Who among the following was the first to give clear-cut evidence of a virus?

Bacteria can be seen by

A. Naked eye

B. Compound microscope

C. Hand lens

D. Electron microscope

In the life cycle of a virulent bacteriophage, the period of production of new phage particles is called

A. Latent period phase

B. Vegetative phase

C. Adsorption phase

D. Liberation phase

In which kind of xylem parenchyma the parenchyma cells occur singly among the fibres and tracheids?

A. Boundary apotracheal type

B. Terminal apotracheal type

C. Banded apotracheal type

D. Diffuse apotracheal type

Which of the following approaches is mainly used to construct classification on the basis of observable characters which can be felt and tested practically?

A. Metric approach

B. Empirical approach

C. Numerical approach

D. None of the above