Bio 181 practice exams

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.

A

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

A B

28. What is the correct order of binding by the following proteins at the origin of replication? (choose ONE) *image 19 A. DNA pol III B. Primase C. Helicase D. Ligase A. A, B, C, D B. C, B, A, D C. B, C, A, D D. C, B, D, A E. B, C, D, 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.

B

Which of the following are MOST similar in nucleotide sequence? (choose ONE) A. homologous chromosomes B. non-homologous chromosomes C. sister chromatids D. non-sister chromatids E. complementary strands of DNA

C

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

C

Why are primers needed for DNA replication? (choose ONE) A. They help with the joining of Okazaki fragments B. They provide energy to catalyze the formation of the phosphodiester bonds C. DNA polymerase can only add on to an existing polynucleotide chain D. The primers help with the proofreading function of DNA pol E. They unwind the double helix

C

What feature of double-stranded DNA makes it necessary to have a leading strand and a lagging strand during replication? (choose ONE) A. the hydrogen bonding between the bases B. the negative charge on the sugar-phosphate backbone C. the polar characteristics of the deoxyribose sugars D. the antiparallel orientation of the strands E. the fact that DNA is less chemically stable than RNA

D

In humans, ability to roll the tongue (R) is dominant to being unable to roll (r). Having freckles (F) is dominant to having no freckles (f). A man heterozygous for both traits marries a woman heterozygous for both traits. What is the probability that they will have a child with freckles? (choose ONE) A. 9/16 B. 3/16 C. 1/16 D. 3/4 E. 1/4

D

In observing DNA replication in the lab, you notice that in some cells, a defect occurs in which DNA replication proceeds, but the RNA primers are not removed and replaced with DNA. Which enzyme is MOST likely to be defective in these cells? (choose ONE) A. helicase B. RNA primase C. DNA polymerase III D. DNA polymerase I E. DNA ligase

D

Mendel's law (or principle) of segregation states that (choose ONE) A. each diploid organism has two copies of each gene. B. the two alleles go into separate gametes when the homologous pair on which they exist separate during Meiosis I. C. there is a 50/50 chance that a gamete will get either allele. D. a, b, and c are correct E. none of the above answers is correct

D

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

D

Chromosomal mutations (choose ONE) A. can be caused by errors during cell division. B. are typically seen only in older people. C. are usually repaired by DNA polymerase. D. can be caused by methylation. E. none of these answers is correct

A

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

A

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 (mutations) most likely occur in drug-resistant viruses? (choose ONE) 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

Suppose that three critical amino acids in the active site of a specific enzyme are alanine, valine, and leucine (see amino acid table at end of exam). Which of the following characteristics would you predict the substrate to possess in order to bind the active site of this enzyme? (choose ONE) A. relatively hydrophobic B. hydrophilic, with a negative charge C. hydrophilic, with a positive charge D. hydrophilic, but without a charge E. either hydrophilic or hydrophobic

A

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

A

Use the figures below to answer the following three questions. (all are choose ONE) *image 18 A DNA molecule acting as template strand for RNA pol or DNA pol looks like that shown in diagram A. a B. b C. c D. none of the above

A

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

A

Membrane-enclosed organelles (choose ALL) A. allow cells to dedicate separate spaces for incompatible reactions. B. can vary in type, number and size amongst cells of the same organism. C. within the same cell will have same basic conditions of pH, so that proteins all maintain their shapes and functions. D. help the cell save energy, due to extra efficiency and lower energy demands. E. are quite similar in eukaryotic and prokaryotic cells.

A B

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.

A B

Which of the following is true of BOTH first- and second-division nondisjunction? (choose ALL) A. Gametes are produced with extra chromosomes. B. Gametes are produced with missing chromosomes. C. Sister chromatids fail to separate. D. Homologous chromosomes fail to separate. E. Half of the gametes will be normal, and half will be mutated.

A B

Which of the following point mutations is UNLIKELY to change a protein's ability to function? (choose ALL) A. one that occurs in a noncoding region of the DNA. B. one that results in a new codon that specifies the same amino acid as the original codon. C. one that occurs in somatic cells. D. one that creates a new codon that codes for an amino acid of the same size as the originally-specified amino acid. E. one that occurs in germline cells (cells that produce gametes).

