Bio 181 practice Exams 120 Questions with Verified Answers
Which of the following are NOT effective for mastering new ideas and forming long-term
... [Show More] memories that can be accessed and used months or even years later? (choose ALL)
A. Concentrating intense studying to the hours before an exam.
B. sleep
C. reading and re-reading the textbook chapters and notes several times
D. practicing remembering ideas and vocabulary through self-quizzing
E. elaboration: putting ideas in your own words and connecting them to what you already now - CORRECT ANSWER A
C
A scientist can test a hypothesis by (choose ALL)
A. doing experiments.
B. making careful observations.
C. creating a theory.
D. asking a question.
E. none of the above is correct - CORRECT ANSWER A
B
A boy observes a bird outside of his window. He notices that the bird repeatedly cocks its head to one side before pecking the ground. The boy suspects that when the bird cocks its head it is actually listening for worms or insects underground, and watches for several days. If the boy notes that the bird routinely catches a worm after cocking its head, would these observations prove his hypothesis to be correct? (choose ONE)
A. Yes, and no further experiments are needed.
B. No, this observation supports the boy's hypothesis, but does not prove it.
C. No, because this is only a single observation.
D. No; this proves the boy's hypothesis is incorrect.
E. Yes, but further experiments are needed. - CORRECT ANSWER B
Regarding the laws of thermodynamics, (choose ALL)
A. the first law states that the degree of entropy (disorder) in the universe tends to increase.
B. living organisms are energy transformers: they acquire energy from the environment and transform it into a form of chemical energy that cells can use.
C. the first law states that energy can neither be created nor destroyed.
D. living organisms violate the laws of thermodynamics, because they are highly ordered (the opposite of a tendency towards increasing disorder).
E. living organisms violate the laws of thermodynamics because they use up energy. - CORRECT ANSWER B
C
Rifampin is an antibiotic used to treat the bacterium M. tuberculosis which causes the disease tuberculosis in humans. Rifampin works by binding to and disabling bacterial ribosomes. A tuberculosis patient was treated with rifampin for 3 months. He initially seemed to be cured, and rifampin therapy was discontinued. But when he was retested some months later, his lungs were teeming with a mutant strain M. tuberculosis. A second round of drug therapy with rifampin was started, but it was ineffective, and the patient died. Which of the following statements are TRUE about this scenario? (choose ALL)
A. The patient became resistant to the antibiotic, and it no longer worked.
B. Rifampin interferes with protein synthesis in normal M. tuberculosis cells.
C. The mutations were caused by the presence of the antibiotic.
D. The mutations already existed in the population of bacteria and were selected for by the antibiotic. - CORRECT ANSWER B
D
E
The type of bond that connects each of the hydrogen atoms to the oxygen atom within a single water molecule is (choose ONE)
A. a hydrogen bond
B. an ionic attraction
C. an oxygen bond
D. a polar covalent bond
E. a nonpolar covalent bond - CORRECT ANSWER D
The type of bond that connects two water molecules to each other in liquid water, and that thus would be broken when the water boils to form steam is (choose ONE)
A. a hydrogen bond
B. an ionic attraction
C. an oxygen bond
D. a polar covalent bond
E. a nonpolar covalent bond - CORRECT ANSWER A
Regarding the chemical bonding that characterizes biological molecules (choose ONE)
A. in H-bonds (hydrogen bonds), one atom loses an electron to another atom; the two atoms then have opposite charges and are attracted to one another.
B. covalent bonds form between atoms with opposite partial charges.
C. partial charges in atoms occur when they form covalent bonds with atoms of the differing electronegativity.
D. ionic attractions are the strongest kinds of bonds in biological molecules in cells.
E. hydrophobic effects and Van der Waals forces are too weak to play any significant role in biological molecules. - CORRECT ANSWER C
A pair of atoms joined by a polar covalent bond (choose ONE)
A. share electrons equally, so the charge is spread evenly across both atoms.
B. has a partial positive charge on one atom, and a partial negative charge on the other.
C. is unlikely to form H-bonds with water.
D. would be unlikely to be soluble in water.
E. would be able to diffuse freely in a nonpolar solvent. - CORRECT ANSWER B
Regarding the terms hydrophobic and hydrophilic, (choose ALL)
A. hydrophilic molecules are polar.
B. the atoms in hydrophilic molecules share electrons ~equally in their covalent bonds.
C. polar molecules dissolve in water-- meaning that the covalent bonds break and the atoms of the polar molecule separate.
