1572958
Descripción
Test por Hollie Trillo, actualizado hace más de 1 año
|
Creado por Hollie Trillo
hace alrededor de 10 años
|
|
Pregunta 1
Pregunta
Which of the following is most generally false relating to energy?
Respuesta
-
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
Pregunta 2
Pregunta
Which of the following is most generally true relating to energy?
Respuesta
-
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
Pregunta 3
Pregunta
Which of the following best describes why ATP is important in cells?
Respuesta
-
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
Pregunta 4
Pregunta
Which of following is false with respect to enzymes?
Respuesta
-
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
Pregunta 5
Pregunta
Which respect to energy metabolism, which of the following statements is false?
Respuesta
-
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
Pregunta 6
Pregunta
Which of the following statements best describes the process of aerobic respiration?
Respuesta
-
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
Pregunta 7
Pregunta
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?
Respuesta
-
Animalia
-
Eukarya
-
Archaea
-
Fungi
-
Protista
Pregunta 8
Pregunta
What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?
Respuesta
-
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
Pregunta 9
Pregunta
In the cells of some organisms, mitosis occurs without cytokinesis. This will result in:
Respuesta
-
cells with more than one nucleus
-
cell cycles lacking an S phase
-
destruction of chromosomes
-
cells that are unusually small
-
cells lacking nuclei
Pregunta 10
Pregunta
In an analysis of the nucleotide composition of DNA, which of the following will be found?
Respuesta
-
A + C = G + T
-
G + C = T + A
-
A = G and C = T
-
A = C
Pregunta 11
Pregunta
Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication?
Respuesta
-
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
Pregunta 12
Pregunta
A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is
Respuesta
-
3' UGA 5'
-
3' UCA 5'
-
5' TCA 3'
-
3' ACU 5'
-
either UCA or TCA
Pregunta 13
Pregunta
Which of the following is true of fermentation?
Respuesta
-
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
Pregunta 14
Pregunta
Which of the following statements is generally false?
Respuesta
-
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
Pregunta 15
Pregunta
Which of the following is generally true?
Respuesta
-
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
Pregunta 16
Pregunta
Which one of the following statements is false?
Respuesta
-
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
Pregunta 17
Pregunta
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
Respuesta
-
chromatid assembly
-
the formation of the mitotic spindle
-
the S phase of the cell cycle
-
anaphase
-
formation of the centrioles
Pregunta 18
Pregunta
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?
Respuesta
-
cell wall components and DNA
-
chlorophyll and cell walls
-
organelle density and enzymatic activity
-
organelle density and cell walls
-
chlorophyll and DNA
Pregunta 19
Pregunta
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?
Respuesta
-
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
Pregunta 20
Pregunta
Which of the following provides some evidence that RNA probably evolved before DNA?
Respuesta
-
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
Pregunta 21
Pregunta
A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which of the following might this illustrate?
Respuesta
-
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
Pregunta 22
Pregunta
There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the facts that
Respuesta
-
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
Pregunta 23
Pregunta
Which of the following is the first event to take place in translation in eukaryotes?
Respuesta
-
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
Pregunta 24
Pregunta
When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by
Respuesta
-
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
Pregunta 25
Pregunta
Why might a point mutation in DNA make a difference in the level of a protein's activity?
Respuesta
-
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
Pregunta 26
Pregunta
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?
Respuesta
-
eukaryotic tRNAs
-
eukaryotic polymerases
-
a bacterial promotor sequence
-
eukaryotic ribosomal subunits
-
the introns
Pregunta 27
Pregunta
The tryptophan operon is a repressible operon that is
Respuesta
-
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
Pregunta 28
Pregunta
A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in
Respuesta
-
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
Pregunta 29
Pregunta
The lactose operon is likely to be transcribed when
Respuesta
-
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
Pregunta 30
Pregunta
All of the following are part of a prokaryotic cell except
Respuesta
-
a cell wall
-
an endoplasmic reticulum
-
ribosomes
-
a plasma membrane
-
DNA
Pregunta 31
Pregunta
What is the structural feature that allows DNA to replicate?
Respuesta
-
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
Pregunta 32
Pregunta
White blood cells engulf bacteria through what process?
