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Questions and Answers
What is the effect of a high Pfr concentration on flowering in short day plants?
What happens when a flash of far red light is applied after a flash of red light?
What is the role of Pfr in regulating flowering in plants?
What is the effect of a light interruption on the dark period in plants?
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What is the specific response of plants to the last flash of light?
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What is the name of the nervous system that is stimulated when an individual is scared or in a fight or flight situation?
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What is the result of the unequal distribution of ions between the interior of cells and surrounding fluid?
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What is the primary function of the sympathetic nervous system in a fight or flight situation?
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What is the term for the charge difference, or voltage across the plasma membrane?
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What is the main reason for the division of plants into short-day, long-day, and day-neutral plants?
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What is the effect of the sympathetic nervous system on the digestive system in a fight or flight situation?
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Which type of plant flowers when the dark period is longer than the critical night length?
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What is the term for the state of the neuron when it is not actively transmitting a signal?
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What is the minimum duration of uninterrupted darkness required for flowering to occur?
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What is the role of phytochromes in plants?
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What happens if the duration of the night is longer than the critical night length but is interrupted by light?
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Which type of plant flowers when it reaches a certain stage of maturity, regardless of the day length?
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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
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Description
Explore the role of light in regulating flowering in plants, including the effects of red and far-red light on phytochrome-mediated responses. Learn how high Pfr concentrations influence flowering in short-day and long-day plants.
