Test
Biology of Cells
Preguntas del test (120)
1Which of the following is most generally false relating to energy?
- AKinetic energy relates to movement
- BPotential energy arises from the location or structure of matter
- CEnergy cannot be converted between forms
- DLight is the main way energy enters our ecosystem
- EThe disorder of the universe is increasing
2Which of the following is most generally true relating to energy?
- ACatabolic pathways are associated with an increase in entropy
- BFree energy is the non-entropic energy change for a process
- CSpontaneous processes take in free energy from their surroundings
- DMetabolic pathways in a cell have evolved to reach equilibrium
- EAn endergonic process gives out energy
3Which of the following best describes why ATP is important in cells?
- AIt can bind to DNA
- BIt removes phosphate groups from proteins
- CIts ribose sugar is an energy source
- DIt gives out energy when the bond to the terminal phosphate is broken
- EIt accepts electrons from respiration
4Which of following is false with respect to enzymes?
- AThey speed up certain reactions
- BThey lower the activation energy barrier for certain reactions
- CThey can change shape when a substrate binds
- DThey can only be regulated by molecules binding to their active site
- EThey can be subject to feedback inhibition
5Which respect to energy metabolism, which of the following statements is false?
- ACells need energy from external sources
- BEnergy obtained from nutrients is primarily stored as ATP
- CEnergy metabolism depends on reduction of organic compounds, such as sugars
- DCarbohydrates, fats and proteins are all sources of fuel for respiration
- EElectrons from redox reactions are often transferred to NAD+ making NADH
6Which of the following statements best describes the process of aerobic respiration?
- AIt converts glucose to methane
- BIt primarily generates NADH
- CIt is the oxidation of pyruvate
- DIt makes ATP, mostly through substrate-level phorphorylation
- EIt links redox reactions to create high energy molecules
7A water sample from a hot thermal vent contained a single-celled organism that had a cell wall but lacked a nucleus. What is most likely it's classification?
- AAnimalia
- BEukarya
- CArchaea
- DFungi
- EProtista
8What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?
- ANucleus > ER > Golgi
- BER > Golgi > vesicles that fuse with plasma membrane
- CER > Lysosomes > vesicles that fuse with plasma membrane
- DGolgi > ER > lysosomes
- EER > Golgi > nucleus
9In the cells of some organisms, mitosis occurs without cytokinesis. This will result in:
- Acells with more than one nucleus
- Bcell cycles lacking an S phase
- Cdestruction of chromosomes
- Dcells that are unusually small
- Ecells lacking nuclei
10In an analysis of the nucleotide composition of DNA, which of the following will be found?
- AA + C = G + T
- BG + C = T + A
- CA = G and C = T
- DA = C
11Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication?
- AG-C rich regions, polymerases, chromosome nicks
- Bnucleosome loosening, four dNTPS, four rNTPS
- Cligase, primers, nucleases
- Dtopoisomerases, telomerases, polymerases
- Edouble-stranded DNA, four kinds of dNTPs, primers, origins
12A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is
- A3' UGA 5'
- B3' UCA 5'
- C5' TCA 3'
- D3' ACU 5'
- Eeither UCA or TCA
13Which of the following is true of fermentation?
- AIt produces glucose
- BIt has a net production of NADH
- CThere is a net consumption of ATP to produce pyruvate
- DDuring the process, lactate is converted into ethanol
- EIt produces less ATP per glucose than aerobic respiration does
14Which of the following statements is generally false?
- AFermentation takes place in mitochondria
- BGlycolysis takes place in the cytosol
- CIn lactate fermentation, production of lactate from pyruvate consumes NADH
- DATP is produced during fermentation
- EOxygen is not consumed by fermentation
15Which of the following is generally true?
- AThe citric acid cycle in eukaryotes produces acetyl CoA
- BThe citric acid cycle in eukaryotes consumes NADH
- CDuring oxidative phosphorylation NAD+ and FAD are consumed
- DDuring oxidative phosphorylation CO2 is produced
- EDuring oxidative phosphorylation energy is dissipated as electrons progress through the transport chain
16Which one of the following statements is false?
