<p>I have a copy of the book for AP Bio. I haven’t really used it yet, but just scanning through it several times, it seems decent. It’s really general and brief compared to Cliffs, so don’t expect a lot of details. But it is targeted toward concepts are frequently tested on the exam.</p>
<p>[ul][li]Which of the following causes stomates to close?[/li][list]<a href=“A”></a> Stimulations of the blue light sensor in the guard cells
<a href=“B”></a> Active transport of H+ out of the guard cells into the surrounding cells
<a href=“C”></a> Depletion of CO2 within the air spaces of the leaf
<a href=“D”></a> Increase in sunlight
<a href=“E”>*</a> Increase in the abscisic acid in the guard cells[/ul][/list]</p>
<p>Hard choice between B and E. B sounds right because ions or a solute is flowing out meaning that water will flow out and it will close… tough choice</p>
<p>It is E. There are three main events that cause stomates to close: a lack of water, an increase in temperature, and an elevated concentration of abscissic acid.</p>
<p>Letter choice B is characteristic of the opening of stomates.</p>
<p>No… My book said when the stomata needs to open K+ ions or something flow into the cells of the guard cells. This creates a hypertonic solution and thus results in water flow INTO the cells, thus making the turgid. The increase in size puts pressure on the stomata and opens it. (This is from my Campbell reece book. I can find it later if you really want me too. haha)</p>
<p>Letter choice B considered the effect of the transport of *protons<a href=“H+”>/i</a> out of the guard cells, not K+. Stomate opening does indeed correlate with the transport of H+ out of guard cells, rendering option B incorrect. But yes, you are correct that the transport of K+ into the guard cells would stimulate stomate opening. But we were after a process that would faciliate their closing, which is true of the scenario in choice E.</p>
<p>Yeah, but we have to explain the evolutionary basis. I guess I could write about oxygen and photosynthetic activity with cyanobacteria, but it would be very rudimentary. I just read over my book twice and I see no evoluntionary basis.</p>
<p>My very rudimentary understanding is that bacterial flagella respond depending if they are in an isotonic, hypertonic, or hypotonic solution and beat their flagella at random until they are somewhere where they are “happy” this would be chemotaxis</p>
<p>Phototaxis happens in protists such as euglenids i believe where a certain wavelength of light hits their eyespot and causes their flagella to move towards the light (I suppose it could be away from light but i wouldn’t know why they would)</p>
<p>An example of the an advantage of chemotaxis might be: You are in a solution low in ionX so you beat you flagella till you are a solution hgh in ionX
phototaxis:You move towards the light, above your competitors=more light=more foood=more reproduction=you go on to outcompete everyone and become a new species congrats.</p>