Review chapter 3 biology

69) Every atom of the same element has an equal number of electrons and protons.

TRUE

4) Which of the following best explains the molecular complexity of living organisms? A) Each organism has its own unique set of monomers for use in constructing polymers. B) A small number of monomers can be assembled into large polymers with many different combinations/sequences. C) Although there are not many biological molecules in cells, each one has many different functions. D) Condensation reactions can create different polymers because they can combine virtually any molecules in the cell. E) The large number of different monomers allows for the construction of many polymers.

B) A small number of monomers can be assembled into large polymers with many different

48) The human body must maintain a constant pH. In the blood, bicarbonate serves as a(n) ________ to help maintain the necessary pH. A) base B) buffer C) solvent D) acid

B) buffer

29) Cholesterol, testosterone, and estrogen are examples of A) proteins. B) waxes. C) steroids. D) nucleic acids. E) fatty acids.

C) steroids.

16) Maltose is made from A) glucose and fructose. B) two peptides. C) two glucose molecules. D) glucose and galactose.

C) two glucose molecules.

19) Where is glycogen stored in vertebrate animals? A) Teeth and bones B) Fat cells C) Pancreas and blood D) Brain and kidneys E) Liver and muscles

E) Liver and muscles

36) Hydrogen bonding can take place between a hydrogen atom and what other atom? A) Nitrogen B) Nitrogen, oxygen, and fluorine C) Fluorine D) Hydrogen E) Oxygen

E) Oxygen

59) The bonding of two amino acid molecules to form a larger molecule requires which of the following? A) Both removal of a water molecule and formation of a hydrogen bond B) Formation of a hydrogen bond C) Formation of a glycosidic bond D) Addition of a water molecule E) Removal of a water molecule

E) Removal of a water molecule

68) Isotopes are atoms of the same element that have different numbers of protons.

FALSE

71) The attractive force that holds two or more water molecules together is an example of an ionic bond.

FALSE

75) Most liquids become less dense upon solidification, but water is different in that it becomes denser when it solidifies.

FALSE

77) Phospholipids have hydrophilic tail regions and hydrophobic head regions.

FALSE

70) Acids have pH values below 7, whereas bases have pH values above 7.

TRUE

72) When water freezes, stable hydrogen bonds form between the water molecules that create an open, six-sided (hexagonal) arrangement.

TRUE

24) Which of the following can serve as an energy source and as structural support in plant cells? A) Carbohydrates B) Nucleic acids C) Proteins D) Lipids

A) Carbohydrates

25) Which of the following categories includes monosaccharide monomers? A) Carbohydrates B) Proteins C) Nucleic acids D) Lipids

A) Carbohydrates

64) Your friend is trying to learn about how to kill bacteria. She reads that preservatives such as citric 64) acid are added to foods because the acidic environment kills bacteria by denaturing their proteins. She thinks this sounds like a lot of scientific jargon and asks you what it means. How can you explain it in simpler terms? A) Denaturing means that the proteins of the bacteria lose their structure and can't function, so the bacteria die. B) Denaturing refers to the fact that the bacterial cells divide too quickly and die. C) The acid causes the cells to swell and burst open, also known as denaturation. D) Denaturing their proteins means that the proteins in bacteria are converted into carbohydrates

A) Denaturing means that the proteins of the bacteria lose their structure and can't function, so the bacteria die.

31) When 1 gram of each of these food sources is consumed, which yields the greatest amount of energy in calories? A) Fat B) Phenylalanine C) Sucrose D) Glucose E) Polypeptide

A) Fat

18) Free radicals contain unpaired electrons in their outermost energy shell, so they react readily with 18) other atoms or molecules to reach a more stable state. Which of the following could potentially be a free radical? A) Fluorine (atomic number 9) B) Magnesium (atomic number 12) C) Helium (atomic number 2) D) Neon (atomic number 10)

A) Fluorine (atomic number 9)

53) What maintains the secondary structure of a protein? A) Hydrogen bonds B) Disulfide bonds C) Peptide bonds D) Ionic bonds

A) Hydrogen bonds

29) What type of bond is easily disrupted in aqueous solutions (one in which the solvent is water)? 29) A) Ionic B) Covalent C) Polar covalent

A) Ionic

72) Which of these is NOT a nucleic acid or nucleotide? A) LDL B) RNA C) DNA D) ATP

A) LDL

37) The fat substitute Olestra contains a sucrose backbone with six to eight fatty acids attached. How is this different from a naturally occurring fat? A) Naturally occurring fats contain a glycerol and three fatty acids. B) It isn't Olestra and natural fats have the same structure, just different tastes. C) Naturally occurring fats contain a glycerol, two fatty acids, and a phosphate group. D) Naturally occurring fats contain a sucrose backbone and three fatty acid chains.

