Bio

5) Fluorine has an atomic number of 9 and a mass number of 19. How many electrons are needed to complete the valence shell of a fluorine atom? A) 1 B) 3 C) 0 D) 7 E) 9

A) 1

Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? A) 8% B) 16% C) 31% D) 42% E) It cannot be determined from the information provided

A) 8%

38) In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of A) ATP, CO2, and ethanol (ethyl alcohol). B) ATP, CO2, and lactate. C) ATP, NADH, and pyruvate. D) ATP, pyruvate, and oxygen. E) ATP, pyruvate, and acetyl CoA

A) ATP, CO2, and ethanol (ethyl alcohol).

29) Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy A) C6H12O6 is oxidized and O2 is reduced. B) O2 is oxidized and H2O is reduced. C) CO2 is reduced and O2 is oxidized. D) C6H12O6 is reduced and CO2 is oxidized. E) O2 is reduced and CO2 is oxidized.

A) C6H12O6 is oxidized and O2 is reduced.

39) Which of the following best summarizes the relationship between dehydration reactions and hydrolysis? A) Dehydration reactions assemble polymers, and hydrolysis reactions break down polymers. B) Dehydration reactions eliminate water from lipid membranes, and hydrolysis makes lipid membranes water permeable. C) Dehydration reactions can occur only after hydrolysis. D) Hydrolysis creates monomers, and dehydration reactions break down polymers. E) Dehydration reactions ionize water molecules and add hydroxyl groups to polymers; hydrolysis reactions release hydroxyl groups from polymers.

A) Dehydration reactions assemble polymers, and hydrolysis reactions break down polymers.

8) Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements is correct about the atoms in ammonia (NH3)? A) Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge. B) The nitrogen atom has a strong positive charge; each hydrogen atom has a strong positive charge. C) Each hydrogen atom has a slight negative charge; the nitrogen atom has a strong positive charge. D) The nitrogen atom has a slight positive charge; each hydrogen atom has a slight negative charge. E) There are covalent bonds between the hydrogen atoms and polar bonds between each hydrogen atom and the nitrogen atom.

A) Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge.

12) According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids? A) They can move laterally along the plane of the membrane. B) They frequently flip-flop from one side of the membrane to the other. C) They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane. D) They are free to depart from the membrane and dissolve in the surrounding solution. E) They have hydrophilic tails in the interior of the membrane.

A) They can move laterally along the plane of the membrane.

25) Which of the following statements correctly describes cis-trans isomers? A) They have variations in arrangement around a double bond. B) They have an asymmetric carbon that makes them mirror images. C) They have the same chemical properties. D) They have different molecular formulas. E) Their atoms and bonds are arranged in different sequences.

A) They have variations in arrangement around a double bond.

27) Which of the following statements correctly describes cis-trans isomers? A) They have variations in arrangement around a double bond. B) They have an asymmetric carbon that makes them mirror images. C) They have the same chemical properties. D) They have different molecular formulas. E) Their atoms and bonds are arranged in different sequences.

A) They have variations in arrangement around a double bond.

11) Which of the following is not considered to be a weak molecular interaction? A) a covalent bond B) a van der Waals interaction C) an ionic bond in the presence of water D) a hydrogen bond E) both a hydrogen bond and a covalent bond

A) a covalent bond

12) Which of the following is not considered to be a weak molecular interaction? A) a covalent bond B) a van der Waals interaction C) an ionic bond in the presence of water D) a hydrogen bond E) both a hydrogen bond and a covalent bond

A) a covalent bond

8) Water molecules are able to form hydrogen bonds with A) compounds that have polar covalent bonds. B) oils. C) oxygen gas (O2) molecules. D) chloride ions. E) any compound that is not soluble in water.

A) compounds that have polar covalent bonds.

23) A chemical reaction that has a positive ΔG is correctly described as A) endergonic. B) endothermic. C) enthalpic. D) spontaneous. E) exothermic

A) endergonic.

33) Which of the following solutions would require the greatest amount of base to be added to bring the solution to neutral pH? A) gastric juice at pH 2 B) vinegar at pH 3 C) tomato juice at pH 4 D) black coffee at pH 5 E) household bleach at pH 12

A) gastric juice at pH 2

30) Which of the following is not a polymer? A) glucose B) starch C) cellulose D) chitin E) DNA

A) glucose

32) The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the α form. Which of the following could amylase break down? A) glycogen B) cellulose C) chitin D) glycogen and chitin only E) glycogen, cellulose, and chitin

A) glycogen

27) Some of the drugs used to treat HIV patients are competitive inhibitors of the HIV reverse transcriptase enzyme. Unfortunately, the high mutation rate of HIV means that the virus rapidly acquires mutations with amino acid changes that make them resistant to these competitive inhibitors. Where in the reverse transcriptase enzyme would such amino acid changes most likely occur in drugresistant viruses? A) in or near the active site B) at an allosteric site C) at a cofactor binding site D) in regions of the protein that determine packaging into the virus capsid E) such mutations could occur anywhere with equal probability

A) in or near the active site

9) A strong acid like HCl A) ionizes completely in an aqueous solution. B) increases the pH when added to an aqueous solution. C) reacts with strong bases to create a buffered solution. D) is a strong buffer at low pH. E) both ionizes completely in aqueous solutions and is a strong buffer at low pH.