Respuesta
-
osmosis
-
phagocytosis
-
pinocytosis
-
receptor-mediated exocytosis
-
exocytosis
Pregunta 33
Pregunta
Which of the following types of molecules are the major structural components of the cell membrane?
Respuesta
-
phospholipids and cellulose
-
nucleic acids and proteins
-
phospholipids and proteins
-
proteins and cellulose
-
glycoproteins and cholesterol
Pregunta 34
Pregunta
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?
Respuesta
-
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
Pregunta 35
Pregunta
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?
Respuesta
-
8%
-
16%
-
31%
-
42%
-
It cannot be determined from the information provided.
Pregunta 36
Pregunta
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:
Respuesta
-
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
Pregunta 37
Pregunta
What is meant by the description "anti-parallel" regarding the strands that make up DNA?
Respuesta
-
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
Pregunta 38
Pregunta
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?
Respuesta
-
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
Pregunta 39
Pregunta
To repair a thymine dimer by nucleotide excision repair, in which order do the necessary enzymes act?
Respuesta
-
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
Pregunta 40
Pregunta
What is the function of topoisomerase?
Respuesta
-
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
Pregunta 41
Pregunta
In eukaryotes, general transcription factors
Respuesta
-
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
Pregunta 42
Pregunta
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
Respuesta
-
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
Pregunta 43
Pregunta
A principal problem with inserting an unmodified mammalian gene into a BAC, and then getting that gene expressed in bacteria, is that
Respuesta
-
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
Pregunta 44
Pregunta
The reason for using Taq polymerase for PCR is that
Respuesta
-
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
Pregunta 45
Pregunta
What do we mean when we use the terms monohybrid cross and dihybrid cross?
Respuesta
-
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
Pregunta 46
Pregunta
Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties?
Respuesta
-
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
Pregunta 47
Pregunta
Two plants are crossed, resulting in offspring with 3:1 ratio for a particular trait. What does this suggest?
Respuesta
-
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
Pregunta 48
Pregunta
Which of the following would you expect of a eukaryote lacking telomerase?
Respuesta
-
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
Pregunta 49
Pregunta
If cells were unable to produce histone proteins, which of the following would be a likely effect?
Respuesta
-
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
Pregunta 50
Pregunta
Why do histones bind tightly to DNA?
Respuesta
-
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
Pregunta 51
Pregunta
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?
Respuesta
-
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
Pregunta 52
Pregunta
The nitrogenous base adenine is found in all members of which group?
Respuesta
-
proteins, triglycerides, and testosterone
-
proteins, ATP, and DNA
-
ATP, RNA, and DNA
-
a glucose, ATP, and DNA
-
proteins, carbohydrates, and ATP
Pregunta 53
Pregunta
Which of the following statements best describes the termination of transcription in prokaryotes?
Respuesta
-
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
Pregunta 54
Pregunta
Which of the following does not occur in prokaryotic eukaryotic gene expression, but does in eukaryotic gene expression?
Respuesta
-
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
Pregunta 55
Pregunta
Which of the following is a function of a poly-A signal sequence?
Respuesta
-
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
Pregunta 56
Pregunta
In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a globin protein?
Respuesta
-
ligase
-
RNA polymerase I
-
RNA polymerase II
-
RNA polymerase III
-
primase
Pregunta 57
Pregunta
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?
Respuesta
-
0%
-
100%
-
25%
-
50%
-
75%
Pregunta 58
Pregunta
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?
Respuesta
-
epistasis
-
multiple alleles
-
incomplete dominance
-
codominance
-
pleiotropy
Pregunta 59
Pregunta
Which of the following DNA mutations is most likely to be damaging to the protein it specifies?
Respuesta
-
a codon substitution
-
a base-pair deletion
-
a substitution in the last base of a codon
-
a codon deletion
-
a point mutation
Pregunta 60
Pregunta
Lipid soluble hormones
Respuesta
-
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
Pregunta 61
Pregunta
The human mitochondrial genome has approx
Respuesta
-
5000 base pairs
-
6000 base pairs
-
9000 base pairs
-
16,000 base pairs
-
50,000 base pairs
Pregunta 62
Pregunta
Which of the following is most generally true of mitochondrial disorders?