A) Naturally occurring fats contain a glycerol and three

42) Which of the following is LEAST affected by the presence of water? A) Nonpolar covalent bond B) Polar covalent bond C) Ionic bond D) Hydrogen bond E) Electron-proton interaction

A) Nonpolar covalent bond

75) Which of these biological molecules contain genetic information? A) Nucleic acids B) Carbohydrates C) Lipids D) Proteins

A) Nucleic acids

58) Which of the following refers to the amino acid sequence of proteins? A) Primary B) Secondary C) Tertiary D) Quaternary

A) Primary

61) Which of the following biological molecules are composed of amino acid subunits? A) Proteins B) Lipids C) Carbohydrates D) Nucleic acids

A) Proteins

62) Which of the following may possess primary, secondary, tertiary, and quaternary structures? A) Proteins B) Carbohydrates C) Nucleic acids D) Lipids

A) Proteins

21) Which of the following provides long-term energy storage for plants? A) Starch B) ATP C) Glycogen D) Glucose E) Cellulose

A) Starch

43) What happens when hydrochloric acid (HCl) dissociates in pure water? A) The HCl molecules separate into H+ and Cl- ions. B) The pH of the solution increases. C) The HCl molecules float on top of the water. D) The water has a decrease of H+ ions. E) The concentration of OH- ions increases.

A) The HCl molecules separate into H+ and Cl- ions.

33) A single covalent chemical bond represents the sharing of how many electrons? 33) A) Two B) Three C) One D) Four E) Six

A) Two

35) New government regulations require that foods containing trans fats be labeled appropriately. A trans fat is formed when food manufacturers turn liquid oils into solid fats by adding hydrogen to vegetable oils. This hydrogenation process produces a solid fat because adding the hydrogen A) allows the fatty acid chains to pack together more tightly. B) causes a phospholipid to form. C) forms a wax molecule. D) allows fats to form tertiary and quaternary structures.

A) allows the fatty acid chains to pack together more tightly.

38) Two categories of organic compounds typically provide energy for living systems. Representatives of these two classes are A) carbohydrates and proteins. B) carbohydrates and lipids. C) proteins and nucleic acids. D) lipids and proteins. E) carbohydrates and nucleic acids.

A) carbohydrates and proteins.

54) Water moves through a plant because of the property of A) cohesion. B) high heat of vaporization. C) high specific heat. D) high heat of fusion.

A) cohesion.

15) The carbohydrate in DNA is A) deoxyribose. B) phosphate. C) glucose. D) ribose. E) cellulose.

A) deoxyribose.

1) A substance with specific properties that cannot be broken down or converted into another substance is called a(n) A) element. B) mixture. C) molecule. D) compound. E) ion.

A) element.

46) A neutral solution A) has equal amounts of H+ and OH-. B) has no H+. C) has a pH of 0. D) has no OH-. E) is hydrophobic.

A) has equal amounts of H+ and OH-.

45) If a substance measures 7 on the pH scale, that substance A) has equal concentrations of H+ and OH- ions. B) is basic. C) probably lacks OH- ions. D) has a higher concentration of OH- than H+ ions. E) may be lemon juice.

A) has equal concentrations of H+ and OH- ions.

10) If digestion is ________, then synthesis is ________. A) hydrolysis;dehydration synthesis B) inorganic;organic C) dehydration synthesis; hydrolysis D) organic; inorganic

A) hydrolysis;dehydration synthesis

15) Atoms or molecules that have gained or lost electrons are called A) ions. B) covalent. C) acids. D) bases. E) buffers.

A) ion

49) Milk of magnesia is often used to treat stomach upset. It has a pH of 10. Based on this information, milk of magnesia A) is a base. B) is hydrophobic. C) has the same pH as stomach acid. D) is an acid.

A) is a base.

26) The atomic number of hydrogen is 1. Based on this fact, all of the following must be true of hydrogen gas (H2) EXCEPT that it A) is a polar molecule. B) shares one pair of electrons between the two hydrogen atoms. C) uses covalent bonds to form the molecule. D) is a stable molecule.

A) is a polar molecule.

59) If you place a paper towel in a dish of water, the water will A) move up the towel as the water adheres to the paper towel while the cohesive water molecules stay bound to each other. B) dissolve the towel because water is a good solvent. C) separate into H+ and OH- ions, which will react with the paper towel molecules. D) move away from the towel because water molecules have hydrophobic interactions. E) move up the towel because water molecules move quickly as it vaporizes.

A) move up the towel as the water adheres to the paper towel while the cohesive water molecules stay bound to each other.

3) The atomic number of an atom is defined as the A) number of protons in the atomic nucleus. B) number of neutrons in the atomic nucleus. C) total number of electrons and neutrons. D) number of electrons in the outermost energy level. E) total number of energy shells.

A) number of protons in the atomic nucleus.