A) ionizes completely in an aqueous solution.

9) Movement of vesicles within the cell depends on what cellular structures? A) microtubules and motor proteins B) actin filaments and microtubules C) actin filaments and ribosomes D) centrioles and motor proteins E) actin filaments and motor proteins

A) microtubules and motor proteins

12) Hydrophobic substances such as vegetable oil are A) nonpolar substances that repel water molecules. B) nonpolar substances that have an attraction for water molecules. C) polar substances that repel water molecules. D) polar substances that have an affinity for water. E) charged molecules that hydrogen-bond with water molecules.

A) nonpolar substances that repel water molecules.

16) Hydrophobic substances such as vegetable oil are A) nonpolar substances that repel water molecules. B) nonpolar substances that have an attraction for water molecules. C) polar substances that repel water molecules. D) polar substances that have an affinity for water. E) charged molecules that hydrogen-bond with water molecules.

A) nonpolar substances that repel water molecules.

3) If radioactive deoxythymidine triphosphate (dTTP) is added to a culture of rapidly growing bacterial cells, where in the cell would you expect to find the greatest concentration of radioactivity? A) nucleus B) cytoplasm C) endoplasmic reticulum D) nucleoid E) ribosomes

A) nucleus

29) A covalent bond is likely to be polar when A) one of the atoms sharing electrons is much more electronegative than the other atom. B) the two atoms sharing electrons are equally electronegative. C) oxygen is one of the two atoms sharing electrons. D) one of the atoms has absorbed more energy than the other atom. E) the two atoms sharing electrons are different elements.

A) one of the atoms sharing electrons is much more electronegative than the other atom.

19) What is the pH of a solution with a hydroxyl ion [OH-] concentration of 10-12 M? A) pH 2 B) pH 4 C) pH 10 D) pH 12 E) pH 14

A) pH 2

25) Based on your knowledge of the polarity of water molecules, the solute molecule depicted in the center here is most likely: A) positively charged. B) negatively charged. C) without charge. D) hydrophobic. E) nonpolar.

A) positively charged.

31) The ATP made during glycolysis is generated by A) substrate-level phosphorylation. B) electron transport. C) photophosphorylation. D) chemiosmosis. E) oxidation of NADH to NAD+.

A) substrate-level phosphorylation.

35) Which of the following pairs of atoms would be most likely to form an ionic bond?

B

6) If an atom of sulfur (atomic number 16) were allowed to react with atoms of hydrogen (atomic number 1), which of the molecules below would be formed?

B

3) An atom has 6 electrons in its outer shell. How many unpaired electrons does it have? A) 0 B) 2 C) 4 D) 6 E) 2 or 4

B) 2

7) What is the maximum number of covalent bonds an element with atomic number 8 can make with hydrogen? A) 1 B) 2 C) 3 D) 4 E) 6

B) 2

44) f one strand of a DNA molecule has the sequence of bases 5'ATTGCA3', the other complementary strand would have the sequence A) 5'TAACGT3'. B) 5'TGCAAT3'. C) 5'UAACGU3'. D) 3'UAACGU5'. E) 5'UGCAAU3'.

B) 5'TGCAAT3'.

15) Which of the following effects is produced by the high surface tension of water? A) Lakes don't freeze solid in winter, despite low temperatures. B) A water strider can walk across the surface of a small pond. C) Organisms resist temperature changes, although they give off heat due to chemical reactions. D) Evaporation of sweat from the skin helps to keep people from overheating. E) Water flows upward from the roots to the leaves in plants.

B) A water strider can walk across the surface of a small pond.

18) The molar mass of glucose (C6 H12O6) is 180 g/mol. Which of the following procedures should you carry out to make a 0.5 M solution of glucose? A) Dissolve 0.5 g of glucose in a small volume of water, and then add more water until the total volume of solution is 1 L. B) Dissolve 90 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L. C) Dissolve 180 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L. D) Dissolve 0.5 g of glucose in 1 L of water. E) Dissolve 180 g of glucose in 0.5 L of water

B) Dissolve 90 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L.

