Question 1

In Griffith's experiment (see Experiment 4 in the first image), what was the key finding that led to the concept of transformation in bacteria?

Accepted Answer

Living R strain bacteria mixed with heat-killed S strain bacteria killed the mice, and live S strain bacteria could be recovered from the dead mice.

Question 2

Which molecule did Hershey and Chase label with radioactive phosphorus to demonstrate that it was the genetic material entering the bacterial cell? (Refer to the third image.)

Accepted Answer

Viral DNA

Question 3

According to Chargaff's rules and the data in the fourth image, if a species has 23% adenine (A), what is the expected percentage of thymine (T)?

Accepted Answer

23%

Question 4

Which scientist used X-ray diffraction to help reveal the double helix structure of DNA? (See the fifth image.)

Accepted Answer

Rosalind Franklin

Question 5

What is the significance of the antiparallel arrangement of DNA strands, as shown in the sixth image?

Accepted Answer

It permits complementary base pairing and proper replication.

Question 6

Based on the Meselson-Stahl experiment (seventh image), which model of DNA replication was supported by their results?

Accepted Answer

Semi-conservative

Question 7

During DNA replication (see the eighth image), what is the role of the parental DNA strands?

Accepted Answer

They serve as templates for the synthesis of new complementary strands.

Question 8

Which enzyme is responsible for relieving DNA supercoiling ahead of the replication fork, as shown in the ninth image?

Accepted Answer

Topoisomerase

Question 9

In the context of DNA replication origins (see the tenth image), which statement is correct?

Accepted Answer

Prokaryotic chromosomes have a single origin of replication, while eukaryotic chromosomes have multiple origins.

Question 10

What is the direction of DNA synthesis by DNA polymerase, as depicted in the thirteenth image?

Accepted Answer

5' to 3'

Question 11

Which strand is synthesized discontinuously in short fragments during DNA replication, as shown in the fifteenth image?

Accepted Answer

Lagging strand

Question 12

In the replication fork diagram (sixteenth image), which strand (A or B) is the lagging strand, and why?

Accepted Answer

A is the lagging strand, as DNA is always synthesized in the 5' to 3' manner.

Question 13

Which enzyme covalently joins Okazaki fragments together on the lagging strand, as shown in the seventeenth image?

Accepted Answer

DNA ligase

Question 14

If a mutation occurred in the gene encoding single-stranded binding protein (see ninth image), what would be the most likely effect on DNA replication?

Accepted Answer

The separated DNA strands would re-anneal or degrade, halting replication.

Question 15

Which of the following best explains why DNA polymerase cannot initiate synthesis of a new DNA strand by itself (see thirteenth image)?

Accepted Answer

It requires a free 3' OH group provided by an RNA primer.

Question 16

In the context of the Meselson-Stahl experiment (seventh image), what would be the expected result after two rounds of replication if DNA replication were dispersive?

Accepted Answer

All DNA molecules would be a mix of old and new DNA in every strand.

The Molecular Basis of Inheritance: DNA Structure, Replication, and Technology

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