D. polar molecules can H-bond, or form electromagnetic attractions, with water molecules.
E. hydrophobic molecules can move (diffuse) freely in water. - CORRECT ANSWER A
D
Based on your knowledge of the chemical properties of water molecules, and given that solute substance A depicted here can move freely in water, you can conclude that substance A most likely (choose ALL) *image 1
A. has a positive (or partial positive) charge
B. has a negative (or partial negative) charge
C. is without charge or partial charge
D. is hydrophilic
E. is nonpolar - CORRECT ANSWER A
D
What important feature of noncovalent, weak bonds (such as H-bonds and ionic attractions) makes them so important in cells? (choose ONE)
A. They can withstand changes in temperature and pH that disrupt covalent bonds.
B. They are just as strong in water as out of water—which is not true for covalent bonds.
C. They are strong in a cellular environment, giving them greater stability.
D. They are weak in a cellular environment, so they can easily be made, broken, and reformed.
E. None of the above is correct. - CORRECT ANSWER D
Which of the molecules above would be found in a polypeptide? (choose ONE) *image 2
A. A only
B. B only
C. C only
D. More than one of the above. - CORRECT ANSWER A
Which of the molecules shown above is/are polar? (choose ONE) *image 2
A. A only
B. B only
C. C only
D. C and D only
E. A, B and D only - CORRECT ANSWER E
Which of the molecules shown above would be least soluble in water? (choose ONE) *image 2
A. A only
B. B only
C. C only
D. A and B are equally insoluble
E. A, B and C are equally insoluble - CORRECT ANSWER C
Lipids (e.g., fatty acids) differ from the other 3 classes of macromolecules--proteins, carbohydrates, and nucleic acids-- in that (choose ALL)
A. lipids are mostly made up atoms that share electrons equally.
B. lipids are the only ones that form polymers.
C. lipids cannot move freely in water; they are not water soluble.
D. lipids play no role in energy storage or cell signaling.
E. lipids are mostly hydrophobic. - CORRECT ANSWER A
C
E
The figure below shows two plasma membranes and the phospholipids that form them. Which of the following statements about this topic are correct? (choose ALL) *image 3
A. Membrane A has lower permeability because the phospholipid heads are nonpolar and they block diffusion.
B. Membrane A has lower permeability because its fatty acid tails are saturated.
C. The fatty acid tails in membrane B allow for higher permeability because they pack tightly together via Van der Waals forces.
D. Membrane B allows for easier diffusion of molecules in and out of the cell.
E. Both of these membranes slow the diffusion of polar molecules into and out of the cell. - CORRECT ANSWER B
D
E
Polymers are assembled and dis-assembled via condensation and hydrolysis reactions. Which of the following statements are correct about this topic? (choose ALL) *image 4
A. Diagram A) shows a condensation reaction, in which an enzyme pulls out a water in order to join two monomers.
B. Diagram B) shows an exergonic reaction that would potentially release energy for the cell to use.
C. Diagram A) shows an enzyme-catalyzed reaction; the reaction in B) is spontaneous, and thus requires no enzyme.
D. The reaction in diagram A results in a decrease in entropy, and thus requires an input of energy to occur.
E. Reaction A) is a catabolic reaction; B) is an anabolic reaction. - CORRECT ANSWER A
B
D
Regarding the structure of amino acids, (choose ALL) *image 5
A. the amino acid pictured above is classified as polar, because of the negatively-charged oxygen on the carboxyl and the positively-charged nitrogen on the amino group of the backbone.
