Which of the following statements about phytochrome is true?

• A

  $P_r$ absorbs yellow light and becomes $P_{f r}$.
• Correct answer
  B

  $\mathrm{P}_{\mathrm{r}}$ absorbs red light and becomes $\mathrm{P}_{\mathrm{fr}}$.
• C

  $\mathrm{P}_{\mathrm{fr}}$ absorbs red light and becomes $\mathrm{P}_{\mathrm{r}}$.
• D

  $P_{\text {fr }}$ absorbs yellow light and becomes $P_r$.

Solution

Phytochrome is an amorphous photoreceptor chromoprotein. It exists in two interconvertible forms i.e., $\mathrm{P}_{\mathrm{r}}$ and $\mathrm{P}_{\mathrm{fr}}$.

Hence, the correct answer is option: 'B'.