Question 1

Which of the following best describes the key finding of the Hershey-Chase experiment?

Accepted Answer

DNA, not protein, is the genetic material because only DNA entered the bacterial cells and directed viral replication.

Question 2

A scientist isolates DNA from a new species and finds it contains 22% adenine. According to Chargaff's rules, what percentage of guanine would you expect to find?

Accepted Answer

28%

Question 3

In Griffith's experiment, what was the significance of mixing heat-killed pathogenic bacteria with live non-pathogenic bacteria?

Accepted Answer

It revealed that a genetic factor (later identified as DNA) from dead bacteria could transform live bacteria, making them pathogenic.

Question 4

Which element was used to label DNA in the Hershey-Chase experiment, and why was it chosen?

Accepted Answer

Phosphorus, because it is found in DNA but not in protein.

Question 5

Which of the following statements about the structure of DNA is correct?

Accepted Answer

The sugar-phosphate backbone is on the outside, and the nitrogenous bases are paired in the center.

Question 6

A DNA sample from a certain organism contains 30% cytosine. What is the expected percentage of thymine in this DNA?

Accepted Answer

20%

Question 7

Which scientist(s) provided the first direct evidence that DNA is the transforming substance responsible for heredity?

Accepted Answer

Avery, McCarty, and MacLeod

Question 8

What is the significance of the antiparallel arrangement of DNA strands?

Accepted Answer

It is necessary for the function of enzymes involved in DNA replication and transcription.

Question 9

Which of the following best explains why proteins were initially considered as candidates for genetic material instead of DNA?

Accepted Answer

Proteins have a greater variety of structures and functions compared to DNA.

Question 10

A mutation causes a DNA strand to have 35% guanine. According to Chargaff's rules, what percentage of adenine would you expect in this DNA?

Accepted Answer

15%

Question 11

Which of the following is a direct result of complementary base pairing in DNA?

Accepted Answer

The ability of DNA to replicate accurately.

Question 12

In the context of DNA structure, what is a phosphodiester bond?

Accepted Answer

A bond between the phosphate group of one nucleotide and the 3' hydroxyl group of another.

Question 13

Which historical experiment first demonstrated the phenomenon of transformation in bacteria?

Accepted Answer

Griffith's experiment

Question 14

A DNA molecule is analyzed and found to have 18% thymine. What is the expected percentage of cytosine?

Accepted Answer

32%

Question 15

Which of the following best describes the contribution of Rosalind Franklin to the discovery of DNA structure?

Accepted Answer

She provided X-ray diffraction images that revealed the helical structure of DNA.

Question 16

If a DNA sample from a bacterium contains 25.5% guanine, what is the expected percentage of adenine?

Accepted Answer

24.5%

Question 17

Why is the directionality (5' to 3' and 3' to 5') of DNA strands important for cellular processes?

Accepted Answer

It determines how enzymes interact with DNA during replication and transcription.

Question 18

Which of the following best explains why the percentages of adenine and thymine are similar in DNA?

Accepted Answer

Adenine pairs with thymine via hydrogen bonds, so their amounts are equal.

Question 19

Which of the following is NOT a correct pairing of scientist(s) and their discovery?

Accepted Answer

Chargaff – DNA is the transforming substance

Question 20

A medical researcher is studying a genetic disease caused by a mutation that disrupts the hydrogen bonding between guanine and cytosine. Which of the following consequences is most likely?

Accepted Answer

The accuracy of DNA replication will decrease due to improper base pairing.

DNA as Genetic Material: Discovery, Structure, and Experimental Evidence

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