Biology TEST: Chapter 2 the Chemistry of Life (Form: Mrk 2008)

Biology TEST: Chapter 2 The Chemistry of Life (Form: mrk 2008)

Do not write on this test form.

Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. Darken your choice on the Scantron answer sheet.

____ 1. The three particles that make up an atom are a. protons, neutrons, and isotopes. b. neutrons, isotopes, and electrons. c. positives, negatives, and electrons. d. protons, neutrons, and electrons. ____ 2. Isotopes are atoms of the same element with the same number of protons and a. a different number of electrons. b. a different number of molecules. c. a different number of neutrons. d. the same number of neutrons. ____ 3. Which of the following is a use of radioactive isotopes? a. can determine the ages of rocks and fossils b. can be used to treat cancer and kill bacteria that cause food to spoil c. used as “tracers” to follow the movements of substances within organisms d. all of the above ____ 4. Which of the following terms describes a substance formed by the combination of two or more elements in definite proportions? a. compound b. isotope c. nucleus d. enzyme ____ 5. A covalent bond is formed as the result of a. transferring electrons. b. sharing an electron pair. c. transferring protons. d. sharing a proton pair. ____ 6. What type of electron is available to form bonds? a. valence b. nucleus c. ionic d. covalent ____ 7. What type of ion forms when an atom loses electrons? a. neutral b. positive c. negative d. possibly positive or negative ____ 8. The most abundant compound in most living things is a. carbon dioxide. b. water. c. sodium chloride. d. sugar. ____ 9. Water molecules are polar, with the a. oxygen side being slightly positive and the hydrogen side being slightly negative. b. oxygen and hydrogen sides being slightly positive. c. oxygen and hydrogen sides being slightly negative. d. oxygen side being slightly negative and the hydrogen side being slightly positive. ____ 10. Solutions that contain concentrations of H+ ions lower than pure water a. have pH values below 7. b. are acids. c. are bases. d. are enzymes. ____ 11. Amino acid is to protein as a. fat is to lipid. b. DNA is to RNA. c. sugar is to fat. d. simple sugar is to starch. ____ 12. A monosaccharide is a a. carbohydrate. b. lipid. c. nucleic acid. d. protein. ____ 13. Which of the following organic compounds is the main source of energy for living things? a. carbohydrates b. lipids c. nucleic acids d. proteins ____ 14. Which of the following is NOT a function of proteins? a. store and transmit heredity b. help to fight disease c. control the rate of reactions and regulate cell processes d. build tissues such as bone and muscle ____ 15. Which of the following statements about enzymes is NOT true? a. Enzymes work best at a specified pH. b. All enzymes work inside cells. c. Enzymes are proteins. d. Enzymes are organic catalysts. ____ 16. Which of the following statements is true about catalysts? a. Catalysts slow down the rate of chemical reactions. b. All catalysts are enzymes. c. Catalysts are used up during a chemical reaction. d. Catalysts lower the activation energy of a chemical reaction. ____ 17. Enzymes affect the reactions in living cells by changing the a. products of the reaction. b. speed of the reaction. c. temperature of the reaction. d. pH of the reaction. ____ 18. What is the process that changes one set of chemicals into another set of chemicals? a. cohesion b. adhesion c. chemical reaction d. dissolving ____ 19. What is the term used to describe the energy needed to get a reaction started? a. adhesion energy b. activation energy c. cohesion energy d. chemical energy

Modified True/False Indicate whether the sentence or statement is true or false. Mark “A” for true or “B” for false on the Scantron answer sheet.

____ 20. Scientists show the composition of compounds by a kind of shorthand known as a chemical formula. ____ 21. When atoms share six electrons, they are joined by a double bond. ____ 22. Adhesion is responsible for the surface of the water in a graduated cylinder that is slightly curved at the sides. ____ 23. When sugar is dissolved in water, the sugar and water are chemically combined. ____ 24. A substance with equal numbers of ions and ions is an alkaline solution. ____ 25. Buffers are weak acids or bases that can react with strong acids or bases to prevent sudden changes in pH. ____ 26. Lipids are important parts of biological membranes and waterproof coverings. ____ 27. Polysaccharides are formed through the process known as polymerization. ____ 28. The substances that are present when a chemical reaction begins are the products. ____ 29. The chemical reaction of and is irreversible.

Completion Complete each sentence on this page and the next using the word bank below. If the answer chosen is made up of a letter combination, darken ALL the letters that make up that combination. a. acid ab. OH- ions bd. electrons b. -ase ac. nucleus be. hydrogen c. covalent ad. ionic cd. base d. chemical ae. H+ ions ce. polarity e. monomers bc. -ose de. products

30. Most of the mass of an atom is concentrated in the ______. 31. If an atom contains 15 protons, it must contain 15 ______. 32. Because they have the same number of protons and electrons, all isotopes of an element have the same ______properties. 33. A chemical bond formed by the transfer of electrons is a(an) ______bond. 34. A water molecule is polar because there is an uneven distribution of electrons between the oxygen and the ______atoms. 35. Water’s ______allows it to dissolve compounds such as table salt (NaCl). 36. The stomach produces a(an) ______to help digest food. 37. The pH scale is a measurement system that indicates the concentration of ______in solution. 38. Complex carbohydrates are to monosaccharides as polymers are to ______. 39. The elements or compounds produced by a chemical reaction are known as ______. 40. The name of an enzyme usually ends in ______.

USING SCIENCE SKILLS

Atomic Mass Element Symbol Protons Neutrons Electrons Number Number Hydrogen H 1 1 Helium He 2 4 Carbon C 6 6 Oxygen O 8 8 Neon Ne 10 10 20 Aluminum Al 13 27 Zinc Zn 30 30 65

Figure 2-1

41. Calculating Based on Figure 2-1, what is the mass number of carbon? a. 6 b. 7 c. 8 d. 12 42. Applying Concepts Based on Figure 2-1, what is the atomic number of oxygen? a. 8 b. 16 c. 24 d. not enough information 43. Applying Concepts Using Figure 2-1, how many electrons does an atom of aluminum contain? a. 13 b. 26 c. 27 d. not enough information 44. Applying Concepts According to Figure 2-1, an atom of which element contains two neutrons? a. H b. O c. He d. Al 45. Applying Concepts Based on Figure 2-1, which element has a mass number of 16? a. He b. Al c. H d. O

USING SCIENCE SKILLS Figure 2-3

46. Applying Concepts According to Figure 2-3, which enzyme would you expect to find in a bacterium growing in a hot spring? a. Enzyme X b. Enzyme Y c. both X and Y d. neither X nor Y 47. Using Tables and Graphs According to Figure 2-3, at what temperature do the two enzymes have the same amount of activity? a. about 20 º C b. about 35 º C c. about 45 º C d. about 70 º C 48. Using Tables and Graphs According to Figure 2-3, which enzyme has an optimum temperature of 40C? a. Enzyme X b. Enzyme Y c. both X and Y d. neither X nor Y 49. Applying Concepts Based on Figure 2-3, which enzyme would have the most activity in humans? a. Enzyme X b. Enzyme Y c. both X and Y d. neither X nor Y 50. Using Tables and Graphs Based on Figure 2-3, which enzyme is active over the largest temperature range? a. Enzyme X b. Enzyme Y c. both X and Y d. neither X nor Y