Respuesta
-
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
Pregunta 63
Pregunta
Common clinical features of myopathy do not include
Respuesta
-
ptosis
-
myopathy
-
optic atrophy
-
diabetes mellitus
-
thyroid disease
Pregunta 64
Pregunta
What is the likely inheritance of a disorder that has 2 apparently normal parents, an affected daughter and son, and two healthy sons?
Respuesta
-
autosomal dominant condition
-
autosomal recessive condition
-
sex linked condition
-
new mutation in offspring
-
none of the above
Pregunta 65
Pregunta
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
Respuesta
-
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
Pregunta 66
Pregunta
Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on the specificity in the
Respuesta
-
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
Pregunta 67
Pregunta
There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that
Respuesta
-
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
Pregunta 68
Pregunta
Which of the following is a function of a signal peptide?
Respuesta
-
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
Pregunta 69
Pregunta
The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in
Respuesta
-
a base-pair substitution
-
a nucleotide mismatch
-
a frameshift mutation
-
a polypeptide missing an amino acid
-
a nonsense mutation
Pregunta 70
Pregunta
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?
Respuesta
-
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
Pregunta 71
Pregunta
Graves disease
Respuesta
-
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
Pregunta 72
Pregunta
Tetraploidy is how many sets of chromosomes?
Respuesta
-
one
-
two
-
three
-
four
-
five
Pregunta 73
Pregunta
Downs syndrome is a consequence of
Respuesta
-
trisomoy 5
-
trisomoy 8
-
trisomoy 13
-
trisomoy 15
-
trisomoy 21
Pregunta 74
Pregunta
Osteoporosis is most common in
Respuesta
-
young women
-
older men
-
elderly Maori females
-
elderly Caucasian females
-
elderly with no racial preference
Pregunta 75
Pregunta
Which of these statements is NOT true of genetic disorders?
Respuesta
-
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
Pregunta 76
Pregunta
Which of these is not an X-linked condition?
Respuesta
-
colour blindness
-
Duchenne muscular dystrophy
-
Haemophilia A
-
Haemophilia B
-
Mitochondrial myopathy
Pregunta 77
Pregunta
Which of these statements best describes our knowledge of the accurate inheritance of extranuclear genes?
Respuesta
-
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
Pregunta 78
Pregunta
A lack of which molecule would result in the cell's inability to "turn off" genes?
Respuesta
-
operon
-
inducer
-
promotor
-
ubiquitin
-
co-repressor
Pregunta 79
Pregunta
Which of the following mechanisms is used to coordinate the expression of multiple, related genes in eukaryotic cells?
Respuesta
-
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
Pregunta 80
Pregunta
If you were to observe the activity of methylated DNA, you would expect it to
Respuesta
-
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
Pregunta 81
Pregunta
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?
Respuesta
-
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
Pregunta 82
Pregunta
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?
Respuesta
-
"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
Pregunta 83
Pregunta
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
Respuesta
-
RNA interference
-
RNA obstruction
-
RNA blocking
-
RNA targeting
-
RNA disposal
Pregunta 84
Pregunta
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
Respuesta
-
Duchenne muscular dystrophy
-
Mitochondrial myopathy
-
Graves disease
-
Cushings syndrome
-
Polymyositis (inflammation of muscle
Pregunta 85
Pregunta
Which of the following is NOT an example of a virus promoting cancer?
Respuesta
-
Human papilloma virus
-
Ebstein Barr virus
-
Hepatitis B virus
-
Influenza virus
-
Human T cell lymphotropic virus
Pregunta 86
Pregunta
Which of the following best describes siRNA?
Respuesta
-
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
Pregunta 87
Pregunta
BRCA1 and BRCA2 are considered to be tumor-suppressor genes because
Respuesta
-
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
Pregunta 88
Pregunta
Which of the following statements describes proto-oncogenes?
Respuesta
-
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
Pregunta 89
Pregunta
The cancer-causing forms of the Ras proteins are involved in which of the following processes?
Respuesta
-
cell-cell adhesion
-
cell division
-
relaying a signal from a growth factor receptor
-
DNA replication
-
DNA repair
Pregunta 90
Pregunta
The host range of a virus is determined by
Respuesta
-
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
Pregunta 91
Pregunta
Which of the following statements about the DNA in one of your brain cells is true?
