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Control Systems

Phytochrome and photomorphogenesis

  • 2 things to know
  • Papers 2 and 3

Overview

Recall questions on phytochrome as a photoreceptor pigment, photomorphogenesis and flowering, the interconversion of Pr and Pfr by red and far-red light, Pfr as the active form, and how its reversion in darkness lets plants measure day length.

What you need to know

Answer each one before you reveal it.

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Process

How does the slow reversion of Pfr to Pr in darkness allow plants to respond to day length?

Process

How does phytochrome control flowering?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What type of molecule is phytochrome?

    Model answer

    Phytochrome is a photoreceptor pigment.

  2. 2

    What process in plants does phytochrome control?

    Model answer

    Phytochrome controls flowering in plants.

  3. 3

    Define photomorphogenesis.

    Model answer

    Photomorphogenesis is the effect of light on plant development and growth.

  4. 4

    Which pigment controls photomorphogenesis in plants?

    Model answer

    Phytochrome.

  5. 5

    What wavelength of light does the Pr form of phytochrome absorb?

    Model answer

    Red light.

  6. 6

    What wavelength of light does the Pfr form of phytochrome absorb?

    Model answer

    Far-red light.

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