24) Why is ATP an important molecule in metabolism? A) Its hydrolysis provides an input of free energy for exergonic reactions. B) It provides energy coupling between exergonic and endergonic reactions. C) Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy.D) Its terminal phosphate bond has higher energy than the other two. E) It is one of the four building blocks for DNA synthesis.

B) It provides energy coupling between exergonic and endergonic reactions.

26) A compound contains hydroxyl groups as its predominant functional group. Which of the following statements is true concerning this compound? A) It lacks an asymmetric carbon, and it is probably a fat or lipid. B) It should dissolve in water. C) It should dissolve in a nonpolar solvent. D) It won't form hydrogen bonds with water. E) It is hydrophobic.

B) It should dissolve in water.

26) The R group or side chain of the amino acid serine is -CH2-OH. The R group or side chain of the amino acid leucine is -CH2-CH-(CH3)2. Where would you expect to find these amino acids in a globular protein in aqueous solution? A) Serine would be in the interior, and leucine would be on the exterior of the globular protein. B) Leucine would be in the interior, and serine would be on the exterior of the globular protein. C) Both serine and leucine would be in the interior of the globular protein. D) Both serine and leucine would be on the exterior of the globular protein. E) Both serine and leucine would be in the interior and on the exterior of the globular protein.

B) Leucine would be in the interior, and serine would be on the exterior of the globular protein.

18) Why are hydrocarbons insoluble in water? A) The majority of their bonds are polar covalent carbon-to-hydrogen linkages. B) The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages. C) They are hydrophilic. D) They exhibit considerable molecular complexity and diversity. E) They are lighter than water.

B) The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.

24) Why are hydrocarbons insoluble in water? A) The majority of their bonds are polar covalent carbon-to-hydrogen linkages. B) The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages. C) They are hydrophilic. D) They exhibit considerable molecular complexity and diversity. E) They are lighter than water

B) The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.

15) Why are human steroids considered to be lipids? A) They are essential components of cell membranes. B) They are not soluble in water. C) They are made of fatty acids. D) They are hydrophilic compounds. E) They contribute to atherosclerosis.

B) They are not soluble in water.

13) The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called? A) a covalent bond B) a hydrogen bond C) an ionic bond D) a hydrophilic bond E) a van der Waals interaction

B) a hydrogen bond

35) In cellular respiration, the energy for most ATP synthesis is supplied by A) high energy phosphate bonds in organic molecules. B) a proton gradient across a membrane. C) converting oxygen to ATP. D) transferring electrons from organic molecules to pyruvate. E) generating carbon dioxide and oxygen in the electron transport chain

B) a proton gradient across a membrane.

36) Research indicates that ibuprofen, a drug used to relieve inflammation and pain, is a mixture of two enantiomers; that is, molecules that A) have identical chemical formulas but differ in the branching of their carbon skeletons. B) are mirror images of one another. C) exist in either linear chain or ring forms. D) differ in the location of their double bonds. E) differ in the arrangement of atoms around their double bonds.

B) are mirror images of one another.

23) Compared to a hydrocarbon chain where all the carbon atoms are linked by single bonds, a hydrocarbon chain with the same number of carbon atoms, but with one or more double bonds, will A) be more flexible in structure. B) be more constrained in structure. C) be more polar. D) have more hydrogen atoms. E) have fewer structurally distinct isomers.

B) be more constrained in structure.

22) Differences among organisms are caused by A) large differences in elemental composition from organism to organism. B) differences in the types and relative amounts of organic molecules synthesized by each organism. C) differences in the elements that bond with carbon in each organism. D) differences in the sizes of the organic molecules in each organism. E) differences in inorganic compounds present in each organism.

B) differences in the types and relative amounts of organic molecules synthesized by each organism.

11) Van der Waals interactions result when A) hybrid orbitals overlap. B) electrons are not symmetrically distributed in a molecule. C) molecules held by ionic bonds react with water. D) two polar covalent bonds react. E) a hydrogen atom loses an electron.

B) electrons are not symmetrically distributed in a molecule.

33) A molecule with the formula C18H36O2 is probably a A) carbohydrate. B) fatty acid. C) protein. D) nucleic acid. E) hydrocarbon.

B) fatty acid.

40) One of the primary functions of RNA molecules is to A) transmit genetic information to offspring. B) function in the synthesis of proteins. C) make a copy of itself, thus ensuring genetic continuity. D) act as a pattern or blueprint to form DNA. E) form the genes of higher organisms.

B) function in the synthesis of proteins.

