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Biology of Cells

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Tertiary Biology Quiz am Biology of Cells, erstellt von Hollie Trillo am 03/11/2014.
Hollie Trillo
Quiz von Hollie Trillo, aktualisiert more than 1 year ago
Hollie Trillo
Erstellt von Hollie Trillo vor etwa 10 Jahre
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Zusammenfassung der Ressource

Frage 1

Frage
Which of the following is most generally false relating to energy?
Antworten
  • Kinetic energy relates to movement
  • Potential energy arises from the location or structure of matter
  • Energy cannot be converted between forms
  • Light is the main way energy enters our ecosystem
  • The disorder of the universe is increasing

Frage 2

Frage
Which of the following is most generally true relating to energy?
Antworten
  • Catabolic pathways are associated with an increase in entropy
  • Free energy is the non-entropic energy change for a process
  • Spontaneous processes take in free energy from their surroundings
  • Metabolic pathways in a cell have evolved to reach equilibrium
  • An endergonic process gives out energy

Frage 3

Frage
Which of the following best describes why ATP is important in cells?
Antworten
  • It can bind to DNA
  • It removes phosphate groups from proteins
  • Its ribose sugar is an energy source
  • It gives out energy when the bond to the terminal phosphate is broken
  • It accepts electrons from respiration

Frage 4

Frage
Which of following is false with respect to enzymes?
Antworten
  • They speed up certain reactions
  • They lower the activation energy barrier for certain reactions
  • They can change shape when a substrate binds
  • They can only be regulated by molecules binding to their active site
  • They can be subject to feedback inhibition

Frage 5

Frage
Which respect to energy metabolism, which of the following statements is false?
Antworten
  • Cells need energy from external sources
  • Energy obtained from nutrients is primarily stored as ATP
  • Energy metabolism depends on reduction of organic compounds, such as sugars
  • Carbohydrates, fats and proteins are all sources of fuel for respiration
  • Electrons from redox reactions are often transferred to NAD+ making NADH

Frage 6

Frage
Which of the following statements best describes the process of aerobic respiration?
Antworten
  • It converts glucose to methane
  • It primarily generates NADH
  • It is the oxidation of pyruvate
  • It makes ATP, mostly through substrate-level phorphorylation
  • It links redox reactions to create high energy molecules

Frage 7

Frage
A 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?
Antworten
  • Animalia
  • Eukarya
  • Archaea
  • Fungi
  • Protista

Frage 8

Frage
What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?
Antworten
  • Nucleus > ER > Golgi
  • ER > Golgi > vesicles that fuse with plasma membrane
  • ER > Lysosomes > vesicles that fuse with plasma membrane
  • Golgi > ER > lysosomes
  • ER > Golgi > nucleus

Frage 9

Frage
In the cells of some organisms, mitosis occurs without cytokinesis. This will result in:
Antworten
  • cells with more than one nucleus
  • cell cycles lacking an S phase
  • destruction of chromosomes
  • cells that are unusually small
  • cells lacking nuclei

Frage 10

Frage
In an analysis of the nucleotide composition of DNA, which of the following will be found?
Antworten
  • A + C = G + T
  • G + C = T + A
  • A = G and C = T
  • A = C

Frage 11

Frage
Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication?
Antworten
  • G-C rich regions, polymerases, chromosome nicks
  • nucleosome loosening, four dNTPS, four rNTPS
  • ligase, primers, nucleases
  • topoisomerases, telomerases, polymerases
  • double-stranded DNA, four kinds of dNTPs, primers, origins

Frage 12

Frage
A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is
Antworten
  • 3' UGA 5'
  • 3' UCA 5'
  • 5' TCA 3'
  • 3' ACU 5'
  • either UCA or TCA

Frage 13

Frage
Which of the following is true of fermentation?
Antworten
  • It produces glucose
  • It has a net production of NADH
  • There is a net consumption of ATP to produce pyruvate
  • During the process, lactate is converted into ethanol
  • It produces less ATP per glucose than aerobic respiration does

Frage 14

Frage
Which of the following statements is generally false?
Antworten
  • Fermentation takes place in mitochondria
  • Glycolysis takes place in the cytosol
  • In lactate fermentation, production of lactate from pyruvate consumes NADH
  • ATP is produced during fermentation
  • Oxygen is not consumed by fermentation

