9.1.5 - Photomorphogenesis Flashcards
What is photomorphogenesis?
The process by which plant development is controlled by the levels and type of light.
What is the term used to describe what happens to a seed underground?
Becomes etiolated.
What does it mean if a seed becomes etiolated underground?
Seed grows rapidly using up food reserves and they become tall and thin.
What controls when a seed becomes etiolated?
Phytochromes
Describe the balance of Pfr and Pr in seeds underground?
Contains Pr.
Not exposed to light so no interconversion.
What are 2 types of leaf?
Cotyledon (monocot)
Hooked apical shoot (dicot)
What does a dicot leaf look like?
A traditional leaf.
Veins run in different directions. (branched)
What does a monocot leaf look like?
Spider plants.
Veins run in one direction.
What are some characteristics of etiolation in seedlings?
Rapid stem lengthening but little thickening.
Little root growth.
No leaf growth.
No chlorophyll.
Why do no leaves or chlorophyll grow in the etiolation of a seedling?
So that no energy is wasted.
What happens to the seedling once the tip breaks through the surface of soil?
Elongation of the stem slows down.
Stem straightens.
First leaves open.
Chlorophyll forms and seedlings begin to photosynthesise.
Where are the nodes and internodes on a plant?
nodes are on the stem where leaves grow from.
Internodes are the parts of the stem inbetween leaves.
What controls the change in characteristics of a seedling once is breaks through the soil surface?
Phytochrome interconversion.
The seedling has access to light so the conversion of Pr to Pfr begins.
When Pr is converted to Pfr in the light, what does this cause?
The lengthening in internodes.
Leaves begin to develop.
Chlorophyll produced.