A B

Cells have several ways of repairing DNA damage. Which of the following statements accurately describes the functions of one of these? (choose ALL) A. A phosphodiester bond between two adjacent nucleotides in a DNA strand; the break could be repaired by DNA ligase. B. The enzyme that repairs 99% of mismatched base-pairs during replication is DNA pol III. C. The type of repair that acts as a backup for the DNA proofreading function is mismatch repair. D. DNA proofreading takes place during G1 and G2. E. During the S phase of the cell cycle, excision repair enzymes correct any errors.

A B C

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.

A B C

Which of the following statements about sex chromosomes in most animals, including humans, is correct (assuming no genetic abnormalities)? (choose ALL) A. Males inherit an X chromosome from their mothers only, and can pass it on to their daughters only. B. Males inherit a Y chromosome from their fathers only, and can pass it on to their sons only. C. There are many genes on the X that do not exist on the Y. D. Mothers determine the sex of their offspring. E. A trait encoded by a gene on the Y chromosome can be expressed in either male or females.

A B C

18. Mendel's techniques differed from those of other hybridizers (plant breeders) of his time in that (choose ALL) A. he chose traits determined by a single gene with only two alleles. B. he quantified his results, looking for statistical patterns. C. he kept all his strains 'true-breeding', never mixing plants with different traits. D. he established 'true-breeding' strains, but also did crosses between plants with different traits. E. he did not publish his findings, like many of his competitors did.

A B D

Gene families (choose ALL) A. are the result of gene duplication and divergence. B. are extra copies of a gene, often with slight variations. C. are genetic risk factors for cancer, such as the BRCA genes, that run in families. D. consist of genes that may be expressed at different stages of development, such as the δ-, β-, and ε-hemoglobin genes. E. are genes that collaborate to form pedigrees (family trees).

A B D

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.

A B 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.

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. 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

A B D

The CAC of cellular respiration (choose ALL) *image 14 Acetyl CoA A. results in the oxidation of isocitrate, α-ketoglutarate, succinate. B. releases the last two carbons that were in the glucose as carbon dioxide gas. C. produces some ATPs via oxidative phosphorylation. D. must turn 6 times for each acetyl CoA that enters. E. is a cycle in the sense that the starting reactant, oxaloacetate, is regenerated.

A B E

Which of the following are NOT effective for mastering new ideas and forming long-term 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

A C

13. Aneuploidy (choose ALL) A. means a cell has an abnormal number of chromosomes. B. means a cell has been damaged by ultraviolet light and has been unable to repair the damage. C. means a cell will have a gene dosage problem: either too much or two little of the proteins encoded by the extra/missing chromosome. D. is often the result of nondisjunction. E. means a cell cannot successfully undergo mitosis.

A C D

In the big picture of glucose metabolism, (choose ALL) A. the purpose of photosynthesis is to reduce atmospheric CO2 molecules to glucose, using H2O from the soil (or aqueous environment), and energy from the sun. B. the purpose of cellular respiration is to reduce glucose to CO2 and H2O, and in the process capture some energy with which to synthesize ATP. C. cellular respiration involves transferring chemical energy from glucose to ATP in a series of enzyme-catalyzed steps. D. photosynthesis involves transforming radiant light energy into chemical bond energy. E. in cellular respiration (but not photosynthesis) exergonic reactions are coupled to endergonic reactions.

A C D

Regarding anabolic pathways and catabolic pathways, which of the following statements are correct? (choose ALL) A. Anabolic pathways result in a decrease in entropy; catabolic pathways result in an increase in entropy. B. Anabolic pathways can be used to synthesize ATP; catabolic pathways generally require the hydrolysis of ATP. C. Transcription and translation are both examples of anabolism. D. Transcription and translation must be coupled to catabolic reactions. E. Synthesis of new muscle fibers (proteins) is an example of catabolism.

A C 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.

A C D

What would happen to a cell if cyclin were always present? (choose ALL) *image 16 A. Cdk's would always be activated B. the cell would be unable to undergo cell division C. Cdk's would always be phosphorylating cell cycle proteins. D. the cell would divide rapidly. E. the cell would be unable to utilize ATP as a source of phosphates

A C D

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.

