The signaling molecule for flowering might be released earlier than usual in a long-day plant exposed to flashes of a. far-red light during the night. b. red light during the night. c. red light followed by far-red light during the night. d. far-red light during the day.

Video transcript

Hello everyone. Let's look at our next question. It says flowering is induced earlier than usual when blank as exposed to flashes of red light at night and we have choices of a long day plant, a short day plant a day neutral plant or any plant. Well we know we may be talking about long and short day plants and when we're talking about the response of plants to light and particularly red light, we need to talk about the phyto chrome's, the proteins that have to do with the amount of light and induction of flowering. So our fighter crown, which we're gonna indicate with a P. Exists in two forms. We have P. R. Which is an inactive form and our other form is called P. F. R. Which is the active form. And those subscript refer to the fact that PR responds to red light and PF are too far red wavelengths of light. So when this are inactive PR form is exposed to red light. Whether directly on our problem we have it directly exposed to red light or it's exposed to sunlight. There's many red wavelengths of light and sunlight. It is converted to the inactive form. If it's exposed to far red wavelengths of light, it's converted back to the inactive form. Also in during hours of darkness, this P. F. R. Form is slowly converted back to the PR form in darkness. So when we talk about the induction of flowering we look at the ratio of the amount in this P. F. R. Active form to PR win. This ratio is higher. So either by so by our amount of P. F. R. Being higher or amount of pr getting lower. That promotes flowering in the long day plants. It inhibits flowering in the short day plants. And this makes sense if we want to think over it really quickly because in long day plants they flower when they're shorter hours of darkness, fewer hours for this active form to be converted to the inactive form. So this P. F. R. Amount will be higher and vice versa for short day plants. Short day plants flower as the hours of darkness are more. More of this PF are being converted to the pr that denominator getting larger. If R. P. F. R two P. R ratio decreases. That promotes flowering in short day plants and inhibits flowering in long day plants. So with that in mind let's go back to our problem in our problem. It says our plants are exposed to flashes of red light at night well at night instead of the darkness, causing P. F. R. To go down and pr to go up. We've now shown red light which converts more of the pR into P. F. R. So we have our amount of PF are going up with the results that our ratio is increasing and we know that when this ratio increases, we're looking at flowering is induced earlier is what our question is asking about which kind of plant has flowered induced earlier. Our ratio increases. We promote flowering in long day plants. So the answer to our question, flowering is induced earlier than usual. When blank, that blank should be a long day plant. So that is choice a a long day plant. So when a long day plant is exposed to flashes of red night light at night, flowering will be induced earlier. Just looking at our other choices briefly. Short day plant as the opposite effect. So that's not our answer. A day neutral plant will flower at a certain time, regardless of the amount of light. It won't be affected by that red light. And choice D. Says any plant. Well, again, that will not be the case for a short day or day neutral plants. So choice D. Not our answer. So again, choice a long day plant is the answer here. See you in the next video.