- AHydrophobic molecules associate together to minimise their contact with water
- BIf there is 20% guanine in a molecule of DNA, there must be 30% cytosine in that molecule
- CSteroids are hydrophobic
- DmRNA is exported from the nucleus to allow ribosomal protein synthesis to occur
- EA change in 1 unit of pH comes from a 10-fold change in proton concentration
17Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursoer, tubulin. Surprisingly, this stops mitosis. Specifically, Taxol must affect
- Achromatid assembly
- Bthe formation of the mitotic spindle
- Cthe S phase of the cell cycle
- Danaphase
- Eformation of the centrioles
18You have the technology necessary to measure each of the following in a sample of animal cells: chlorophylls, organelle density, picograms of DNA, cell wall components, and enzymatic activity. Which would you expect to increase significantly from M to G1?
- Acell wall components and DNA
- Bchlorophyll and cell walls
- Corganelle density and enzymatic activity
- Dorganelle density and cell walls
- Echlorophyll and DNA
19Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?
- AOne of the daughter cells, but not the other would have radioactive DNA
- BRadioactive thymine would pair with nonradioactive guanine
- CAll four bases of the DNA would be radioactive
- DDNA in both daughter cells would be radioactive
- ENeither of the two daughter cells would be radioactive
20Which of the following provides some evidence that RNA probably evolved before DNA?
- ARNA polymerase does not require localised unwinding of the DNA
- BDNA polymerase has proofreading function
- CRNA polymerase makes a single stranded molecule
- DRNA polymerase uses DNA as a template
- EDNA polymerase uses primers, usually made of RNA
21A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which of the following might this illustrate?
- AThe sequence evolves very rapidly
- BThe sequence does not mutate
- CThe sequence is found in many but not all promoters
- DThe sequence is transcribed at the start of every gene
- EAny mutation in the sequence is generally selected against
22There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the facts that
- AThe rules for base pairing between the third base of a codon and tRNA are flexible.
- BSome tRNAs have anticodons that recognise four or more different codons
- CMany codons are never used, so the tRNAs that recognise them are dispensible
- DThe DNA codes for all 61 tRNAs but some are then destroyed
- ECompetitive exclusion forces some tRNAs to be destroyed by nucleases
23Which of the following is the first event to take place in translation in eukaryotes?
- ABase pairing of activated methionine-tRNA to AUG of the messenger RNA
- BElongation of the polypeptide
- CThe small subunit of the ribosome recognises and attaches to the 5' cap of mRNA
- DCovalent bonding between the first two amino acids
- EBinding of the larger ribosomal subunit to smaller ribosomal subunits
24When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by
- Aa specific characteristic of the ribosome itself, which distinguishes free ribosomes from bound ribosomes
- Bmoving through a specialised channel of the nucleus
- Ca signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane
- Da signal sequence of RNA that precedes the start codon of the message
- Ea chemical signal given off by the ER
25Why might a point mutation in DNA make a difference in the level of a protein's activity?
- AIt might exchange one serine codon for a different serine codon
- BIt might substitute an amino acid in the active site
- CIt might substitute the N-terminus of the polypeptide for the C-terminus
- DIt might result in a chromosomal translocation
- EIt might exchange one stop codon for another stop codon
26In order for a eukaryotic gene to be engineered into a bacterial colony to be expressed, what must be included in addition to the coding exons of the gene?
- Aeukaryotic tRNAs
- Beukaryotic polymerases
- Ca bacterial promotor sequence
- Deukaryotic ribosomal subunits
- Ethe introns
27The tryptophan operon is a repressible operon that is
- Aturned off only when glucose is present in the growth medium
- Bturned on only when tryptophan is added to the growth medium
- Cpermanently turned on
- Dturned off whenever tryptophan is added to the growth medium
- Eturned on only when glucose is present in the growth medium
28A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in
- Ainactivation of RNA polymerase by alteration of its active site
- Bcontinuous transcription of the structural gene controlled by that regulator
- Ccomplete inhibition of the transcription of the structural gene controlled by that regulator
- Dirreversible binding of the repressor to the operator
- Econtinuous translation of the mRNA because of alteration of its structure
29The lactose operon is likely to be transcribed when
- Athe cyclic AMP and lactose levels are both high within the cell
- Bthe cyclic AMP levels are low
- Cthere is more glucose in the cell than lactose
- Dthere is glucose but no lactose in the cell
- Ethe cAMP level is high and the lactose level is low
30All of the following are part of a prokaryotic cell except
- Aa cell wall
- Ban endoplasmic reticulum
- Cribosomes
- Da plasma membrane
- EDNA
31What is the structural feature that allows DNA to replicate?
