonds involve electron transfer between atoms or molecules. D. Noncovalent bonds form exclusively between polar molecules. 6. Where are hydrophobic interactions most likely to occur? A. on the surface of a water-soluble protein B. inside of a water-soluble protein C. in contact with water molecules D. between two charged molecules E. between two ions 7. Double bonds may join some of the carbons in long hydrocarbon chains such as in fatty acids. When the double bond is in ________ configuration it causes a bend in the hydrocarbon chain. A. trans B. cis C. beta D. alpha 8. Which of the following bonds (that may occur between atoms in biological molecules) would be the LEAST polar? A . C -O B. C=O C . C -H D . C -N 9. Name the following functional groups -OH, -C=O, -COOH, -CHO, -SH, -NH2, -SH 10. Which of the following(s) is/are not linear polymers? A. protein B. glycogen C. cellulose D. amylopectin E. chitin 11. Several minutes after the Big Bang, the universe was cooled down enough for subatomic particles to fuse into hydrogen and helium atoms. No atoms with larger nuclei such as carbon, oxygen were not produced. Even now, most of atoms in the universe are still hydrogen and helium. However, living organisms on Earth have not only hydrogen but also many heavier atoms including carbon, oxygen, nitrogen, and so on. Where did these heavy atoms come from? A. Ancient Earth B. Stars C. Intergalactic space D. Gaseous planets E. Volcanic activity 12. Which of the following is NOT a fundamental property of carbon? A. Carbon-containing molecules are diverse. B. Carbon-containing molecules form stereoisomers. C. Carbon-containing molecules are stable. D. Carbon has a valence of 4. E. Carbon atoms are most likely to form ionic bonds with one another. 13. What is the noncovalent interaction in which two non-polar molecules that are so close that they can experience weak attractive forces? A. H bonds B. ionic bonds C. hydrophobic interactions D. polar covalent bonds E. van der Waals forces 14. Which of the following is the weakest interaction? A. H bond B. covalent bond C. ionic bond D. phosphoanhydride bond E. Van der Waals interaction 15. Why is silicon not suitable for making stable and strong covalent bond to form long chain molecules as carbon that is just above in the periodic table? A. Silicon is too large for its nucleus to attract the valence electrons of neighboring atoms enough to hold molecules together. B. Silicon is too small for its nucleus to attract the valence electrons of neighboring atoms enough to hold molecules together. C. Silicon is too large for its nucleus to attract the protons of neighboring atoms enough to hold molecules together. D. Silicon is too small for its nucleus to attract the protons of neighboring atoms enough to hold molecules together. 16. Biologically, which of the following is the least important characteristic of water? A. Water molecules are polar. B. Water molecules have numerous hydrogen bonds. C. Water is a good solvent. D. Water typically contains isotopes of hydrogen. E. Water has a temperature stabilizing capacity. 17. The low-molecular-weight building blocks of polymers are called _______. A. Oligomers B. monoblocks C. Monomers D. Portions E. Octamers 18. Which of the following are examples of stereoisomers? A. Alanine and glycine B. Adenine and adenosine C. Amylopectin and cellulose D. Galactose and glucose E. choline and ethanolamine 19. Indicate whether the statements below are true or false. If a statement is false, explain why it is false. A. A disaccharide consists of a sugar covalently linked to another molecule such as an amino acid or a nucleotide. B. The hydroxyl groups on monosaccharides are reaction hotspots and can be replaced by other functional groups to produce derivatives of the original sugar. C. The presence of double bonds in the hydrocarbon tail of a fatty acid does not greatly influence its structure. D. Glycerol is a three-carbon compound that connects the fatty acid tails with the polar head group in phospholipids. 20. What bond sets up the branch points in glycogen and amylopectin? A. Alpha(1->4) glycosidic linkages B. Beta(1->4) glycosidic linkages C. Alpha(1->6) glycosidic linkages D. Beta(1->6) glycosidic linkages E. 3'-5' phosphodiester linkages 21. Which of the following polysaccharide bonds is not broken by digestive enzymes produced in mammals? A. Alpha(1->4) glycosidic linkages B. Beta(1->4) glycosidic linkages C. Alpha(1->6) glycosidic linkages D) Beta(1->6) glycosidic linkages E) phosphate ester linkages 22. Which of the following polysaccharides consist(s) of more than one type of building blocks? A. amylopectin B. cellulose C. chitin D. glycoaminoglycan E. A and D 23. Which of the following is not a macromolecule formed by polymerization? A. proteins B. lipids C. polynucleotides D. polysaccharides E. DNA 24. Linseed oil and tristearate are both triacylglycerols and have similar molecular weights. However, linseed oil is liquid at room temperature while tristearate is solid. Explain why. 25. Select steroids from the list below. niacin, guanosine, cholic acid, calcitonin, testosterone, cholestrol, retinoic acid 26. What is the name of four-ringed hydrocarbon common to all steroids? 27. Adenosine is a a. component of RNA. b nucleotide. c. pyrimidine. d. a and b e. all of the above 28. Which of the following statements is false? (a) ATP contains high-energy phosphoanhydride bonds. (b) ATP is sometimes called the “universal currency” in the energy economy of cells. (c) ATP can be incorporated into DNA. (d) ATP can be hydrolyzed to release energy to power hundreds of reactions in cells. (e) ATP comprises a sugar, phosphate groups, and a nitrogenous base. 29. Macromolecules in the cell can often interact transiently as a result of noncovalent interactions. These weak interactions also produce stable, highly specific interactions between molecules. Which of the factors below is the most significant in determining whether the interaction will be transient or stable? (a) the size of each molecule (b) the concentration of each molecule (c) the rate of synthesis (d) surface complementarity between molecules 30. Indicate whether the statements below are true or false. If a statement is false, explain why it is false. A. “Nonpolar interactions” is simply another way of saying “van der Waals attractions.” B. Condensation reactions occur in the synthesis of all the macromolecules found in cells. C. All proteins and RNAs pass through many unstable conformations as they are folded, finally settling on one single, preferred conformation. D. When nonpolar molecules are placed in an aqueous solution, the water molecules surrounding the nonpolar surface become completely disordered. 31. The interactions between two proteins such as an antibody and an antigen or a hormone and its receptor are quite strong despite the fact that these interactions consist of relatively weak noncovalent bonds. How can this be? 32. Triacylglycerol is nonpolar; in contrast, phospholipids are amphipathic molecules. Biomembranes are based on phospholipids rather than on triacylglycerols. Why? 33. Choose the item in column 2 that best matches each item in column 1. 1) weakens ionic bonds in water 2) important in hydrogen bonding 3) structural polysaccharide 4) informational macromolecule 5) membrane structure A) hydroxyl group B) assists in protein assembly C) glycogen D) assists in lipid assembly E) spheres of hydration F) lipid bilayer G) nucleic acid H) cellulose I) ATP J) methyl group ...
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