B. all amino acids are exactly the same in one part of their structure: the amino-alpha carbon-carboxyl backbone.
C. the R-group of the amino acid above is comprised of atoms with approximately-equal electronegativity.
D. if this amino acid were part of a large polypeptide, the polymer would fold so that this amino acid is not in contact with water.
E. this amino acid has an R-group that is hydrophilic, allowing it to diffuse easily in water. - CORRECT ANSWER B
C
D
Figure A below represents a portion of a double-stranded DNA molecule; figure B is a bigger view of the same molecule: two polynucleotides (polymers of nucleotide monomers) held together in a double-helix. Which of the following statements about this topic is FALSE? (choose ONE) *image 6
A. The bold arrows in both diagrams represent the backbone of the DNA: phosphodiester bonds between one nucleotide and the next in the polymer.
B. The bonds that hold the two polynucleotides chains to one another are weak H-bonds.
C. In figure A, two purines nucleotides are covalently bonded to one another.
D. In figure A, guanine and cytosine form a phosphodiester bond with one another.
E. In both figures, a purine of one polynucleotide is always H-bonded to a pyrimidine in the other. - CORRECT ANSWER D
The DNA of a cell is determined to consist of 12% thymine (T). What percentage of the cell's DNA is guanine (G)? (choose ONE)
A. 12%
B. 24%
C. 38%
D. 76%
E. 0% - CORRECT ANSWER C
During the process of transcription, the enzyme RNA polymerase (choose ALL) *image 7
A. catalyzes an anabolic/endergonic reaction only.
B. catalyzes a catabolic/exergonic reaction only.
C. couples an anabolic reaction to a catabolic reaction.
D. synthesizes a phosphodiester bond.
E. hydrolyzes one or more phosphate-phosphate bonds. - CORRECT ANSWER C
D
E
Imagine that your lab is synthesizing a new type of cell. One of your colleagues suggests that your synthetic cell should use prokaryotic systems for all the steps of gene expression (transcription and translation) because prokaryotic protein synthesis is faster than eukaryotic protein synthesis. What characteristics of prokaryotic transcription and translation make the overall process faster than in eukaryotes? (choose ALL)
A. Prokaryotes lack a nuclear envelope, so translation can begin on an mRNA even before transcription of the mRNA is complete.
B. Because prokaryotes use only a few codons, there are fewer tRNAs to sort through.
C. The smaller ribosomes of prokaryotes can move across the mRNA more quickly.
D. the primary transcript in prokaryotes does not undergo further processing, so translation can begin immediately.
E. Multiple proteins can be synthesized from a single, polycistronic mRNA molecule. - CORRECT ANSWER A
D
E
The 5' cap that is added to the RNA during processing: (choose ALL)
A. helps prevent formation of complex three-dimensional structures in the messenger RNA.
B. helps prevent rapid breakdown of the messenger RNA by nucleases.
C. is needed for ribosomes in order to attach to messenger RNA.
D. aids in the accuracy of translation of the messenger RNA into protein.
E. tells the ribosome where to stop translation. - CORRECT ANSWER B
C
Alternative splicing means that (choose ALL):
A. alternating exons, as well as all introns, are removed.
B. some transcripts are spliced, while others are not.
C. some transcripts are spliced correctly and other incorrectly.
D. different spliced mRNAs contain different combinations of exons.
E. multiple different proteins can be synthesized from a single gene - CORRECT ANSWER A
D
E
Regarding the levels of protein structure (choose ALL)
A. the primary structure is the order/sequence of amino acids, held together by covalent bonds.
B. the secondary structure forms due to interactions between amino acids in the polypeptide, and are stabilized by weak bonds.
C. the tertiary structure is the folding of a polypeptide into a 3-dimensional shape, and is stabilized by peptide bonds.