A C E

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

A D

How do plant, animal, and prokaryotic cells differ from one another? (choose ALL) A. Animal cells have mitochondria but not chloroplasts; plants have both types of organelles; prokaryotes have neither. B. Animal cells have mitochondria but not chloroplasts; plants have chloroplast but not mitochondria; prokaryotes have neither. C. Animal and plant cells both have plasma membranes; prokaryotes do not. D. Plant cells have cell walls; some prokaryotes have cell walls; animal cells do not. E. Animal cells have endoplasmic reticulum; plant and prokaryotic cells do not.

A D

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.

A D

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

A 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.

A D E

In the ETC of cellular respiration, (choose ALL) *image 15 A. electron carriers and the transmembrane proteins are oxidized. B. the transmembrane proteins and water are reduced. C. ADP is reduced to ATP by ATPsynthase. D. if there were holes in the outer membrane, ATP synthesis would slow, and but electron carriers would continue to be oxidized. E. without oxygen, no protons would be pumped, and ATP synthesis would soon cease

A D E

Which of the following correctly matches terms with definitions? (choose ALL) A. A gene is a segment of DNA that codes for a protein or RNA; alleles are alternative "recipes" for the protein or RNA. B. Phenotype is the genetic make-up of an individual; genotype is the observable characteristics of an individual. C. A polymorphism is a characteristic or trait that is the result of the interaction of many genes (like human height). D. An individual that is heterozygous for a trait has two different alleles for that trait. E. An individual that is homozygous for a trait can have either two dominant or two recessive alleles.

A D E

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.

B

Choose from the following terms to fill in the blanks in the CORRECT order: (choose ONE) A. ligand B. signaling cell C. receptor D. responding cell In communication between cells, the ______ produces the signaling molecule, also known as the _____; the ______ produces the ______, to which the signaling molecule binds. A. A,B,C,D B. B,A,D,C C. B,C,A,D D. D,C,B,A E. none of the above is correct

B

If DNA repair mechanisms were perfect, which of the following would MOST likely result? (choose ONE) A. Humans would live forever. B. Evolution as we know it would stop because mutations are the only source of new genetic variation. C. The rate of evolutionary change would dramatically increase. D. Humans would stop aging, because aging is a collection of DNA mutations. E. All of these answers are correct

B

If the concept of blending inheritance were true, would variation increase, decrease, or stay the same over time? (choose ONE) A. Variation would increase. B. Variation would decrease. C. Variation would stay the same. D. It is impossible to predict.

B

Mendel's principle of independent assortment of alleles for two different traits corresponds to which part of meiosis? (choose ONE) A. random pairing of homologs during prophase I B. random alignment of homologs at the metaphase plate during metaphase I C. separation of chromosomes in anaphase I D. random alignment of homologs on the metaphase plate during metaphase II E. separation of sister chromatids during anaphase II

B

The development of cancer requires both the ________ of an oncogene and the _______ of a tumor suppressor. (choose ONE) A. activation; activation B. activation; inhibition C. inhibition; activation D. inhibition; inhibition

B

Use the figures below to answer the following three questions. (all are choose ONE) *image 18 The DNA of the chromosome circled in figure I looks like that shown in diagram A. a B. b C. c D. none of the above

B

Which of the following accurately describes the path traveled by a new protein from the initiation of its synthesis until it is released from the cell? (choose ONE) A. plasma membrane RER vesicle Golgi cytosol external environment B. cytosol RER vesicle Golgi plasma membrane external environment C. cytosol SER vesicle Golgi plasma membrane external environment D. nuclear envelope Golgi vesicle RER plasma membrane external environment E. cytosol Golgi RER vesicle plasma membrane external environment

B

Which of the following could explain how some (though not many) people have Down syndrome and have a normal chromosome number? (choose ONE) A. One of the cells during development had trisomy 21 but then died. B. An unbalanced translocation carrying most of chromosome 21 occurred. C. A large enough fragment of one copy of chromosome 21 underwent a deletion. D. Some of the genes in one copy of chromosome 21 were mutated. E. None of these answers is correct.

B

Which of the following receptors is phosphorylated after signal binding? (choose ONE) A. gated ion channels B. protein kinase receptors C. G-coupled protein receptors D. intracellular (cytoplasmic) receptors E. all of the above are correct

B

Why are the X and Y chromosomes NOT considered homologous? (choose ONE) A. because they are from different parents B. because they do not carry the same set of genes C. because they have the same genes, but different alleles D. because the Y chromosome is not made of DNA E. because X chromosome is shaped like an X; the Y chromosome is shaped like a Y.