- AComplementary pairing of the nitrogenous bases
- BTwisting of the molecule to form an alpha-helix
- CSugar-phosphate backbone
- DThree-component structure of nucleotides
- EDisulfide bonding (bridging) of the two helixes
32White blood cells engulf bacteria through what process?
- Aosmosis
- Bphagocytosis
- Cpinocytosis
- Dreceptor-mediated exocytosis
- Eexocytosis
33Which of the following types of molecules are the major structural components of the cell membrane?
- Aphospholipids and cellulose
- Bnucleic acids and proteins
- Cphospholipids and proteins
- Dproteins and cellulose
- Eglycoproteins and cholesterol
34How do the daughter cells at the end of mitosis and cytokineses compare with their parent cell when it was in G1 of the cell cycle?
- Athe daughter cells have half the number of chromosome and half the amount of DNA
- Bthe daughter cells have the same number of chromosomes and twice the amount of DNA
- Cthe daughter cells have the same number of chromosomes and the same amount of DNA
- Dthe daughter cells have half the amount of cytoplasm and half the amount of DNA
- Ethe daughter cells have the same number of chromosomes and half the amount of DNA
35Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?
- A8%
- B16%
- C31%
- D42%
- EIt cannot be determined from the information provided.
36DNA has two functions: It can self-replicate, and it acts as a template for the transcription of RNA. DNA is capable of these functions because:
- AIts two strands are held together by easily broken covalent bonds
- Bits nucleotides can base pair with both ribose and deoxyribose nucleotides
- Cits replication is semi-conservative
- Dreplication and transcription are thermodynamically spontaneous and require no enzymes
37What is meant by the description "anti-parallel" regarding the strands that make up DNA?
- Athe twisting nature of DNA creates non-parallel strands
- BThe 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand
- CBase pairings create unequal spacing between the two DNA strands
- DOne strand is postively charged and the other is negatively charged
- EOne strand contains only purines and the other contains only pyrimidines
38In E. coli, there is a mutation in a gene called dnaB that stops the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?
- ANo proofreading will occur
- BNo replication fork will be formed
- CThe DNA will supercoil
- DReplication will occur via RNA polymerase alone
- EReplication will require a DNA template from another source
39To repair a thymine dimer by nucleotide excision repair, in which order do the necessary enzymes act?
- Aexonuclease, DNA polymerase III, RNA ligase
- Bhelicase, DNA polymerase I, DNA ligase
- CDNA ligase, nuclease, helicase
- DDNA polymerase I, DNA polymerase III, DNA ligase
- Eendonuclease, DNA polymerase I, DNA ligase
40What is the function of topoisomerase?
- Arelieving strain in the DNA ahead of the replication fork
- Belongating new DNA at a replication fork by adding nucleotides to the existing chain
- Cadding methyl groups to bases of DNA
- Dunwinding the double helix
- Estabilising single-stranded DNA at the replication fork
41In eukaryotes, general transcription factors
- Abind to sequences just after the start site of transcription
- Bare required for the expression of specific protein-encoding genes
- Cinhibit RNA polymerase binding to the promoter and begin transcribing
- Dbind to other proteins or to a sequence element within the promoter called the TATA box
- Eusually lead to high level of transcription even without additional specific transcription factors
42Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to
- Acut the plasmid with res enzyme X and then insert the gene into the plasmid
- Bcut the plasmid twice with res enzyme Y and ligate the two fragments onto the ends of the DNA fragments cut with res enzyme X
- Ccut the plasmid with restriction enzyme X and insert the fragments cut with res enzyme Y into the plasmid
- Dcut the DNA again with res enzyme Y and insert these fragments into the plasmid cut with the same enzyme
- Einsert the fragments cut with res enzyme X directly into the plasmid without cutting the plasmid
43A principal problem with inserting an unmodified mammalian gene into a BAC, and then getting that gene expressed in bacteria, is that
- Abacterial RNA polymerase cannot make RNA complementary to mammalian DNA
- Bprokaryotes use a different genetic code from that of eukaryotes
- Cbacteria translate polycistronic messages only
- Dbacteria cannot remove eukaryotic introns
- Ebacterial DNA is not found in a membrane-bounded nucleus and is therefore incompatible with mammalian DNA
44The reason for using Taq polymerase for PCR is that
- Aonly minute amounts are needed for each cycle of PCR
- Bit binds more readily than other polymerases to primer
- Cit has regions that are complementary to primers
- Dit is heat stable and can withstand the temperature changes of the cycler
- Eall of these are correct
45What do we mean when we use the terms monohybrid cross and dihybrid cross?