D. secondary and tertiary structures are unaffected by primary structure.
E. all proteins have quaternary structure. - CORRECT ANSWER A
B
The function of a protein is dependent upon the shape into which the chain of amino acids folds. Many noncovalent interactions are responsible for maintaining the protein's shape. Assume you have isolated a protein from an organism in its proper shape, and you have treated it with an enzyme that selectively targets and breaks only the peptide bonds in the proteins. Would the protein retain its shape under these conditions? (choose ONE)
A. Yes; once noncovalent bonding determines the shape of the protein, the peptide bonds are no longer necessary.
B. Yes; because the noncovalent interactions that maintain the shape of the protein are stronger than the peptide bonds.
C. No; while the noncovalent interaction determine the shape of the protein, the peptide bonds are required to hold the amino acids together.
D. No; proteins contain no peptide bonds, so the shape of the protein would be unaffected. - CORRECT ANSWER C
Denaturation, e.g., of a protein (choose ALL)
A. means that covalent bonds are disrupted by temperature or pH changes.
B. means that covalent bonds are broken, and the molecule (the protein) falls apart.
C. means that the weak bonds that maintain 2ndary and tertiary structure are disrupted.
D. results in loss of function.
E. can expose hydrophobic regions of the protein, and thus result in the loss of solubility in water. - CORRECT ANSWER C
D
E
Which of the following amino acid substitutions would LEAST disrupt the structure (and thus the function) of the short polypeptide shown below? (choose ONE) *image 8
A. cysteine to serine
B. valine to aspartate
C. phenylalanine to tyrosine
D. glycine to isoleucine
E. aspartate to histidine - CORRECT ANSWER A
Regarding the DNA template shown below, and its transcription and translation, which of the following statements are correct? (choose ALL) *image 9
A. There will be 9 uracils in the mRNA for this template.
B. Reading from the 3' end of the mRNA, the sequence is 3' AGUGCC...
C. The polypeptide encoded by this template will consist of exactly 6 amino acids.
D. If there were a mutation in the DNA, such that the 3rd T (bolded) became an A, the resulting mRNA could still be translated by the ribosome, but the sequence of amino acids would be incorrect.
E. If there were a mutation in the DNA, such that the 3rd T (bolded) became an A, the resulting mRNA could not be translated. - CORRECT ANSWER B
C
E
Lipids differ from the other 3 classes of macromolecules, but are similar in other respects. Which of the following statements about this are correct? (choose ALL)
A. hydrophobic effects are an important driver in the formation of macromolecular structures for lipids and proteins.
B. lipids are comprised primarily of atoms that form nonpolar covalent bonds.
C. both lipids and proteins can be amphipathic (with both hydrophobic and hydrophilic parts).
D. lipids are the only macromolecules that make up the structure of membranes in cells.
E. there are covalent bonds between the monomers that make up lipids; the monomers of other classes of macromolecule are held together by weak attractions. - CORRECT ANSWER A
B
C
Phospholipids (choose ALL)
A. have polar tails and nonpolar/hydrophobic heads.
B. form bilayers sheets and vesicles in water because of H-bonding between the long C-H tails of the fatty acids.
C. form bilayer sheets and vesicles in water because of the inability of the lipid tails to hydrogen-bond with water.
D. make effective membrane components because they limit the simple diffusion of most types of polar molecules in and out of the cell.
E. form sturdy, protective membranes when the polar heads of several phospholipids form phosphodiester bonds with one another. - CORRECT ANSWER C
D
Some regions of the plasma membrane, called lipid rafts, have higher concentrations of cholesterol molecules. As a result, these lipid rafts are (choose ALL)
A. more fluid than the surrounding membrane at ambient temperatures.
B. more fluid than the surrounding membrane at high temperatures.
C. more rigid than the surrounding membrane at ambient temperatures.
D. useful in "corralling" particular transmembrane proteins, such as members of the ETCs.
E. likely to detach from the plasma membrane and clog arteries. - CORRECT ANSWER C
D
Transmembrane proteins (choose ALL)
A. can serve as channels or carrier proteins to allow polar molecules across the plasma membrane.
B. can serve as participants in redox reactions.
C. are made entirely of nonpolar amino acids, so that they can sit comfortably in the plasma membrane.
D. can in some cases pump protons (H+) against their gradients; others allow the passive flow of protons with their gradients.
