AP BIO unit 6

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?

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

A simplified model of a DNA replication fork is represented in Figure 1. The protein labeled Enzyme 1 carries out a specific role in the DNA replication process. Which of the following statements best explains the role of Enzyme 1 in the DNA replication process?

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

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?

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

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

II is synthesized continuously in the 5′5′ to 3′3′ direction, and IIIIII is synthesized in segments in the 5′5′ to 3′3′ direction.

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?

Prokaryotic DNA- Single circular chromosome Eukaryotic DNA- Multiple linear chromosomes

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

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

Exposure to ultraviolet (UV) radiation is the leading cause of skin cancer in humans. Figure 1 shows a model of how UV exposure damages DNA. Figure 1. Model of damage to DNA caused by UV exposure Which of the following statements best explains what is shown in Figure 1 ?

UVUV photons cause dimers to form, leading to misshapen DNADNA, which results in replication and transcription errors.

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

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

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?

She inherited an allele with more than 40 CAGCAG repeats in the HTTHTT gene from her father.

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

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

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?

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

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

When trpRtrpR is mutated, the trptrp operon is transcribed regardless of tryptophan levels.