Q3 Test Bio
(A) Transcription (B) Translation (C) Transformation (D) Replication (E) Reverse transcription Process in which a protein is assembled at a ribosome
B
(A) Transcription (B) Translation (C) Transformation (D) Replication (E) Reverse transcription Process in which naked DNA is taken up by a bacterial or yeast cell
C
The phenotypic variation in behavior between the two populations can best be described as resulting from
artificial selection
In Darwinian terms, the fittest individuals of a species are those that
leave the greatest number of reproducing descendants
Evolutionary fitness is measured by
reproductive success
When DNA replicates, each strand of the original DNA molecule is used as a template for the synthesis of a second, complementary strand. Which of the following figures most accurately illustrates enzyme-mediated synthesis of new DNA at a replication fork?
3' to 5' direction
The diagram above represents a segment of the E. coli chromosome that contains the lacI gene and part of the lac operon, a coordinately regulated set of genes that are required for the metabolism of lactose. The presence of lactose, which causes the repressor to be released from the operator, results in increased transcription of the lac operon.
Bacteria growing in the presence of lactose will fluoresce under ultraviolet light.
Which of the following is the most likely consequence of a mutation at the operator locus that prevents binding of the repressor protein?
Beta-galactosidase will be produced, even in the absence of lactose.
A resonable conclusion to draw from the results of the experiment is that
DNA is the genetic material
Which of the following correctly explains where DNA replication will begin on the strand oriented 5′→3′, reading from left to right?
DNA replication will be initiated immediately to the left of the RNA, since DNA polymerase requires an RNA primer.
An answer to which of the following questions would provide the most information about the association between the CFTR mutation and the viscous mucus? Responses
How does the disrupted chloride movement affect the movement of sodium ions and water by the cell?
Plates that have only ampicillin-resistant bacteria growing include which of the following?
IV only
Samples of DNA were isolated from four different individuals and each sample was digested by the same restriction enzymes. Gel electrophoresis was used to separate the resulting DNA fragments and the results are shown above. These data best support which of the following hypotheses?
Individual 2 is the offspring of 1 and 3.
Based on the information given, which of the following is a plausible explanation for the ancestry of the tortoise subspecies?
Individuals with different adaptations in shell shape and leg length best exploited the food resources and left more surviving offspring on each island.
Which of the following correctly explains the process shown in Figure 1 ?
Initiation of transcription is occurring because a strand of RNA is being produced from a DNA template strand.
The claim that gene regulation results in differential gene expression and influences cellular products (albumin or crystalline) is best supported by evidence in which of the following statements?
Liver cells possess transcriptional activators that are different from those of lens cells.
Which of the following best explains the distribution of lactase persistence in the areas shown in Figure 1 ?
Mutations conferring lactase persistence likely arose independently in different geographic areas and offered a selective advantage.
Which of the following best describes an event during step 2 in the simplified model above?
Noncoding sequences are removed from a newly synthesized RNA molecule.
Which of the following best explains the changes in the phenotype frequencies of the stickleback population in Loberg Lake?
Predation in the marine environment is different from predation in Loberg Lake.
A mutation that affects Pitx1 gene function in all tissue types is most likely to be at which of the following genetic loci?
Promoter
As represented in Figure 1 and Figure 2, the phenotypic difference between marine and freshwater sticklebacks involves Pitx1, a gene that influences the formation of the jaw, pituitary gland, and pelvic spine. Enhancer sequences upstream of the Pitx1 genetic locus regulate expression of the Pitx1 gene at the appropriate times and in the appropriate tissues during development. Previous studies have found that a mutation in the hindlimb enhancer interferes with the formation of a pronounced pelvic spine.
Reduced pelvic spines increase the likelihood of escaping predators in freshwater environments.
Freshwater bony fish secrete large volumes of very dilute urine. Many marine bony fish secrete small volumes of concentrated urine. Which of the following best explains the differences in nitrogenous-waste excretion between freshwater and marine bony fish?
The differences arose during divergence, as fish from a common ancestor faced different selective pressures in environments of different osmolarity.
Which of the following could best explain the change in fur color distribution, as shown in the table above?
The field was primarily composed of light-colored soil and little vegetation, affording gray mice protection from predators.