E. do not necessarily extend all the way through the membrane. - CORRECT ANSWER A
B
D
The figure below shows an example of secondary active transport: the import of glucose into the cell against its concentration gradient. Which of the following statements are correct about this example? (choose ALL) *image 10
A. This example includes both active and passive transport.
B. This example includes uniport, symport, and antiport.
C. The energy of ATP is used to set up a Na+ gradient, which will in turn drive the active transport of glucose.
D. Na+ is transported both actively and passively in this example.
E. Glucose is transported both actively and passively in this example. - CORRECT ANSWER A
C
D
In response to seasonal changes in temperature, many organisms must alter the composition of their plasma membranes to maintain the proper degree of fluidity. As winter warms into spring and then summer, which of the following would you predict you would observe in the plasma membranes of organisms that as they adjust to the changing conditions? (choose ONE)
A. an increase in phospholipid fatty acid side chain length and an increase in side chain saturation
B. a decrease in phospholipid fatty acid side chain length and an increase in side chain saturation
C. a decrease in phospholipid fatty acid side chain length and a decrease in side chain saturation
D. an increase in phospholipid fatty acid side chain length and a decrease in side chain saturation - CORRECT ANSWER A
Suppose you are studying the transport of a certain polar molecule across the plasma membrane of cells in culture. Over a period of time, you measure the concentration of a polar molecule inside and outside of the cells. You find that the concentration of the molecule is lower in the cell but is gradually increasing. You also measure the ATP concentration inside the cell and find that it is not changing. Which of the following is probably responsible for the transport of this polar substance into the cell? (choose ONE)
A. endocytosis
B. active transport
C. facilitated diffusion
D. secondary active transport
E. simple diffusion - CORRECT ANSWER C
Why does active transport require ATP? (choose ONE)
A. An input of energy is needed to speed up the rate of facilitated diffusion.
B. An input of energy is needed to allow the movement of molecules from an area of low concentration to an area of high concentration.
C. An input of energy is needed to maintain the shapes of the transport proteins.
D. An input of energy is needed to move nonpolar molecules.
E. An input of energy is needed to maintain the integrity of the membrane. - CORRECT ANSWER B
You are working in a biotech lab to design a microbe that can absorb and deactivate a toxic spill in the Dead Sea—a body of water in which temperatures can exceed 100 degrees F. The toxin is similar in size and polarity to glucose.
In order to maintain homeostasis in these very warm conditions, the microbes would need membranes with (choose ALL)
A. lots of saturated fatty acid tails
B. very long fatty acid tails
C. lots of short, unsaturated fatty acid tails
D. lot of cholesterol
E. many additional transmembrane proteins to maintain pH - CORRECT ANSWER A
B
D
You are working in a biotech lab to design a microbe that can absorb and deactivate a toxic spill in the Dead Sea—a body of water in which temperatures can exceed 100 degrees F. The toxin is similar in size and polarity to glucose.
At the beginning of the toxin clean-up, when the toxin is in higher concentration in the sea than in the cells, in order to import the toxin, the microbes would need (choose ONE)
A. ion channel proteins (in their plasma membranes)
B. transmembrane proteins that are complementary to the toxin
C. to expend ATP to bring in the toxin, either directly or indirectly
D. some kind of chemical gradient, such as Na+ or H+, to bring in the toxin
E. none of the above; the toxin could simply diffuse into the cell with its concentration gradient. - CORRECT ANSWER B
You are working in a biotech lab to design a microbe that can absorb and deactivate a toxic spill in the Dead Sea—a body of water in which temperatures can exceed 100 degrees F. The toxin is similar in size and polarity to glucose.
At the end of the toxin clean-up, when the toxin is in lower concentration outside the cells, in order to import the toxin, the microbes would need (choose ALL)
A. ion channel proteins (in their membranes)
B. transmembrane proteins that are complementary to the toxin
C. to expend ATP to bring in the toxin, either directly or indirectly
D. possibly some kind of chemical gradient, such as Na+ or H+, to bring in the toxin
E. none of the above; the toxin could simply diffuse into the cell with its concentration gradient. - CORRECT ANSWER B
C
D [Show Less]