AP Biology Unit 6 Progress Check MCQ

Which of the following claims about the TYR, TRP2, and TRP1 mammalian genes is most likely to be accurate?

Which of the following claims about the TYR, TRP2, and TRP1 mammalian genes is most likely to be accurate?

A. The TYR, TRP2, and TRP1 genes are located next to each other on a single chromosome and are organized into an operon.

B The TYR, TRP2, and TRP1 genes may be located on different chromosomes but are activated by the same transcription factor.

C The TYR, TRP2, and TRP1 genes are identical genes since they are activated by the same transcription factor.

D The TYR, TRP2, and TRP1 genes may be located on different chromosomes but with identical operator sequences.

B

Which of the following claims best explains why keratinocytes do not produce melanin?

Responses

A. Keratinocytes do not contain the TYR, TRP2, and TRP1 genes.

B Keratinocytes do not contain the MC1R gene.

C Keratinocytes do not express the MITF gene.

D Keratinocytes do not express the POMC gene.

C

Which of the following pieces of evidence would best support the researchers' claim above?

A When researchers applied a drug that activates adenylyl cyclase to the mutant mice's ears, the level of melanin increased.

B When researchers viewed sections of mutant mouse ears under the microscope, they found melanocyte numbers comparable to nonmutant mice.

C When researchers exposed the mutant mice to UV radiation, the amount of POMC mRNA in keratinocytes did not change.

D When researchers exposed the mutant mice to UV radiation, the level of melanin production did not change.

A

Based on the information provided in Figure 1 and Figure 2, which of the following best explains the effects of a mutation in the promoter of the TYR gene that prevents it from being transcribed?

Responses

A DNA damage due to UV radiation will be strongly inhibited, resulting in a positive selection pressure.

B DNA damage due to UV radiation will be strongly inhibited, resulting in a negative selection pressure.

C Skin pigmentation will not be able to change, resulting in a positive selection pressure.

DSkin pigmentation will not be able to change, resulting in a negative selection pressure.

D

Which of the following best explains a process occurring between point 1 and point 2 in Figure 3 ?

Responses

a. α-MSH is produced.

b The TYR gene is transcribed.

c Polypeptides are removed from a protein.

d A poly‑A tail is added to RNA.

D

Which of the following best predicts the phenotype of an individual who is homozygous for this TYR mutation?

Responses

The mutation will cause a single amino acid change in the TYR protein, which will not be enough to disrupt its function. Therefore, those with this mutation will produce melanin in the hair, skin, and eyes and tan in response to UV radiation.

The mutation will cause a single amino acid change in the TYR protein, leading to a nonfunctional TYR protein. Therefore, those with this mutation will lack melanin in the hair, skin, and eyes and will not tan in response to UV radiation.

The mutation will change all subsequent amino acids in the TYR protein, leading to nonfunctional TYR protein. Since the TRP1 and TRP2 genes were not affected, the TRP1 and TRP2 proteins will fill the role of the TYR protein. Therefore, those with this mutation will produce melanin in the hair, skin, and eyes in response to UV radiation.

The mutation will change all subsequent amino acids in the TYR protein, leading to nonfunctional TYR protein. Individuals with this mutation will lack melanin in their hair, skin, and eyes and will not tan in response to UV radiation.

D

Which of the following statements best explains the experimental results observed in Figure 1 ?

Responses

a E. coli in both lanes B and C have been successfully transformed and contain additional genetic information.

b E. coli in lane B have been successfully transformed and contain additional genetic information.

c E. coli in lane C have been successfully transformed and contain additional genetic information.

d Which E. coli have been transformed cannot be determined from this gel.

C

Which of the following best explains how the pattern of DNA arrangement in chromosomes could be used, in most cases, to determine if an organism was a prokaryote or a eukaryote?

(C)Prokaryotic DNA - Single circular chromosome

Eukaryotic DNA - Multiple linear chromosomes

Lynch syndrome is an inherited condition associated with an increased risk for colon cancer, as well as certain other cancers. Mutations in one of several genes involved in DNA repair during DNA replication have been associated with Lynch syndrome. DNA sequencing was performed for an individual. The results indicated that the individual carries one of the dominant alleles that has been associated with Lynch syndrome.

Which of the following best explains how the results should be interpreted?

Responses

A The individual does not have an increased risk of developing cancer because one dominant allele is insufficient to cause the disease.