Frage 15

Frage
Which of the following is generally true?
Antworten
  • The citric acid cycle in eukaryotes produces acetyl CoA
  • The citric acid cycle in eukaryotes consumes NADH
  • During oxidative phosphorylation NAD+ and FAD are consumed
  • During oxidative phosphorylation CO2 is produced
  • During oxidative phosphorylation energy is dissipated as electrons progress through the transport chain

Frage 16

Frage
Which one of the following statements is false?
Antworten
  • Hydrophobic molecules associate together to minimise their contact with water
  • If there is 20% guanine in a molecule of DNA, there must be 30% cytosine in that molecule
  • Steroids are hydrophobic
  • mRNA is exported from the nucleus to allow ribosomal protein synthesis to occur
  • A change in 1 unit of pH comes from a 10-fold change in proton concentration

Frage 17

Frage
Taxol 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
Antworten
  • chromatid assembly
  • the formation of the mitotic spindle
  • the S phase of the cell cycle
  • anaphase
  • formation of the centrioles

Frage 18

Frage
You 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?
Antworten
  • cell wall components and DNA
  • chlorophyll and cell walls
  • organelle density and enzymatic activity
  • organelle density and cell walls
  • chlorophyll and DNA

Frage 19

Frage
Suppose 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?
Antworten
  • One of the daughter cells, but not the other would have radioactive DNA
  • Radioactive thymine would pair with nonradioactive guanine
  • All four bases of the DNA would be radioactive
  • DNA in both daughter cells would be radioactive
  • Neither of the two daughter cells would be radioactive

Frage 20

Frage
Which of the following provides some evidence that RNA probably evolved before DNA?
Antworten
  • RNA polymerase does not require localised unwinding of the DNA
  • DNA polymerase has proofreading function
  • RNA polymerase makes a single stranded molecule
  • RNA polymerase uses DNA as a template
  • DNA polymerase uses primers, usually made of RNA

Frage 21

Frage
A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which of the following might this illustrate?
Antworten
  • The sequence evolves very rapidly
  • The sequence does not mutate
  • The sequence is found in many but not all promoters
  • The sequence is transcribed at the start of every gene
  • Any mutation in the sequence is generally selected against

Frage 22

Frage
There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the facts that
Antworten
  • The rules for base pairing between the third base of a codon and tRNA are flexible.
  • Some tRNAs have anticodons that recognise four or more different codons
  • Many codons are never used, so the tRNAs that recognise them are dispensible
  • The DNA codes for all 61 tRNAs but some are then destroyed
  • Competitive exclusion forces some tRNAs to be destroyed by nucleases

Frage 23

Frage
Which of the following is the first event to take place in translation in eukaryotes?
Antworten
  • Base pairing of activated methionine-tRNA to AUG of the messenger RNA
  • Elongation of the polypeptide
  • The small subunit of the ribosome recognises and attaches to the 5' cap of mRNA
  • Covalent bonding between the first two amino acids
  • Binding of the larger ribosomal subunit to smaller ribosomal subunits

Frage 24

Frage
When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by
Antworten
  • a specific characteristic of the ribosome itself, which distinguishes free ribosomes from bound ribosomes
  • moving through a specialised channel of the nucleus
  • a signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane
  • a signal sequence of RNA that precedes the start codon of the message
  • a chemical signal given off by the ER

Frage 25

Frage
Why might a point mutation in DNA make a difference in the level of a protein's activity?
Antworten
  • It might exchange one serine codon for a different serine codon
  • It might substitute an amino acid in the active site
  • It might substitute the N-terminus of the polypeptide for the C-terminus
  • It might result in a chromosomal translocation
  • It might exchange one stop codon for another stop codon

Frage 26

Frage
In 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?
Antworten
  • eukaryotic tRNAs
  • eukaryotic polymerases
  • a bacterial promotor sequence
  • eukaryotic ribosomal subunits
  • the introns

Frage 27

Frage
The tryptophan operon is a repressible operon that is
Antworten
  • turned off only when glucose is present in the growth medium
  • turned on only when tryptophan is added to the growth medium
  • permanently turned on
  • turned off whenever tryptophan is added to the growth medium
  • turned on only when glucose is present in the growth medium

Frage 28

Frage
A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in
Antworten
  • inactivation of RNA polymerase by alteration of its active site
  • continuous transcription of the structural gene controlled by that regulator
  • complete inhibition of the transcription of the structural gene controlled by that regulator
  • irreversible binding of the repressor to the operator
  • continuous translation of the mRNA because of alteration of its structure

