AP Bio Unit 6 MCQs-Porter Test

3. 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. Plates that have only ampicillin-resistant bacteria growing include which of the following?

IV only

25. For following group of questions first study the description of the situation or data and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet. The diagram below illustrates the results of electrophoresis of DNA sequences obtained from a family of two adults and three children, and amplified using PCR. The bands represent short repeating sequences of variable length. Results for another female (X) are included for comparison. The banding patterns of the DNA fragments reveal that

the mother cannot be the biological parent of all three children

4. A scientist is using an ampicillin-sensitive strain of bacteria that cannot use lactose because it has a nonfunctional gene in the lac operon. She has two plasmids. One contains a functional copy of the affected gene of the lac operon, and the other contains the gene for ampicillin resistance. Using restrictions enzymes and DNA ligase, she forms a recombinant plasmid containing both genes. She then adds a high concentration of the plasmid to a tube of the bacteria in a medium for bacterial growth that contains glucose as the only energy source. This tube (+) and a control tube (-) with similar bacteria but no plasmid are both incubated under the appropriate conditions for growth and plasmid uptake. If no new mutations occur, it would be most reasonable to expect bacterial growth on which of the following plates?

1, 2, 3, and 4 only

17. The processes illustrated in the models depicted above all result in which of the following?

An increase in genetic variation

39. Which of the following best describes the most likely impact on an individual produced from fertilization between one of the daughter cells shown and a normal gamete?

Because nondisjunction occurred in anaphase I, all gametes will have an abnormal chromosome number and the individual will likely exhibit phenotypic evidence of the nondisjunction event.

30. Protoporphyria is a genetic disorder characterized by an extreme sensitivity to sunlight. One form of protoporphyria is caused by a mutation in the ALAS2 gene that results in the accumulation of protoporphyrin, an organic compound, in the blood, liver, and skin. The pedigree in Figure 1 shows the incidence of protoporphyria in a particular family. A researcher claims that an individual has protoporphyria, based on a physical exam. Which of the following techniques would most likely confirm the researcher's claim?

Determining the nucleotide sequence of the individual's ALAS2 alleles

53. Which of the following scientific claims is most consistent with the information provided in Figure 1 ?

Different genes may be regulated by the same transcription factor.

60. Nuclear pores regulate the passage of substances into and out of the nucleus. Antibodies such as mAb414 have been used to inhibit the movement of substances through the nuclear pores of rat liver cells. Scientists cultured rat liver cells (eukaryotic) and bacteria cells (prokaryotic) in separate dishes with radioactively labeled amino acids. A specific gene in both cell types was engineered to synthesize identical polypeptide chains, and translation of this gene was measured. The procedure was repeated with mAb414 (the inhibitor) added to each of the two cell cultures, and translation was monitored again. Which of the following sets of graphs best summarizes the results of the experiments?

Experimental has prokaryotic cell increasing and eukaryotic constant.

22. Investigators studied the interactions between two different proteins, protein I and protein II. Each protein has two structural domains (Figure 1) that represent different functional parts of the protein. Different combinations of the protein domains were tested for their ability to bind to a known DNA sequence, interact with each other, and activate transcription. The results are shown in Table 1. Which of the following best models the interaction of protein I and protein II that results in the transcription of target genes?

G F connected to M L

54. Based on the codon chart above, which of the following amino acid changes is most likely found in the mutated protein?

Glu --> Val

16. Cystic fibrosis is a recessively inherited disorder that results from a mutation in the gene encoding CFTR chloride ion channels located on the surface of many epithelial cells. As shown in the figure, the mutation prevents the normal movement of chloride ions from the cytosol of the cell to the extracellular fluid. As a consequence of the mutation, the mucus layer that is normally present on the surface of the cells becomes exceptionally dehydrated and viscous. An answer to which of the following questions would provide the most information about the association between the CFTR mutation and the viscous mucus?

How does the disrupted chloride movement affect the movement of sodium ions and water by the cell?

1. 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. Plates that have only ampicillin-resistant bacteria growing include which of the following?

IV only

46. 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.

28. 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.

9. Which of the following statements best describes the results seen in Figure 2?

Individuals III-2 and III-3 carry two different alleles of the FXN gene, a mutant allele and a wild-type allele. Individual IV-1 inherited two copies of the mutant allele.

34. Both liver cells and lens cells have the genes for making the proteins albumin and crystalline. However, only liver cells express the blood protein albumin and only lens cells express crystalline, the main protein in the lens of the eye. Both of these genes have enhancer sequences associated with them. 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.

20. 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?

Multiple arrows pointing up towards 5'

15. A model of a process involving nucleic acids is shown in Figure 1. Figure 1. Model of a process involving nucleic acids Which of the following best explains what process is represented in Figure 1 ?

New DNA strands are being synthesized in the 5′ to 3′ direction from their DNA templates.

50. Which of the following best illustrates the flow of information required for the synthesis of proteins encoded in the genome of a retrovirus?

