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General Biology

Learn the toughest concepts covered in Biology1&2 with step-by-step video tutorials and practice problems by world-class tutors

9. Photosynthesis

Review of Photosynthesis


Recap Map of Photosynthesis

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in this video, we're going to do a review of our lesson on photosynthesis by recapping our map of the lesson on photosynthesis, which is down below right here. And so, really, in this video, there's going to be no new information covered. It's all going to be review information from our previous lesson videos. And so if you're already feeling really, really good about photosynthesis, then really you can feel free to skip this video if you like. Because again, there's no new information in this video. It's only gonna be review information. However, if you're a little bit hesitant about photosynthesis or are photosynthesis lesson, then feel free to stick around because this video could be very helpful for you. Now, that being said again, we're gonna recap our map of the lesson on photosynthesis, which is down below right here. And of course, we know that photosynthesis is going to occur inside of the chloroplast of plants here, and so this image that we have in the background represents the chloroplast, and we know that we've been following this map of the lesson on photosynthesis by following the left most branches first, and we talked about photosynthesis occurring in two stages. The first stage was the light reactions, and the second stage was the Calvin cycle. And so we talked about photosynthesis occurring under the conditions where the stone mata of the plant or the leaves were in an open position and recall that the stone mata air, the openings or the pores, or the holes that are found in the leaf that control gas exchange between the leaf itself and the outside environment. And so here we have this tomato and an open position so gas exchange is able to occur. Carbon dioxide gas can diffuse in and oxygen gas can diffuse out. And also water vapor can also diffuse out if the temperatures air too hot. Now. The light reactions is the first stage of photosynthesis, and the light reactions occur in the Thill. A coid of the chloroplast and the pillow coins are those green pancake looking structures that you can see here in the background behind this image. And so the light reactions, as their name implies, is going to use photons of light from our sun, and those photons of light are going to be absorbed by pigments that are found in photo systems and recall There are two photo systems. There's photo system to followed by Photo System one, and ultimately, the light reactions are going to split water molecules. What you see here it takes water molecules, and it splits them to oxidize them to remove electrons from them. And those electrons are going to make their way through an electron transport chain and ultimately be used to generate N a. D. PH this electron taxicab. And as water molecules get split, it creates oxygen gas, and this oxygen gas is the oxygen that's associated with the photosynthesis on photosynthesis producing oxygen. And this oxygen here could either be used by the plant to drive aerobic cellular respiration. Or this oxygen would just diffuse right out of the schtum otta and leave the plant into the outside environment. Now recall that when it comes to the light reactions, we had this interesting story that would help you guys remember the most important components and the most important steps off the light reactions in the correct order. And that was to remember Luke and Ryan. And so Luke and Ryan is supposed to represent the light reactions, and Luke and Ryan they wanted to play their PlayStation to their photo system to, but then they realized that they couldn't find their electronic controllers. And so, uh, the electrons make their way through an electron transport chain. And so then they decided to play their PlayStation one or their photo system one. And then ultimately they realized that their mom had reduced the number of games that they had for their PlayStation one. And that represents the reduction of N A. D P plus into any DPH. And so then Luke and Ryan decided to play Thio, just study chemistry, and the key Me in chemistry represents the Kimmy and Kimmy Oz Moses. And so Kenya's Moses ends up producing the 80 p that's associated with light reactions. And so, ultimately, the light reactions are going to use photons of light and water as reactant and as products. What ends up getting made is oxygen gas as well as any DPH and 80 p. And this n a d. Ph in a teepee is gonna be the energy that's used to power. The Calvin Cycle, which recall the Calvin Cycle, is the second stage of the photosynthesis, and the Calvin cycle occurs in three phases. There is the carbon fixation phase, which uses rube isco theme enzyme that is going to affix carbon dioxide to the starting molecule. Are you BP? And ultimately, the first stable three carbon molecule that's generated is going to be, uh, PG a, uh which is not shown here in this image. But ultimately, PGA is gonna be converted into G three p in this second stage of the Calvin Cycle. G three p synthesis and G three p is the precursor that's needed to create glucose. Who's, which is a sugar that we can see down below right here and then ultimately, the remainder of the G three p is gonna be utilized in this final stage of the Calvin cycle. Are UBP regeneration to regenerate the original molecule? Are you BP? And so one way to help you remember the Calvin cycle was to remember Calvin's can of sugar, and so the can of sugar, the C A n and can were reminding you of the reactant the sea and can remind you of the sea and carbon dioxide. The A n um, can remind you of the A and 80 p and the n and can remind you of the n and N a. D pH. And so a teepee ntd, pH and carbon dioxide are all used as react INTs, and ultimately the product is going to be sugar. And so you think of Calvin's can of sugar, and that can help you remember the Calvin Cycle and, of course, the Calvin cycle. When it uses the 80 p and any DPH those high energy forms, it will convert them into their lower energy forms a, d, p and N a. D p plus, which are needed by the light reactions so that they conform the higher energy version forms. And so this year concludes this entire left hand side of the branch. And so, after we had talked about the normal conditions for photosynthesis, where this the mod are open, then we decided to talk about what happens if the temperatures are too hot and this the model are closed to prevent dehydration. Well, under those conditions, we had talked about photo respiration occurring and how photo respiration occurs mainly in C three plants. But some plants have been able to evolve solutions to this photo respiration problem, which wastes energy in the form of a T, p and N a. D. PH to make carbon dioxide. And so the the plants that have evolved the ability to avoid photo respiration are the C four plants and the camp plants. And these are the same images that we had utilized in our previous lesson videos to discuss these and so recall that the C four plants, uh, kind of sound like a C four explosive. And the C four explosives are gonna bring things into pieces. And so the C four plants have two pieces. They have the mess of Phil cell, and then they have the bundle sheath cell where they separate the light reactions in the Calvin cycle. Good. And ultimately, the cam plants you think of a camel wearing pajama is here. And that can remind you that the camp plants they're going to be found in really, really hot, dry environments like desserts. And that, uh, because the camera was wearing pajama, is that carbon fixation is going to occur different times of the day. You got carbon fixation occurring at night and carbon fixation occurring during the day as well. And again, this is just a recap of what we've already covered in our previous lesson videos. And so this here concludes our recap of the map on photosynthesis, and we'll be able to get some practice applying the concepts that we reviewed here as we move forward. So I'll see you all in our next video.