Frage 29

Frage
The lactose operon is likely to be transcribed when
Antworten
  • the cyclic AMP and lactose levels are both high within the cell
  • the cyclic AMP levels are low
  • there is more glucose in the cell than lactose
  • there is glucose but no lactose in the cell
  • the cAMP level is high and the lactose level is low

Frage 30

Frage
All of the following are part of a prokaryotic cell except
Antworten
  • a cell wall
  • an endoplasmic reticulum
  • ribosomes
  • a plasma membrane
  • DNA

Frage 31

Frage
What is the structural feature that allows DNA to replicate?
Antworten
  • Complementary pairing of the nitrogenous bases
  • Twisting of the molecule to form an alpha-helix
  • Sugar-phosphate backbone
  • Three-component structure of nucleotides
  • Disulfide bonding (bridging) of the two helixes

Frage 32

Frage
White blood cells engulf bacteria through what process?
Antworten
  • osmosis
  • phagocytosis
  • pinocytosis
  • receptor-mediated exocytosis
  • exocytosis

Frage 33

Frage
Which of the following types of molecules are the major structural components of the cell membrane?
Antworten
  • phospholipids and cellulose
  • nucleic acids and proteins
  • phospholipids and proteins
  • proteins and cellulose
  • glycoproteins and cholesterol

Frage 34

Frage
How 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?
Antworten
  • the daughter cells have half the number of chromosome and half the amount of DNA
  • the daughter cells have the same number of chromosomes and twice the amount of DNA
  • the daughter cells have the same number of chromosomes and the same amount of DNA
  • the daughter cells have half the amount of cytoplasm and half the amount of DNA
  • the daughter cells have the same number of chromosomes and half the amount of DNA

Frage 35

Frage
Cytosine 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?
Antworten
  • 8%
  • 16%
  • 31%
  • 42%
  • It cannot be determined from the information provided.

Frage 36

Frage
DNA 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:
Antworten
  • Its two strands are held together by easily broken covalent bonds
  • its nucleotides can base pair with both ribose and deoxyribose nucleotides
  • its replication is semi-conservative
  • replication and transcription are thermodynamically spontaneous and require no enzymes

Frage 37

Frage
What is meant by the description "anti-parallel" regarding the strands that make up DNA?
Antworten
  • the twisting nature of DNA creates non-parallel strands
  • The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand
  • Base pairings create unequal spacing between the two DNA strands
  • One strand is postively charged and the other is negatively charged
  • One strand contains only purines and the other contains only pyrimidines

Frage 38

Frage
In 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?
Antworten
  • No proofreading will occur
  • No replication fork will be formed
  • The DNA will supercoil
  • Replication will occur via RNA polymerase alone
  • Replication will require a DNA template from another source

Frage 39

Frage
To repair a thymine dimer by nucleotide excision repair, in which order do the necessary enzymes act?
Antworten
  • exonuclease, DNA polymerase III, RNA ligase
  • helicase, DNA polymerase I, DNA ligase
  • DNA ligase, nuclease, helicase
  • DNA polymerase I, DNA polymerase III, DNA ligase
  • endonuclease, DNA polymerase I, DNA ligase

Frage 40

Frage
What is the function of topoisomerase?
Antworten
  • relieving strain in the DNA ahead of the replication fork
  • elongating new DNA at a replication fork by adding nucleotides to the existing chain
  • adding methyl groups to bases of DNA
  • unwinding the double helix
  • stabilising single-stranded DNA at the replication fork

Frage 41

Frage
In eukaryotes, general transcription factors
Antworten
  • bind to sequences just after the start site of transcription
  • are required for the expression of specific protein-encoding genes
  • inhibit RNA polymerase binding to the promoter and begin transcribing
  • bind to other proteins or to a sequence element within the promoter called the TATA box
  • usually lead to high level of transcription even without additional specific transcription factors

Frage 42

Frage
Assume 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
Antworten
  • cut the plasmid with res enzyme X and then insert the gene into the plasmid
  • cut the plasmid twice with res enzyme Y and ligate the two fragments onto the ends of the DNA fragments cut with res enzyme X
  • cut the plasmid with restriction enzyme X and insert the fragments cut with res enzyme Y into the plasmid
  • cut the DNA again with res enzyme Y and insert these fragments into the plasmid cut with the same enzyme
  • insert the fragments cut with res enzyme X directly into the plasmid without cutting the plasmid