12) Keratin and silk are examples of ________, whereas glucose and maltose are examples of ________. A) proteins; carbohydrates B) carbohydrates; proteins C) nucleic acids; lipids D) proteins; lipids

A) proteins; carbohydrates

62) If you place a feather on the surface of a bowl of water, the feather remains suspended on the surface due to the A) surface tension of the water. B) polarity of the water. C) density of the water. D) fact that water is a good solvent.

A) surface tension of the water.

76) Different types of living matter often have different forms of the same elements in their bodies. For 89) example, the nitrogen in an animal often has a slightly different atomic structure than the nitrogen in a plant. Recently, nutritionists have discovered how to deduce the diets of various animal species by examining the type of nitrogen (and other elements) inside their bodies. What is the chemical basis behind this scenario? A) Isotopes of the same element have the same atomic number but different atomic masses. B) Radioactive elements can be used to trace the paths of molecules through the body. C) Antioxidants buffer the potential damage that free radicals do to cells. D) Hydrophobic interactions keep water molecules from forming bonds with fats and oils. E) Covalent bonds result when two atoms share electrons.

A)Isotopes of the same element have the same atomic number but different atomic masses.

2) Which of the following is NOT an organic molecule? A) Protein B) Carbon monoxide C) Monosaccharide D) Lipid E) Nucleic acid

B) Carbon monoxide

50) What do carbohydrates, lipids, and proteins have in common? A) All are inorganic molecules. B) Covalent bonding holds these molecules together. C) All are important enzymes that function within the cell. D) Polymers of these organic molecules form monomers via dehydration synthesis reactions.

B) Covalent bonding holds these molecules together.

23) In humans, dental cavities form when Streptococcus mutans bacteria in the mouth hydrolyze sucrose. Which of the following is (are) the products of this reaction? A) Glucose and galactose B) Glucose and fructose C) Starch D) Glycogen

B) Glucose and fructose

10) For an atom to achieve maximum stability and become chemically inert, what must occur? 10) A) Electron pairs are shared. B) Its outermost energy shell must be completely filled with electrons. C) Ionization occurs. D) The number of electrons must equal the number of protons.

B) Its outermost energy shell must be completely filled with electrons.

56) Which of the following is an example of a protein? A) ATP B) Keratin C) Cellulose D) Estroge

B) Keratin

14) Which molecule is a disaccharide? A) Fructose B) Lactose C) Glucose D) Water

B) Lactose

39) Imagine that you have isolated a mysterious liquid from a sample of food. 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 biological molecules does the unknown liquid most likely belong? A) Nucleic acids B) Lipids C) Enzymes D) Carbohydrates E) Proteins

B) Lipids

66) Which of the following is the densest? A) Ice B) Liquid water C) Steam

B) Liquid water

25) What does H-O-H represent? A) Atom of water B) Molecule of water C) Ionic bonding of water D) Mixture including water

B) Molecule of water

28) Which of the following is insoluble in water? A) Sucrose B) Olive oil C) Amino acids D) Salt E) DNA

B) Olive oil

27) Which type of lipid is most important in biological membranes? A) Fat B) Phospholipid C) Oil D) Steroid E) Wax

B) Phospholipid

40) Which of the following results from an unequal sharing of electrons between atoms? A) Nonpolar covalent bond B) Polar covalent bond C) Ionic bond D) Hydrogen bond E) Electron-proton interaction

B) Polar covalent bond

41) Which of the following best explains the attraction of water molecules to each other? 41) A) Nonpolar covalent bond B) Polar covalent bond C) Ionic bond c E) Electron-proton interaction

B) Polar covalent bond

65) Scientists consider prions to be "puzzling" proteins. Which of the following is TRUE about prions? A) Prions are proteins that are denatured more easily than most proteins. B) Prions are proteins that cause nearby proteins to change shape and become infectious. C) Prions are infectious proteins that cannot be denatured by any amount of heat. D) Prions are noninfectious proteins.

B) Prions are proteins that cause nearby proteins to change shape and become infectious.

66) Which of the following correctly matches an organic polymer with its monomers, respectively? A) Lipid; steroids B) Protein;amino acids C) Hydrocarbon; monosaccharides D) DNA; ATP E) Carbohydrate; polysaccharides

B) Protein;amino acids

64) You drop a handful of common table salt into a glass of water. Which of the following best describes what is happening inside the glass at the molecular level? A) Water and sodium form a covalent bond. B) The positively charged hydrogen ends of the water molecules are attracted to chloride ions. C) The positively charged hydrogen ends of the water molecules are attracted to sodium ions. D) Sodium and chloride ions form a covalent bond.

B) The positively charged hydrogen ends of the water molecules are attracted to chloride ions.

33) What property of phospholipids makes them important in cell membranes? A) They contain nucleic acids. B) They have a polar end and a nonpolar end. C) They are an important energy carrier molecule. D) They are part of DNA. E) They are found only in animals.

B) They have a polar end and a nonpolar end.

