Amutant version of mouse-ear cress (arabidopsis thaliana) has been engineered to convert it from a long-day plant to a short-day plant. what is responsible for triggering the development of flowers in this plant?

day length decreases back to a critical length, causing an appropriate decrease in pr : pfr ratio and increased expression of genes required for flowering.

day length increases to a critical length, causing an appropriate increase in pfr : pr ratio and increased expression of genes required for flowering.

day length decreases back to a critical length, causing an appropriate decrease in pfr : pr ratio and increased expression of genes required for flowering.

day length increases to a critical length, causing an appropriate increase in pr : pfr ratio and increased expression of genes required for flowering

option c.

Explanation:

Long Day Plants- The plants which flower when the day length is longer than the critical day length(Plants physiological events such as seed germination, initiation of flowering, asexual reproduction are triggered by a photo-period of specific length, this specific period length is critical day length). Examples- Spinach, wheat and spring barley.

Short Day Plants- The plants which flower when the day length is less than the critical day length. Examples- Soybean and tobacco.

So, In short day plants a flash of red light (Pr) during dark period prevents flowering, and the effect is reversed by the flash of far-red light (Pfr). In case of long day plants a flash of red light (Pr) during night break promotes flowering and a flash of far-red light (Pfr) during dark period prevents flowering.

hence option c.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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colors do exist. the color of the sky is actually violet; humans percieve the color of the sky as blue.