Frage 43

Frage
A principal problem with inserting an unmodified mammalian gene into a BAC, and then getting that gene expressed in bacteria, is that
Antworten
  • bacterial RNA polymerase cannot make RNA complementary to mammalian DNA
  • prokaryotes use a different genetic code from that of eukaryotes
  • bacteria translate polycistronic messages only
  • bacteria cannot remove eukaryotic introns
  • bacterial DNA is not found in a membrane-bounded nucleus and is therefore incompatible with mammalian DNA

Frage 44

Frage
The reason for using Taq polymerase for PCR is that
Antworten
  • only minute amounts are needed for each cycle of PCR
  • it binds more readily than other polymerases to primer
  • it has regions that are complementary to primers
  • it is heat stable and can withstand the temperature changes of the cycler
  • all of these are correct

Frage 45

Frage
What do we mean when we use the terms monohybrid cross and dihybrid cross?
Antworten
  • a monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents
  • a monohybrid produces a single progeny, whereas a dihybrid produces two progeny
  • a monohybrid results in a 9:3:3:1 ratio whereas a dihybrid gives 3:1
  • a dihybrid cross involves organisms that are heterozygous for two characteristics and a monohybrid cross involves only one
  • a monohybrid is performed for one generation, dihybrid for two

Frage 46

Frage
Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties?
Antworten
  • the traits blended together during fertilisation
  • no genes interacted to produce the parental phenotype
  • different genes interacted to produce the parental phenotype
  • one phenotype was completely dominant over another
  • each allele affected phenotypic expression

Frage 47

Frage
Two plants are crossed, resulting in offspring with 3:1 ratio for a particular trait. What does this suggest?
Antworten
  • That the parents were true breeding for contrasting traits
  • that each offspring has the same alleles for each of two traits
  • that a blending of traits has occured
  • that the parents were both heterozygous for a single trait
  • that the trait shows incomplete dominance

Frage 48

Frage
Which of the following would you expect of a eukaryote lacking telomerase?
Antworten
  • a high probability of somatic cells becoming cancerous
  • production of Okazaki fragments
  • inability to repair thymine dimers
  • a reduction in chromosome length in gametes
  • high sensitivity to sunlight

Frage 49

Frage
If cells were unable to produce histone proteins, which of the following would be a likely effect?
Antworten
  • there would be an increase in the amount of "satellite" DNA produced during centrifugation
  • the cell's DNA couldn't be packed into its nucleus
  • spindle fibers would not form during prophase
  • amplification of other genes would compensate for the lack of histones
  • pseudogenes would be transcribed to compensate for the decreased protein in the cell

Frage 50

Frage
Why do histones bind tightly to DNA?
Antworten
  • Histones are positively charged, and DNA is negatively charged.
  • Histones are negatively charged, and DNA is positively charged.
  • Both histones and DNA are strongly hydrophobic
  • Histones are covalently linked to the DNA
  • Histones are highly hydrophobic, and DNA is hydrophillic

Frage 51

Frage
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?
Antworten
  • A gene from an organism can theoretically be expressed by any other organism
  • All organisms have experienced convergent evolution
  • DNA was the first genetic material
  • The same codons in different organisms translate into the different amino acids
  • Different organisms have different numbers of different types of amino acids

Frage 52

Frage
The nitrogenous base adenine is found in all members of which group?
Antworten
  • proteins, triglycerides, and testosterone
  • proteins, ATP, and DNA
  • ATP, RNA, and DNA
  • a glucose, ATP, and DNA
  • proteins, carbohydrates, and ATP

Frage 53

Frage
Which of the following statements best describes the termination of transcription in prokaryotes?
Antworten
  • RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase
  • RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript
  • RNA polymerase transcribes through an intron, and the snRNPs cause the polymerase to let go of the transcript
  • Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome
  • RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA

Frage 54

Frage
Which of the following does not occur in prokaryotic eukaryotic gene expression, but does in eukaryotic gene expression?
Antworten
  • mRNA, tRNA, and rRNA are transcribed
  • RNA polymerase binds to the promoter
  • A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end
  • Transcription can begin as soon as translation has begun even a little
  • RNA polymerase requires a primer to elongate the molecule

Frage 55

Frage
Which of the following is a function of a poly-A signal sequence?
Antworten
  • It adds the poly-A tail to the 3' end of the mRNA
  • It codes for a sequence in eukaryotic transcripts that signals enzymatic cleavage ~ 10-35 nucleotides away
  • It allows the 3' end of the mRNA to attach to the ribosome
  • It is a sequence that codes for the hydrolysis of the RNA polymerase
  • It adds a 7-methylguanosine cap to the 3' end of the mRNA