Review of Photosynthesis Example 1

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all right. So here we have an example problem that wants us to complete the following diagram that's down below by filling in all of the blanks. And so notice that this diagram has the light reactions over here occurring inside of the pillow, coy IDs. And then it has the Calvin cycle over here occurring in this Troma. And so really, what we need to recall from our previous lesson videos is that the light reactions is, of course, going to use light as one of the reactant. And not only does it use life, but it also uses water as one of the reactant since, and so ultimately, in terms of the products of the light reactions, it ends up producing oxygen gas, or 02 and then it also ends up producing chemical energy in the form of ATP and N a. D. PH. And this 80 p and N a. D. PH is going to be utilized by the Calvin Cycle Azaz energy source to drive the reactions. And so the Calvin cycle over here, which is occurring in the strom of the chloroplast, is going to utilize carbon dioxide gas as a reactant or co two as a reactant, and ultimately it's going to utilize the 80 p and N a. D pH along with the CO two, and it's going to be able to produce glucose as one of the products here. And, of course, as it consumes the A t p and N a. D pH. It's going to convert them into their lower energy forms. So that would be a D. P and N a. D p plus. And so ultimately, this is filling out the entire diagram here to review the two major stages of photosynthesis, the light reactions and the Calvin cycle. And so this here concludes our example problem, and I'll see you all in our next video.

All of these are similarities between the light reactions in photosynthesis and the electron transport chain/chemiosmosis in cellular respiration EXCEPT which of these answers?


A key difference between aerobic cellular respiration and the light reactions of photosynthesis is (are):