- Aa monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents
- Ba monohybrid produces a single progeny, whereas a dihybrid produces two progeny
- Ca monohybrid results in a 9:3:3:1 ratio whereas a dihybrid gives 3:1
- Da dihybrid cross involves organisms that are heterozygous for two characteristics and a monohybrid cross involves only one
- Ea monohybrid is performed for one generation, dihybrid for two
46Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties?
- Athe traits blended together during fertilisation
- Bno genes interacted to produce the parental phenotype
- Cdifferent genes interacted to produce the parental phenotype
- Done phenotype was completely dominant over another
- Eeach allele affected phenotypic expression
47Two plants are crossed, resulting in offspring with 3:1 ratio for a particular trait. What does this suggest?
- AThat the parents were true breeding for contrasting traits
- Bthat each offspring has the same alleles for each of two traits
- Cthat a blending of traits has occured
- Dthat the parents were both heterozygous for a single trait
- Ethat the trait shows incomplete dominance
48Which of the following would you expect of a eukaryote lacking telomerase?
- Aa high probability of somatic cells becoming cancerous
- Bproduction of Okazaki fragments
- Cinability to repair thymine dimers
- Da reduction in chromosome length in gametes
- Ehigh sensitivity to sunlight
49If cells were unable to produce histone proteins, which of the following would be a likely effect?
- Athere would be an increase in the amount of "satellite" DNA produced during centrifugation
- Bthe cell's DNA couldn't be packed into its nucleus
- Cspindle fibers would not form during prophase
- Damplification of other genes would compensate for the lack of histones
- Epseudogenes would be transcribed to compensate for the decreased protein in the cell
50Why do histones bind tightly to DNA?
- AHistones are positively charged, and DNA is negatively charged.
- BHistones are negatively charged, and DNA is positively charged.
- CBoth histones and DNA are strongly hydrophobic
- DHistones are covalently linked to the DNA
- EHistones are highly hydrophobic, and DNA is hydrophillic
51The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?
- AA gene from an organism can theoretically be expressed by any other organism
- BAll organisms have experienced convergent evolution
- CDNA was the first genetic material
- DThe same codons in different organisms translate into the different amino acids
- EDifferent organisms have different numbers of different types of amino acids
52The nitrogenous base adenine is found in all members of which group?
- Aproteins, triglycerides, and testosterone
- Bproteins, ATP, and DNA
- CATP, RNA, and DNA
- Da glucose, ATP, and DNA
- Eproteins, carbohydrates, and ATP
53Which of the following statements best describes the termination of transcription in prokaryotes?
- ARNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase
- BRNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript
- CRNA polymerase transcribes through an intron, and the snRNPs cause the polymerase to let go of the transcript
- DOnce transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome
- ERNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA
54Which of the following does not occur in prokaryotic eukaryotic gene expression, but does in eukaryotic gene expression?
- AmRNA, tRNA, and rRNA are transcribed
- BRNA polymerase binds to the promoter
- CA poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end
- DTranscription can begin as soon as translation has begun even a little
- ERNA polymerase requires a primer to elongate the molecule
55Which of the following is a function of a poly-A signal sequence?
- AIt adds the poly-A tail to the 3' end of the mRNA
- BIt codes for a sequence in eukaryotic transcripts that signals enzymatic cleavage ~ 10-35 nucleotides away
- CIt allows the 3' end of the mRNA to attach to the ribosome
- DIt is a sequence that codes for the hydrolysis of the RNA polymerase
- EIt adds a 7-methylguanosine cap to the 3' end of the mRNA
56In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein?
- Aligase
- BRNA polymerase I
- CRNA polymerase II
- DRNA polymerase III
- Eprimase
57When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype?
- A0%
- B100%
- C25%
- D50%
- E75%
58Cystic fibrosis affects the lungs, pancreas, the digestive system, and other organs, resulting in symptoms ranging from breathing difficulties to recurrent infections. Which of the following terms best describes this?
