51.
Which of the following bacterium causes crown gall disease in plants?

52.
Fossils of blue green algae were found in lime stones with the age almost as old as

53.
They have also proved extremely useful in our quest of knowledge of outer space.

54.
Chemicals like ________ may be added to different foods or fruits to prevent or retard the growth microorganisms.

55.
Eutrophication is the result of