Frage 56

Frage
In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein?
Antworten
  • ligase
  • RNA polymerase I
  • RNA polymerase II
  • RNA polymerase III
  • primase

Frage 57

Frage
When 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?
Antworten
  • 0%
  • 100%
  • 25%
  • 50%
  • 75%

Frage 58

Frage
Cystic 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?
Antworten
  • epistasis
  • multiple alleles
  • incomplete dominance
  • codominance
  • pleiotropy

Frage 59

Frage
Which of the following DNA mutations is most likely to be damaging to the protein it specifies?
Antworten
  • a codon substitution
  • a base-pair deletion
  • a substitution in the last base of a codon
  • a codon deletion
  • a point mutation

Frage 60

Frage
Lipid soluble hormones
Antworten
  • have a receptor on the surface of the cell
  • include the catecholamines
  • can diffuse through the lipid bilayer
  • exclude the sex hormones
  • have receptors coupled to 2 messenger systems to mediate their effect

Frage 61

Frage
The human mitochondrial genome has approx
Antworten
  • 5000 base pairs
  • 6000 base pairs
  • 9000 base pairs
  • 16,000 base pairs
  • 50,000 base pairs

Frage 62

Frage
Which of the following is most generally true of mitochondrial disorders?
Antworten
  • they are always transmitted via maternal inheritance
  • they are always transmitted via paternal inheritance
  • a male does not transmit a mutation to his offspring
  • they often occur following a mutation that occurs de novo
  • can be cured by genetic techniques

Frage 63

Frage
Common clinical features of myopathy do not include
Antworten
  • ptosis
  • myopathy
  • optic atrophy
  • diabetes mellitus
  • thyroid disease

Frage 64

Frage
What is the likely inheritance of a disorder that has 2 apparently normal parents, an affected daughter and son, and two healthy sons?
Antworten
  • autosomal dominant condition
  • autosomal recessive condition
  • sex linked condition
  • new mutation in offspring
  • none of the above

Frage 65

Frage
A 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
Antworten
  • many noncoding stretches of nucleotides are present in mRNA
  • there is redundancy and ambiguity in the genetic code
  • many nucleotides are needed to code for each amino acid
  • nucleotides break off and are lost during the transcription process
  • there are termination exons near the beginning of mRNA

Frage 66

Frage
Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on the specificity in the
Antworten
  • binding of ribosomes to mRNA
  • shape of the A and P sites of ribosomes
  • bonding of the anticodon to the codon
  • attachment of amino acids to tRNAs
  • bonding of the anticodon to the codon and the attachment of amino acids to tRNAs

Frage 67

Frage
There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that
Antworten
  • some tRNAs have anticodons that recognise four or more different codons
  • the rules for base pairing between the third base of a codon and tRNA are flexible
  • many codons are never used, so the tRNAs that recognise them are dispensible
  • the DNA codes for all 61 tRNAs but some are then destroyed
  • competitive exclusion forces some tRNAs to be destroyed by nucleases

Frage 68

Frage
Which of the following is a function of a signal peptide?
Antworten
  • To direct an mRNA molecule into the cisternal space of the ER
  • to bind RNA polymerase to DNA and initiate transcription
  • to terminate translation of the messenger RNA
  • to translocate polypeptides across the ER membrane
  • to signal the initiation of transcription

Frage 69

Frage
The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in
Antworten
  • a base-pair substitution
  • a nucleotide mismatch
  • a frameshift mutation
  • a polypeptide missing an amino acid
  • a nonsense mutation

Frage 70

Frage
Which 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?
Antworten
  • a deletion of a codon
  • a deletion of two nucleotides
  • a substitution of the third nucleotide of an ACC codon
  • a substitution of the first nucleotide of a GGG codon
  • an insertion of a codon

Frage 71

Frage
Graves disease
Antworten
  • is a disorder of cortisol expression
  • is associated with weight gain
  • is a result of excess TSH hormone production
  • has a characteristic eye appearance
  • is most common in childhood

Frage 72

Frage
Tetraploidy is how many sets of chromosomes?
Antworten
  • one
  • two
  • three
  • four
  • five

Frage 73

Frage
Downs syndrome is a consequence of
Antworten
  • trisomoy 5
  • trisomoy 8
  • trisomoy 13
  • trisomoy 15
  • trisomoy 21

Frage 74

Frage
Osteoporosis is most common in
Antworten
  • young women
  • older men
  • elderly Maori females
  • elderly Caucasian females
  • elderly with no racial preference

