Nicotiana sylvestris flowers only during long days and N.tobacum flower only during long days in the labortory undre different photoperiods , they can be induced to flower at the same time and can be cross fertized to flower aat the and can be corss fertillzed to produce self - fertile offsping .What is the best reason for considering N. syvestris and N . tobacum to be separate species

Options

A. the connot interbreed to natures
B. they are reproductively distinct
C. they are physiologically distinct
D. they are morphologically distinct

Answer

A

Explanation

The process by which N, is reduced to NH, is called nitrogen fixation. Nitrogenase enzyme catalyzes this reduction. It is only carried out by prokaryotic microorganisms. Principal N-fixers include certain free-living cyanobacteria in symbiotic associations with fungi in lichens or with ferns, mosses, and liverworts, and by bacteria or other microbes associated symbiotically with roots, especially those of legumes. About 15 per cent of the nearly 20,000 species in the fabaceae (Leguminosae) family have been examined for N, fixation, and approximately 90 per cent of these have root nodules in which fixation occurs. So without active nitrogenase enzyme, there will be no N, fixation in legumes.