B

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.

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 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.

B

29. Given that this trait is X-linked recessive, which of the following individuals must be heterozygous? (choose ALL) *image 21 A. M (the father) B. F (the mother) C. 1 D. 2 E. 5

B C

In Mendelian genetics, a relationship between alleles of a gene, in which one is completely dominant to the other, means that in diploid organisms (choose ALL) A. it is necessary to have two copies of the dominant allele in order to express the dominant phenotype. B. it is necessary to have two copies of the recessive allele in order to express the recessive phenotype. C. the phenotype of the heterozygote is indistinguishable from that of the homozygous dominant. D. the genotypes of both homozygous dominant and heterozygous individuals is obvious from their phenotypes. E. none of the above answers is correct

B C

NAD plays roles in several stages of glucose metabolism; according to the diagram below (choose ALL) A. NAD in its reduced form is an oxidizing agent. B. NAD in its reduced form can pass electrons to another molecule. C. molecule AH2 could be glucose, pyruvate, or isocitrate. D. molecule AH2 gives up protons (H+) to NAD. E. molecule B could be any of the molecules that make up the ETC of respiration.

B C

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.

B C

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.

B C

The figure below shows that (choose ALL) *image 11 A. the synthesis of ATP is exergonic. B. the hydrolysis of ATP releases energy. C. the hydrolysis of ATP can be coupled to an endergonic reaction. D. the hydrolysis of ATP can be used to fuel exergonic reactions. E. endergonic reactions (e.g. active transport) can be used to fuel the synthesis of ATP.

B C

Which of the following statements about cancer are correct? (choose ALL) A. Cancer is an infectious disease (you can catch it from and pass it on to others). B. Oncogenes are viral genes or mutated proto-oncogenes that lead to out-of-control cell division. C. Tumor suppressor genes are genes that encode proteins whose normal job it is to put the "brakes" on cell division. D. The genes that encode p53 and p21 are examples of proto-oncogenes ("go" signals to cell division) E. The genes that encode cell adhesion proteins (that hold cells together, and thus prevent metastasis) are considered proto-oncogenes.

B C

In a test cross, (choose ALL) A. the purpose is to determine the genotype of an individual exhibiting the recessive phenotype. B. the purpose is to determine the genotype of an individual exhibiting the dominant phenotype. C. an individual with unknown genotype is crossed against one with known genotype. D. if there are any offspring exhibiting the recessive phenotype, the unknown is heterozygous. E. if there are any offspring exhibiting the dominant phenotype, the unknown is heterozygous.

B C D

In the first three stages of cellular respiration (glycolysis, pyruvate oxidation, and the CAC), the chemical energy in glucose is transferred to (choose ALL) A. ATP and CO2 B. NADH C. ATP D. FADH2 E. proton pumps and ATP

B C 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.

B C D

When in the cell cycle would you find sister chromatids? (choose ALL) A. G1 B. S C. G2 D. M E. cytokinesis

B C D

Which of the following statements correctly matches the stage of the cell cycle with its characteristic activities? (choose ALL) A. In G1, the cell is preparing for cell division. B. In S, the cell is synthesizing sister chromatids. C. In G2, the cell is preparing for cell division. D. In M, the cell sorts a copy of each chromosome into two new daughter nuclei. E. In M, the cell divides into 2 new daughter cells.

B C 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 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.

B C D

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.

B C E

Two reactions are shown below. Which of the following statements are correct about these reactions? (choose ALL) Reaction 1: C6H12O6 + 6O2 6CO2 + 6H2O Reaction 2: 6CO2 + 6H2O C6H12O6 + 6O2 A. Reaction 1 is endergonic; Reaction 2 is exergonic. B. There is more potential energy in the reactants than in the products for Reaction 1 only. C. In Reaction 1, carbons are oxidized; in Reaction 2, carbons are reduced. D. Both reactions result in a decrease in entropy. E. Oxygen is reduced to water in Reaction 1; water is oxidized to O2 in Reaction 2.

