Question

Read the following statements and choose the most appropriate option.
A. Agrobacterium tumefaciens is a pathogen of several monocot plants.
B. Exonucleases remove nucleotides from the ends of the DNA whereas endonucleases make cuts at specific positions within the DNA.

• A. A is true and B is false
• B. A is false and B is true
• C. Both A and B are true
• D. Both A and B are false

Answer 1

The correct option is B A is false and B is true

Agrobacterium tumefaciens is a bacterium which is a pathogen of several dicot plants. Its infection in monocot plants is limited. This bacterium naturally delivers its “T-DNA” piece of Tumor inducing (Ti) plasmid to the host. This leads to transformation of normal plant cells into tumor cells to produce chemicals required by the bacterial pathogen. So, statement A is false.

An endonuclease cleaves the phosphodiester bond between two consecutive nucleotides present within the DNA molecule. Those cleaving DNA sequences at a particular site are called restriction endonucleases. Hind III, EcoR I, and BamH I are a few examples of restriction endonucleases.
Exonucleases remove nucleotides from the ends of the DNA. Hence, statement B is true.