Question 1

Which of the following best describes the major finding of Frederick Griffith's experiment with Streptococcus pneumoniae?

Accepted Answer

DNA from a virulent strain can transform a non-virulent strain into a virulent one.

Question 2

Which chemical component is NOT found in the backbone of DNA?

Accepted Answer

Thymine

Question 3

According to Chargaff’s rules, which equation correctly represents the relationship between the nitrogenous bases in double-stranded DNA?

Accepted Answer

$$(A + G) = (T + C)$$

Question 4

Which feature of DNA allows it to encode heritable traits and self-replicate?

Accepted Answer

Its double helix structure with complementary base pairing

Question 5

What is the main reason DNA replication is described as 'semi-conservative'?

Accepted Answer

Each new DNA molecule contains one old strand and one newly synthesized strand.

Question 6

Which type of bond is responsible for holding the two DNA strands together?

Accepted Answer

Hydrogen bonds

Question 7

Why is DNA synthesis on the lagging strand discontinuous?

Accepted Answer

Because DNA polymerase can only synthesize DNA in the $$5' \rightarrow 3'$$ direction, and the strands are antiparallel.

Question 8

Which enzyme is responsible for joining Okazaki fragments during DNA replication?

Accepted Answer

DNA ligase

Question 9

In eukaryotic cells, what is the role of telomerase during DNA replication?

Accepted Answer

It extends the ends of chromosomes to prevent loss of genetic material.

Question 10

Which of the following statements about Okazaki fragments is TRUE?

Accepted Answer

They are short DNA segments synthesized on the lagging strand.

Question 11

A mutation causes a cell to lack telomerase activity. What is the most likely consequence for this cell?

Accepted Answer

Chromosomes will become progressively shorter with each cell division.

Question 12

Which of the following is a purine base found in DNA?

Accepted Answer

Adenine

Question 13

During DNA replication, which enzyme synthesizes short RNA primers on the lagging strand?

Accepted Answer

Primase

Question 14

Which of the following best explains why cancer cells often have high levels of telomerase?

Accepted Answer

To maintain chromosome length and allow unlimited cell division.

Question 15

Which of the following is TRUE regarding the directionality of DNA synthesis?

Accepted Answer

DNA synthesis always proceeds in the $$5' \rightarrow 3'$$ direction.

Question 16

Which of the following is a function of the sliding clamp during DNA replication?

Accepted Answer

It holds DNA polymerase in place on the DNA template.

Question 17

Which of the following best describes the structure of a nucleotide in DNA?

Accepted Answer

A phosphate group, a deoxyribose sugar, and a nitrogenous base

Question 18

Which of the following is the correct sequence of events for lagging strand synthesis?

Accepted Answer

Primase synthesizes RNA primer, DNA polymerase elongates fragment, DNA polymerase removes RNA, DNA ligase joins fragments

Question 19

Which of the following medical conditions is associated with defects in the telomere cap structure, leading to premature aging?

Accepted Answer

Werner syndrome

Question 20

Which of the following statements about eukaryotic DNA replication is FALSE?

Accepted Answer

Eukaryotic chromosomes have a single origin of replication.

DNA Structure and Replication: Key Concepts and Mechanisms

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