Assertion : Photomodulation of flowering is a phytochrome - regulated process. Reason : Active form of…
Assertion : Photomodulation of flowering is a phytochrome - regulated process.
Reason : Active form of phytochrome (Pfr) directly induces floral induction in shoot buds.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false.
Solution
Flowering is a phytochrome regulated process. Phytotchrome is a blue protein pigment with a molecular mass of about $125 \mathrm{k} \mathrm{Da}$ (kilodaltons). Phytochrome occurs in two interconvertible form $P_R$ (which absorbs red light) and $\mathrm{P}_{\mathrm{fr}}$ (which absorbs far red light). The studies with mutants of Arabidopsis support and prove that the $\mathrm{P}_{\mathrm{fr}}$ is the active form of phytochrome. When $\mathrm{P}_{\mathrm{R}}$ molecules are exposed to red light, most of them absorb it and converted to $\mathrm{P}_{\mathrm{fr}}$. This causes floral induction in the shoot.