Download Exam I, Chapters 2-8, Sept. 20, 2000, Section 01

Exam I, Chapters 2-8, Sept. 20, 2000, Section 01
1) An atomic form of an element containing different numbers of neutrons is
A) a polar atom.
B) an isomer.
C) radioactive.
D) an ion.
E) an isotope.
2) What do atoms form when they share electron pairs?
A) isotopes
B) elements
C) aggregates
D) molecules
E) ions
3) Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following state
ments is correct about ammonia (NH3 )?
A) Each hydrogen atom has a slight negative charge.
B) The nitrogen atom has a strong positive charge.
C) Each hydrogen atom has a partial positive charge.
D) There are covalent bonds between the hydrogen atoms.
E) The nitrogen atom has a partial positive charge.
4)
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5) 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 of the same element.
C) the two atoms sharing electrons are different elements.
D) the two atoms sharing electrons are equally electronegative.
E) it is between two atoms that are both very strong electron acceptors.
6)
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7) What do the four elements most abundant in life--carbon, oxygen, hydrogen, and nitrogen-have in common?
A) They all have the same number of valence electrons.
B) Each element exists in only one isotopic form.
C) They are equal in electronegativity.
D) They all have unpaired electrons in their valence shells.
E) They are elements produced only by living cells.
8) The partial negative charge at one end of a water molecule is attracted to the partial positive
charge of another water molecule. What is this attraction called?
A) an ionic bond
B) a hydration shell
C) a hydrophobic bond
D) a hydrogen bond
E) a covalent bond
9) What would be the pH of a solution with a hydroxyl ion concentration (OHÐ) of 10-10 M?
A) 8
B) 4
C) 2
D) 14
E) 10
10) Water's high specific heat is mainly a consequence of the
A) fact that water is a poor heat conductor.
B) high specific heat of oxygen and hydrogen atoms.
C) absorption and release of heat when hydrogen bonds break and form.
D) small size of the water molecules.
E) inability of water to dissipate heat into dry air.
11) What do cohesion, surface tension, and adhesion have in common with reference to water?
A) All increase when temperature increases.
B) All are produced by covalent bonding.
C) All are properties related to hydrogen bonding.
D) All have to do with nonpolar covalent bonds.
Exam I, Chapters 2-8, Sept. 20, 2000, Section 01
E) Both A and C are correct.
12) At what temperature is water at its densest?
A) 32e C
B) 0e C
C) 100e C
D) 4e C
E) 212e C
13) What is the maximum number of hydrogen bonds a water molecule can form with
neighboring water molecules?
A) five
B) three
C) one
D) two
E) four
14) A compound contains hydroxyl groups as its predominant functional group. Which of the
following statements is true concerning this compound?
A) It is probably a lipid.
B) It should dissolve in a nonpolar solvent.
C) It is hydrophobic.
D) It should dissolve in water.
E) It won't form hydrogen bonds with water.
15) Which property of the carbon atom gives it compatibility with a greater number of different
elements than any other type of atom?
A) Carbon has 6-8 neutrons.
B) Carbon has a valence of 4.
C) Carbon forms ionic bonds.
D) Only A and C are correct.
E) A, B, and C are correct.
The following questions refer to the list of functional groups below. Each group may be used once, more
than once, or not at all.
A.
-- OH
B.
-- C=O
C.
-- COOH
D.
-- NH2
E.
-- SH
16) helps stabilize proteins by forming covalent cross-links within or between protein molecules
17) Which two functional groups are always found in amino acids?
A) carboxyl and amine
B) ketone and amine
C) amine and sulfhydryl
D) alcohol and aldehyde
E) carbonyl and carboxyl
18) A chemist wishes to make an organic molecule less acidic. Which of the following functional
groups should she add to the molecule?
A) carboxyl
B) phosphate
C) hydroxyl
D) sulfhydryl
E) amino
19) Which type of molecule would be most abundant in a typical cell?