- Aepistasis
- Bmultiple alleles
- Cincomplete dominance
- Dcodominance
- Epleiotropy
59Which of the following DNA mutations is most likely to be damaging to the protein it specifies?
- Aa codon substitution
- Ba base-pair deletion
- Ca substitution in the last base of a codon
- Da codon deletion
- Ea point mutation
60Lipid soluble hormones
- Ahave a receptor on the surface of the cell
- Binclude the catecholamines
- Ccan diffuse through the lipid bilayer
- Dexclude the sex hormones
- Ehave receptors coupled to 2 messenger systems to mediate their effect
61The human mitochondrial genome has approx
- A5000 base pairs
- B6000 base pairs
- C9000 base pairs
- D16,000 base pairs
- E50,000 base pairs
62Which of the following is most generally true of mitochondrial disorders?
- Athey are always transmitted via maternal inheritance
- Bthey are always transmitted via paternal inheritance
- Ca male does not transmit a mutation to his offspring
- Dthey often occur following a mutation that occurs de novo
- Ecan be cured by genetic techniques
63Common clinical features of myopathy do not include
- Aptosis
- Bmyopathy
- Coptic atrophy
- Ddiabetes mellitus
- Ethyroid disease
64What is the likely inheritance of a disorder that has 2 apparently normal parents, an affected daughter and son, and two healthy sons?
- Aautosomal dominant condition
- Bautosomal recessive condition
- Csex linked condition
- Dnew mutation in offspring
- Enone of the above
65A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that
- Amany noncoding stretches of nucleotides are present in mRNA
- Bthere is redundancy and ambiguity in the genetic code
- Cmany nucleotides are needed to code for each amino acid
- Dnucleotides break off and are lost during the transcription process
- Ethere are termination exons near the beginning of mRNA
66Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on the specificity in the
- Abinding of ribosomes to mRNA
- Bshape of the A and P sites of ribosomes
- Cbonding of the anticodon to the codon
- Dattachment of amino acids to tRNAs
- Ebonding of the anticodon to the codon and the attachment of amino acids to tRNAs
67There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that
- Asome tRNAs have anticodons that recognise four or more different codons
- Bthe rules for base pairing between the third base of a codon and tRNA are flexible
- Cmany codons are never used, so the tRNAs that recognise them are dispensible
- Dthe DNA codes for all 61 tRNAs but some are then destroyed
- Ecompetitive exclusion forces some tRNAs to be destroyed by nucleases
68Which of the following is a function of a signal peptide?
- ATo direct an mRNA molecule into the cisternal space of the ER
- Bto bind RNA polymerase to DNA and initiate transcription
- Cto terminate translation of the messenger RNA
- Dto translocate polypeptides across the ER membrane
- Eto signal the initiation of transcription
69The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in
- Aa base-pair substitution
- Ba nucleotide mismatch
- Ca frameshift mutation
- Da polypeptide missing an amino acid
- Ea nonsense mutation
70Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product?
- Aa deletion of a codon
- Ba deletion of two nucleotides
- Ca substitution of the third nucleotide of an ACC codon
- Da substitution of the first nucleotide of a GGG codon
- Ean insertion of a codon
71Graves disease
- Ais a disorder of cortisol expression
- Bis associated with weight gain
- Cis a result of excess TSH hormone production
- Dhas a characteristic eye appearance
- Eis most common in childhood
72Tetraploidy is how many sets of chromosomes?
- Aone
- Btwo
- Cthree
- Dfour
- Efive
73Downs syndrome is a consequence of
- Atrisomoy 5
- Btrisomoy 8
- Ctrisomoy 13
- Dtrisomoy 15
- Etrisomoy 21
74Osteoporosis is most common in
- Ayoung women
- Bolder men
- Celderly Maori females
- Delderly Caucasian females
- Eelderly with no racial preference
75Which of these statements is NOT true of genetic disorders?
- Afor a recessive X linked trait to be expressed, a female needs 2 copies
- Bfor a recessive X linked trait to be expressed, a male needs 1 copy
- CX linked recessive conditions are more commonly expressed in females
- DX linked recessive conditions are more commonly expressed in males
- EX linked genes follow specific patterns of inheritance
76Which of these is not an X-linked condition?
- Acolour blindness
- BDuchenne muscular dystrophy
- CHaemophilia A
- DHaemophilia B
- EMitochondrial myopathy
77Which of these statements best describes our knowledge of the accurate inheritance of extranuclear genes?