37) What maintains the secondary structure of a protein? A) peptide bonds B) hydrogen bonds between the amino group of one peptide bond and the carboxyl group of another peptide bond C) disulfide bonds D) hydrophobic interactions E) hydrogen bonds between the R groups

B) hydrogen bonds between the amino group of one peptide bond and the carboxyl group of another peptide bond

19) White blood cells engulf bacteria through what process? A) exocytosis B) phagocytosis C) pinocytosis D) osmosis E) receptor-mediated exocytosis

B) phagocytosis

38) Which level of protein structure do the α helix and the β pleated sheet represent? A) primary B) secondary C) tertiary D) quaternary E) primary, secondary, tertiary, and quaternary

B) secondary

5)Which level of protein structure do the α helix and the β pleated sheet represent? A) primary B) secondary C) tertiary D) quaternary E) primary, secondary, tertiary, and quaternary

B) secondary

5) The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and therefore abundant in liver cells? A) rough ER B) smooth ER C) Golgi apparatus D) nuclear envelope E) transport vesicles

B) smooth ER

37) If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized by carbon dioxide and water, how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water? A) 0 B) 1 C) 12 D) 14 E) 15

C) 12

42) If a DNA sample were composed of 10% thymine, what would be the percentage of guanine? A) 10 B) 20 C) 40 D) 80 E) impossible to tell from the information given

C) 40

36) Upon chemical analysis, a particular polypeptide was found to contain 100 amino acids. How many peptide bonds are present in this protein? A) 101 B) 100 C) 99 D) 98 E) 97

C) 99

28) Which of the following statements describes enzyme cooperativity? A) A multienzyme complex contains all the enzymes of a metabolic pathway. B) A product of a pathway serves as a competitive inhibitor of an early enzyme in the pathway. C) A substrate molecule bound to an active site of one subunit promotes substrate binding to the active site of other subunits. D) Several substrate molecules can be catalyzed by the same enzyme. E) A substrate binds to an active site and inhibits cooperation between enzymes in a pathway.

C) A substrate molecule bound to an active site of one subunit promotes substrate binding to the active site of other subunits.

What are the products of linear photophosphorylation? A) heat and fluorescence B) ATP and P700 C) ATP and NADPH D) ADP and NADP E) P700 and P680

C) ATP and NADPH

24) At which bond would water need to be added to achieve hydrolysis of the peptide, back to its component amino acid? A) A B) B C) C D) D E) E

C) C

Which drawing in the figure above depicts an atom with a valence of 2? A) A B) B C) C D) D E) E

C) C

45) Among these biological polymers, which has the least structural variety? A) polysaccharides B) proteins C) DNA D) RNA

C) DNA

2) Why is each element unique and different from other elements in chemical properties? A) Each element has a unique atomic mass. B) Each element has a unique atomic weight. C) Each element has a unique number of protons in its nucleus. D) Each element has a unique number of neutrons in its nucleus. E) Each element has different radioactive properties.

C) Each element has a unique number of protons in its nucleus.

1) What is the reason that a modern electron microscope (TEM) can resolve biological images to the subnanometer level, as opposed to tens of nanometers achievable for the best super-resolution light microscope? A) The focal length of the electron microscope is significantly longer. B) Contrast is enhanced by staining with atoms of heavy metal. C) Electron beams have much shorter wavelengths than visible light. D) The electron microscope has a much greater ratio of image size to real size. E) The electron microscope cannot image whole cells at one time.

C) Electron beams have much shorter wavelengths than visible light.

14) Which of the following statements is correct about diffusion? A) It is very rapid over long distances. B) It requires an expenditure of energy by the cell. C) It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration. D) It is an active process in which molecules move from a region of lower concentration to one of higher concentration. E) It requires integral proteins in the cell membrane

C) It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

32) In addition to ATP, what are the end products of glycolysis? A) CO2 and H2O B) CO2 and pyruvate C) NADH and pyruvate D) CO2 and NADH E) H2O, FADH2, and citrate

C) NADH and pyruvate

34) Which of the following is true regarding saturated fatty acids? A) They are the predominant fatty acid in corn oil. B) They have double bonds between carbon atoms of the fatty acids. C) They are the principal molecules in lard and butter. D) They are usually liquid at room temperature. E) They are usually produced by plants.

C) They are the principal molecules in lard and butter.

30) Which of the following descriptions best fits the class of molecules known as nucleotides? A) a nitrogenous base and a phosphate group B) a nitrogenous base and a pentose sugar C) a nitrogenous base, a phosphate group, and a pentose sugar D) a phosphate group and an adenine or uracil E) a pentose sugar and a purine or pyrimidine

C) a nitrogenous base, a phosphate group, and a pentose sugar

41) Which of the following descriptions best fits the class of molecules known as nucleotides? A) a nitrogenous base and a phosphate group B) a nitrogenous base and a pentose sugar C) a nitrogenous base, a phosphate group, and a pentose sugar D) a phosphate group and an adenine or uracil E) a pentose sugar and a purine or pyrimidine

C) a nitrogenous base, a phosphate group, and a pentose sugar

13) In order for a protein to be an integral membrane protein it would have to be A) hydrophilic. B) hydrophobic. C) amphipathic, with at least one hydrophobic region. D) completely covered with phospholipids. E) exposed on only one surface of the membrane.