B C E

Which of the following is MOST likely to result in a nonfunctional polypeptide? (choose ALL) A. silent mutation B. nonsense mutation C. missense mutation D. substitution of a valine for a leucine E. change in shape

B C E

Which of the following statements are correct about cell signaling? (choose ALL) A. Endocrine signals are distributed to only some of the body's cells. B. Contact-dependent signaling does not involve the release of signal molecules. C. Transmembrane (cell-surface) receptors bind polar signal molecules. D. Intracellular (cytoplasmic) receptors bind to either polar or nonpolar signal molecules. E. The binding of signal to receptor changes receptor shape.

B C E

Cells in a organisms take on their specialized roles--such as blood cells, brain cells, etc-- (choose ALL) A. because each different cell type has a different set of genes. B. through differential gene expression. C. usually by getting rid of the genes that they will not need in their specialized roles. D. in part due to the different surface receptors they express; this will determine what signals they can respond to.

B D

In quorum sensing between bacterial cells, such as the example presented in the text and in class, bacterial cells are stimulated to take up DNA from the surrounding environment (choose ALL) A. when the density of other bacterial cells in their population (and their signal molecules) is low. B. when the density of bacterial cells (and their signal molecules) is high. C. without needing a receptor molecule (since no signal is involved). D. providing the bacteria with the opportunity to pick some new, useful genes. E. using a signaling system that is unique to prokaryotes.

B D

The figure below shows that (choose ALL) *image 16 A. when [ADP] is high in the cell, this means that there is also plenty of ATP, and thus the reactions of glycolysis and the CAC should slow down. B. when [ATP] is high in the cell, there are various places where ATP can act as an allosteric inhibitor to enzymes in the cell. C. if NADH is high in the cell, the ETC is running efficiently, and NADH can activate enzymes involved in the CAC. D. allosteric inhibition and activation allow cells to fine-tune the rates of metabolic pathways.

B D

Cyclins and Cdk's (cyclin-dependent kinases) are important molecules in regulating the cell cycle. Specifically, (choose ALL) *image 16 A. cyclins block cell division by binding Cdk's. B. Cdk's become active kinases when activated by cyclin. C. once activated, Cdk's synthesize ATP. D. activated Cdk's can phosphorylate other molecules. E. activated Cdk's can change the functions of other molecules.

B D E

Regarding the cross above, (choose ALL) A. the genes for tongue-rolling and freckles are on the same chromosome and do not assort independently. B. in the F1 offspring, one member of a homologous pair of chromosomes will have the R allele; the other member of that pair will have the r allele. C. in the F1 offspring, one member of a homologous pair of chromosomes will have the F allele; the other member of that pair will have the R allele. D. during meiosis II, the F and f alleles will segregate into different gametes. E. there are two different ways for the 2 tetrads to line up relative to one another at metaphase I, leading eventually to 4 genetically-different daughter cells.

B D E

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.

B D 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.

B D E

In a simple Mendelian monohybrid cross between a true-breeding pea plant that produces purple flowers (dominant) and one that produces white flowers (recessive), (choose ALL) A. all of the F1 offspring will be lavender (pale purple). B. the F2 generation will include ~3/4 purple-flowered plants and ¼ white-flowered plants. C. white flowers will not appear again in subsequent generations. D. each F1 offspring will pass on the allele for purple flowers to all of its offspring. E. the alleles for white flowers and purple flowers are on different members of a homologous pair of chromosomes.

B E

29. The diagram above shows a replication bubble with two replication forks, each moving out in opposite directions from the origin of replication, which is indicated by the arrow. What are the first six nucleotides of the new leading strand synthesized from the top parental strand? (choose ONE) *image 19 A. 3' CAGAUC 5' B. 5' CAATAT 5' C. 5' CAAUAU 3' D. 3' UAAAUU 5' E. 3' AUGAUA 3'

C

30. Regarding PCR (Polymerase Chain Reaction) (choose ONE) A. the purpose is to determine the exact sequence of A's, T's, C's and G's in a small sample of DNA. B. the purpose is to sort small pieces of DNA by size. C. the purpose is to amplify a small piece of DNA. D. helicase is used to separate the strands of the double helix. E. necessary components are DNA template, primase, helicase, and dNTPs

C

For the DNA template strand show below, which of the following statements is correct? (choose ONE) *image 20 A. The cDNA for this template would contain 7 U's and 4 C's. B. The mature mRNA for this template would be exactly 9 amino-acid-specifying codons long. C. The polypeptide synthesized from this template would be exactly 6 amino acids long. D. The cDNA would be synthesized by DNA pol III during G1 of the cell cycle. E. The mRNA would be synthesized by DNA pol III during G1 of the cell cycle.