Frage 75

Frage
Which of these statements is NOT true of genetic disorders?
Antworten
  • for a recessive X linked trait to be expressed, a female needs 2 copies
  • for a recessive X linked trait to be expressed, a male needs 1 copy
  • X linked recessive conditions are more commonly expressed in females
  • X linked recessive conditions are more commonly expressed in males
  • X linked genes follow specific patterns of inheritance

Frage 76

Frage
Which of these is not an X-linked condition?
Antworten
  • colour blindness
  • Duchenne muscular dystrophy
  • Haemophilia A
  • Haemophilia B
  • Mitochondrial myopathy

Frage 77

Frage
Which of these statements best describes our knowledge of the accurate inheritance of extranuclear genes?
Antworten
  • There are always inherited maternally
  • They are always inherited paternally
  • They can come from either parent
  • They are more commonly from the mother
  • They are more commonly from the father

Frage 78

Frage
A lack of which molecule would result in the cell's inability to "turn off" genes?
Antworten
  • operon
  • inducer
  • promotor
  • ubiquitin
  • co-repressor

Frage 79

Frage
Which of the following mechanisms is used to coordinate the expression of multiple, related genes in eukaryotic cells?
Antworten
  • Genes are organised into clusters, with local chromatin structures influencing the expression of all the genes at once
  • The genes all have the same enhancer sequences regardless of genomic location, and allow activators to turn on their transcription simultaneously
  • The genes are organised into large operons, allowing them to be transcribed as a single unit
  • A single repressor is able to turn off several related genes
  • Environmental signals enter the cell and bind directly to promoters

Frage 80

Frage
If you were to observe the activity of methylated DNA, you would expect it to
Antworten
  • be replicating nearly continuously
  • be unwinding in preparation for protein synthesis
  • have turned off or slowed down the process of transcription
  • be very actively transcribed and translated
  • induce protein synthesis by not allowing repressors to bind to it

Frage 81

Frage
When 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?
Antworten
  • DNA supercoiling at or around H1
  • methylation and acetylation of histone tails
  • hydrolysis of DNA molecules where they are wrapped around the nucleosome core
  • accessibility of heterochromatin to phosphorylating enzymes
  • nucleotide excision and reconstruction

Frage 82

Frage
The 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?
Antworten
  • "junk" DNA that serves no purpose
  • rRNA and tRNA coding sequences
  • DNA that is translated directed without being transcribed
  • non-protein-coding DNA that is transcribed into several kinds of small RNAs with biological function
  • non-protein-coding DNA that is transcribed into several kinds of small RNAs without biological function

Frage 83

Frage
The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called
Antworten
  • RNA interference
  • RNA obstruction
  • RNA blocking
  • RNA targeting
  • RNA disposal

Frage 84

Frage
What 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
Antworten
  • Duchenne muscular dystrophy
  • Mitochondrial myopathy
  • Graves disease
  • Cushings syndrome
  • Polymyositis (inflammation of muscle

Frage 85

Frage
Which of the following is NOT an example of a virus promoting cancer?
Antworten
  • Human papilloma virus
  • Ebstein Barr virus
  • Hepatitis B virus
  • Influenza virus
  • Human T cell lymphotropic virus

Frage 86

Frage
Which of the following best describes siRNA?
Antworten
  • a short double-stranded RNA, one of whose strands can complement and inactivate a sequence mRNA
  • a single-stranded RNA that can, where it has internal complementary base pairs, fold into cloverleaf patterns
  • a double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor
  • a portion of rRNA that allows it to bind to several ribosomal proteins in forming large or small subunits
  • a molecule, known as a DICER, that can degrade other mRNA sequences

Frage 87

Frage
BRCA1 and BRCA2 are considered to be tumor-suppressor genes because
Antworten
  • they prevent infection by retroviruses that cause cancer
  • their normal products protect the cell by participating in repair of DNA damage
  • the mutant forms of either one of these promote breast cancer
  • the normal genes make estrogen receptors
  • they block penetration of breast cells by chemical carcinogens

Frage 88

Frage
Which of the following statements describes proto-oncogenes?
Antworten
  • their normal function is to suppress tumor growth
  • they can code for proteins associated with cell growth
  • They are introduced to a cell initially by retroviruses
  • They are underexpressed in cancer cells
  • They are produced by somatic mutations induced by carcinogens

