Question

1. Retroviruses
   1. make RNA from an RNA template
   2. make DNA from a foreign DNA template
   3. use regular polymerase working in reverse
   4. make DNA from an RNA template

2.    The introns in tRNA are removed by
   1. ribozymes
   2. exonucleases
   3. endonucleases
   4. lyases

3. The subunit that directs the RNA polymerase to the promoters is the
   1. a                    b. s                          c. b                  d. b’

4.   The number of tRNAs required for synthesis of proteins in E. coli is
   1. 32 or more
   2. no more than 20
   3. at least 50
   4. exactly 20 as the number of aa

5.   The number of processes that regulates gene expression is
   1. 7                      b. 8                          c. 9                  d. 10

Answer 1

1. Retroviruses

Ans- d. Make DNA from an RNA template.

Retroviruses make copies of DNA from RNA template in the process known as reverse transcriptase. Retrovirus is a type of virus and it uses RNA as genetic material.

2. Ans c. Endonucleases

The introns are removed from tRNA by the enzyme known as tRNA splicing endonucleases. Removal of tRNA occur at specific location.

3. Ans a. a

The alpha (a) subunit of RNA polymerase is responsible for initiation of transcription. The a subunit directs the RNA polymerase to promoter.

4. Ans- a. 32 or more

The total number of t RNA is depend on organism. In E. coli consist 43 different  tRNA molecule.