- AThere are always inherited maternally
- BThey are always inherited paternally
- CThey can come from either parent
- DThey are more commonly from the mother
- EThey are more commonly from the father
78A lack of which molecule would result in the cell's inability to "turn off" genes?
- Aoperon
- Binducer
- Cpromotor
- Dubiquitin
- Eco-repressor
79Which of the following mechanisms is used to coordinate the expression of multiple, related genes in eukaryotic cells?
- AGenes are organised into clusters, with local chromatin structures influencing the expression of all the genes at once
- BThe genes all have the same enhancer sequences regardless of genomic location, and allow activators to turn on their transcription simultaneously
- CThe genes are organised into large operons, allowing them to be transcribed as a single unit
- DA single repressor is able to turn off several related genes
- EEnvironmental signals enter the cell and bind directly to promoters
80If you were to observe the activity of methylated DNA, you would expect it to
- Abe replicating nearly continuously
- Bbe unwinding in preparation for protein synthesis
- Chave turned off or slowed down the process of transcription
- Dbe very actively transcribed and translated
- Einduce protein synthesis by not allowing repressors to bind to it
81When DNA is compacted by histones into chromatin fibres, the DNA is unable to interact with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin must constantly alter its structure. Which process mediates this dynamic activity?
- ADNA supercoiling at or around H1
- Bmethylation and acetylation of histone tails
- Chydrolysis of DNA molecules where they are wrapped around the nucleosome core
- Daccessibility of heterochromatin to phosphorylating enzymes
- Enucleotide excision and reconstruction
82The number of protein-coding sequences is much smaller than expected. Which of the following accounts for the most of the DNA that does not code for proteins?
- A"junk" DNA that serves no purpose
- BrRNA and tRNA coding sequences
- CDNA that is translated directed without being transcribed
- Dnon-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function
- Enon-protein-coding DNA that is transcribed into several kinds of small RNAs without biological function
83The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called
- ARNA interference
- BRNA obstruction
- CRNA blocking
- DRNA targeting
- ERNA disposal
84What is the most likely diagnosis for this condition: A 6 year old boy presents to the paediatrician with muscle weakness that is making it difficult for him to walk. He has an older brother with the same condition. His medical notes refer to "Gowers sign" being positive
- ADuchenne muscular dystrophy
- BMitochondrial myopathy
- CGraves disease
- DCushings syndrome
- EPolymyositis (inflammation of muscle
85Which of the following is NOT an example of a virus promoting cancer?
- AHuman papilloma virus
- BEbstein Barr virus
- CHepatitis B virus
- DInfluenza virus
- EHuman T cell lymphotropic virus
86Which of the following best describes siRNA?
- Aa short double-stranded RNA, one of whose strands can complement and inactivate a sequence mRNA
- B a single-stranded RNA that can, where it has internal complementary base pairs, fold into cloverleaf patterns
- Ca double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor
- Da portion of rRNA that allows it to bind to several ribosomal proteins in forming large or small subunits
- Ea molecule, known as a DICER, that can degrade other mRNA sequences
87BRCA1 and BRCA2 are considered to be tumor-suppressor genes because
- Athey prevent infection by retroviruses that cause cancer
- Btheir normal products protect the cell by participating in repair of DNA damage
- Cthe mutant forms of either one of these promote breast cancer
- Dthe normal genes make estrogen receptors
- Ethey block penetration of breast cells by chemical carcinogens
88Which of the following statements describes proto-oncogenes?
- Atheir normal function is to suppress tumor growth
- Bthey can code for proteins associated with cell growth
- CThey are introduced to a cell initially by retroviruses
- DThey are underexpressed in cancer cells
- EThey are produced by somatic mutations induced by carcinogens
89The cancer-causing forms of the Ras proteins are involved in which of the following processes?
- Acell-cell adhesion
- Bcell division
- Crelaying a signal from a growth factor receptor
- DDNA replication
- EDNA repair
90The host range of a virus is determined by
- Athe proteins in the host's cytoplasm
- Bthe enzymes produced by the virus before it infects the cell
- Cthe enzymes carried by the virus
- Dwhether its nucleic acid is DNA or RNA
- Ethe proteins on its surface and that of the host
91Which of the following statements about the DNA in one of your brain cells is true?