11) Hydrolysis may be correctly described as the A) constant removal of hydrogen atoms from a carbohydrate. B) breaking of a compound into its subunits by using water to break the bond between monomers. C) removal of water from a polymer. D) heating of a compound in order to drive off its excess water and to concentrate its volume.

B) breaking of a compound into its subunits by using water to break the bond between monomers.

54) Complex, three-dimensional, tertiary structures of proteins result from A) ionic and hydrogen bonds B) hydrogen and disulfide bonds. C) disulfide bonds. D) hydrogen bonds. E) ionic bonds.

B) hydrogen and disulfide bonds.

40) Cell membranes are an example of a lipid bilayer. In this lipid bilayer, both the outside of the cell and the inside of the cell are ________ in nature. A) hydrophilic B) hydrophobic C) watery D) polar E) charged

B) hydrophobic

70) Adenosine triphosphate (ATP) is an example of a(n) A) protein. B) nucleotide. C) inorganic molecule. D) carbohydrate. E) lipid.

B) nucleotide.

71) A nucleotide is made of a A) phospholipid, sugar, and nitrogenous base. B) phosphate, sugar, and nitrogenous base. C) phosphate, protein, and nitrogenous base. D) phospholipid, sugar, and protein.

B) phosphate, sugar, and nitrogenous base.

18) Chitin is an example of a A) monomer. B) polysaccharide. C) triglyceride. D) nucleic acid. E) peptide.

B) polysaccharide.

11) An atom's nucleus is composed of A) protons only. B) protons and neutrons. C) protons and electrons. D) neutrons and electrons. E) neutrons only.

B) protons and neutrons.

12) The formation of ions involves the A) sharing of protons. B) gain or loss of neutrons. c D) sharing of electrons. E) gain or loss of protons.

B) protons and neutrons.

19) Free radicals are considered dangerous because they A) attack the atomic nucleus. B) steal electrons from other atoms, causing those atoms to become unstable. C) damage oxygen and cause it to become an antioxidant. D) emit dangerous radiation.

B) steal electrons from other atoms, causing those atoms to become unstable.

65) Your friend does a belly flop into a swimming pool. The stinging pain he feels is most likely due to 65) theA) pH of the water. B) surface tension of water (caused by the large number of hydrogen bonds that form between water molecules). C) hydrophobic nature of your friend's skin. D) fact that water is a good solvent.

B) surface tension of water (caused by the large number of hydrogen bonds that form between water molecules).

3) You are telling your friend that organic molecules are all made up of carbon backbones with 3) hydrogens. She doesn't understand how there can be so many different organic molecules if they all are made up of the same basic components. You explain that organic molecules A) vary because they possess different isotopes of carbon. B) vary because they possess different functional groups. C) are different because of the different types of hydrogen bonds that form. D) actually all have the same structure but differ in the number of electrons.

B) vary because they possess different functional groups.

5) Large biological molecules are synthesized by removing A) covalent bonds. B) water. C) peptides. D) oxygen. E) carbon.

B) water.

32) Which of the following pairs has the most similar chemical properties to each other? 32) A) 12C and 28Si B) 1H and 22Na C) 12C and 14C D) 16O and 32S E) 1H and 2He

C) 12C and 14C

69) How many hydrogen bonds exist between a G-C base pair? A) 1 B) 2 C) 3 D) 4

C) 3

7) Iron is an important element in human body cells. If iron has an atomic number of 26, what does 7) this tell you about this element? A) An iron atom is unable to become an isotope. B) An iron atom has 13 protons and 13 neutrons. C) An iron atom has 26 protons. D) An iron atom has 13 electrons and 13 protons.

C) An iron atom has 26 protons.

58) What determines the cohesiveness of water molecules? A) Hydrophobic interactions B) Covalent bonds C) Hydrogen bonds D) Ionic bonds

C) Hydrogen bonds

6) What type of chemical reaction results in the breakdown of organic polymers into their respective subunits? A) Ionization B) Condensation C) Hydrolysis D) Oxidation

C) Hydrolysis

39) Which of the following results from a transfer of electron(s) between atoms (e.g., NaCl)? A) Nonpolar covalent bond B) Polar covalent bond C) Ionic bond D) Hydrogen bond E) Electron-proton interaction

C) Ionic bond

50) What is meant by the statement that water has a high specific heat? A) Water freezes easily. B) Water can heat up to only a certain temperature. C) It can absorb a lot of energy without changing temperature. D) The boiling point of water is low. E) It grows hot quickly.

C) It can absorb a lot of energy without changing temperature.

34) Lard is a solid fat at room temperature. What does this tell you about the triglycerides in lard? A) Lard is composed of unsaturated fats. B) The fats in lard are not organic molecules. C) Lard is composed of saturated fats. D) The fats in lard are mostly phospholipids.

C) Lard is composed of saturated fats.

