Question 1

Which experiment first demonstrated the principle of 'transformation' in bacteria, suggesting that genetic information could be transferred between cells?

Accepted Answer

Griffith (1928)

Question 2

In Griffith's experiment, what was the outcome when heat-killed virulent (Type S) bacteria were mixed with live non-virulent (Type R) bacteria and injected into mice?

Accepted Answer

The mice died, and live Type S bacteria were recovered from them.

Question 3

Avery, MacLeod, and McCarty's experiments showed that which molecule was responsible for transformation in bacteria?

Accepted Answer

DNA

Question 4

In the Hershey and Chase experiment, which radioactive label was found inside the bacterial cells after infection by bacteriophage?

Accepted Answer

Phosphorus-32, indicating DNA entered the cell

Question 5

Which of the following is NOT a criterion for the hereditary material?

Accepted Answer

It must be composed of 20 different amino acids.

Question 6

What is the structural difference between purines and pyrimidines in DNA?

Accepted Answer

Purines have a double ring structure, while pyrimidines have a single ring structure.

Question 7

According to Chargaff's rules, which of the following is true for double-stranded DNA?

Accepted Answer

The amount of guanine equals the amount of cytosine.

Question 8

Which type of bond connects the sugar and phosphate groups in the DNA backbone?

Accepted Answer

Phosphodiester bond

Question 9

How many hydrogen bonds are formed between adenine and thymine in a DNA molecule?

Accepted Answer

$$2$$

Question 10

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Question 11

During DNA replication, which enzyme synthesizes the new DNA strand by adding nucleotides to the exposed template?

Accepted Answer

DNA polymerase

Question 12

What is the function of DNA ligase during DNA replication?

Accepted Answer

It connects Okazaki fragments by forming phosphodiester bonds.

Question 13

If a segment of DNA has the sequence $$5'-ATCGGTA-3'$$, what is the sequence of its complementary strand?

Accepted Answer

$$3'-TAGCCAT-5'$$

Question 14

Which of the following best describes the semi-conservative model of DNA replication?

Accepted Answer

Each new DNA molecule consists of one original strand and one new strand.

Question 15

Which of the following is a correct description of an Okazaki fragment?

Accepted Answer

A short segment of DNA synthesized discontinuously on the lagging strand.

Question 16

Which of the following statements about the sugar-phosphate backbone of DNA is correct?

Accepted Answer

It is composed of alternating deoxyribose and phosphate groups.

Question 17

Which nitrogenous base is found in DNA but not in RNA?

Accepted Answer

Thymine

Question 18

A scientist isolates a molecule with the following components: deoxyribose sugar, phosphate group, and cytosine. What is this molecule?

Accepted Answer

A nucleotide

Question 19

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

Accepted Answer

Proteins are composed of 20 different amino acids, providing a more complex 'alphabet' than DNA.

Question 20

Which of the following is a real-world application of the principle of transformation discovered by Griffith?

Accepted Answer

Development of vaccines using heat-killed bacteria to induce immunity.

Discovery of DNA as the Hereditary Material

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