Download BCOR 11: Exam 1

BCOR 11: Exam 1
Fall, 2006
Name________________________________ Section ______
1) 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) When blood glucose level rises, the pancreas secretes insulin, and as a result blood glucose level declines. Such
regulation of blood glucose level is the result of
A) catalytic feedback.
B) positive feedback.
C) negative feedback.
D) bioinformatic regulation.
E) both A and B
3) 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
4) According to Charles Darwin, organisms of a particular species are adapted to their environment when they
possess
A) non-inheritable traits that have enhanced their survival in the local environment.
B) non-inheritable traits that have enhanced their reproductive success in the local environment.
C) non-inheritable traits that have enhanced their survival and reproductive success in the local environment.
D) inheritable traits that have enhanced their survival and reproductive success in the local environment.
E) inheritable traits that have decreased their survival and reproductive success in the local environment.
5) An ionic bond is formed when:
A) the hydrogen of one water molecule is attracted to the oxygen of another water molecule
B) one atom loses an electron and another gains that electron, resulting in an attraction between the two atoms
C) two atoms each donate electrons to a third atom
D) two atoms share the outer layer of electrons
E) one atom donates an electron becoming negative while another atom gains the electron becoming positive
6) 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
7) The reactive properties (or chemical behavior) of an atom depend primarily 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 of the atom.
E) hybridized orbitals in the atom.
8) A molecule of carbon dioxide (CO2) 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 from the carbon atom that
must be shared with 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
9) 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.
10). Which of the following best describes the relationship between the atoms described below?
Atom 1
Atom 2
1
1
H
3
H
1
A) They are isomers.
B) They are polymers.
C) They are isotopes.
D) They contain 1 and 3 protons respectively.
E) They each contain 1 neutron.
Figure 1
11) Refer to Figure 1. Which drawing depicts the electron configuration of oxygen (
16
8
O) ?
A) A
B) ..B
C) ..C
D) ..D
E) ..E
12) In a single molecule of water, the two hydrogen atoms are bonded to a single oxygen atom by
A) hydrogen bonds.
B) nonpolar covalent bonds.
C) polar covalent bonds.
D) ionic bonds.
E) van der Waals interactions.
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 hydrophobic bond
14) 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.
Figure 2
15) How many grams of the molecule in Figure 2 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
C) 60
D) 150
E) 342
16) 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
17) 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.
18) What is the reason why hydrocarbons are not soluble in water?
A) The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.
B) The majority of their bonds are polar 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 C4H10?
A) 1
B) 2
C) 4
D) 3
E) 11
20) Which is the best description of a carbonyl group?
A)
B)
C)
D)
E)
an oxygen joined to a carbon by a single covalent bond
a nitrogen and two hydrogens joined to a carbon by covalent bonds
a carbon joined to two hydrogens by single covalent bonds
a sulfur and a hydrogen joined to a carbon by covalent bonds
a carbon atom joined to an oxygen by a double covalent bond
21) 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 to 8 neutrons.
B) Carbon has a valence of 4.
C) Carbon forms ionic bonds.
D) A and C only.
E) A, B, and C.
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) In Figure 3, which molecule is water-soluble because it has a functional group that is an alcohol? A
24) In Figure 3, which molecule can increase the concentration of hydrogen ions in a solution and is therefore an
organic acid? D
25) Research suggests that side effects from Ritalin, the drug used to treat attention deficit disorder, may be caused
by contamination of enantiomers, or molecules that
A) have identical three-dimensional shapes.
B) are mirror images of one another.
C) lack an asymmetric carbon.
D) differ in the location of their double bonds.
E) differ in their electrical charge.
26) Which two functional groups are always found in amino acids?
A) ketone and aldehyde
B) carbonyl and carboxyl
C) carboxyl and amino
D) phosphate and sulfhydryl
E) hydroxyl and aldehyde
27) 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.
28) 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.
Figure 4
29) The molecule shown in Figure 4 is a
A) polysaccharide.
