BCOR 11: Exam 1 Name Section Dr. G. Delay Red = Correct Answer Blue = partial Credit Fall, 2005

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1 BCOR 11: Exam 1 Name Section Dr. G. Delay Red = Correct Answer Blue = partial Credit Fall, ) Which of the following statements concerning prokaryotic and eukaryotic cells is not correct? A) Prokaryotic cells lack a membrane-bound nucleus. B) Prokaryotic cells contain small membrane-enclosed organelles. C) Eukaryotic cells contain a membrane-bound nucleus. D) DNA, or deoxyribonucleic acid, is present in both prokaryotic cells and eukaryotic cells. E) DNA or deoxyribonucleic acid is present in the nucleus of eukaryotic cells. 2) What is a hypothesis? A) a tentative explanation that can be tested and is falsifiable B) the same thing as an unproven theory C) a verifiable observation sensed directly, or sensed indirectly with the aid of scientific instrumentation D) a fact based on qualitative data that is testable E) a fact based on quantitative data that is falsifiable 3) According to Charles Darwin, organisms of a particular species are adapted to their environment when they possess A) non-inheritable traits that enhance their survival in the local environment. B) non-inheritable traits that enhance their reproductive success in the local environment. C) non-inheritable traits that enhance their survival and reproductive success in the local environment. D) inheritable traits that enhance their survival and reproductive success in the local environment. E) inheritable traits that decrease their survival and reproductive success in the local environment. 4) An atom with an atomic number of 9 and a mass number of 19 would have an atomic mass of approximately A) 9 daltons B) 9 grams C) 10 daltons D) 10 grams E) 19 daltons 5) Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient energy, a possible result is that A) an electron may move to an electron shell farther out from the nucleus. B) an electron may move to an electron shell closer to the nucleus. C) the atom may become a radioactive isotope. D) the atom would become a positively charged ion or cation. E) the atom would become a negatively charged ion or anion. 6) The reactive properties or chemical behavior of an atom depend on the number of A) valence shells in the atom. B) orbitals found in the atom. C) electrons in each orbital of the atom. D) electrons in the outer valence shell in the atom. E) hybridized orbitals in the atom. 7) A molecule of carbon dioxide (CO 2 ) is formed when one atom of carbon (atomic number 6) is covalently bonded with two atoms of oxygen (atomic number 8). What is the total number of electrons that must be shared between the carbon atom and the oxygen atoms in order to complete the outer electron shell of all three atoms? A) 1 B) 2 C) 3 D) 4 E) 5

2 8) A covalent bond is likely to be polar when A) one of the atoms sharing electrons is more electronegative than the other atom. B) the two atoms sharing electrons are equally electronegative. C) the two atoms sharing electrons are of the same element. D) it is between two atoms that are both very strong electron acceptors. E) the two atoms sharing electrons are different elements. 9) What results from a transfer of electron(s) between atoms? A) a nonpolar covalent bond B) a polar covalent bond C) an ionic bond D) a hydrogen bond E) a hydrophobic interaction 10) 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 hydrophobic bond 11) Which of the following is possible due to 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) Water can act as a solvent. E) The ph of water remains exactly neutral. 12) Which bonds must be broken for water to vaporize? A) ionic bonds B) nonpolar covalent bonds C) polar covalent bonds D) hydrogen bonds E) covalent bonds Figure 1 13) How many grams of the molecule in Figure 1 would be required to make 1 L of a 0.5 M solution of the molecule? (Carbon = 12, Oxygen = 16, Hydrogen = 1) A) 29 B) 30 Hint: Several students appeared not to see that this was for a 0.5 M solution. C) 60 D) 150 E) ) Which of the following solutions has the greatest concentration of hydrogen ions [H + ]? 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

