Question 1

Which experiment provided the first strong evidence that DNA, and not protein, is the genetic material in bacteria?

Accepted Answer

Avery, MacLeod, and McCarty's experiment using DNAse, RNAse, and protease

Question 2

Which of the following best describes the structure of a nucleosome?

Accepted Answer

A segment of DNA wrapped around a histone octamer, with linker DNA and histone H1 associated

Question 3

Which of the following statements about DNA supercoiling is correct?

Accepted Answer

Topoisomerase II introduces double-strand breaks to manage supercoiling

Question 4

A DNA sample is heated and its absorbance at 260 nm increases. What is the most likely explanation for this observation?

Accepted Answer

The DNA is being denatured, causing strand separation

Question 5

Which of the following is a function of telomeres in eukaryotic chromosomes?

Accepted Answer

They protect chromosome ends from shortening during replication

Question 6

Which of the following modifications is most likely to result in a more open chromatin structure and increased gene expression?

Accepted Answer

Histone acetylation

Question 7

A protein is synthesized in the cytosol but needs to enter the nucleus. Which sequence is required for its import?

Accepted Answer

Nuclear localization signal (NLS)

Question 8

Which of the following best explains why the melting temperature ($$T_m) of $$DNA increases with higher GC content?

Accepted Answer

GC pairs form three hydrogen bonds, making the DNA more stable

Question 9

Which of the following is NOT a feature of the B-form DNA double helix?

Accepted Answer

Left-handed helix

Question 10

Which of the following statements about chromatin is correct?

Accepted Answer

Heterochromatin is generally transcriptionally inactive

Question 11

Which of the following best describes the role of the SWI/SNF chromatin remodeling complex?

Accepted Answer

It slides or removes nucleosomes to make DNA more accessible

Question 12

Which of the following is true about the Ran-GTP gradient in nuclear transport?

Accepted Answer

Ran-GTP promotes the release of cargo from importin inside the nucleus

Question 13

Which of the following is a characteristic of LINEs (Long Interspersed Nuclear Elements) in the human genome?

Accepted Answer

They contain genes required for their own mobilization

Question 14

Which of the following best describes the function of centromeres?

Accepted Answer

They serve as attachment sites for kinetochores during cell division

Question 15

Which of the following statements about mitochondrial and chloroplast DNA is correct?

Accepted Answer

Both organelles have circular chromosomes without histones

Question 16

A scientist is using fluorescent in situ hybridization (FISH) to detect a specific DNA sequence in human cells. Which of the following best describes the principle behind this technique?

Accepted Answer

A fluorescently labeled single-stranded DNA probe hybridizes to its complementary sequence in the genome

Question 17

Which of the following best explains why bacterial chromosomes are typically negatively supercoiled?

Accepted Answer

Negative supercoiling makes the DNA more compact and easier to separate for replication and transcription

Question 18

Which of the following is a direct consequence of the antiparallel orientation of DNA strands?

Accepted Answer

The 5' end of one strand aligns with the 3' end of the other

Question 19

Which of the following is true regarding the packaging of eukaryotic DNA?

Accepted Answer

Histone H1 is important for the formation of the 30-nm fiber

Question 20

Which of the following best describes the difference between tandemly repeated DNA and interspersed repeated DNA?

Accepted Answer

Tandem repeats are arranged in a row, while interspersed repeats are scattered throughout the genome

The Structural Basis of Cellular Information: DNA, Chromosomes, and the Nucleus

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