2) If you examined the human body on a chemical composition basis, which of the following 2) combinations of elements would be most common? A) C, H, Ca, Cl B) O, C, P, S C) O, C, H, N D) O, C, N, Na E) C, N, Ca, S

C) O, C, H, N

55) The four polypeptides that are joined together to make functional hemoglobin represent which level of protein organization? A) Tertiary structure B) Primary structure C) Quaternary structure D) Secondary structure

C) Quaternary structure

38) Which of the following is an example of hydrogen bonding? A) The bond between H of one water molecule and H of a separate water molecule B) The bond between the H of a water molecule and H of a hydrogen molecule C) The bond between O of one water molecule and H of a separate water molecule D) The bond between O and H in a single molecule of water E) The bond between O of one water molecule and O of a separate water molecule

C) The bond between O of one water molecule and H of a separate water molecule

13) Dehydration synthesis involves the removal of a hydrogen ion and a hydroxyl ion. What happens next? A) The hydrogen ion becomes an isotope. B) A large polymer is split apart into small monomers. C) The hydrogen and hydroxyl ions combine to form water. D) A polysaccharide is released from a monosaccharide.

C) The hydrogen and hydroxyl ions combine to form water.

47) How do buffers work? A) They accept and release OH-. B) They monitor the blood pH. C) They accept and release H+. D) They convert H+ and OH- to water. E) They soak up extra acid and base.

C) They accept and release H+

44) Which of the following statements about lipids is incorrect? A) They are used for energy storage. B) They are large chains of nonpolar hydrocarbons. C) They are short chains of polar hydrocarbons. D) They are hydrophobic and water insoluble. E) They are primary component of cell membranes.

C) They are short chains of polar hydrocarbons.

37) Which statement is an accurate description of water molecules? 37)A) They are uncharged and nonpolar. B) They are charged and nonpolar. C) They are slightly charged and polar. D) They are ionically bonded.

C) They are slightly charged and polar.

77) All animals need oxygen gas (O2) for their primary cellular-level functioning. Inside the cell, O2 is 90) split apart into oxygen atoms. Eventually, electrons that are flowing through the cell will be "received" by this oxygen. But first, the electrons combine with protons present in the cell to form a basic element that has a single proton and a single electron. Then this element combines with the oxygen to form a certain chemical compound. In this scenario, what chemical compound is produced when this element combines with oxygen? A) Ozone (O3) B) Bicarbonate (HCO3) C) Water (H2O) D) Carbon dioxide (CO2)

C) Water (H2O)

63) The specific heat of water is 10 times greater than that of iron. You place a metal pot full of water on the stove to heat it up. You touch the metal handle of the pot when the water is still only lukewarm. Which of the following best describes what happens? A) You find that the handle is cooler than the water in the pot. B) You find that both the water and the handle are the same temperature. C) You burn your finger and pull your hand away from the hot metal handle. D) You determine that metal pots full of water produce acids and bases.

C) You burn your finger and pull your hand away from the hot metal handle.

20) An example of a structural polysaccharide is A) starch. B) glucose. C) cellulose. D) glycogen. E) maltose.

C) cellulose

27) Polar covalent bonds form when A) more than one pair of electrons is shared. B) an acid and a base are combined. C) electrons are shared unequally between atoms. D) atoms from two molecules are repelling each other. E) ions are formed.

C) electrons are shared unequally between atoms.

22) The element carbon has atomic number 6. Carbon most likely A) donates two electrons to another atom. B) shares two electrons with another atom. C) forms four covalent bonds. D) forms ionic bonds with other atoms.

C) forms four covalent bonds.

67) Unlike a rock, a reptile can sit in the hot sunshine without its body temperature soaring quickly. This is because the water in its body A) has a low specific heat. B) is a poor solvent. C) has a high specific heat. D) is a good solvent.

C) has a high specific heat.

34) Polar molecules A) are always ions. B) have an equal distribution of electric charge. C) have an unequal distribution of electric charge. D) have an overall negative electric charge. E) have an overall positive electric charge.

C) have an unequal distribution of electric charge.

22) Lactose is a disaccharide of glucose and galactose, and its digestion requires the actions of the enzyme lactase. If lactose is eaten as part of the diet but is not digested by lactase, this sugar is then metabolized by bacteria in the intestine, leading to the symptoms of lactose intolerance. Lactose intolerance, therefore, results from a(n) A) lack of dehydration synthesis of lactose. B) inability of the body to produce lactose. C) lack of hydrolysis of lactose. D) low blood lactose level.

C) lack of hydrolysis of lactose.

30) Triglycerides are A) always composed of carbon rings. B) a main component of cellular membranes. C) made from glycerol and fatty acids. D) hydrophilic. E) polymers of amino acids.

C) made from glycerol and fatty acids.

52) The fact that salt dissolves in water is best explained by the) A) hydrophobic nature of salt. B) slightly charged nature of water molecules. C) polar nature of water molecules. D) hydrophobic nature of the water. E) ionic nature of water molecules.