B The individual has an increased risk of developing colon cancer.

C Because the person's DNA has the mutation, other family members must have cancer.

D Results cannot be interpreted until testing determines if additional mutated alleles are present.

B

Given the results shown in Figure 1, which of the following correctly describes a relationship between the two species?

Responses

Species B is the ancestor of species A because it has fewer bands.

Species A is more complex than species B because it has more bands.

Species B has more short fragments of DNA than species A does.

Species A has more short fragments of DNA than species B does.

C

Which of the following best helps explain how the process represented in Figure 1 produces DNA molecules that are hybrids of the original and the newly synthesized strands?

Responses

A Each template strand is broken down into nucleotides, which are then used to synthesize both strands of a new DNA molecule.

B Each template strand is broken into multiple fragments, which are randomly assembled into two different DNA molecules.

C Each newly synthesized strand is associated with another newly synthesized strand to form a new D N A molecule.

D Each newly synthesized strand remains associated with its template strand to form two copies of the original DNA molecule.

D

Which of the following graphs best predicts the data collected during the experiment?

D. Up, Medium, Up (GRAPH)

Retroviruses such as HIV and hepatitis B virus use RNA as their genetic material rather than DNA. In addition, they contain molecules of reverse transcriptase, an enzyme that uses an RNA template to synthesize complementary DNA.

Which of the following best predicts what will happen when a normal cell is exposed to a retrovirus?

Responses

A The reverse transcriptase will cut the host DNA into fragments, destroying the host cell.

B The reverse transcriptase will insert the viral RNA into the host's genome so it can be transcribed and translated.

C The reverse transcriptase will produce DNA from the viral RNA, which can be incorporated into the host's genome and then transcribed and translated.

D The reverse transcriptase will force the host ribosomes to translate the viral RNA prior to polypeptide assembly.

C

Which of the following statements best explains what is shown in Figure 1 ?

Responses

a UV exposure triggers DNA replication, which results in rapid cell proliferation.

b Naturally occurring dimers are removed by the UV photons, causing misshapen DNA, which results in replication errors.

c The hydrogen bonds between base pairs absorb the UV photons, separating the two DNA strands, which results in rapid DNA replication.

d UV photons cause dimers to form, leading to misshapen DNA, which results in replication and transcription errors.

D

Which of the following evidence best supports a claim that tryptophan functions as a corepressor?

Responses

a Normal expression of trpR causes the trp operon to be transcribed regardless of tryptophan levels.

b When the operator sequence is mutated, the trp operon is not transcribed.

c The trpR gene codes for a repressor protein that has a DNA binding domain.

d When trpR is mutated, the trp operon is transcribed regardless of tryptophan levels.

D

A cell needs to metabolize the substrate illustrated in Figure 1 for a vital cellular function. Which of the following best explains the long-term effect on the cell of splicing that yields only enzyme C mRNA?

Responses

A The cell will die because it is unable to metabolize the substrate without enzyme A, which is structurally specific for the substrate shown.

B The cell will remain healthy because all three of the above enzymes can metabolize the substrate, as they are from the same gene.

C the cell will remain healthy because the enzyme C mRNA will undergo alternative splicing again until it transformed into enzyme A mRNA.

D The cell will remain healthy because enzyme-substrate interactions are nonspecific and enzyme C will eventually metabolize the substrate.

A

Which of the following statements best explains the role of Enzyme 1 in the DNA replication process?

Responses

A Enzyme 1 is a DNA ligase that joins together the DNA fragments at a replication fork to form continuous strands.

B Enzyme 1 is a DNA primase that catalyzes the synthesis of RNA primers on the lagging strand of a replication fork.

C Enzyme 1 is a DNA polymerase that synthesizes new DNA by using the leading and lagging strands of a replication fork as templates.

D Enzyme 1 is a topoisomerase that relieves tension in the overwound DNA in front of a replication fork.

B

Small single-stranded RNA molecules called microRNAs (miRNAs) are capable of base pairing with specific binding sites in the 3′ untranslated region of many mRNA transcripts. Transcription of gene Q yields an mRNA transcript that contains such an miRNA binding site, which can associate with miRNA‑delta, a specific miRNA molecule.

Which of the following best supports the claim that binding of miRNA‑delta to the miRNA binding site inhibits translation of gene Q mRNA?

Responses

A When the promoter for gene Q is altered, transcription is inhibited.