C) amphipathic, with at least one hydrophobic region.

20) The movement of potassium into an animal cell requires A) low cellular concentrations of sodium. B) high cellular concentrations of potassium. C) an energy source such as ATP. D) a cotransport protein. E) a potassium channel protein

C) an energy source such as ATP.

10) The element present in all organic molecules is A) hydrogen. B) oxygen. C) carbon. D) nitrogen. E) phosphorus.

C) carbon.

14) Which two functional groups are always found in amino acids? A) ketone and methyl B) carbonyl and amino C) carboxyl and amino D) amino and sulfhydryl E) hydroxyl and carboxyl

C) carboxyl and amino

25) Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? A) denaturization of the enzyme B) allosteric inhibition C) competitive inhibition D) saturation of the enzyme activity E) insufficient cofactors

C) competitive inhibition

20) If the pH of a solution is increased from pH 5 to pH 7, it means that the A) concentration of H+ is twice (2X) what it was at pH 5. B) concentration of H+ is one-half (1/2) what it was at pH 5. C) concentration of OH- is 100 times greater than what it was at pH 5. D) concentration of OH- is one-hundredth (0.01X) what it was at pH 5. E) concentration of H+ is 100 times greater and the concentration of OH- is one-hundredth what they were at pH 5.

C) concentration of OH- is 100 times greater than what it was at pH 5.

23) A carbon atom is most likely to form what kind of bond(s) with other atoms? A) ionic B) hydrogen C) covalent D) covalent bonds and hydrogen bonds E) ionic bonds, covalent bonds, and hydrogen bonds

C) covalent

31) What is the chemical reaction mechanism by which cells make polymers from monomers? A) phosphodiester linkages B) hydrolysis C) dehydration reactions D) ionic bonding of monomers E) the formation of disulfide bridges between monomers

C) dehydration reactions

32) What is the chemical reaction mechanism by which cells make polymers from monomers? A) phosphodiester linkages B) hydrolysis C) dehydration reactions D) ionic bonding of monomers E) the formation of disulfide bridges between monomers

C) dehydration reactions

35) There are 20 different amino acids. What makes one amino acid different from another? A) different side chains (R groups) attached to a carboxyl carbon B) different side chains (R groups) attached to the amino groups C) different side chains (R groups) attached to an α carbon D) different structural and optical isomers E) different asymmetric carbons

C) different side chains (R groups) attached to an α carbon

40) There are 20 different amino acids. What makes one amino acid different from another? A) different side chains (R groups) attached to a carboxyl carbon B) different side chains (R groups) attached to the amino groups C) different side chains (R groups) attached to an α carbon D) different structural and optical isomers E) different asymmetric carbons

C) different side chains (R groups) attached to an α carbon

2) The advantage of light microscopy over electron microscopy is that A) light microscopy provides for higher magnification than electron microscopy. B) light microscopy provides for higher resolving power than electron microscopy. C) light microscopy allows one to view dynamic processes in living cells. D) light microscopy provides higher contrast than electron microscopy. E) specimen preparation for light microcopy does not produce artifacts.

C) light microscopy allows one to view dynamic processes in living cells.

7) A covalent chemical bond is one in which A) electrons are removed from one atom and transferred to another atom so that the two atoms become oppositely charged. B) protons and neutrons are shared by two atoms so as to satisfy the requirements of both atoms. C) outer-shell electrons of two atoms are shared so as to satisfactorily fill the outer electron shells of both atoms. D) outer-shell electrons of one atom are transferred to fill the inner electron shell of another atom. E) an electron occupies a hybrid orbital located between the nuclei of two atoms

C) outer-shell electrons of two atoms are shared so as to satisfactorily fill the outer electron shells of both atoms.

30) When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes A) hydrolyzed. B) hydrogenated. C) oxidized. D) reduced. E) an oxidizing agent.

C) oxidized.

11) Which of the following types of molecules are the major structural components of the cell membrane? A) phospholipids and cellulose B) nucleic acids and proteins C) phospholipids and proteins D) proteins and cellulose E) glycoproteins and cholesterol

C) phospholipids and proteins

10) All of the following serve an important role in determining or maintaining the structure of plant cells. Which of the following are distinct from the others in their composition? A) microtubules B) microfilaments C) plant cell walls D) intermediate filaments E) nuclear lamina

C) plant cell walls

31) The two molecules shown in the figure above are best described as A) optical isomers. B) enantiomers. C) structural isomers. D) cis-trans isomers. E) chain length isomers.

