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Bio 1113 Exam 1
| Question | Answer |
|---|---|
| Which of the following is not a characteristic of all living organisms? a) they are capable of evolving. b) they are composed of cells. c) they can reproduce. d) they are capable of conscious thought. e) they acquire and use energy. | d) they are capable of conscious thought. |
| Atoms that have the same number of protons and electrons are electrically neutral because _____. | the positive charges on the protons and the negative charges on the electrons cancel each other out. |
| Which of the following atoms acquires the most negative charge in a covalent bond with hydrogen? a) C b) N c) O d) S | c) O |
| Magnesium has an atomic number of 12. What is the most stable charge for a magnesium ion? | +2 charge |
| Nitrogen has three vacancies in its outer electron shell. What type of bond will nitrogen form with hydrogen? How many hydrogen atoms would one nitrogen atom bind to fill its valence shell? (You might need to reference the electronegativity scale) | polar covalent bond; 3 hydrogen atoms |
| What contributes to the high surface tension of water? | hydrogen bonding, polar covalent bonds, cohesion |
| In your small intestine during digestion, pancreatic enzymes break down proteins by _____ reactions into _____. | hydrolysis, amino acids |
| Changing a single amino acid in a protein consisting of 325 amino acids would ________. | always alter the primary structure of the protein, sometimes alter the tertiary structure of the protein and its biological activity |
| The sequence of one strand of DNA is shown below. Which of the following is the sequence of its complementary strand? 3′ ATTTGGCC 5′ | 5′ TAAACCGG 3′ |
| What determines the primary structure of DNA? | the sequence of deoxyribonucleotides |
| What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration(condensation) reactions? | C18H32O16 |
| The enzyme amylase can break glycosidic linkage between glucose monomers in the α-form. Which of the following could amylase break down? | Amylose and amylopectin |
| Which of the following explains why sterols (or steroids) are considered to be lipids? | They can mix with other lipids |
| Are the bonds that chlorine forms with sodium (to form NaCl) and with carbon (to form CCl4) the same in both compounds? | No, NaCl is formed by an ionic bond, and CCl4 would be formed by covalent bonds. |
| Which of the following occurs when a covalent bond forms? | Electrons in valence shells are shared between atoms. |
| What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons? | 6 |
| An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many protons does boron have? | 5 |
| Fluorine's atomic number is 9 and its atomic mass is 19. How many neutrons does fluorine have? | 10 |
| Which kinds of bonds are present in a single water molecule? | polar covalent bonds |
| A substance that gives up a proton during a chemical reaction, raising the hydrogen ion concentration of water, is most appropriately called _____. | an acid |
| Which of the following contains a polar covalent bond? | O-H |
| The hydrogen bonds among water molecules endow water with which property? | Water has a high specific heat. |
| Liquid water has surface tension, a high specific heat, and functions effectively as a solvent for polar covalent and ionically bonded molecules. What feature of water imparts these properties? | Water readily forms hydrogen bonds with other water molecules, and with polar solutes. |
| Which property of water explains the observation that pigs often cover themselves in mud on hot days? | Water's high heat of vaporization is used to cool off the pig as the water in mud takes up a large amount of heat from the body to change from liquid to gas. |
| What property of the element silicon has led some biologists to propose that silicon-based (rather than carbon-based) life-forms may have arisen on other planets? | The number of valence electrons in silicon is the same as carbon, which means that the number of covalent bonds formed would be the same. |
| Determine what type of functional group is present on formaldehyde (CH2O). What property is associated with this group? | A carbonyl functional group that is known to react with other compounds to produce larger molecules |
| What are the defining characteristics of a condensation reaction? | Two monomers are covalently bonded together, and a water molecule is produced. |
| Which functional group contains nitrogen? | Amino |
| Which of these functional groups is known to be used for acting as an acid? | carboxyl group |
| What is unusual about the peptide bond compared to the other covalent bonds that form the polypeptide backbone? | Peptide bonds behave like double bonds in terms of stability and lack of movement of atoms around the bond. |
| Where would amino acid residues with nonpolar R-groups be found within the overall structure of a folded globular protein such as chymotrypsin? | Nonpolar amino acid residues would be found in the interior of chymotrypsin. |
| What type of bond is directly involved in the formation of an alpha-helix? | Hydrogen bonds between amino acid residues |
| Which of the following statements about protein primary structure is true? | Primary structure is produced by the unique sequence of amino acids in a protein. |
| Based on what you know of the peptide bonds that link together amino acid residues, why would proline's side chain reduce the flexibility of the backbone? | Proline's side chain is covalently bonded to the nitrogen in the core amino group as well as to the central carbon, restricting movement. |
| The condensation reaction that forms nucleic acid polymers occurs between a _____ group on one nucleotide and a _____ group on a second nucleotide. | phosphate; hydroxyl |
| Single strands of nucleic acids are directional, meaning that there are two different ends. What functional groups define the two different ends of a strand? | a free hydroxyl group on the 3' carbon; a free phosphate group on the 5' carbon |
| What is the difference between a ribonucleotide and a deoxyribonucleotide? | Ribonucleotides have a hydroxyl group on the 2 carbon of their sugar subunit. |
| What are three ways monosaccharides differ from one another? | the location of their carbonyl group; the orientations of their hydroxyl groups; the number of carbon atoms they contain |