A) protein
B) water
C) hydrocarbon
D) carbohydrate
E) lipid
20) The formation of polymers is most precisely described as an example of
A) anabolism.
B) catabolism.
C) hydrolysis.
D) metabolism.
E) hydrophilic interactions.
21) If three molecules of a fatty acid that has the formula C16 H22 O2 are joined to a molecule of
glycerol (C3 H8 O3 ), then the resulting molecule would have the formula
A) C48 H72 O8 .
D) C51 H74 O9 .
22)
B) C51 H68 O6 .
E) C48 H66 O6 .
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C) C51 H72 O8 .
Exam I, Chapters 2-8, Sept. 20, 2000, Section 01
23) Condensation synthesis reactions are used in forming which of the following compounds?
A) triglycerides
B) polysaccharides
C) proteins
D) Only A and C are correct.
E) A, B, and C are correct.
24) The alpha helix and the beta pleated sheet are both common forms found in which level of
structure of proteins?
A) primary
B) tertiary
C) secondary
D) quaternary
25) Which of the following descriptions best fits the class of molecules known as nucleotides?
A) a five-carbon sugar and adenine or uracil
B) a nitrogen base and a five-carbon sugar
C) a five-carbon sugar and a purine or pyrimidine
D) a nitrogen base, a phosphate group, and a five-carbon sugar
E) a nitrogen base and a phosphate group
26) What would be an expected consequence of changing one amino acid in a particular protein?
A) All of the below are expected.
B) The primary structure would be changed.
C) The number of amino acids present would stay the same.
D) The tertiary structure might be changed.
E) The biological activity of this protein might be altered.
27) What is a common feature of both starch and glycogen?
A) Both contain repeated monomers of glucose and galactose.
B) Both form microfibrils that give support to connective tissue.
C) They are polymers of glucose.
D) They are important structural components of plant cell walls.
E) They are water-soluble disaccharides.
28) Which of the following is true for exergonic reactions?
A) The reactions upgrade the free energy in the products at the expense of energy from the
surroundings.
B) The products have less free energy than the reactants.
C) Reactants will always be completely converted to products.
D) A net input of energy from the surroundings is required for the reactions to proceed.
E) The products have more free energy than the reactants.
29) A solution of starch at room temperature does not spontaneously decompose rapidly to a
sugar solution because
A) the activation energy barrier cannot be surmounted in most of the starch molecules.
B) starch hydrolysis is nonspontaneous.
C) the hydrolysis of starch to sugar is endergonic.
D) the starch solution has less free energy than the sugar solution.
E) starch cannot be hydrolyzed in the presence of so much water.
30) Correct statements regarding ATP include:
I.
ATP (adenosine triphosphate) serves as a main energy shuttle inside cells.
II.
ATP drives endergonic reaction in the cell by the enzymatic transfer of the
phosphate group to specific reactants.
III.
The regeneration of ATP from ADP and phosphate is an endergonic reaction.
A) I and III only
B) I, II, and III
C) I only
D) II only
E) III only
31) The transfer of free energy from catabolic pathways to anabolic pathways is best called
A) feedback regulation.
B) entropy.
Exam I, Chapters 2-8, Sept. 20, 2000, Section 01
C) energy coupling.
D) cooperativity.
E) bioenergetics.
32) During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a
DG = -20 kcal/mole. You double the amount of enzyme in the reaction and the DG now equals
A) -20 kcal/mole.
B) -40 kcal/mole.
C) +40 kcal/mole.
D) -10 kcal/mole.
E) It is not possible to calculate the answer with the data given.
33) Catabolic pathways
A) release energy as they degrade polymers to monomers.
B) lead to the synthesis of catabolic compounds.
C) consume energy to build up polymers from monomers.
D) do not depend on enzymes.
34) The hydrolysis of sucrose by sucrase results in
A) bringing glucose and fructose together to form sucrose.