C) structural isomers.

1) At which level of protein structure are interactions between the side chains (R groups) most important? A) primary B) secondary C) tertiary D) all of the above

C) tertiary

39) The tertiary structure of a protein is the A) bonding together of several polypeptide chains by weak bonds. B) order in which amino acids are joined in a polypeptide chain. C) unique three-dimensional shape of the fully folded polypeptide. D) organization of a polypeptide chain into an α helix or β pleated sheet. E) overall protein structure resulting from the aggregation of two or more polypeptide subunits.

C) unique three-dimensional shape of the fully folded polypeptide.

37) One liter of a solution of pH 2 has how many more hydrogen ions (H+) than 1 L of a solution of pH 6? A) 4 times more B) 16 times more C) 40,000 times more D) 10,000 times more E) 100,000 times more

D) 10,000 times more

13) What is the hydrogen ion [H+] concentration of a solution of pH 8? A) 8 M B) 8 x 10-6 M C) 0.01 M D) 10-8 M E) 10-6 M

D) 10-8 M

16) An atom has 5 electrons in its outer shell. How many unpaired electrons does it have? A) 0 B) 1 C) 2 D) 3 E) 4

D) 3

26) Which of the following is true of enzymes? A) Nonprotein cofactors alter the substrate specificity of enzymes. B) Enzyme function is increased if the 3-D structure or conformation of an enzyme is altered. C) Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. D) Enzymes increase the rate of chemical reaction by lowering activation energy barriers. E) Enzymes increase the rate of chemical reaction by providing activation energy to the substrate.

D) Enzymes increase the rate of chemical reaction by lowering activation energy barriers.

6) Which of the following produces and modifies polysaccharides that will be secreted? A) lysosome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome

D) Golgi apparatus

9) Which of the following molecules contains the most polar covalent bond? A) H2 B) O2 C) CO2 D) H2O E) CH4

D) H2O

21) Which of the following is true of metabolism in its entirety in all organisms? A) Metabolism depends on a constant supply of energy from food. B) Metabolism depends on an organism's adequate hydration. C) Metabolism uses all of an organism's resources. D) Metabolism consists of all the energy transformation reactions in an organism. E) Metabolism manages the increase of entropy in an organism.

D) Metabolism consists of all the energy transformation reactions in an organism.

15) Which of the following statements correctly describes the normal tonicity conditions for typical plant and animal cells? A) The animal cell is in a hypotonic solution, and the plant cell is in an isotonic solution. B) The animal cell is in an isotonic solution, and the plant cell is in a hypertonic solution. C) The animal cell is in a hypertonic solution, and the plant cell is in an isotonic solution. D) The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution. E) The animal cell is in a hypertonic solution, and the plant cell is in a hypotonic solution.

D) The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution.

21) Which of the following statements is true about buffer solutions? A) They maintain a constant pH when bases are added to them but not when acids are added to them. B) They maintain a constant pH when acids are added to them but not when bases are added to them. C) They maintain a relatively constant pH of approximately 7 when either acids or bases are added to them. D) They maintain a relatively constant pH when either acids or bases are added to them. E) They are found only in living systems and biological fluids.

D) They maintain a relatively constant pH when either acids or bases are added to them.

2) Oxygen has an atomic number of 8 and a mass number of 16. Thus, what is the atomic mass of an oxygen atom? A) exactly 8 grams B) exactly 8 daltons C) approximately 16 grams D) approximately 16 daltons E) 24 amu (atomic mass units)

D) approximately 16 daltons

28) Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified? A) as a pentose B) as a hexose C) as a monosaccharide D) as a disaccharide E) as a polysaccharide

D) as a disaccharide

1) About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter? A) carbon, sodium, hydrogen, nitrogen B) carbon, oxygen, phosphorus, hydrogen C) oxygen, hydrogen, calcium, nitrogen D) carbon, hydrogen, nitrogen, oxygen E) carbon, oxygen, nitrogen, calcium

D) carbon, hydrogen, nitrogen, oxygen

6) If the pH of a solution is decreased from 9 to 8, it means that the A) concentration of H+ has decreased to one-tenth (1/10) what it was at pH 9. B) concentration of H+ has increased tenfold (10X) compared to what it was at pH 9. C) concentration of OH- has increased tenfold (10X) compared to what it was at pH 9. D) concentration of H+ has increased tenfold (10X) and the concentration of OH- has decreased to onetenth (1/10) what they were at pH 9.