C) polar nature of water molecules.

60) Sweating is a useful cooling mechanism for humans because water A) is an outstanding solvent. B) takes up a great deal of heat in changing from its solid state to its liquid state. C) takes up a great deal of heat in changing from its liquid state to its gaseous state. D) can exist in two states at temperatures common on Earth. E) ionizes readily.

C) takes up a great deal of heat in changing from its liquid state to its gaseous state.

23) Sodium (Na), atomic number 11, has a tendency to lose an electron in the presence of chlorine. After losing the electron, Na has ________ protons in its nucleus. A) 10 B) 12 C) 22 D) 11 E) 21

D) 11 E) 21

48) Proteins are constructed using how many different amino acids? A) 4 B) 1,000 C) 100 D) 20 E) More than 5,000

D) 20

20) Scientists recommend a diet rich in antioxidants to stay healthy. What occurs at the atomic level to 20) explain this recommendation? A) Antioxidants cause an increase in pH, which is necessary for neutrality in cells. B) Antioxidants steal electrons, which gives cells extra energy. C) Antioxidants are inert and do not interact with free radicals. D) Antioxidants prevent free radicals from attacking other atoms or molecules.

D) Antioxidants prevent free radicals from attacking other atoms or molecules.

56) When the acidic level of human blood increases, how is the proper balance of hydrogen ions (H +) 56) restored? A) H+ ion-donor levels increase. B) Carbonic acid eats up the extra OH- ions. C) Bicarbonate (HCO3-) releases H+ ions that combine with excess OH- ions to form H2O. D) Bicarbonate (HCO3-) accepts H+ ions and forms carbonic acid.

D) Bicarbonate (HCO3-) accepts H+ ions and forms carbonic acid.

5) Which four elements make up approximately 96% of living matter? 5) A) Carbon, phosphorus, hydrogen, sulfur B) Carbon, oxygen, calcium, sulfur C) Oxygen, hydrogen, calcium, sodium D) Carbon, hydrogen, nitrogen, oxygen E) Carbon, sodium, chlorine, magnesium

D) Carbon, hydrogen, nitrogen, oxygen

7) Which of the following reactions is an example of dehydration synthesis? A) Glycogen → glucose subunits B) Peptide → alanine + glycine C) Fat → fatty acids + glycerol D) Glucose + galactose → lactose E) Cellulose → glucose

D) Glucose + galactose → lactose

26) When the level of glucose in your blood is high, your body is able to store excess glucose in the liver by forming glycogen. When blood glucose levels fall, this stored glucose can be released. Based on this information, which of the following is TRUE? A) Glycogen is a highly branched functional group that forms a larger glucose polymer. B) Glucose is a polysaccharide that can join to form the monosaccharide glycogen. C) Glucose is not an organic molecule, but glycogen is an organic molecule. D) Glycogen is a polysaccharide formed by joining excess monosaccharides of glucose.

D) Glycogen is a polysaccharide formed by joining excess monosaccharides of glucose.

28) Which of the following represents a molecule characterized by polar covalent bonding? 28) A) NaCl B) O2 C) H2 D) H2O E) CH4

D) H2O

51) Which of the following properties of water enable(s) it to function as a regulator of temperature for living organisms? (Hint: Think about what happens when you are sunbathing.) A) High heat of vaporization B) High specific heat C) High specific heat and high heat of vaporization D) High specific heat and low heat of vaporization E) Low specific heat

D) High specific heat and low heat of vaporization

73) Suppose you have discovered a new virus and have isolated its nucleic acids. What feature could 73) you look for to determine whether the nucleic acids of this virus are RNA or DNA? A) If it is RNA, there will be no adenine. B) If is RNA, it will contain deoxyribose. C) If it is DNA, the virus will not contain proteins. D) If it is RNA, it will contain ribose.

D) If it is RNA, it will contain ribose.

41) Which of the following biological molecules possess large nonpolar regions, making them insoluble in water? A) Carbohydrates B) Proteins C) Nucleic acids D) Lipids

D) Lipids

42) Which of the following groups is crucial to the structure and function of the sex hormones estrogen and testosterone? A) Proteins B) Carbohydrates C) Nucleic acids D) Lipids

D) Lipids

61) In general, a substance that carries an electric charge can dissolve in water. Given this fact, which of the following would most likely NOT dissolve in water? A) Polar covalent molecules B) Ionic compounds C) NaCl D) Nonpolar molecules

D) Nonpolar molecules

74) Which of the following biological molecules are composed of monomer units containing a sugar, a phosphate group, and a nitrogen-containing base? A) Proteins B) Lipids C) Carbohydrates D) Nucleic acids

D) Nucleic acids

63) Your classmate is trying to keep all the facts about biological molecules straight. He asks you to explain how amino acids and proteins are related. What do you tell him? A) Amino acids are formed by joining together many proteins. B) Proteins are a portion of an amino acid. C) Proteins are chains of carbohydrates, and amino acids are a type of lipid. D) Proteins are made up of chains of amino acids.

