Auxin enhances cell elongation in all of these ways except a. increased uptake of solutes. b. gene activation. c. acid-induced denaturation of cell wall proteins. d. cell wall loosening.

Video transcript

Welcome back. Here's our next question, Which one is not an effect of oxen in plants. Oxen is a plant hormone. That, as we recall from our content videos is involved in trumpism of plants, the bending of plants towards light towards gravity. And it's a pretty complicated process that goes on. So I'd like to just um we recall from our content videos um but I'd like to just kind of briefly summarize it so that we can think of all these steps going on before we evaluate our answer. Just got our little tiny diagram here, so we can think of our plant cell with a rigid cell wall around it. Well, the first thing we're going to see happening with oxen, oxen activates jeans, four proteins that cause hydrogen ions to be pumped into the cell wall. So we're going to look at our diagram just to remind ourselves, we see hydrogen ions that positive charge and they are being pumped inside the cell wall. So now imagine our cell wall with a bunch of hydrogen ions in there. Well, the result of that is if we recall our cell wall is made up of cellular strands that are packed very tightly together by hydrogen bonds between the strands when we pump all those protons in there that breaks the hydrogen bonds between cellular strands. Well, since those hydrogen bonds are what's holding them together so tightly so that no little water molecules or anything like that can enter. Now we've broken those bonds so we end up creating gaps where water molecules can enter the cell wall. So we've now along with our hydrogen. We've now got extra water molecules in here packed into the gaps between the cellular strands. Well that change from having tightly packed strands to having these gaps with water entered into them. The end result is that the cell wall lucents or becomes more plastic. So that's kind of this first stage of this whole process. Now, I'm gonna go back to our diagram so we can think about what else might be the result of what's going on here. What we've jumped, pumped all these positively charged ions into the cell wall and we've created an electrochemical gradient between the cell and the cell wall and to try and equalize that. What we're going to have is potassium ions which are also positively charged diffusing across into the cell. Down that electrochemical gradients. So now we've just taken up a bunch of positively charged potassium ions into our cell. Well, what happens when we increase the concentration of a saw, you like potassium? We've got somebody else coming into the cell. Water diffuses into the cell by osmosis to try and diffuse to try and decrease the concentration of that potassium Well, we've got water entering a cell, the cell enlarges as a result of that water entering into it. So our final step here is the cell is sort of swelling up with water. We've got the cell and large is and as that sell enlarges it is able to do that because it used to have a rigid cell wall again around it. The cell wall now looser allows the cell to elongate where before it was held in place. So the end result of this whole oxen process is that our cell can elongate. So in areas where there's more oxen you're going to see cell elongation which allows that trumpism to happen. So with that in mind let's look through our answer choices and evaluate them. So Choice A. Says it increases cell elongation. Well as we just discussed, yes our cell gets larger are looser cell walls allow the cell to elongate so that is a result of oxen and effective oxen. So it's not our answer. Choice. Choice B says it activates genes involved in cell elongation. While the beginning of this whole process we began with oxen activating the genes for the proteins that cause that hydrogen to enter the cell wall. So that is also an effective oxen. So we eliminate Choice B. Choice C says it increases the plasticity of the cell wall. Well yes we saw that that as a result of the breaking of the hydrogen bonds between the cellulose the cell wall is loosened. It becomes more plastic so that is not our answer either since that is also an effective oxen. And finally we C. Choice D. Says it decreases the uptake of salutes. Well we saw here the cell has an increased uptake of potassium of that salute. So we do not see a decrease but an increase in the uptake of salutes, so that is not an effective oxen, and therefore Choice D. Is our correct answer. So Choice D decreases the uptake of salutes is not an effect of oxen implants. See the next video.