B Translation of Q mRNA is inhibited regardless of whether the miRNA binding site sequence is altered.

C Translation of Q mRNA is inhibited in the absence of miRNA‑delta.

D When the miRNA binding site sequence is altered, translation of Q mRNA occurs in the presence of miRNA-delta.

D

All cells must transcribe rRNA in order to construct a functioning ribosome. Scientists have isolated and identified rRNA genes that contribute to ribosomal structure for both prokaryotes and eukaryotes. Figure 1 compares the transcription and processing of prokaryotic and eukaryotic rRNA.

Figure 1. Comparison of rRNA processing in prokaryotes and eukaryotes

Which of the following statements provides the best explanation of the processes illustrated in Figure 1 ?

Responses

A Introns are removed from the pre-rRNA, and the mature rRNA molecules are joined and then translated to produce the protein portion of the ribosome.

B Introns are removed from the pre-rRNA, and each mature rRNA molecule is translated to produce the proteins that make up the ribosomal subunits.

C Sections of the pre-rRNA are removed, and the mature rRNA molecules are available to combine with proteins to form the ribosomal subunits.

D Sections of the pre-rRNA are removed, and the mature rRNA molecules are available to bring different amino acids to the ribosome.

C

Huntington's disease, an autosomal dominant disorder, is caused by a mutation in the HTT gene. The HTT gene contains multiple repeats of the nucleotide sequence CAG. A person with fewer than 35 CAG repeats in the HTT gene is unlikely to show the neurological symptoms of Huntington's disease. A person with 40 or more CAG repeats almost always becomes symptomatic. Due to errors in meiosis, an individual without symptoms of Huntington's disease can produce gametes with a larger number of CAG repeats than there are in their somatic cells.

A woman develops Huntington's disease. Her father had the disorder. Her mother did not, and there is no history of the disorder in the mother's family. Which of the following best explains how the woman inherited Huntington's disease?

Responses

A She inherited an allele with fewer than 40 CAG repeats in the HTT gene because her mother did not have Huntington's disease.

B She inherited an allele with more than 40 CAG repeats in the HTT gene from her father.

C Her mother produced eggs that all have more than 40 repeats in the HTT gene.

D Her mother produced eggs that all have fewer than 40 CAG repeats in the HTT gene.

B

Which of the following best explains how this model illustrates DNA replication of both strands as a replication fork moves?

Responses

A I and IV are synthesized continuously in the 5′ to 3′ direction.

B II and III are synthesized in segments in the 3' to 5' direction.

C I is synthesized continuously in the 5′ to 3′ direction, and III is synthesized in segments in the 5′ to 3′ direction.

D II is synthesized in segments after DNA polymerase is released from synthesizing strand IV.

C

Which claim is most consistent with the information provided by the diagram and current scientific understanding of gene regulation and expression?

Responses

A Reversible changes in the DNA sequence may influence how a gene is expressed in a cell.

B Some sequences of DNA can interact with regulatory proteins that control transcription.

C This is an inducible operon controlled by several regulatory factors.

D The transcription factor may produce mutations in the binding site at the promoter sequence inhibiting the synthesis of the protein.

B

Cystic fibrosis (CF) is a progressive genetic disease that causes persistent lung infections and affects the ability to breathe. CF is inherited in an autosomal recessive manner, caused by the presence of mutations in both copies of the gene for the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Partial nucleotide sequences and the corresponding amino acid sequences for an unaffected individual and an affected individual are modeled in Figure 1.

Figure 1. CFTR protein sequences in unaffected and affected individuals

Based on the information in Figure 1, which type of mutation explains the nature of the change in DNA that resulted in cystic fibrosis in the affected individual?

Responses

A Substitution, because the amino acid tryptophan is replaced with glycine.

B Insertion, because an extra guanine is present, which changes the reading frame.

C Deletion, because a thymine is missing, which changes the reading frame.

.

D Duplication, because the amino acid leucine occurs twice, which changes the reading frame.

C

Nucleotide base pairing in DNA is universal across organisms. Each pair (T−A; C−G) consists of a purine and a pyrimidine. Which of the following best explains how the base pairs form?

Responses

A Ionic bonds join two double-ringed structures in each pair.

B Hydrogen bonds join two single-ringed structures in each pair.

C Hydrogen bonds join a double-ringed structure to a single-ringed structure in each pair.

D Covalent bonds join a double-ringed structure to a single-ringed structure in each pair.

C