D) Proteins are made up of chains of amino acids.

17) Sulfur is an essential element in the human body, and studying its characteristics is important in 17) understanding human physiology. Sulfur atoms have six electrons in their outer shell. Based on this information, which of the following is TRUE? A) Sulfur is an important isotope of hydrogen. B) Sulfur is inert. C) Sulfur has eight electrons in its outer shell. D) Sulfur can form important molecules using covalent bonds.

D) Sulfur can form important molecules using covalent bonds.

6) Imagine that you have been hired as a chemist and your first task is to examine a newly discovered 6) atom. The paperwork you are given states that its atomic number is 110. What does this mean? A) The atom contains 55 protons and 55 neutrons. B) The atom contains 55 electrons. C) The atom is an isotope. D) The atom contains 110 protons.

D) The atom contains 110 protons.

21) Which of the following best explains why a particular atom may not form compounds easily? 21) A) The atom has an uneven number of protons. B) The atom has seven electrons in its outer shell. C) The atom has no electrons. D) The atom's outer energy shells are completely full.

D) The atom's outer energy shells are completely full.

4) Phosphorus has an atomic number of 15, so what is the distribution of its electrons? A) The first, second, and third energy levels have 5 electrons each. B) The electron arrangement cannot be determined from the atomic number alone. C) The first energy level has 8 and the second has 7. D) The first energy level has 2, the second has 8, and the third has 5. E) The first energy level has 2 and the second has 13.

D) The first energy level has 2, the second has 8, and the third has 5.

44) An atom of nitrogen attracts electrons more strongly than an atom of hydrogen. In an ammonia molecule (NH3), which of the following best describes the electrical charge of the individual atoms? A) The nitrogen is slightly positive. B) The nitrogen becomes neutral. C) The hydrogens are strongly negative. D) The nitrogen is slightly more negative. E) Charges balance out and none of the atoms has any charge.

D) The nitrogen is slightly more negative.

79) In this scenario, how are the soap, dirt/oil, and water arranged at the molecular level? A) The soap is converted into a lipid that binds to the dirt/oil while repelling the water. B) The soap molecules encase the dirt/oil within a small droplet that has a hydrophobic exterior and a hydrophilic interior. C) Water and dirt/oil form covalent bonds inside a small droplet that has a soap -based outer membrane. D) The soap molecules encase the dirt/oil within a small droplet that has a hydrophilic exterior and a hydrophobic interior.

D) The soap molecules encase the dirt/oil within a small droplet that has a hydrophilic exterior and a hydrophobic interior.

78) In this scenario, what is the most likely procedure beer makers use to produce alcohol from starchy 97) grains? A) The starch is converted into glycogen, which is easier for the yeast to digest. B) The starch is converted into a polymer of many glucose molecules before being used. C) Water is used to break the bonds between glucose subunits in the starch, in a form of dehydration synthesis. D) The starch is broken down into mono- and/or disaccharides by hydrolysis before use.

D) The starch is broken down into mono- and/or disaccharides by hydrolysis before use.

43) Which of the following is TRUE about waxes? A) They are an important food source, and most animals have enzymes for breaking them down. B) They are a type of complex carbohydrate. C) They are unsaturated and most similar to proteins. D) They are saturated fats and are solid at normal outdoor temperatures.

D) They are saturated fats and are solid at normal outdoor temperatures.

30) If sulfur has an atomic number of 16, how many covalent bonds can it form with other atoms? 30) A) Four B) Six C) Zero D) Two E) Eight

D) Two

57) Which type of molecule is most abundant in a typical cell? A) Carbohydrate B) Nucleic acids C) Lipid D) Water E) Protein

D) Water

57) For ice to melt, it has to A) increase its property of cohesion. B) increase its heat of vaporization. C) become less dense. D) absorb heat from its surroundings.

D) absorb heat from its surroundings.

14) The formation of sodium chloride (NaCl) is the result of A) chemical unreactivity. B) repelling between the same charges. C) covalent bonding. D) attraction between opposite charges.

D) attraction between opposite charges.

9) In dehydration synthesis, the atoms that make up a water molecule come from A) oxygen. B) enzymes. C) only one of the reactants. D) both of the reactants. E) carbohydrates.

D) both of the reactants.

9) Radioactive isotopes are biological tools that are often used to 9) A) build up a store of calcium in a cell. B) increase the pH of blood. C) measure the size of fossils. D) detect brain tumors and other important medical technologies.

D) detect brain tumors and other important medical technologies.

31) The part of the atom that has the greatest biological interest and interactions with other atoms is 31) the A) proton. B) innermost electron shell. C) neutron. D) electron.

D) electron.