- AEach gene lies immediately adjacent to an enhancer
- BThe majority of genes are likely to be transcribed
- CIt is the same as the DNA in one of your heart cells
- DMany genes are groups into operon-like clusters
- EMost of the DNA codes for proteins
92Red green colour blindness is caused by a sex-linked recessive gene. What is the probability that the first son born to a colour blind man and a woman with normal vision whose father was colour blind will also be colour blind?
- A1/4
- B1/2
- Cc1
- Dnil
- E1/3
93Which of the following is most generally false?
- AA water molecule is polar
- BSodium chloride forms an ionic solid
- CWater hydrogen bonds to chloride ions
- DWater forms van der Waals interaction with sodium ions
- EWater does not form van der Waals interactions with chloride ions
94Which of the following is most generally true?
- ABases have a positive charge
- BAcids have a low pH
- CThe proton concentration in neutral water is 10-7 M
- DWhen a solution is buffered there is an equal balance of protons and hydroxide ions
- ECarbon dioxide dissolves in water to give a basic solution
95Which of the following is NOT a property of carbon that is important in the context of living systems?
- AIt forms strong bonds to other carbon atoms
- BIt can form molecules with a variety of different shapes
- CCompounds consisting of only hydrogen and carbon are hydrophilic
- DThe tetrahedral shape of carbon in some molecules allows it to form enantiomers
- ECarbon can form strong bonds with oxygen, hydrogen, nitrogen and sulphur
96Which of the following molecules is a polymer built from structurally related building blocks?
- ALeucine
- BAdenoside triphosphate
- CA fatty acid
- DCellulose
- ECholesterol
97Most human-infecting viruses are maintained in the human population only. However, a zoonosis is a disease that is transmitted from other vertebrates to humans, at least sporadically, without requiring viral mutation. Which of the following is the best example of a zoonosis?
- ARabies
- BHerpesvirus
- CSmallpox
- DHIV
- EHepatitis virus
98Which of the following accounts for someone who has had a herpesvirus-mediated cold sore or genital sore getting flare-ups for the rest of his or her life?
- Areinfection by a closely related herpesvirus of a different strain
- Breinfection by the same herpesvirus strain
- Ccoinfection with an unrelated virus that causes the same symptoms
- Dcopies of the herpesvirus genome maintained in a latently infected host cell
- Eexpression of miRNA by host cell suppressing viral replication
99In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host genes. Therefore, which of the following would you expect of the genes of the bacteriophage?
- Aregulation via acetylation of histones
- Bpositive control mechanisms rather than negative
- Ccontrol of more than one gene in an operon
- Dreliance on transcription activators
- Eutilization of eukaryotic polymerases
100Why do RNA viruses appear to have higher rates of mutation?
- AReplication of their genomes does not involve the proofreading steps of DNA replication
- BRNA viruses replicate faster
- CRNA viruses are more sensitive to mutagens
- DRNA nucleotides are more unstable than DNA nucleotides
- ERNA viruses can incorporate a variety of nonstandard bases
101Antiviral drugs that have become useful are usually associated with which of the following properties?
- Aability to remove all viruses from the infected host
- Binterference with the viral reproduction
- Cprevention of the host from becoming infected
- Dremoval of viral proteins
- Eremoval of viral mRNAs
102What mediates the assembly of new viruses?
- Ahost cells chaperones
- Bassembly proteins coded for by the host nucleus
- Cassembly proteins coded for by the viral genes
- Dviral RNA intermediates
- Enothing; they self-assemble
103How does a bacterial cell protect its own DNA from restriction enzymes?
- Aadding methyl groups to adenines and cytosines
- Busing DNA ligase to seal the bacterial DNA into a closed circle
- Cadding histones to protect the double-stranded DNA
- Dforming "sticky ends" of bacterial DNA to prevent the enzyme from attaching
- Ereinforcing the bacterial DNA structure with covalent phosphodiester bonds
104Which of the following statements about fats is most generally false?
- ASaturated fats form solis at room temperature
- BFats do not hydrogen bond to water
- CThere are 3 fatty acids in a phospholipid
- Da cis double bond in a fatty acid helps reduce membrane rigidity
- EThe polar head group of a phospholipid helps it interact with water
105Entropy can be described as
- AAn energy term that increases the universe over time
- BA measure of the energy available within bonds
- CAn energy term always decreases outside a living system
- DA force that decreases in spontaneous events
- EAn energy term that always increases within a living system
106There is no change in Gibbs free energy
- AWithin a system that is doing work
- BDuring glycolysis
- CWithin a living organism
- DIn a reaction at dynamic equilibrium
- EDuring the citric acid cycle
107Which of the following statements is false?