B) polypeptide.
C) saturated fatty acid.
D) triacylglycerol.
E) unsaturated fatty acid.
Figure 5
30) The chemical reaction illustrated in Figure 5 results in the formation of a (an)
A) ionic bond.
B) peptide bond.
C) glycosidic linkage.
D) ester linkage.
E) phosphodiester linkage.
31) 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.
32) The R group or side chain of the amino acid serine is –CH2-OH. The R group or side chain of the amino acid
alanine is –CH3. Where would you expect to find these amino acids in a globular protein in aqueous solution?
A) Serine would be in the interior, and alanine would be on the exterior of the globular protein.
B) Alanine would be in the interior, and serine would be on the exterior of the globular protein.
C) Both serine and alanine would be in the interior of the globular protein.
D) Both serine and alanine would be on the exterior of the globular protein.
E) Both serine and alanine would be in the interior and on the exterior of the globular protein.
33) Which of the following descriptions best fits the class of molecules known as nucleotides?
A) a nitrogenous base and a phosphate group
B) a pentose sugar, two nitrogenous bases, and two phosphates
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
34) Which of the following is an example of hydrolysis?
A) the reaction of two monosaccharides, forming a disaccharide with the release of water
B) the synthesis of two amino acids, forming a peptide with the release of water
C) the reaction of a fat, forming glycerol and fatty acids with the release of water
D) the reaction of a fat, forming glycerol and fatty acids with the utilization of water
E) the synthesis of a nucleotide from a phosphate, a pentose sugar, and a nitrogenous base with the production of
a molecule of water
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) The organelle that functions as a protein sorting and distributing station is the cell is called
A) Nucleus
B) Golgi apparatus
C) Mitochondrion
D) Ribosomes
E) cytosol
37) Muscle cells require more energy than most other cells. Therefore, muscle cells would be expected to have more
_____ than most other cells.
A) mitochondria
B) cell membranes
C) chromosomes
D) ribosomes
E) nuclei
38) 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
39) Which structure is the site of the synthesis of proteins that may be exported from the cell?
A)
B)
C)
D)
E)
rough ER
lysosomes
plasmodesmata
Golgi vesicles
tight junctions
40) 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
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) A biologist ground up some plant leaf cells and then centrifuged the mixture to fractionate the organelles.
Organelles in one of the heavier fractions could produce ATP in the light, while organelles in the lighter fraction
could produce ATP in the dark. The heavier and lighter fractions are most likely to contain, respectively,
A) mitochondria and chloroplasts.
B) chloroplasts and peroxisomes.
C) peroxisomes and chloroplasts.
D) chloroplasts and mitochondria.
E) mitochondria and peroxisomes.
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) 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
45) The proteins in the plasma membrane that allow chemical substances like nutrients to pass in and out of the cell
are referred to as _______________.
A) receptors
B) hormones
C) transporters
D) phospholipids
E) Golgi apparatus
46) The lateral mobility (fluidity) of lipids and proteins in membranes is in part a consequence of
A) the lack of covalent bonds between the lipid and protein components of the membrane.
B) the 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
47) 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
48) What membrane-surface molecules are thought to be most important as cells recognize each other?
A) phospholipids
B) integral proteins
C) peripheral proteins
D) cholesterol
E) glycoproteins
49) 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
50) 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.
D) hypotonic to fresh water but hypertonic to the salt solution.
E) isotonic with fresh water but hypotonic to the salt solution.
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 movement of a substance across a biological membrane against its concentration gradient with the help of
energy input is
A) diffusion.
B) active transport.
C) osmosis.
D) facilitated diffusion.
E) exocytosis.
53) The sodium-potassium pump is called an electrogenic pump because it
A) pumps equal quantities of Na+ and K+ across the membrane.
B) pumps hydrogen ions into the cell.
C) contributes to the membrane potential.
D) ionizes sodium and potassium atoms.
E) pumps hydrogen ions out of the cell.
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.