1. When applying the process of science, which of these is tested? a. an observation b. a result c. a hypothesis d. a question e.

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1 BCOR 11 Exam 1, 2004 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1. When applying the process of science, which of these is tested? a. an observation b. a result c. a hypothesis d. a question e. a prediction 2. Which four elements make up approximately 96% of living matter? a. carbon, hydrogen, nitrogen, oxygen b. carbon, sodium, chlorine, magnesium c. carbon, sulfur, phosphorus, hydrogen d. carbon, oxygen, sulfur, calcium e. oxygen, hydrogen, calcium, sodium 3. The mass number of an element can be easily approximated by adding together the number of a. protons and electrons. b. neutrons and electrons. c. isotopes of the atom. d. protons and neutrons. e. electron orbitals in each energy level. 4. How do isotopes of a single element differ from each other? a. ability to form ions b. number of protons c. number of neutrons d. valence electron distribution e. number of electrons 5. The reactive properties or chemical behavior of an atom depend on the number of a. orbitals found in the atom. b. valence shells in the atom. c. electrons in each orbital in the atom. d. electrons in the outer valence shell in the atom. e. hybridized orbitals in the atom.

2 6. How many electrons would be expected in the outermost electron shell of an atom with atomic number 20? a. 4 b. 1 c. 0 d. 20 e Each phosphodiester linkage in DNA or RNA includes a phosphate joined by covalent bonds to a. two bases b. Two sugars c. Two additional phosphates d. A sugar, a base and a phosphate e. A sugar and a base 8. Which of the following represents a polar covalent bond? a. H-O b. C-C c. H-H d. O-O e. C-H 9. The ionic bond of sodium chloride is formed when a. sodium gains an electron from chlorine. b. chlorine gains an electron from sodium. c. sodium and chlorine share an electron pair. d. sodium and chlorine both lose electrons from their outer valence shells. e. chlorine gains a proton from sodium. 10. Van der Waals interactions result when a. two polar covalent bonds react. b. electrons are not symmetrically distributed in a molecule. c. hybrid orbitals overlap. d. molecules held by ionic bonds react with water. e. a hydrogen atom loses an electron. 11. Which of the following best describes chemical equilibrium? a. There are equal concentrations of reactants and products. b. Reactions continue with no net change on the concentrations of reactants and products. c. Reactions stop only when all reactants have been converted to products. d. Concentrations of products are high. e. Reactions have stopped.

3 12. In a single molecule of water, the two hydrogen atoms are bonded to a single oxygen atom by a. van der Waals interactions. b. hydrogen bonds. c. polar covalent bonds. d. nonpolar covalent bonds. e. ionic bonds. 13. Why does ice float in liquid water? a. Ice always has air bubbles that keep it afloat. b. The liquid water molecules have more energy and can push up the ice. c. Hydrogen bonds keep the molecules of ice farther apart than in liquid water. d. The crystalline lattice of ice causes it to be denser than liquid water. e. The ionic bonds between the molecules in ice prevent the ice from sinking. 14. Hydrophobic substances like vegetable oil are a. ionic substances that dissolve in water. b. ionic or polar substances that have an affinity for water. c. non-ionic or nonpolar substances that have an affinity for water. d. ionic or polar substances that repel water. e. non-ionic or nonpolar substances that repel water. 15. The molecular weight of glucose is 180g. To make a 0.5 Msolution of glucose, you should do which of the following? a. Dissolve 90 mg (milligrams) of glucose in 1 L of water. b. Dissolve 0.5 g of glucose in 1 L of water. c. Dissolve 50 g of glucose in 1 L of water. d. Dissolve 90 g of glucose in 100 ml of water. e. Dissolve 90 g of glucose in water, and then add more water until the total volume of the solution is 1 L. 16. What do cohesion, surface tension, and adhesion have in common with reference to water? a. All are produced by covalent bonding. b. All increase when temperature increases. c. All have to do with nonpolar covalent bonds. d. All are properties related to hydrogen bonding. e. Both a and c are correct.

