Question

Nicotiana sylvestris flowers only during long days while Nicotiana tobacum flowers only during short days. If raised in the laboratory under different photoperiods, they can be induced to flower at the same time and can be cross fertilized to produce self-fertile offsprings.
What is the best reason for considering N. sylvestris and N. tobacum to be separate species?

• A. They are physiologically distinct
• B. They are morphologically distinct
• C. They can interbreed in nature
• D. They are reproductively distinct

Answer 1

The correct option is D They are reproductively distinct

Biological concept of species says that only the members of a species can breed freely in nature to produce fertile offsprings. The plant tobacco (Nicotiana) has two different species, Nicotiana tobaccum and Nicotiana sylvestris. These two species cannot reproduce freely. They are reproductively distinct.