49) The specific function of a protein is determined by the A) number of peptide bonds it contains. B) fatty acids that are joined together in the polypeptide. C) number of disulfide bonds. D) exact sequence of amino acids. E) hydrophilic head attached to the hydrophobic tail.

D) exact sequence of amino acids.

36) All of the following lipids or lipid components are hydrophobic EXCEPT A) unsaturated fats. B) waxes. C) fatty acid tails. D) fatty acid heads. E) saturated fats.

D) fatty acid heads.

52) All of the following are polysaccharides EXCEPT A) chitin. B) glycogen. C) starch. D) glucose.

D) glucose.

60) A denatured protein differs from a normal protein because it A) contains many disulfide bonds. B) is composed of nucleotides. C) does not contain amino acids. D) has lost its usual secondary and tertiary structures.

D) has lost its usual secondary and tertiary structures.

13) If a certain atom has a tendency to lose two electrons, that atom can then become a(n) A) polar molecule. B) water molecule. C) isotope. D) ion.

D) ion.

45) HDL and LDL are different types of cholesterol found in the blood. These compounds are A) carbohydrates. B) proteins. C) nucleic acids. D) lipids.

D) lipids.

1) Prions are known to cause A) sickle cell anemia. B) the common cold. C) herpes. D) mad cow disease.

D) mad cow disease.

47) Enzymes are specialized ________ that catalyze chemical reactions within the body. A) nucleic acids B) lipids C) carbohydrates D) proteins

D) proteins

46) The group of biological molecules that are most diverse in function is A) nucleic acids. B) carbohydrates. C) lipids. D) proteins.

D) proteins.

24) Carbon has atomic number 6. Carbon most likely A) shares neutrons. B) loses electrons. C) shares protons. D) shares electrons. E) loses protons.

D) shares electrons.

8) Carbon-14 is often used for carbon dating, where scientists measure the rate of carbon-14 decay to 8) determine the age of items. Carbon-14 contains six protons and eight neutrons. During the process of carbon-14 decay, one of its eight neutrons becomes a proton and an electron is emitted. Which of the following is the best explanation of what has occurred? A) The resulting atom is still carbon-14. B) An ionic bond has formed. C) The resulting atom has a more stable nucleus. D) The resulting atom is now a different element because the number of protons has changed.

D)The resulting atom is now a different element because the number of protons has changed.

51) A peptide bond forms between which of these groups? A) Hydroxyl and carboxyl B) Carboxyl and aldehyde C) Amino and aldehyde D) Phosphate and hydroxyl E) Carboxyl and amino

E) Carboxyl and amino

8) Which of the following best summarizes the relationship between dehydration reactions and hydrolysis? A) Dehydration reactions can occur only after hydrolysis. B) Hydrolysis creates monomers, and dehydration reactions destroy them. C) Hydrolysis creates polysaccharides, and dehydration creates monosaccharides. D) Dehydration reactions occur only in animals, and hydrolysis reactions occur only in plants. E) Dehydration reactions assemble polymers, and hydrolysis breaks them down.

E) Dehydration reactions assemble polymers, and hydrolysis breaks them down.

17) The fiber in your diet is actually A) protein. B) starch. C) glycogen. D) ATP. E) cellulose.

E) cellulose.

16) Most biological molecules are joined by A) hydrogen bonds. B) peptide bonds. C) disulfide bonds. D) ionic bonds. E) covalent bonds.

E) covalent bonds.

55) Water molecules are cohesive because they 55) A) make up 60% to 90% of an organism's body weight. B) contain protons. C) are repelled by nonpolar molecules. D) stick to other polar molecules. E) form hydrogen bonds.

E) form hydrogen bonds.

35) The hydrogen bond between two water molecules forms because water is A) nonpolar. B) a large molecule. C) hydrophobic. D) a small molecule. E) polar.

E) polar.

53) Hydrophilic molecules A) are repelled by water. B) do not readily dissolve in water. C) are neutral and nonpolar. D) form hydrogen bonds among themselves. E) readily dissolve in water.

E) readily dissolve in water.

68) DNA carries genetic information in its A) helical form. B) tertiary structure. C) phosphate groups. D) sugar groups. E) sequence of bases.

E) sequence of bases.

67) The "backbone" of a nucleic acid molecule is made of A) NAD+ and FAD. B) amino acids. C) lipids. D) ATP molecules. E) sugar and phosphate groups.

E) sugar and phosphate groups.

32) Fats and oils are made of A) two fatty acids and one carboxyl acid. B) three amino acids and one glycerol. C) one glycogen and two phospholipids. D) three glycerols and three fatty acids. E) three fatty acids and one glycerol.

E) three fatty acids and one glycerol.

73) Water surface tension is a result of the cohesive nature of water molecules.

TRUE

74) To maintain a constant pH, buffers act to either accept or release H+.

TRUE

76) Functional groups determine the characteristics and chemical reactivity of organic molecules.

TRUE