3 15) Amino acids are acids because they always possess which functional group? A) amino B) carbonyl C) carboxyl The amino group has the properties of a BASE (check pg 65) D) sulfhydryl E) aldehyde 16) If the ph of a solution is increased from ph 5 to ph 7, it means that the concentration of A) H + is 2 times greater than what it was at ph 5. B) H + is 2 times less than what it was at ph 5. C) OH - is 100 times greater than what it was at ph 5. D) OH - is 100 times less than what it was at ph 5. E) H + is 100 times greater and the concentration of OH - is 100 times less than what they were at ph 5. 17) One of the buffers that contribute to ph stability in human blood is carbonic acid (H 2 CO 3 ). Carbonic acid is a weak acid that dissociates into a bicarbonate ion (HCO 3 - ) and a hydrogen ion (H + ). Thus, H 2 CO 3 HCO H + If the ph of the blood drops, one would expect A) a decrease in the concentration of H 2 CO 3 and an increase in the concentration of HCO 3 -. B) the concentration of hydroxide ion (OH - ) to increase. C) the concentration of bicarbonate ion (HCO 3 - ) to increase. D) the HCO 3 - to act as a base and remove excess H + with the formation of H 2 CO 3. E) the HCO 3 - to act as an acid and remove excess H + with the formation of H 2 CO 3. 18) What is the reason why hydrocarbons are not soluble 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. 19) How many structural isomers are possible for a substance having the molecular formula C 4 H 10? A) 1 B) 2 C) 4 D) 3 E) 11 Figure 2 Glucose Galactose 20) Observe the structures of glucose and galactose in Figure 2. These two molecules are A) geometric isotopes. B) enantiomers. Check the definitions for each type of isomer on page 70. C) geometric isomers. D) structural isomers. E) nonisotopic isomers.

4 21) 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. 22) A chemist wishes to make an organic molecule less acidic. Which of the following functional groups should be added to the molecule in order to do so? A) carboxyl B) sulfhydryl C) hydroxyl D) amino E) phosphate Figure 3 23) Which molecule in Figure 3 has a carbonyl functional group in the form of a ketone? C 24) Which of the following best summarizes the relationship between dehydration reactions and hydrolysis? A) Dehydration reactions assemble polymers, and hydrolysis breaks down polymers. B) Hydrolysis only occurs in the urinary system, and dehydration reactions only occur in the digestive tract. C) Dehydration reactions can occur only after hydrolysis. D) Hydrolysis creates monomers, and dehydration reactions break down polymers. E) A and C are correct. Figure 4 25) If 128 molecules of the general type shown in Figure 4 were covalently joined together in sequence, the single molecule that would result would be a A) polysaccharide. B) polypeptide. C) polyunsaturated lipid. D) monosaccharide. E) disaccharide. 26) Which of the following is true of both starch and cellulose? A) They are both polymers of glucose. B) They are geometric isomers of each other. C) They can both be digested by humans. D) They are both used for energy storage in plants. E) They are both structural components of the plant cell wall.

5 27) A molecule with the formula C 18 H 36 O 2 is probably a A) carbohydrate. B) lipid. Hints: 1) count the number of N and 2) check page 75 for lipids C) protein. D) nucleic acid. E) hydrocarbon. Figure 5 28) What is the structure shown in Figure 5? A) starch molecule B) protein molecule C) steroid molecule D) cellulose molecule E) phospholipid molecule Figure 6 29) The chemical reaction illustrated in Figure 6 results in the formation of a (an) A) ionic bond. B) peptide bond. Hint: Linking two amino acids. C) glycosidic linkage. D) ester linkage. E) phosphodiester linkage. 30) What is the term used for a change in a protein's three-dimensional shape or conformation due to disruption of hydrogen bonds, disulfide bridges, or ionic bonds? A) hydrolysis B) stabilization C) destabilization D) renaturation E) denaturation 31) 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

6 32) In the double helix structure of nucleic acids, cytosine hydrogen bonds to A) deoxyribose. B) ribose. C) adenine. D) thymine. E) guanine. 33) If one strand of a DNA molecule has the sequence of bases 5'TTAGCA3', the other complementary strand would have the sequence A) 5'TTAGCA3'. B) 3'AATCGT5'. Hint: check page 88 C) 5'UUACGU3'. D) 3'UUTGCU5'. E) 5'UUTGCU3'. 34) The element nitrogen is present in all of the following except A) proteins. B) monosaccharides. C) nucleic acids. D) amino acids. E) DNA. 35) All of the following are part of a prokaryotic cell except A) DNA. B) a cell wall. C) an endoplasmic reticulum. D) ribosomes. E) a plasma membrane. 36) Which of the following compounds require the presence of the nuclear pores to move between the cytoplasm and the interior of the nucleus? A) ribosomal RNA B) messenger RNA C) proteins synthesized in the cytoplasm that are part of ribosomes D) A and B only E) A, B, and C 37) Which of the following organelles is not a common destination for small vesicles that bud off the Golgi apparatus? A) plasma membrane B) lysosomes C) vacuole D) nuclear envelope E) all of the above 38) Which structure is the site of the synthesis of proteins that may be exported from the cell? A) rough ER B) lysosomes C) plasmodesmata D) Golgi vesicles E) tight junctions