B) production of water from the sugar as bonds are broken between the glucose monomers.
C) the release of free water from sucrose as the bonds between glucose and fructose are broken.
D) breaking the bond between glucose and fructose and forming new bonds from water.
35) Organelles that contain DNA include
A) ribosomes.
B) mitochondria.
C) chloroplasts.
D) Only B and C are correct.
E) A, B, and C are correct.
36) Plasmodesmata in plant cells are MOST similar in function to which of the following
structures in animal cells?
A) desmosomes
B) gap junctions
C) tight junctions
D) glycocalyx
E) peroxisomes
37) A cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma
membrane, and mitochondria. It could be a cell from
A) a bacterium.
B) a plant or an animal.
C) a plant, but not an animal.
D) an animal, but not a plant.
E) any kind of organism.
38) Cells can be described as having a cytoskeleton of internal structures that contribute to the
shape, organization, and movement of the cell. All of the following are part of the cytoskeleton
EXCEPT
A) microtubules.
B) actin.
C) intermediate filaments.
D) microfilaments.
E) the cell wall.
Refer to the following five terms to answer the next questions. Choose the most appropriate term for
each phrase. Each term may be used once, more than once, or not at all.
A. mitochondria
D. lysosomes
B. Golgi apparatus
C. rough endoplasmic reticulum
E. smooth endoplasmic reticulum
39) sorts out mixtures of substances and sends them to their proper destinations
40) Which type of organelle is primarily involved in the synthesis of lipids?
A) ribosomes
B) contractile vacuoles
C) mitochondria
D) lysosomes
E) smooth endoplasmic reticulum
Exam I, Chapters 2-8, Sept. 20, 2000, Section 01
41) A primary objective of cell fractionation is
A) to view the structure of cell membranes.
B) to identify the enzymes outside the organelles.
C) to separate the major organelles so their particular functions can be determined.
D) to determine the size of various organelles.
42) Carrier molecules in the plasma membrane are required for
A) diffusion.
B) osmosis.
C) facilitated diffusion only.
D) active transport only.
E) both facilitated diffusion and active transport.
43) One of the functions of cholesterol in animal cell membranes is to
A) store energy.
B) maintain membrane fluidity.
C) speed diffusion.
D) facilitate transport of ions.
E) phosphorylate ADP.
44) Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small in
testine, however, rapidly move large quantities of glucose from the glucose-rich food into their
glucose-poor cytoplasm. Using this information, which transport mechanism is most probably
functioning in the intestinal cells?
A) facilitated diffusion
B) active transport pumps
C) phagocytosis
D) exocytosis
E) simple diffusion
45) Which of the following would indicate that facilitated diffusion was taking place?
A) A substance was diffusing much faster than the physical condition indicated it should.
B) Substances were moving against the diffusion gradient.
C) ATP was being rapidly consumed as the substance moved.
D) A substance was moving from a region of low concentration into a region of higher
concentration of the substance.
E) A substance was slowing as it moved down its concentration gradient.
46) Which of the following is a characteristic feature of a carrier protein in a plasma membrane?
A) It requires energy to function.
B) It has few, if any, hydrophobic amino acids.
C) It exhibits a specificity for a particular type of molecule.
D) It is a peripheral membrane protein.
E) It works against diffusion.
47) A membrane protein with hydrophobic regions
A) would be considered a peripheral protein.
B) would be highly soluble in water.
C) would be more fluid than those lacking hydrophobic regions.
D) could not span the lipid bilayer.
E) would contain nonpolar amino acids in the hydrophobic regions.
48) The main problem with the Davson-Danielli model of membrane structure was that
A) it did not account for the phospholipid bilayer.
B) There is nothing wrong with the model, and it is accepted today by cell biologists.
C) early electron micrographs in the 1950s clearly did not support the model.
D) phospholipid fluidity was impossible.
E) it placed membrane proteins in a layer on the membrane surface.