Questions and Answers
What is the effect of a high Pfr concentration on flowering in short day plants?
Inhibits flowering
What happens when a flash of far red light is applied after a flash of red light?
The effect of red light is cancelled
What is the role of Pfr in regulating flowering in plants?
It activates the flowering hormone (florigen)
What is the effect of a light interruption on the dark period in plants?
Signup and view all the answers
What is the specific response of plants to the last flash of light?
Signup and view all the answers
What is the name of the nervous system that is stimulated when an individual is scared or in a fight or flight situation?
Signup and view all the answers
What is the result of the unequal distribution of ions between the interior of cells and surrounding fluid?
Signup and view all the answers
What is the primary function of the sympathetic nervous system in a fight or flight situation?
Signup and view all the answers
What is the term for the charge difference, or voltage across the plasma membrane?
Signup and view all the answers
What is the main reason for the division of plants into short-day, long-day, and day-neutral plants?
Signup and view all the answers
What is the effect of the sympathetic nervous system on the digestive system in a fight or flight situation?
Signup and view all the answers
Which type of plant flowers when the dark period is longer than the critical night length?
Signup and view all the answers
What is the term for the state of the neuron when it is not actively transmitting a signal?
Signup and view all the answers
What is the minimum duration of uninterrupted darkness required for flowering to occur?
Signup and view all the answers
What is the role of phytochromes in plants?
Signup and view all the answers
What happens if the duration of the night is longer than the critical night length but is interrupted by light?
Signup and view all the answers
Which type of plant flowers when it reaches a certain stage of maturity, regardless of the day length?
Signup and view all the answers
Study Notes
Plant Photoperiodism
- High Pfr (far-red light) concentration inhibits flowering in short-day plants (SDPs) but stimulates flowering in long-day plants (LDPs)
- Pfr is converted from Pr (red light) and activates the flowering hormone (florigen)
Types of Photoperiodic Plants
- Short-day plants (SDPs): flower when dark period is longer than critical night length (e.g., some soybean varieties, Chrysanthemums)
- Long-day plants (LDPs): flower when dark period is shorter than critical night length (e.g., Iris)
- Day-neutral plants: flower when they reach a certain stage of maturity (e.g., Spinach)
Critical Night Length (CNL)
- Minimum length of uninterrupted darkness needed to determine flowering
- Duration of night length controls flowering in photoperiodic plants
Light Interference with Photoperiodism
- A flash of red light shortens the dark period, promoting flowering in LDPs
- A flash of far-red light cancels the effect of red light, inhibiting flowering in SDPs
- The last flash of light determines the response of the plant to the dark period
Neuron Structure and Action
- Similar structure and action, but often antagonistic effects
- Rest and digest (parasympathetic nervous system) vs. fight or flight (sympathetic nervous system)
Membrane Potential
- The charge difference or voltage across the plasma membrane due to unequal ion distribution
- Inside the cell is negatively charged relative to the outside
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
