Question 1

Which type of chemical bond links nucleotides together in a single strand of DNA?

Accepted Answer

Phosphodiester bond

Question 2

Which of the following best describes the orientation of the two strands in a DNA double helix?

Accepted Answer

The strands are antiparallel, one runs 5' to 3' and the other 3' to 5'

Question 3

Which nitrogenous base pairs with cytosine in a DNA molecule?

Accepted Answer

Guanine

Question 4

What is the chemical structure of the sugar molecule in DNA?

Accepted Answer

Deoxyribose

Question 5

During DNA replication, in which direction are new DNA strands synthesized?

Accepted Answer

5' to 3'

Question 6

If one strand of DNA has the sequence 5’-ACGTT-3’, what is the sequence of the complementary strand (written 5' to 3')?

Accepted Answer

5’-AACGT-3’

Question 7

Which of the following statements about the Hershey-Chase experiment is correct?

Accepted Answer

They used $$^{32}P to $$label DNA and $$^{35}S to $$label protein, showing that DNA enters the bacterial cell.

Question 8

What is the significance of Rosalind Franklin’s X-ray diffraction photo (Photo 51) in the discovery of DNA structure?

Accepted Answer

It revealed the helical structure and periodicity of DNA.

Question 9

Which of the following is a direct piece of evidence that DNA is the genetic material?

Accepted Answer

Recombinant DNA technology allows expression of human genes in bacteria.

Question 10

In the Avery-MacLeod-McCarty experiment, which enzyme treatment prevented transformation of R strain bacteria?

Accepted Answer

DNase

Question 11

Which of the following best explains why $$^{32}P$$ and $$^{35}S$$ were chosen for the Hershey-Chase experiment?

Accepted Answer

$$^{32}P is $$incorporated into DNA and $$^{35}S$$ into protein, allowing distinction between the two macromolecules.

Question 12

Which of the following is NOT a nitrogenous base found in DNA?

Accepted Answer

Uracil

Question 13

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

Accepted Answer

The two strands are held together by hydrogen bonds between complementary bases.

Question 14

Which of the following is an example of indirect evidence that DNA is the genetic material?

Accepted Answer

Correlation between DNA content and chromosome sets in gametes and diploids

Question 15

A scientist injects a mouse with a mixture of heat-killed virulent S strain and living non-virulent R strain bacteria. The mouse dies, and living S strain bacteria are recovered from its blood. What does this experiment demonstrate?

Accepted Answer

DNA from the S strain transformed the R strain into virulent bacteria

Question 16

Which of the following best describes the major structural difference between DNA and RNA?

Accepted Answer

DNA contains deoxyribose and thymine, while RNA contains ribose and uracil

Question 17

Which of the following is a real-world application of recombinant DNA technology?

Accepted Answer

Production of human insulin in bacteria

Question 18

What is the distance between adjacent base pairs in the DNA double helix?

Accepted Answer

$$3.4$$ \AA

Question 19

Which scientist(s) provided the first direct experimental proof that DNA is the biomolecule responsible for heredity?

Accepted Answer

Avery, MacLeod, and McCarty

Question 20

A transgenic mouse expresses a human gene and passes it to its offspring. What does this demonstrate?

Accepted Answer

DNA from one species can be expressed and inherited in another species

DNA Structure and Evidence for DNA as Genetic Material

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