Question

How many statements are correct for phytochromes?

1. Phytochrome pigment exists in two forms.
2. Two forms of phytochrome are interconvertible.
3. P_fr form of phytochrome inhibits flowering in SDP, during day time.
4. P_fr form of phytochrome inhibits flowering in LDP, during day time.
5. During day time P_r form accumulates in plants.

Options

• only I

• I, II and III only

• I, II, III and IV only

• II, II, IV and V only

Answer 1

I, II and III only

Explanation:

I & II: Phytochrome exists as two interconvertible forms P_r (red‑absorbing) and P_fr (far‑red‑absorbing). 

III: P_fr inhibits flowering in short‑day plants.