D) concentration of H+ has increased tenfold (10X) and the concentration of OH- has decreased to onetenth (1/10) what they were at pH 9.

17) Ions diffuse across membranes through specific ion channels A) down their chemical gradients. B) down their concentration gradients. C) down the electrical gradients. D) down their electrochemical gradients. E) down the osmotic potential gradients.

D) down their electrochemical gradients.

21) Which type of bond must be broken for water to vaporize? A) ionic bonds B) both hydrogen bonds and ionic bonds C) polar covalent bonds D) hydrogen bonds E) both polar covalent bonds and hydrogen bonds

D) hydrogen bonds

7) In a plant cell, DNA may be found A) only in the nucleus. B) only in the nucleus and mitochondria. C) only in the nucleus and chloroplasts. D) in the nucleus, mitochondria, and chloroplasts. E) in the nucleus, mitochondria, chloroplasts, and peroxisomes.

D) in the nucleus, mitochondria, and chloroplasts.

8) One of the key innovations in the evolution of eukaryotes from a prokaryotic ancestor is the endomembrane system. What eukaryotic organelles or features might have evolved as a part of, or as an elaboration of, the endomembrane system? A) plasma membrane B) chloroplasts C) mitochondria D) nuclear envelope E) none of these

D) nuclear envelope

3) Each base pair of a DNA molecule contains: A) two pyrimidine bases B) two purine bases C) only sulfydryl containing bases D) one purine and one pyrimidine base.

D) one purine and one pyrimidine base.

18) An organism with a cell wall would most likely be unable to take in materials through A) diffusion. B) osmosis. C) active transport. D) phagocytosis. E) facilitated diffusion.

D) phagocytosis.

The figure above shows the structures of glucose and fructose. These two molecules are A) geometric isotopes. B) enantiomers. C) cis-trans isomers. D) structural isomers. E) nonisotopic isomers

D) structural isomers.

27) One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). Thus, H2CO3 ↔ HCO3- + H+ If the pH of the blood drops, one would expect A) a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3-. B) the concentration of hydroxide ion (OH-) to increase. C) the concentration of bicarbonate ion (HCO3-) to increase. D) the HCO3- to act as a base and remove excess H+ with the formation of H2CO3. E) the HCO3- to act as an acid and remove excess H+ with the formation of H2CO3.

D) the HCO3- to act as a base and remove excess H+ with the formation of H2CO3.

36) The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation in eukaryotic cells is A) oxidation of glucose to CO2 and water. B) the thermodynamically favorable flow of electrons from NADH to the mitochondrial electron transport carriers. C) the final transfer of electrons to oxygen. D) the proton-motive force across the inner mitochondrial membrane. E) the thermodynamically favorable transfer of phosphate from glycolysis and the citric acid cycle intermediate molecules of ADP.

D) the proton-motive force across the inner mitochondrial membrane.

17)The structure depicted in to the right shows the A) 1-4 linkage of the α glucose monomers of starch. B) 1-4 linkage of the β glucose monomers of cellulose. C) double-helical structure of a DNA molecule. D) α helix secondary structure of a polypeptide. E) β pleated sheet secondary structure of a polypeptide.

D) α helix secondary structure of a polypeptide.

17) How many molecules of glucose (C6H12O6 molecular mass = 180 daltons) would be present in 90 grams of glucose? A) 90 × 10^23 B) (6.02/180) × 10^23 C) (6.02/90) × 10^23 D) (90 x 6.02) × 10^23 E) (90/180) × 6.02 × 10^23

E) (90/180) × 6.02 × 10^23

4) From its atomic number of 15, it is possible to predict that the phosphorus atom has A) 15 neutrons. B) 15 protons. C) 15 electrons. D) 8 electrons in its outermost electron shell. E) 15 protons and 15 electrons.

E) 15 protons and 15 electrons.

19) What are the primary differences between RNA and DNA? A) RNA has an oxygen in the pentose sugar that is not present in DNA B) RNA does not use the base Thymine C) RNA is Single Stranded D) RNA can form more complex structures than DNA E) All of the above

E) All of the above

4) The Golgi apparatus has a polarity or sidedness to its structure and function. Which of the following statements correctly describes this polarity? A) Transport vesicles fuse with one side of the Golgi and leave from the opposite side. B) Proteins in the membrane of the Golgi may be sorted and modified as they move from one side of the Golgi to the other. C) Lipids in the membrane of the Golgi may be sorted and modified as they move from one side of the Golgi to the other. D) Soluble proteins in the cisternae (interior) of the Golgi may be sorted and modified as they move from one side of the Golgi to the other. E) All of the above correctly describe polar characteristics of the Golgi function.

