phototropism Flashcards
flashcard
What is a condition that affects plant growth called?
Stimulus
Define tropism.
The directional growth or movement of an organism in response to a stimulus
What type of tropism is associated with light?
Phototropism
List three types of tropism.
- Phototropism (light)
- Hydrotropism (water)
- Geotropism (gravity)
What is photomorphogenesis?
The regulatory effect of light on the growth, development and differentiation of plant cells, tissues and organs
What does the term ‘phototropism’ refer to?
The movement of a plant toward or away from light
What is a photoreceptor?
A specialized protein that is able to detect and react to light
Define photoperiodism.
The growth, development and other responses of plants and animals according to the length of day and/or night
What does ‘photo’ mean in the context of phototropism?
Light
What does ‘tropism’ mean?
Turning
What hormone is involved in plant responses to light?
Auxins
What are phytochromes sensitive to?
Red and far-red light
What is the role of cryptochromes?
They respond to blue light, influencing growth and circadian rhythms
What do phototropins mediate?
Plant responses to directional light, promoting phototropism
What type of light promotes flowering and fruiting?
Red Light
Fill in the blank: ______ Light can inhibit growth and affect flowering time.
Far-Red
What type of light encourages vegetative growth and leaf expansion?
Blue Light
Describe the mechanism of phototropism in four steps.
- Light of wavelength 450 nm illuminates the plant.
- The photoreceptor receives the light, reacts to it, and initiates a response.
- Auxin moves to a darker side in the stem when exposed to light.
- Auxin releases hydrogen ions in the shaded region of the stem which causes a decrease in pH, activating expansion.
List three importance of light for plants.
- Essential for Photosynthesis
- Energy Storage
- Influences Growth