In sticklebacks, which of the following is most likely to occur if the jaw enhancer is disabled instead of the hindlimb enhancer?
The jaw does not develop normally, but a pronounced pelvic spine does develop because the Pitx1 gene is expressed in the developing pelvis but not in the developing jaw.
The diagram above represents a segment of the E. coli chromosome that contains the lacI gene and part of the lac operon, a coordinately regulated set of genes that are required for the metabolism of lactose. The presence of lactose, which causes the repressor to be released from the operator, results in increased transcription of the lac operon.
The lacZ gene is highly expressed only when lactose is available.
To evaluate the reliability of the results, it would be best to know which of the following?
The number of males in each sample
The features of this model provide evidence for which explanation of why all growing strands are synthesized in a 5′ to 3′ direction?
The phosphate group, attached to the 5′ carbon of the dTMP, forms a covalent bond with the oxygen atom attached to the 3′ carbon of the growing strand.
Which of the following best explains how the expression of a eukaryotic gene encoding a protein will differ if the gene is expressed in a prokaryotic cell instead of in a eukaryotic cell?
The protein will be made but will not function, because prokaryotes cannot remove introns.
What was the purpose of treating the extract with protein-degrading enzymes in Procedure II ?
To demonstrate that the transforming factor is not a protein
Which of the following best explains why the brown-feathered phenotype in tawny owls has increased over the past 28 years?
With milder winters, the advantage of gray feathers that blend into a snowy environment has decreased.
(A) Transcription (B) Translation (C) Transformation (D) Replication (E) Reverse transcription Process in which RNA is produced by using a DNA template
A
Which of the following best describes how sticklebacks in the same population with identical copies of the Pitx1 gene can still show phenotypic variation in the pelvic spine character?
Expression of the Pitx1 gene is affected by mutations at other genetic loci.
Which of the following describes the most likely consequence of a negative feedback pathway involving the lac operon?
Expression of the lac operon diminishes as lactose is depleted.
In a transformation experiment, a sample of E. coli bacteria was mixed with a plasmid containing the gene for resistance to the antibiotic ampicillin (ampr). Plasmid was not added to a second sample. Samples were plated on nutrient agar plates, some of which were supplemented with the antibiotic ampicillin. The results of E. coli growth are summarized below. The shaded area represents extensive growth of bacteria; dots represent individual colonies of bacteria.
IV only
The Trp operon is a coordinately regulated group of genes (trpA-trpE) that are required for tryptophan biosynthesis in E. coli. Based on the figure above, which of the following correctly describes the regulation of the Trp operon?
In the presence of tryptophan, the repressor is active and binds to the Trp operator, preventing RNA polymerase from transcribing the operon.
Which of the following best explains how the prokaryotic expression of a metabolic protein can be regulated when the protein is already present at a high concentration?
Repressor proteins can be activated and bind to regulatory sequences to block transcription.
Which of the following statements best explains the data set?
Since the %A and the %T are approximately the same in each sample, adenine and thymine molecules must pair up in a double-stranded DNA molecule.
Figure 2. Mean survival ±2���¯ following different times in ARD. Individual C. elegans were held in ARD and subsequently given access to food, whereupon their survival times were determined.
The ability to enter ARD provides a strong selective advantage because reproduction can occur despite periods of food scarcity.
What was the purpose of treating the extract with DNAse in Procedure III ?
To serve as a negative control by demonstrating that transformation does not occur without DNA
In the late 1980s, sticklebacks from a marine population colonized Loberg Lake, a freshwater lake in Alaska. Starting in 1990, researchers sampled fish from the lake every four years and recorded the armor-plate phenotypes of the male sticklebacks in each sample. The armor-plate phenotypes were categorized as either complete (plates extending from head to tail), partial (plates extending from head to abdomen), or low (a few plates near the head only). The results are shown in the table below.
Year in which the sample was collected
tRNA molecules deliver amino acids to ribosomes where the amino acid next
is covalently bonded to a growing polypeptide
Which of the following figures correctly depicts the interactions at the lac operon when lactose is NOT being utilized? (The legend below defines the shapes of the molecules illustrated in the options.)
represser protein binded to operator region
Maximal transcription of the lac operon requires
the presence of cyclic AMP and lactose