7 39) In animal cells, hydrolytic enzymes are packaged to prevent general destruction of cellular components. Which of the following organelles functions in this compartmentalization? A) chloroplast B) lysosome C) central vacuole D) peroxisome E) glyoxysome 40) Which of the following produces and modifies polysaccharides that will be secreted? A. lysosome B. vacuole C. mitochondrion D. Golgi apparatus E. peroxisome 41) Of the following, what do both mitochondria and chloroplasts have in common? A) ATP is produced. B) DNA is present. C) Ribosomes are present. D) B and C only E) A, B, and C are correct. 42) Which of the following are capable of converting light energy to chemical energy? A) chloroplasts B) mitochondria C) leucoplasts D) peroxisomes E) Golgi bodies 43) Microfilaments are well known for their role in which of the following? A) ameboid movement B) formation of cytoplasmic streaming C) contracting of muscle cells D) A and B only E) A, B, and C 44) Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through A) plasmodesmata. B) intermediate filaments. C) tight junctions. D) desmosomes. E) gap junctions. 45) The lateral mobility (fluidity) of lipids and proteins in membranes is a consequence of A) lack of covalent bonds between the lipid and protein components of the membrane. Hint: pg 126 B) weak hydrophilic interactions among the components in the interior of the membrane. C) the presence of liquid water in the interior of the membrane. D) A and B only E) A, B, and C

8 46) What is one of the functions of cholesterol in animal cell membranes? A) facilitates transport of ions B) stores energy C) maintains membrane fluidity D) speeds diffusion E) phosphorylates ADP 47) What kinds of molecules pass through a cell membrane most easily? A) large and hydrophobic B) small and hydrophobic C) large polar D) ionic E) monosaccharides such as glucose 48) Water passes quickly through cell membranes because A) the bilayer is hydrophilic. B) it moves through hydrophobic channels. C) water movement is tied to ATP hydrolysis. D) it is a small, polar, charged molecule. E) it moves through aquaporins in the membrane. 49) Celery stalks that are immersed in fresh water for several hours become stiff and hard. Similar stalks left in a salt solution become limp and soft. From this we can deduce that the cells of the celery stalks are A) hypotonic to both fresh water and the salt solution. B) hypertonic to both fresh water and the salt solution. C) hypertonic to fresh water but hypotonic to the salt solution. Hint: Pg 133 D) hypotonic to fresh water but hypertonic to the salt solution. E) isotonic with fresh water but hypotonic to the salt solution. 50) You are working on a team that is designing a new drug. In order for this drug to work, it must enter the cytoplasm of specific target cells. Which of the following would not be a factor that determines whether the molecule enters the cell? A) size of the drug molecule B) polarity of the drug molecule C) charge on the drug molecule D) similarity of the drug molecule to other molecules transported by the target cells E) lipid composition of the target cells' plasma membrane 51) All of the following membrane activities require energy from ATP hydrolysis except A) facilitated diffusion. B) active transport. C) Na + ions moving out of the cell. D) proton pumps. E) translocation of potassium into a cell. 52) The main difference(s) between facilitated diffusion and active transport is (are) A) facilitated diffusion moves substances down their concentration gradient and active transport moves them against their gradient. B) facilitated diffusion does not rely on cellular energy and active transport does. C) facilitated diffusion uses channel or carrier proteins and active transport does not. D) A and B only E) A, B, and C

9 53) A major factor that determines the voltage across the membrane, called a membrane potential, in many cells is the result of A) water potential through aquaporins in the plasma membrane B) chemical gradients resulting from the charge of ions and their covalent bonds C) signals that cause conformational changes in leak channels that allow Na + into the cell and K + out of the cell D) active transport of Na + out of a cell and K + into a cell E) electrochemical gradients created by leak channels 54) Which of the following characterizes the sodium-potassium pump? A) Sodium ions are pumped against their gradient. B) Potassium ions are pumped against their gradient. C) The pump protein undergoes a conformational change. D) Only A and B are correct. E) A, B, and C are all correct.

10 8) When two atoms are equally electronegative, they will interact to form A) equal numbers of isotopes. B) ions. C) polar covalent bonds. D) nonpolar covalent bonds. E) ionic bonds. 8) Ions diffuse across membranes down their A) chemical gradients. B) concentration gradients. C) electrical gradients. D) electrochemical gradients. E) A and B are correct.