C

If the enzyme that catalyzes step 3, isocitrate α-Ketoglutarate, were irreversibly inhibited, image 14 (choose ONE) A. the concentration of citrate in the cell would quickly decrease. B. the concentration of isocitrate would quickly decrease. C. the production of ATP and the reduction of electron carriers would quickly decrease. D. the concentration of oxaloacetate would increase for a bit, but then plateau (level off). E. the rate of ATP production by the ETC would be unaffected.

C

In the lab, you strip off all the proteins on the surface of cells by using a protease (an enzyme that destroys proteins). When you then add a specific signaling molecule, the cell still responds. Why is this? (choose ONE) A. The signaling molecule doesn't need a receptor. B. The signaling molecule is polar and can diffuse into the cell. C. The signal receptor is in the cytoplasm. D. The signaling molecule is nonpolar and binds to a cell-surface (transmembrane receptor).

C

In the metabolic pathway illustrated below, the starting material (substrate A) is converted equally to one of two end products, E or G. Use the diagram of the pathway below to answer the following question. Letters indicate the substrates and products, and numbers indicate the enzymes. In this pathway, the intermediate, C, is a substrate for both enzyme 3 and enzyme 5 and is converted with equal efficiency to D and F. *image 12 If end product E inhibits enzyme 3, which of the following would you expect to observe? (choose ONE) A. an increase in the production of C B. a decrease in the production of D and F C. a decrease in the production of E, but no change in the production of G D. a decrease in the production of E and G E. an increase in the production of A

C

In which of the following scenarios would cell signaling be prevented? (choose ONE) A. The nicotine in cigarette smoke binds to and activates the acetylcholine receptor in the plasma membrane of neurons in the brain. B. Proteins on the surface of cells in taste buds called umami receptors bind to glutamates and nucleotides in food, changing the membrane potential of these cells and telling the brain "This is savory". C. Allergy medicines, called antihistamines, bind to and block histamine receptors; this keeps fluid in capillaries that would otherwise be released and cause watery eyes and stuffy noses.

C

Mendel's principle of segregation corresponds to what part of meiosis? (choose ONE) A. condensation of the chromosomes in prophase I B. alignment of the homologs in metaphase I C. separation of homologs in anaphase I D. alignment of the chromosomes in metaphase II E. separation of the sister chromatids in anaphase II

C

Red-green color blindness is a sex-linked recessive trait in humans. If a carrier female (heterozygous for the trait) mated with an affected male, what would be the expected outcome? (choose ONE) A. None of the offspring would be color blind. B. None of the daughters would be color blind. C. Half of the daughters would be color blind. D. All of the sons would be color blind. E. c and d are correct

C

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.

C

Several human disorders are associated with defects in sorting and delivery of new proteins to their proper destinations in cells. These disorders are often associated with defects in which organelle? (choose ONE) A. plasma membrane B. SER C. Golgi D. nucleus E. lysosomes

C

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

C

Taxol is an anticancer drug that disrupts microtubule spindle formation, thus stopping cell division. Specifically, Taxol must (choose ONE) A. disrupt the formation of sister chromatids. B. deactivate RB, and thus blocks normal cell division. C. prevent the cell from separating chromosomes into daughter cells. D. prevent new cell wall formation. E. inhibit cyclin production.

C

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%

C

The deletion of 3 nucleotides in the reading frame can (choose ONE) A. cause a nonsense mutation in the reading frame. B. cause a frameshift mutation in the reading frame. C. result in the loss of one amino acid from the encoded polypeptide. D. cause a missense mutation in the reading frame. E. none of the above is correct

C

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.

C

The segregation of alleles corresponds to the separation of (choose ONE) A. genes. B. genotypes. C. chromosomes. D. phenotypes.