Frage 89

Frage
The cancer-causing forms of the Ras proteins are involved in which of the following processes?
Antworten
  • cell-cell adhesion
  • cell division
  • relaying a signal from a growth factor receptor
  • DNA replication
  • DNA repair

Frage 90

Frage
The host range of a virus is determined by
Antworten
  • the proteins in the host's cytoplasm
  • the enzymes produced by the virus before it infects the cell
  • the enzymes carried by the virus
  • whether its nucleic acid is DNA or RNA
  • the proteins on its surface and that of the host

Frage 91

Frage
Which of the following statements about the DNA in one of your brain cells is true?
Antworten
  • Each gene lies immediately adjacent to an enhancer
  • The majority of genes are likely to be transcribed
  • It is the same as the DNA in one of your heart cells
  • Many genes are groups into operon-like clusters
  • Most of the DNA codes for proteins

Frage 92

Frage
Red 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?
Antworten
  • 1/4
  • 1/2
  • c1
  • nil
  • 1/3

Frage 93

Frage
Which of the following is most generally false?
Antworten
  • A water molecule is polar
  • Sodium chloride forms an ionic solid
  • Water hydrogen bonds to chloride ions
  • Water forms van der Waals interaction with sodium ions
  • Water does not form van der Waals interactions with chloride ions

Frage 94

Frage
Which of the following is most generally true?
Antworten
  • Bases have a positive charge
  • Acids have a low pH
  • The proton concentration in neutral water is 10-7 M
  • When a solution is buffered there is an equal balance of protons and hydroxide ions
  • Carbon dioxide dissolves in water to give a basic solution

Frage 95

Frage
Which of the following is NOT a property of carbon that is important in the context of living systems?
Antworten
  • It forms strong bonds to other carbon atoms
  • It can form molecules with a variety of different shapes
  • Compounds consisting of only hydrogen and carbon are hydrophilic
  • The tetrahedral shape of carbon in some molecules allows it to form enantiomers
  • Carbon can form strong bonds with oxygen, hydrogen, nitrogen and sulphur

Frage 96

Frage
Which of the following molecules is a polymer built from structurally related building blocks?
Antworten
  • Leucine
  • Adenoside triphosphate
  • A fatty acid
  • Cellulose
  • Cholesterol

Frage 97

Frage
Most 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?
Antworten
  • Rabies
  • Herpesvirus
  • Smallpox
  • HIV
  • Hepatitis virus

Frage 98

Frage
Which 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?
Antworten
  • reinfection by a closely related herpesvirus of a different strain
  • reinfection by the same herpesvirus strain
  • coinfection with an unrelated virus that causes the same symptoms
  • copies of the herpesvirus genome maintained in a latently infected host cell
  • expression of miRNA by host cell suppressing viral replication

Frage 99

Frage
In 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?
Antworten
  • regulation via acetylation of histones
  • positive control mechanisms rather than negative
  • control of more than one gene in an operon
  • reliance on transcription activators
  • utilization of eukaryotic polymerases

Frage 100

Frage
Why do RNA viruses appear to have higher rates of mutation?
Antworten
  • Replication of their genomes does not involve the proofreading steps of DNA replication
  • RNA viruses replicate faster
  • RNA viruses are more sensitive to mutagens
  • RNA nucleotides are more unstable than DNA nucleotides
  • RNA viruses can incorporate a variety of nonstandard bases

Frage 101

Frage
Antiviral drugs that have become useful are usually associated with which of the following properties?
Antworten
  • ability to remove all viruses from the infected host
  • interference with the viral reproduction
  • prevention of the host from becoming infected
  • removal of viral proteins
  • removal of viral mRNAs

Frage 102

Frage
What mediates the assembly of new viruses?
Antworten
  • host cells chaperones
  • assembly proteins coded for by the host nucleus
  • assembly proteins coded for by the viral genes
  • viral RNA intermediates
  • nothing; they self-assemble

Frage 103

Frage
How does a bacterial cell protect its own DNA from restriction enzymes?
Antworten
  • adding methyl groups to adenines and cytosines
  • using DNA ligase to seal the bacterial DNA into a closed circle
  • adding histones to protect the double-stranded DNA
  • forming "sticky ends" of bacterial DNA to prevent the enzyme from attaching
  • reinforcing the bacterial DNA structure with covalent phosphodiester bonds

Frage 104

Frage
Which of the following statements about fats is most generally false?
Antworten
  • Saturated fats form solis at room temperature
  • Fats do not hydrogen bond to water
  • There are 3 fatty acids in a phospholipid
  • a cis double bond in a fatty acid helps reduce membrane rigidity
  • The polar head group of a phospholipid helps it interact with water