4 17. One of the buffers that contribute to ph stability inhuman blood is carbonic acid. Carbonic acid (H 2 CO 3 ) is a weak acid that when placed in an aqueous solution dissociates into a bicarbonate ion (HCO 3 ) and a hydrogen ion ( H + ) Thus, H 2 CO 3 HCO 3 + H + If the ph of the blood increases, one would expect: a. an increase in the concentration of H 2 CO 3 and a decrease in the concentration of H 2 O b. a decrease in the concentration of HCO 3 and an increase in the concentration of both H 2 CO 3 and H 2 O c. a decrease in the concentration of HCO 3 and an increase in the concentration of H 2 O d. an increase in the concentration of HCO 3 and a decrease in the concentration of H 2 O e. a decrease in the concentration of H 2 CO 3 and an increase in the concentration of H 2 O 18. Which type of molecule would be most abundant in a typical prokaryotic or eukaryotic cell? a. hydrocarbon b. protein c. carbohydrate d. water e. lipid 19. Which property of the carbon atom gives it compatibility with a greater number of different elements than any other type of atom? a. Carbon forms ionic bonds. b. Carbon has six to eight neutrons. c. Carbon has a valence of 4. d. Only a and c are correct. e. a, b, and c are correct. 20. What type of bonds does carbon have a tendency to form? a. ionic b. non reactive carbon does not form bonds c. covalent d. Only a and c are correct. e. hydrogen

5 21. What is the reason why hydrocarbons are not soluble in water? a. They are hydrophilic. b. They are lighter than water. c. The C-H bond is nonpolar d. The C-H bond is polar e. They are large molecules. 22. The two molecules shown in Figure 1 are best described as a. structural isomers. b. geometric isomers. c. nonisotopic isomers. d. radioactive isotopes. e. enantiomers. 23. Recent research suggests that side effects from Ritalin, the drug used to treat attention deficit disorder, may be caused by contamination of enantiomers, or molecules that a. differ in the location of their double bonds. b. are mirror images of one another. c. have identical three-dimensional shapes. d. differ in their electrical charge. e. lack an asymmetric carbon.

6 24. From Figure 2, which molecule is water-soluble because it has a functional group that is an alcohol? a. d and e b. a and d c. a and c d. a and c and d e. c and d 25. From Figure 2, which two molecules contain a carbonyl group? a. H C H a. b and c b. d and e c. c and d d. a and b e. a and e 26. From Figure 2, which molecule increases the concentration of I hydrogen ions in a solution and is therefore an organic acid?

7 27. Identify the asymmetric carbon in the molecule shown in Figure 3. d 28. Polymers of polysaccharides, fats, and proteins are all synthesized from monomers by a. the removal of water (dehydration reactions). b. ionic bonding of the monomers. c. the addition of water to each monomer. d. the formation of disulfide bridges between monomers. e. connecting monosaccharides together. 29. Carbohydrates normally function in animals as a. energy-storage molecules. b. the functional units of lipids. c. a component of triglycerides. d. sites of protein synthesis. e. enzymes in the regulation of metabolic processes. 30. Consider a polysaccharide consisting of 828 glucose molecules. The total hydrolysis of the polysaccharide would result in the production of a. 828 glucose molecules and 828 water molecules. b. 827 glucose molecules and 827 water molecules. c. 827 water molecules. d. 827 glucose molecules e. 828 glucose molecules and no water molecules. 31. What maintains the secondary structure of a protein? a. hydrogen bonds b. electrostatic charges c. ionic bonds d. peptide bonds e. disulfide bridges