C

Use the figures below to answer the following three questions. (all are choose ONE) *image 18 The DNA of the chromosome circled in figure II looks like that shown in diagram A. a B. b C. c D. none of the above

C

What is one reason that a woman with genotype 47, XXX is not phenotypically different from a 46, XX female? (choose ONE) A. The X chromosome carries only genes dealing with being a female, so having an extra one doesn't matter. B. The extra X chromosome becomes active only in non-reproductive areas of the body. C. Only one X chromosome is active in each cell, regardless of how many X chromosomes there are in the cell. D. We have enzymes that recognize and degrade extra X chromosomes, insuring that each cell has only two X's. E. None of these answers is correct.

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.

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.

C D

The figure below shows a process in which (choose ALL) *image 13 A. the synthesis of the nucleic acid threonine from several precursor molecules. B. threonine, -ketobutyrate, and isoleucine are all enzymes in this metabolic pathway. C. isoleucine is complementary in shape and chemical properties to an inhibitor binding site on the enzyme that catalyzes the first step in this pathway. D. as isoleucine increases in concentration in the cell, it would increasingly reduce its own synthesis. E. if isoleucine were in low concentrations in the cell, the synthesis of -ketobutyrate from threonine would slow.

C D

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.

C D E

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.

C D E

Scientists isolate cells in various phases of the cell cycle, and measure the amount of DNA at various stages. Given that x is the amount of DNA in a cell in G1, which of the following statements are correct about this scenario? (choose ALL) A. A cell found to have DNA = 1x could be in G2. B. A cell found to have DNA = 1.5x could be in G2. C. A cell found to have DNA = 1.5x must be in S. D. A cell found to have DNA = 2x could be in G2. E. A cell found to have DNA = 2x could be in M.

C D E

During mitosis in this same cell, in the diagram above, (choose ALL) *image 17 A. the homologous pairs of chromosomes will line up together at metaphase; there will be 2 tetrads. B. crossing over will occur between the homologous chromosomes during prometaphase. C. the homologous pairs will line up independently of one another at metaphase (no tetrads). D. the cell will be temporarily haploid until cytokinesis takes place. E. the purpose will be to generate two, identical diploid cells.

C E

A chromosomal segment that breaks off and attaches to another chromosome is called a (choose ONE) A. deletion B. duplication C. inversion D. translocation E. reciprocal translocation

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.

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.

D

Which of the following cell types would likely have the MOST extensive system of smooth endoplasmic reticulum? (choose ONE) A. skin cells B. pancreatic cells that secrete digestive enzymes C. pancreatic cells that secrete the peptide hormone insulin D. ovary cells that secrete the steroid hormone estrogen E. central nervous system

D

You detect a cell in which there is an increased rate of single base-pair changes in the newly synthesized DNA. Which function of which protein is MOST likely disrupted in this situation? (choose ONE) A. the unwinding function of helicase B. the winding stress relief of topoisomerase C. the fragment joining function of DNA ligase D. the proofreading function of DNA pol III E. the strand separation function of single-stranded binding proteins

D

The definition of mutation is "any heritable change in the genetic material." The qualifier "heritable" is necessary because (choose ALL) A. most changes in genetic material are harmful to the organism. B. changes in the genetic material occur at random within the genome. C. changes in the genetic material occur without regard to the needs of the organism. D. most changes in the genetic material are repaired soon after they occur. E. changes in RNA are not passed on to offspring.

D E

A population of mosquitoes is exposed to the pesticide DDT for several generations. At the end of that time, most individuals in the population are resistant to DDT. The MOST likely reason for this is (choose ONE) A. DDT caused the mutation that led to resistance. B. By chance, new mutations that led to DDT resistance arose after DDT was used. C. Somatic mutations in the original populations were passed on the subsequent generations. D. Random mutations in each generation after exposure made the mosquitos resistant to DDT. E. None of these answers is correct.

E

Which of the following statements about the relationships between DNA, chromosomes, and genes is FALSE? (choose ONE) A. Chromosomes are made of DNA wrapped around histones. B. Genes are made of DNA. C. A gene is part of a chromosome. D. A chromosome contains many genes. E. A chromosome usually consists of two sister chromatids and looks like an X.

E

Which of the following types of cellular activities can be a response to cell signaling? (choose ONE) A. cell division is triggered B. gene expression patterns are changed C. enzyme activities are changed D. cell signals are released to communicate with other cells. E. all of the above are correct

E

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

E