[Campbell Biology P.919] Based on the information provided regarding phytochromes, which sta... | Practice Question

Based on the information provided regarding phytochromes, which statement is correct about their function and light conversion?

  • A: Blue-light photoreceptors control photoperiodism.
  • B: Red light converts Pfr to Pr, turning the phytochrome "off."
  • C: Far-red light converts Pr to Pfr, leading to plant responses.
  • D: The Pfr form of phytochrome triggers plant responses.

Explanation

According to the diagram under Concept 39.3, red light converts Pr to Pfr, and the Pfr form is shown leading to 'Responses'. The text also states that 'Red light turns phytochrome "on,"' implying Pfr is the active form that triggers responses, while far-red light turns it 'off' by converting Pfr back to Pr. Blue-light photoreceptors have distinct functions from phytochromes regarding photoperiodism.