AP Biology Tri 2 Exam

Which of the following is most likely to create a genetic variation in the population?

DNA polymerase errors during replication.

The diagram above shows a developing worm embryo at the four-cell stage. Experiments have shown that when cell 3 divides, the anterior daughter cell gives rise to muscle and gonads and the posterior daughter cell gives rise to the intestine. However, if the cells of the embryo are separated from one another early during the four-cell stage, no intestine will form. Other experiments have shown that if cell 3 and cell 4 are recombined after the initial separation, the posterior daughter cell of cell 3 will once again give rise to normal intestine. Which of the following is the most plausible explanation for these findings?

A cell surface protein on cell 4 signals cell 3 to induce formation of the worm intestine.

The vertebrate forelimb initially develops in the embryo as a solid mass of tissue. As development progresses, the solid mass near the end of the forelimb is remodeled into individual digits. Which of the following best explains the role of apoptosis in remodeling of the forelimb?

Apoptosis involves the destruction of extra cells in the developing forelimb, which provides nutrients for phagocytic cells.

Enzyme used during replicated to attach okazaki fragments to each other

DNA ligase

Enzyme used to position nucleotides during DNA replication

DNA polymerase

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.

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.

Which of the following statements best describes the role of cyclic amp in the signal transduction pathway?

It acts as a second messenger that helps relay and amplify the signal within the cell.

Based on figure 1, which of the following statements best describes the epinephrine signaling pathway?

It involves enzymes activating other enzymes.

Both mitosis and meiosis begin with a parent cell that is diploid. Which of the following best describes how mitosis and meiosis result in daughter cells with different number of chromosomes?

Mitosis produces two identical diploid daughter cells after one round of division. Meiosis produces four haploid daughter cells after two rounds of division.

Which of the following statements best explains why there are fewer colonies on plate IV than on plate III?

Not all E. coli cells are successfully transformed

Enzyme used in the sythesis of mRNA

RNA polymerase

Enzyme found in retroviruses that produce DNA from an RNA template

Reverse Transcriptase

Which of the following statements best explains the data set?

Since the %A and the %T are the approximately same in each sample, adenine and thymine molecules must pair up in a double-stranded DNA molecule.

The data above represents the results of three different crosses involving the inheritance of a gene that determines whether a certain organism is blue or white. Which of the following best explains the mechanism of inheritance of the gene?

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

Based on the model of the eukaryotic cell cycle regulation shown in the figure, which of the following best describes the effect of a drug that blocks the production of the mitotic cyclin?

The cell would be prevented from entering mitosis, and the cell would stop dividing.

Which of the following statements best explains how the genes for antibiotic resistance can be transmitted between bacteria without the exchange of bacterial chromosomal DNA?

The genes for antibiotic resistance are located on a plasmid that can be passed to neighboring bacteria.

Which of the following statements best describes how a growth factor stimulates cell division from outside a cell?

The growth factor binds to receptors on the cell surface, initiating a signal transduction pathway that activates specific target genes.

The researches calculate a chi-square value of 4.6 and choose a significance level of p=0.05. Which of the following statements best completes the chi square goodness of fit test?

The null hypothesis cannot be rejected as the chi square value is less than the critical value of 7.82

Researches studying cell cycle regulation in budding yeast have observed that a mutation in the cdc15 gene causes cell cycle arrest in telophase when the yeast cells are incubated at an elevated temperature. Which of the following statements best predicts the effect of the cell cycle arrest on proliferating yeast cells?

The yeast cells will replicate their chromosomes but will fail to complete cytokinesis.

DNA replication occurs

during the S phase of the cell cycle

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?

its the one with the multiple arrows going away towards the 5' end.

Most cells that have become transformed into cancer cells have which of the following characteristics when compared to normal healthy cells?

shorter cell cycle