Respuesta
-
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
Pregunta 92
Pregunta
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?
Respuesta
-
1/4
-
1/2
-
c1
-
nil
-
1/3
Pregunta 93
Pregunta
Which of the following is most generally false?
Respuesta
-
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
Pregunta 94
Pregunta
Which of the following is most generally true?
Respuesta
-
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
Pregunta 95
Pregunta
Which of the following is NOT a property of carbon that is important in the context of living systems?
Respuesta
-
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
Pregunta 96
Pregunta
Which of the following molecules is a polymer built from structurally related building blocks?
Respuesta
-
Leucine
-
Adenoside triphosphate
-
A fatty acid
-
Cellulose
-
Cholesterol
Pregunta 97
Pregunta
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?
Respuesta
-
Rabies
-
Herpesvirus
-
Smallpox
-
HIV
-
Hepatitis virus
Pregunta 98
Pregunta
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?
Respuesta
-
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
Pregunta 99
Pregunta
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?
Respuesta
-
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
Pregunta 100
Pregunta
Why do RNA viruses appear to have higher rates of mutation?
Respuesta
-
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
Pregunta 101
Pregunta
Antiviral drugs that have become useful are usually associated with which of the following properties?
Respuesta
-
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
Pregunta 102
Pregunta
What mediates the assembly of new viruses?
Respuesta
-
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
Pregunta 103
Pregunta
How does a bacterial cell protect its own DNA from restriction enzymes?
Respuesta
-
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
Pregunta 104
Pregunta
Which of the following statements about fats is most generally false?
Respuesta
-
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
Pregunta 105
Pregunta
Entropy can be described as
Respuesta
-
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
Pregunta 106
Pregunta
There is no change in Gibbs free energy
Respuesta
-
Within a system that is doing work
-
During glycolysis
-
Within a living organism
-
In a reaction at dynamic equilibrium
-
During the citric acid cycle
Pregunta 107
Pregunta
Which of the following statements is false?
Respuesta
-
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
Pregunta 108
Pregunta
ATP is useful as an energy shuttle because
Respuesta
-
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
Pregunta 109
Pregunta
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
Respuesta
-
Inhibitors binding to the active site
-
Cooperatively between protein subunits
-
Inhibitors binding to an allosteric site
-
Feedback inhibition
-
Activators binding to the active site
Pregunta 110
Pregunta
The main provider of energy to drive ecosystems on earth is
Respuesta
-
Oxygen
-
ATP
-
Light
-
Pyruvatc
-
Glucose
Pregunta 111
Pregunta
Fermentation does not
Respuesta
-
Couple with glycolysis
-
Produce ATP
-
Consume pyruvate
-
Use the electron transport chain
-
Use NADH/NAD+
Pregunta 112
Pregunta
A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using
Respuesta
-
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
Pregunta 113
Pregunta
Which of the following is used to make complementary DNA (cDNA) from RNA?
Respuesta
-
restriction enzymes
-
gene cloning
-
DNA ligase
-
gel electrophoresis
-
reverse transcriptase
Pregunta 114
Pregunta
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
Respuesta
-
2, 1, 4
-
1, 3, 2, 4
-
3, 4, 1, 2
-
3, 4, 2
-
2, 3, 4
Pregunta 115
Pregunta
DNA microarrays have made a huge impact on genomic studies because they
Respuesta
-
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
Pregunta 116
Pregunta
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:
Respuesta
-
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
Pregunta 117
Pregunta
Glycolysis in eukaryotes
Respuesta
-
Occurs only when oxygen is present
-
Takes place in mitochondria
-
Generates energy at every step
-
Generates NADH
-
Produces lactate
Pregunta 118
Pregunta
The citric acid cycle in eukaryotes
Respuesta
-
Uses citrate from glycolysis
-
Produces acetyl CoA
-
Is a cytosolic process
-
Forms CO2
-
Consumes NADH
Pregunta 119
Pregunta
During oxidative phosphorylation
Respuesta
-
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
Pregunta 120
Pregunta
Fermentation does not
Respuesta
-
Use an electron transport chain
-
Produce CO2
-
Consume pyruvate
-
Consume O2
-
Occur in the cytosol
¿Quieres crear tus propios Tests gratis con GoConqr? Más información.