| The _____ functional group can always be found in a carbohydrate molecule. | hydroxyl |
| Galactosemia is a potentially fatal disease that occurs in humans who lack the enzyme that converts galactose to glucose. If you were a physician treating a person with this disease, which of the following would you have them exclude from their diet? | Lactose |
| Which of the following types of molecules would have the highest capacity to store chemical energy? | A six-carbon molecule rich in C-H bonds, such as a lipid |
| In a DNA double helix, what kind of chemical bonds form between the complementary nitrogenous bases? | Hydrogen bonds |
| If nucleotides from the DNA of a human were quantified and 30 percent of them contained the base adenine, what percentage of them would contain the base guanine? | 20 percent |
| How does the structure of DNA allow it to be copied? | After separating the strands of a DNA double helix, each template strand can be copied to make two identical DNA molecules. |
| Which of the following correctly matches the lipid with its description? | Steroids have a distinctive four-ring structure with variable side groups attached. |
| How do the phospholipids in archaea differ from those in other cells? | They have isoprenoid tails instead of fatty acid tails. |
| Cooking oil lipids consist of long, unsaturated hydrocarbon chains. Would you expect these molecules to form membranes spontaneously? Why or why not? | No, because they have no polar end to interact with water. |
| Lipids are organic compounds characterized by their _____. | insolubility in water and their solubility in organic solvents |
| Lipids are insoluble in water because _____. | they contain nonpolar C-C and C-H bonds |
| Which of the following is true of membrane lipids? | They contain a hydrophilic head group and a hydrophobic tail. |
| A trout moves from a warm environment into a cold environment. Predict how the saturation status of hydrocarbon chains might change to ensure proper membrane fluidity in the new cold environment. | The hydrocarbons would become less saturated to increase the fluidity of the membrane. |
| Which statement describes what happens once equilibrium is reached between the interior of a vesicle and the surrounding solution? | There is no directional movement of solute or water across the membrane. |
| What two conditions must be present for osmosis to occur? | A concentration gradient and a membrane that allows water to pass but not the solute |
| If a solution surrounding a cell is hypertonic relative to the inside of the cell, how will water move? | The net movement of water will be out of the cell via osmosis. |
| Lipid vesicles are formed containing pure water. If these vesicles are transferred to a solution that contains a rather high concentration of solutes, the solution outside the vesicle is said to be_____. | hypertonic |
| If a solution surrounding a cell is hypertonic relative to the inside of the cell, how will water move? | It will move out of the cell via osmosis. |
| In terms of structure, how do channel proteins differ from carrier proteins? | Channel proteins form pores in the membrane, and carrier proteins undergo conformational changes to shuttle molecules across the membrane. |
| Suppose a cell is placed in a solution with a high concentration of potassium and no sodium. How would the cellular sodium-potassium pump function in this environment? | It would continue using ATP to pump sodium out of the cell and potassium into the cell. |
| Which of the following statements regarding gated channels is false? | Gated channels facilitate the passage of small, nonpolar molecules such as O2 across the plasma membrane. |
| The movement of molecules through a plasma membrane channel protein is always _____. | down the molecule's electrochemical gradient |
| L-dopa is used to treat _____. | Parkinson's disease |
| In a neutral solution the concentration of _____. | hydrogen ions is equal to the concentration of hydroxide ions |
| What type of information is used to direct different polypeptides to fold into different shapes? | type of amino acids that make up the polypeptide; order of amino acids that make up the polypeptide |
| A water molecule can bond to up to _____ other water molecules by ____ bonds. | four ... hydrogen |
| The unequal sharing of electrons within a water molecule makes the water molecule _____. | polar |
| The innermost electron shell of an atom can hold up to _____ electrons. | 2 |
| The mass number of an atom is 15, and its atomic number is 7. The atom probably has ... | 8 neutrons in the nucleus. |
| Which statement is true of atoms? | Electrons determine the atom's size. |
| Dr. Jones says an atom has 3 electrons in the first shell and four electrons in the second shell. Someone should tell Dr. Jones that ... | the first shell shouldn't have 3 electrons. |
| Which statement is true of the energy levels of electrons in shells? | The valence shell has higher energy than other occupied shells. |
| Two atoms always represent the same element if they have ... | the same number of protons. |
| Identify three possible components of a DNA nucleotide. | deoxyribose, phosphate group, thymine |
| DNA double helices are soluble in water but insoluble in alcohol. How do these physical properties reflect the chemical structure of the DNA molecule? | The charged phosphate groups and sugars of DNA are hydrophilic. |
| Single strands of nucleic acids are directional, meaning that there are two different ends. What functional groups define the two different ends of a strand? | a free hydroxyl group on the 3' carbon; a free phosphate group on the 5' carbon |
| Glycogen is _____. | a polysaccharide found in animals |
| Which of these is a source of lactose? | milk |
| In fat synthesis, ________ and fatty acids combine to make fats plus ________. | glycerol; water |
| Which of the differences listed here could be found among molecules of the same monosaccharide? | There is a difference in the orientation of a hydroxyl group in the ring form;There is a difference in the overall shape of the molecule- one is a ring and the other is linear. |
| Which of the following accurately describes a reason why fats store more energy than carbohydrates? | Compared to carbohydrates, fatty acid chains have a higher ratio of bonds with high potential energy to bonds with low potential energy. |
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lilak7