8 32. The bonding of two amino acid molecules to form a larger molecule requires the a. release of a water molecule. b. releace c. addition of a water molecule. d. addition of a nitrogen atom. e. Both C and D are correct. 33. The R group or side chain of the amino acid serine is CH The R group or side chain of the amino acid alanine is CH Where would you expect to find these amino acids in globular protein in aqueous solution? a. Both serine and alanine would be on the exterior of the globular protein. B. b. Alanine would be in the interior, and serine would be on the exterior of the globular protein. c. Both serine and alanine would be in the interior and on the exterior of the globular protein. d. Serine would be in the interior, and alanine would be on the exterior of the globular protein. e. Both serine and alanine would be in the interior of the globular protein. 34. Which of the following statements best summarizes structural differences between DNA and RNA? a. DNA is not a polymer, but RNA is. b. DNA has different purine bases from RNA. c. DNA contains a different sugar from RNA. d. RNA is a double helix, but DNA is not. e. RNA is a protein, whereas DNA is a nucleic acid. 35. If one strand of a DNA molecule has the sequence of bases ATTGCA, the other complementary strand would have the sequence a. UAACGU. b. TLTUCGU. c. TAACGT. d. TUUGCT. e. TAAGCT. 36. A primary objective of cell fractionation is a. to view the structure of cell membranes. b. to identify the enzymes outside the organelles. c. to crack the cell wall so the cytoplasmic contents can be released. d. to separate the major organelles so their particular functions can be determined. e. to determine the size of various organelles.

9 37. Which of the following is not a part of the endomembrane system? a. rough endoplasmic reticulum b. lysosomes c. Golgi apparatus d. smooth endoplasmic reticulum e. mitochondria 38. Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules? a. glucose b. starches c. lipids d. proteins e. steroids 39. Of the following, which is probably the most common route for membrane flow in the endomembrane system? a. tonoplast plasma membrane nuclear envelope smooth ER b. Golgi lysosome ER plasma membrane c. nuclear envelope lysosome Golgi plasma membrane d. ER chloroplasts mitochondrion cell membrane e. rough ER vesicles Golgi plasma membrane 40. Which of the following pairs is mismatched? a. nucleus - DNA replication b. nucleolus - ribosomal RNA c. lysosome - protein synthesis d. cytoskeleton - microtubules e. cell membrane - lipid bilayer 41. Grana, thylakoids, and stroma are all components found in a. mitochondria. b. cilia and flagella. c. nuclei. d. chloroplasts. e. lysosomes. 42. Of the following, which cell structure would most likely be visible with a light microscope? a. microtubule b. ribosome c. nuclear pore d. mitochondrion e. nucleus

10 43. All of the structures listed below are associated with movement in cells or by cells except a. dynein. b. myosin. c. flagella. d. cilia. e. peroxisomes. 44. Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through a. tight junctions. b. gap junctions. c. desmosomes. d. intermediate filaments. e. plasmodesmata. 45. Which of the following intercellular junctions are common in epithelial tissue? a. desmosomes b. plasmodesmata c. tight junctions d. both a and c e. a, b and c 46, The presence of cholesterol in the plasma membranes of some animals a. makes the animal more susceptible to circulatory disorders. b. enables the membrane to stay fluid more easily when cell temperature drops. c. enables the animal to add hydrogen atoms to unsaturated phospholipids. d. makes the membrane less flexible, so it can sustain greater pressure from within the cell. e. enables the animal to remove hydrogen atoms from saturated phospholipids. 47. According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids? a. They have hydrophilic tails in the interior of the membrane. b. They Occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane. c. They are free to depart from the membrane and dissolve in the surrounding solution. d. They frequently flip-flop from one side of the membrane to the other. e. They can move laterally along the plane of the membrane. 48. All of the following are functions of plasma membrane proteins except a. cell-cell recognition. b. intercellular joining. c. protein synthesis. d. transport. e. signal transduction.

11 49. What membrane-surface molecules are thought to be most important as cells recognize each other? a. glycoproteins b. phospholipids c. integral proteins d. peripheral proteins e. cholesterol 50. The kinds of molecules that pass through a lipid bilayer most easily are a. ionic. b. large polar molecules. c. small and hydrophobic. d. monosaccharides such as glucose. e. large and hydrophobic. Bonus Question 1. One of the first models for membranes was one proposed by Davson and Daneilli, the sandwich model. That model has been modified to one called a fluid mosaic. In class we discussed how the fluid mosaic model for cell membranes as been further modified to include (fill in blank).