RNA --> DNA --> RNA --> Protein

40. Researchers studying new viruses analyzed the genetic material found in four different virus samples to determine the percent nitrogen base composition of each virus. The data are shown in the table. Which of the following samples most likely contains a double-stranded RNA virus?

Sample 1

10. Erwin Chargaff investigated the nucleotide composition of DNA. He analyzed DNA from various organisms and measured the relative amounts of adenine (A), guanine (G), cytosine (C), and thymine (T) present in the DNA of each organism. Table 1 contains a selected data set of his results. 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.

42. PCR is a technique used to copy a target DNA sequence. Researchers often use DNA polymerase from Thermus aquaticus, a bacteria species that lives around hydrothermal vents. Which of the following best explains why the polymerase from the species T. aquaticus is often used for PCR?

T. aquaticus polymerase does not denature at high temperatures.

51. Figure 1 represents part of a process that occurs in eukaryotic cells. There are untranslated regions (UTR) in this sequence. Which of the following best explains the process represented by Figure 1 ?

The enzyme-regulated processing of pre‑mRNA into mature mRNA

23. Figure 1. A karyotype obtained from a sample of human cells A karyotype is a representation of all the metaphase chromosomes in a sample of cells from a particular individual (Figure 1). Which of the following most likely explains how the chromosomes circled in Figure 1 could cause a genetic disorder in the person from whom the cells were obtained?

The extra chromosome will affect the levels of RNA transcribed from certain genes and the amount of protein produced from those genes in each cell.

2. 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. Which of the following best explains why there is no growth on plate II?

The initial E. coli culture was not ampicillin-resistant.

38. 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?

The one that goes A T G C

32. Lactose digestion in E. coli begins with its hydrolysis by the enzyme β-galactosidase. The gene encoding β-galactosidase, lacZ, is part of a coordinately regulated operon containing other genes required for lactose utilization. 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.)

The one where its just the repressor protein

33. Lactose digestion in E. coli begins with its hydrolysis by the enzyme β-galactosidase. The gene encoding β-galactosidase, lacZ, is part of a coordinately regulated operon containing other genes required for lactose utilization. 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.)

The one with just the repressor protein

8. If a gene that encodes a green fluorescent protein (GFP) is substituted for the structural genes of the operon, activation of the regulatory sequences can be assayed by GFP expression. A culture of E. coli cells underwent a transformation procedure with a plasmid containing the regulatory sequences of the ara operon directly upstream of the gene encoding the GFP. The plasmid also confers ampicillin resistance to bacteria. Samples were then plated on different types of culture media. (Note: The GFP fluoresces only under UV light, not under white light.) The table below shows the results. Which of the following can best be used to justify why the GFP is expressed by E. coli cells after transformation with the plasmid?

The presence of arabinose in the nutrient agar activated the expression of the genes located downstream of the ara operon regulatory sequences.

29. 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.

7. Arsenic is a toxic element found in both aquatic and terrestrial environments. Scientists have found genes that allow bacteria to remove arsenic from their cytoplasm. Arsenic enters cells as arsenate that must be converted to arsenite to leave cells. Figure 1 provides a summary of the arsenic resistance genes found in the operons of three different bacteria. E. coli R773 is found in environments with low arsenic levels. Herminiimonas arsenicoxydans and Ochrobactrum tritici are both found in arsenic‑rich environments. Researchers claim that bacteria that live in environments heavily contaminated with arsenic are more efficient at processing arsenic into arsenite and removing this toxin from their cells. Justify this claim based on the evidence shown in Figure 1.

There are multiple operons controlling the production of proteins that process and remove arsenite from cells in both H. arsenicoxydans and O. tritici. In contrast, E. coli has only one operon devoted to arsenic removal.

43. Phytochromes are molecules that change light stimuli into chemical signals, and they are thought to target light-activated genes in plants. A study was conducted to determine how certain cell proteins were made in a plant cell using a phytochrome. Figures 1 and 2 represent findings from the study. Use the response models shown in Figures 1 and 2 to justify the claim that phytochromes regulate the transcription of genes leading to the production of certain cellular proteins.

When inactive phytochrome Pr is activated by red light to become phytochrome Pfr, it is transported into the nucleus where it binds to the transcription factor PIF3 at the promoter. This stimulates transcription, ultimately leading to protein production. Far-red light inactivates the phytochrome, which will turn transcription off by not binding to PIF3.

5. A sterile agar plate, I, is streaked with a pure culture of bacteria by means of aseptic techniques. Paper discs treated with the antibiotics Aureomycin (A) and penicillin (P) are placed at opposite sides of the plate, as shown in the diagram above. The plate is examined after a 24-hour incubation period, and a clear ring is discovered around disc A, but not around disc P. Within the clear ring around disc A, a single bacterial colony with physical characteristics like those of the pure culture is observed. A second sterile agar plate, II, is then streaked with this single colony and also incubated with antibiotics. The single colony found within the clear ring in plate I is most likely made up of the descendants of a bacterial cell that

contained information conferring resistance to Aureo-mycin