- AAnabolic metabolism builds complex molecules from more simple ones
- BCatabolism generates energy
- CAn enzyme increases the amount of a product formed at equilibrium
- DSome of the energy stored in food is lost as heat
- ECatabolic processes increase entropy within the cell
108ATP is useful as an energy shuttle because
- AIt breaks down to provdie energy without needing a catalyst
- BIt can donate a phosphate group to a molecule, creating a phosphorylated intermediate
- CHydrolysis of ATP to ADP provides more energy than is required to produce ATP from ADP
- DThe Gibbs free energy change for ATP hydrolysis is positive
- EIt localises within membranes
109Which of the following does not represent a common mechanism for regulation of enzyme activity in response to an instantaneous change in a metabolic demand
- AInhibitors binding to the active site
- BCooperatively between protein subunits
- CInhibitors binding to an allosteric site
- DFeedback inhibition
- EActivators binding to the active site
110The main provider of energy to drive ecosystems on earth is
- AOxygen
- BATP
- CLight
- DPyruvatc
- EGlucose
111Fermentation does not
- ACouple with glycolysis
- BProduce ATP
- CConsume pyruvate
- DUse the electron transport chain
- EUse NADH/NAD+
112A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using
- ARNA polymerase to transcribe the gene
- Ba restriction enzyme to cut the gene into shorter pieces
- Creverse transcriptase to reconstruct the gene from its mRNA
- DDNA polymerase to reconstruct the gene from its polypeptide product
- EDNA ligase to put together fragments of the DNA that codes for a particular polypeptide
113Which of the following is used to make complementary DNA (cDNA) from RNA?
- Arestriction enzymes
- Bgene cloning
- CDNA ligase
- Dgel electrophoresis
- Ereverse transcriptase
114Which of the following best describes the complete sequence of steps occurring during every cycle of PCR?
1. The primers hybridize to the target DNA
2. The mixture is heated to a high temperature to denature the double-stranded target DNA
3. Fresh DNA polymerase is added
4. DNA polymerase extends the primers to make a copy of the target DNA- A2, 1, 4
- B1, 3, 2, 4
- C3, 4, 1, 2
- D3, 4, 2
- E2, 3, 4
115DNA microarrays have made a huge impact on genomic studies because they
- Acan be used to eliminate the function of any gene in the genome
- Bcan be used to introduce entire genomes into bacterial cells
- Callow the expression of many or even all of the genes in the genome
- Dall physical maps of the genome to be assembled in very short time
- Edramatically enhance the efficiency of the restriction enzymes
116For a particular microarray assay (DNA chip), cDNA has been made from the mRNAs of a dozen patients' breast tumor biopsies. The researchers will be looking for:
- Aa particular gene that is amplified in all or most of the patient samples
- Ba pattern of fluorescence that indicates which cells are overproliferating
- Ca pattern shared among some or all of the samples that indicates gene expression differing from control samples
- Da group of cDNAs that act differently from those on the rest of the grid
- Ea group of cDNAs that match those in non-breast cancer control samples from the same population
117Glycolysis in eukaryotes
- AOccurs only when oxygen is present
- BTakes place in mitochondria
- CGenerates energy at every step
- DGenerates NADH
- EProduces lactate
118The citric acid cycle in eukaryotes
- AUses citrate from glycolysis
- BProduces acetyl CoA
- CIs a cytosolic process
- DForms CO2
- EConsumes NADH
119During oxidative phosphorylation
- ANAD+ and FAD are consumed
- BATP is generated from the electron transport chain
- CEnergy is dissipated as electrons progress through the transport chain
- DCarbon dioxide is produced
- EProtons are pumped into the mitochondrial matrix
120Fermentation does not
- AUse an electron transport chain
- BProduce CO2
- CConsume pyruvate
- DConsume O2
- EOccur in the cytosol
Información
- Descripción
- Tertiary Biology Test sobre Biology of Cells, creado por Hollie Trillo el 03/11/2014.
- Autor
- Hollie Trillo
- Idioma
- English
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