Frage 105

Frage
Entropy can be described as
Antworten
  • An energy term that increases the universe over time
  • A measure of the energy available within bonds
  • An energy term always decreases outside a living system
  • A force that decreases in spontaneous events
  • An energy term that always increases within a living system

Frage 106

Frage
There is no change in Gibbs free energy
Antworten
  • Within a system that is doing work
  • During glycolysis
  • Within a living organism
  • In a reaction at dynamic equilibrium
  • During the citric acid cycle

Frage 107

Frage
Which of the following statements is false?
Antworten
  • Anabolic metabolism builds complex molecules from more simple ones
  • Catabolism generates energy
  • An enzyme increases the amount of a product formed at equilibrium
  • Some of the energy stored in food is lost as heat
  • Catabolic processes increase entropy within the cell

Frage 108

Frage
ATP is useful as an energy shuttle because
Antworten
  • It breaks down to provdie energy without needing a catalyst
  • It can donate a phosphate group to a molecule, creating a phosphorylated intermediate
  • Hydrolysis of ATP to ADP provides more energy than is required to produce ATP from ADP
  • The Gibbs free energy change for ATP hydrolysis is positive
  • It localises within membranes

Frage 109

Frage
Which of the following does not represent a common mechanism for regulation of enzyme activity in response to an instantaneous change in a metabolic demand
Antworten
  • Inhibitors binding to the active site
  • Cooperatively between protein subunits
  • Inhibitors binding to an allosteric site
  • Feedback inhibition
  • Activators binding to the active site

Frage 110

Frage
The main provider of energy to drive ecosystems on earth is
Antworten
  • Oxygen
  • ATP
  • Light
  • Pyruvatc
  • Glucose

Frage 111

Frage
Fermentation does not
Antworten
  • Couple with glycolysis
  • Produce ATP
  • Consume pyruvate
  • Use the electron transport chain
  • Use NADH/NAD+

Frage 112

Frage
A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using
Antworten
  • RNA polymerase to transcribe the gene
  • a restriction enzyme to cut the gene into shorter pieces
  • reverse transcriptase to reconstruct the gene from its mRNA
  • DNA polymerase to reconstruct the gene from its polypeptide product
  • DNA ligase to put together fragments of the DNA that codes for a particular polypeptide

Frage 113

Frage
Which of the following is used to make complementary DNA (cDNA) from RNA?
Antworten
  • restriction enzymes
  • gene cloning
  • DNA ligase
  • gel electrophoresis
  • reverse transcriptase

Frage 114

Frage
Which 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
Antworten
  • 2, 1, 4
  • 1, 3, 2, 4
  • 3, 4, 1, 2
  • 3, 4, 2
  • 2, 3, 4

Frage 115

Frage
DNA microarrays have made a huge impact on genomic studies because they
Antworten
  • can be used to eliminate the function of any gene in the genome
  • can be used to introduce entire genomes into bacterial cells
  • allow the expression of many or even all of the genes in the genome
  • all physical maps of the genome to be assembled in very short time
  • dramatically enhance the efficiency of the restriction enzymes

Frage 116

Frage
For 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:
Antworten
  • a particular gene that is amplified in all or most of the patient samples
  • a pattern of fluorescence that indicates which cells are overproliferating
  • a pattern shared among some or all of the samples that indicates gene expression differing from control samples
  • a group of cDNAs that act differently from those on the rest of the grid
  • a group of cDNAs that match those in non-breast cancer control samples from the same population

Frage 117

Frage
Glycolysis in eukaryotes
Antworten
  • Occurs only when oxygen is present
  • Takes place in mitochondria
  • Generates energy at every step
  • Generates NADH
  • Produces lactate

Frage 118

Frage
The citric acid cycle in eukaryotes
Antworten
  • Uses citrate from glycolysis
  • Produces acetyl CoA
  • Is a cytosolic process
  • Forms CO2
  • Consumes NADH

Frage 119

Frage
During oxidative phosphorylation
Antworten
  • NAD+ and FAD are consumed
  • ATP is generated from the electron transport chain
  • Energy is dissipated as electrons progress through the transport chain
  • Carbon dioxide is produced
  • Protons are pumped into the mitochondrial matrix

Frage 120

Frage
Fermentation does not
Antworten
  • Use an electron transport chain
  • Produce CO2
  • Consume pyruvate
  • Consume O2
  • Occur in the cytosol
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