E) All of the above correctly describe polar characteristics of the Golgi function.

22) The molar mass of glucose is 180 g/mol. Which of the following procedures should you carry out to make a 1 M solution of glucose? A) Dissolve 1 g of glucose in 1 L of water. B) Dissolve 180 g of glucose in 1 L of water. C) Dissolve 180 g of glucose in 180 g of water. D) Dissolve 180 milligrams (mg) of glucose in 1 L of water. E) Dissolve 180 g of glucose in 0.8 L of water, and then add more water until the total volume of the solution is 1 L.

E) Dissolve 180 g of glucose in 0.8 L of water, and then add more water until the total volume of the solution is 1 L.

33) Why is glycolysis described as having an investment phase and a payoff phase? A) It both splits molecules and assembles molecules. B) It attaches and detaches phosphate groups. C) It uses glucose and generates pyruvate. D) It shifts molecules from cytosol to mitochondrion. E) It uses stored ATP and then forms a net increase in ATP.

E) It uses stored ATP and then forms a net increase in ATP.

34) Buffers are substances that help resist shifts in pH by A) releasing H+ to a solution when acids are added. B) donating H+ to a solution when bases are added. C) releasing OH- to a solution when bases are added. D) accepting H+ from a solution when acids are added. E) both donating H+ to a solution when bases are added, and accepting H+ when acids are added.

E) both donating H+ to a solution when bases are added, and accepting H+ when acids are added.

22) A system at chemical equilibrium A) consumes energy at a steady rate. B) releases energy at a steady rate. C) consumes or releases energy, depending on whether it is exergonic or endergonic. D) has zero kinetic energy. E) can do no work.

E) can do no work.

38) The two molecules shown in the figure above are best described as A) enantiomers. B) radioactive isotopes. C) structural isomers. D) nonisotopic isomers. E) cis-trans isomers.

E) cis-trans isomers.

43) The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA A) is a six-carbon sugar and the sugar in RNA is a five-carbon sugar. B) can form a double-stranded molecule. C) is an aldehyde sugar and the sugar in RNA is a keto sugar. D) is in the α configuration and the sugar in RNA is in the β configuration. E) contains one less oxygen atom.

E) contains one less oxygen atom.

16) The phosphate transport system in bacteria imports phosphate into the cell even when the concentration of phosphate outside the cell is much lower than the cytoplasmic phosphate concentration. Phosphate import depends on a pH gradient across the membrane-more acidic outside the cell than inside the cell. Phosphate transport is an example of A) passive diffusion. B) facilitated diffusion. C) active transport. D) osmosis. E) cotransport.

E) cotransport.

29) Molecules with which functional groups may form polymers via dehydration reactions? A) hydroxyl groups B) carbonyl groups C) carboxyl groups D) either carbonyl or carboxyl groups E) either hydroxyl or carboxyl groups

E) either hydroxyl or carboxyl groups

33) The amino acids of the protein keratin are arranged predominantly in an α helix. This secondary structure is stabilized by A) covalent bonds. B) peptide bonds. C) ionic bonds. D) polar bonds. E) hydrogen bonds.

E) hydrogen bonds.

34) During cellular respiration, acetyl CoA accumulates in which location? A) cytosol B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) mitochondrial matrix

E) mitochondrial matrix

20) Consider two solutions: solution X has a pH of 4; solution Y has a pH of 7. From this information, we can reasonably conclude that A) solution Y has no free hydrogen ions (H+). B) the concentration of hydrogen ions in solution X is 30 times as great as the concentration of hydrogen ions in solution Y. C) the concentration of hydrogen ions in solution Y is 1,000 times as great as the concentration of hydrogen ions in solution X. D) the concentration of hydrogen ions in solution X is 3 times as great as the concentration of hydrogen ions in solution Y. E) the concentration of hydrogen ions in solution X is 1,000 times as great as the concentration of hydrogen ions in solution Y.

E) the concentration of hydrogen ions in solution X is 1,000 times as great as the concentration of hydrogen ions in solution Y.

10) What bonding or interaction is most likely to occur among a broad array of molecules of various types (polar, nonpolar, hydrophilic, hydrophobic)? A) covalent bonding B) polar covalent bonding C) ionic bonding D) hydrogen bonding E) van der Waals interactions

E) van der Waals interactions

14) Sulfur is in the same column of the periodic table as oxygen, but has electronegativity similar to carbon. Compared to water molecules, molecules of H2S A) will ionize more readily. B) will have greater cohesion to other molecules of H2S. C) will have a greater tendency to form hydrogen bonds with each other. D) will have a higher capacity to absorb heat for the same change in temperature. E) will not form hydrogen bonds with each other.

E) will not form hydrogen bonds with each other.