Bio Study Exam

An unbarred male heterozygous for the rose-comb trait is crossed with a barred female with a single comb. What proportion of the resulting progeny are expected to be barred males with single combs?

.25

A true breeding female with wild type wings and white eyes is crossed with a male with vestigial wings and red eyes. What proportion of the offspring are expected to be males with wild-type wings and white eyes?

.50

Calculate the number of nucleotides in the mRNA that encode only the amino acids in the transmembrane portion of the protein.

72 nucleotides.

The unknown molecule should be classified as which type of molecule?

D) A nucleic acid

Based on the information above, which of the following mutations is the most likely cause of sickle-cell anemia?

A) A single base-pair substitution in the gene encoding the beta-subunit

HBB gene...such a mutation would most likely result in altered

A) All properties of the molecule as a result of abnormal interactions between adjacent hemoglobin molecules

Which of the following is the most likely outcome of replacing the lacZ gene in the E. coli lac operon with the gene encoding GFP?

A) Bacteria growing in the presence of lactose will fluoresce under ultraviolet light.

Based on the data in Table 1, which of the following best explains why there are no individuals with constricted pods in the F1 generation?

A) Inflated pod shape is dominant to constricted pod shape

GULO gene in lemurs...which of the following pairs of predictions is most helpful in explaining the discrepancy?

A) [No change to the protein | A premature stop codon..]

Which of the following is the most likely consequence of a mutation at the operator locus that prevents binding of the repressor protein?

B) Beta-galactosidase will be produces, even in the absence of lactose

Which of the following best describes how sticklebacks in the same population with identical copies of the Pitx1 genes can still show phenotypic variation in the pelvic spine character?

B) Expression of the Pitx1 gene is affected by mutations at other genetic loci.

The Trp operon...based on the figure above, which of the following correctly describes the regulation of the Trp operon?

B) 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 biotechnology approaches could be used to identify ferritin mRNA in a sample of total cellular RNA?

B) RNA samples could be separated by size using agarose gel electrophoresis and incubated with labeled single-stranded DNA molecules that are complementary to the ferritin mRNA.

Which of the following best describes the structure of the viral genome?

B) Single-stranded DNA

Which of the following is the most likely effect of the mutation at nucleotide position 7 in the GULO gene of humans?

B) The deletion of the single nucleotide causes a frame shift, changing the primary structure downstream of the mutation and resulting in a nonfunctional protein.

In Drosophila melanogaster the allele for wild-type tan body color (B) is dominant...which of the following best explains the observed results of the cross?

B) The genes for body color and wing shape are located close to each other on the same chromosome.

Which of the following provides the best justification for an assumption that might have been used in the computer simulation?

B) The purple allele is dominant to the white allele because all the offspring from the cross of the purple-flowered and white-flowered plants had purple flowers.

Which of the following best explains how organisms regulate ferritin protein levels in response to available iron?

B) Translation of ferritin mRNA is stimulated by iron.

All of the following are likely steps that would lead to the production of these gel patterns EXCEPT

B) Using a different restriction enzyme to treat the DNA of each individual

Which of the following best represents the DNA of the two daughter cells produced when a bacterial cell with this particular mismatch replicates its DNA and divides?

B) [A,T mutant; G,C normal]

Which of the following describes a metabolic consequence of a shortage of oxygen in muscle cells?

C) A buildup of lactic acid in the muscle tissue due to fermentation

Which of the following describes the most likely consequence of a negative feedback pathway involving the lac operon?

C) Expression of the lac operon diminishes as lactose is depleted

The pedigree suggests that the gene is on a nuclear chromosome, and not on mitochondrial DNA, because

C) Maternal mitochondrial mutations are inherited by all of a mother's offspring.

Which of the following represents the correct polypeptide...

C) Met-Val-Thr-Lys-Phe-Gly-His

In Table 1, the ratio of phenotypes in the offspring from the testcross with F1 plants that had purple flowers and inflated pods suggests that the genes for flower color and pod shape are located

C) On a different chromosome

Which of the following is one way in which these two segments would differ?

C) Segment 1 would become denatured at a lower temperature than would segment 2 because A-T base pairs have two hydrogen bonds whereas G-C base pairs have three

Based on the diagram, which of the following most likely contributes to the specific expression pattern of gene X?

C) The activator is a sequence-specific DNA-binding protein that is present in some tissues but not in other

The banding patterns of the DNA fragments reveal that

C) The mother cannot be the biological parent of all three children

Which statement would scientists from the 1930s cite as the strongest evidence that proteins...

D) DNA is made up of four different types of nucleotides, whereas proteins are made up of 20 different types of amino acids, enabling proteins to create many more chemical messengers than DNA can.

The tertiary structure and function of a polypeptide is principally determined by the

D) Interactions between amino acids present in the polypeptide

Which of the following best describes an even during step 2 in the simplified model below?

D) Noncoding sequences are removed from a newly synthesized RNA molecule.

A mutation that affects Pitx1 gene function in all tissue types is most likely to be at which of the following genetic loci?

D) Promoter

Which of the following represents a cross between a white-eyed female and a red-eyed male?

D) Rr XtXt * Rr XtY

The data above represents the results of three different crosses...which of the following best explains the mechanism of inheritance of the gene?

D) The allele for blue is an X-linked dominant allele because there are no blue male offspring in cross 2.

In sticklebacks, which of the following is most likely to occur if the jaw enhancer is disabled instead of the hindlimb enhancer?

D) 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.

Which of the following best explains the contribution of the lac operon to the metabolic efficiency of a bacterial cell?

D) The lacZ gene is highly expressed only when lactose is available.

Given the codon chart...what would be the effect of a mutation that deletes the G at the beginning of the DNA sequence?

D) The reading frame of the sequence would shift, causing a change in the amino acid sequence after that point.

Which of the following figures most accurately illustrates enzyme-mediated synthesis of new DNA at a replication fork?

D) [Oyazaki fragments going left along 5-->3, straight arrow going right along 3-->5]

Which of the figures correctly depicts the interactions at the lac operon when lactose is NOT being utilized?

D) [Promoter | Operator (repressor protein) | Structural Genes]