If Meselson and Stahl's experiment is continued for four generations in bacteria, the ratio of N15/N15: N15/N14: N14/N14 containing DNA in the fourth generation would be:

1.	1:1:0	2.	1:4:0
3.	0:1:3	4.	0:1:7

If the sequence of nitrogen bases of the coding strand of DNA in a transcription unit is:

5' -ATGAATG-3',

the sequence of bases in its RNA transcript would be;

1. 5'-AUGAAUG-3'

2. 5'-UACUUAC-3'

3. 5'-CAUUCAU-3'

4. 5'-GUAAGUA-3'

The RNA polymerase holoenzyme transcribes:

1. the promoter, structural gene and the terminator region

2. the promoter and the terminator region

3. the structural gene and the terminator region

4. the structural gene only.

If the base sequence of a codon in mRNA is 5'-AUG-3', the sequence of tRNA pairing with it must be:

1. 5'-UAC-3'

2. 5'-CAU-3'

3. 5'-AUG-3'

4. 5'-GUA-3'

The amino acid attaches to the tRNA at its:

1. 5' - end

2. 3' - end

3. Anti codon site

4. DHU loop

To initiate translation, the mRNA first binds to:

1. The smaller ribosomal sub-unit,

2. The larger ribosomal sub-unit

3. The whole ribosome

4. No such specificity exists.

In E.coli, the lac operon gets switched on when:

1. lactose is present and it binds to the repressor

2. repressor binds to operator

3. RNA polymerase binds to the operator

4. lactose is present and it binds to RNA polymerase

Identify the incorrect statement regarding the comparison of an RNA and a DNA molecule:

Griffith wanted to make a vaccine to prevent pneumonia. He injected heat-killed S-strain bacteria into the mice for this purpose. How can a killed bacteria help in making a vaccine?

The functions of the telomeres include: