Question

Assertion : Phytochrome exists in two form $P_r$ and $P_{fr}$
Reason : $P_r$ form stimulates and $P_{fr}$ form inhibit flowering.

• A. If both the assertion and reason are true and the reason is a correct explanation of the assertion
• B. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
• C. If the assertion is true but the reaon is false
• D. If both the assertion and reason are false
• E. If the assertion is false but reason is true

Answer 1

The correct option is C If the assertion is true but the reaon is false

Light energy become effective when it is absorbed by a pigment. These pigments are called phytochromes. It occurs in two forms namely $P_r$ and $P_{fr}$. The two forms are interconvertible. The $P_r$ form absorbs red light of 660 nm and changes to $P_{fr}$. The $P_{fr}$ form absorb far red light of 730 nm and changed to $P_r$. The $P_{fr}$ form stimulates whereas $P_r$ form inhibit flowering. $P_{fr}$ form of phytochrome is the active form. The $P_r$ form is not considered to be active. So, the correct answer is c'If the assertion is true but the reason is false'