This eighth-grade science lesson is about the digestive system. Specifically, it focuses on saliva and the breakdown of starch into sugar. It is the 11th lesson in a sequence of 28 lessons on systems and the animal world. The lesson is 51 minutes in duration. There are 34 students in the class.

00:00:14Uh, today let's summarize the results of the experiment we did yesterday, such as what happened to iodine and what happened to the Benedict's solution.
00:00:26And then, things we understand from these results. On the right side of the report sheet there are two items writte, (1), (2)
00:00:33(1) is what is learned from the iodine reaction.
00:00:39(2) is what is learned from the Benedict's solution reaction.
00:00:43I want you to summarize these two. I want you to discuss it in a group, but, don't form groups yet.
00:00:54Uh, based on your results, we will eventually have a class summary.
00:01:00Since it will be written down in your notebooks, please write the title of the experiment in your notebook.
00:01:55Now you are going to form groups and discuss, but there is one thing I want to confirm before that.
00:02:01That is Benedict's solution. Benedict's solution.
00:02:06If we say Benedict's solution, I think you all have it written down in your notebook but, what is it?
00:02:13Benedict's solution. Which one is it?
00:02:17What is it used for? Makoto. How about you?
00:02:21Benedict's solution. What do you think?
00:02:23It's not written in my notebook.
00:02:25It's not written in your notebook. I see. How about you, Tsuyoshi?
00:02:29It is used to detect sugar.
00:02:31Right. Yes. It is used to detect sugar. What do we do with it, Tsuyoshi?
00:02:38Heat it.
00:02:39Yes. Heat it. And then? What happens when we can tell that there is sugar?
00:02:43It turns red.
00:02:44It turns red.
00:02:46When it turns red. That's all right. It is red anyway.
00:02:49The material we used this time was a substance called starch, and the other one which will be detected by the Benedict's solution is sugar, right?
00:03:01I would like to touch on these two items just to explain something.
00:03:07The substance called starch- in the second year, science division one, which we studied in the first semester.
00:03:13All substances are made up of molecules. We talked about things like this, or like this, that are all made up of molecules.
00:03:24But starch is- well, starch is also made up of molecules, but the molecules of starch are like this, long molecules, like this. Longer and longer. Long molecules.
00:03:40At a glance, starch is a huge thing. The molecules are long. That's how it looks.
00:03:47But on the other hand, sugar's molecule is short. Its molecule is short. At a glance, the molecule is small compared to starch.
00:04:01When we include these issues in our consideration, the discussion will be easier.
00:04:07So, today, you will form groups.
00:04:11Uh, this... this needs to be focused... uh... yes.
00:04:17This is same as your report sheet.
00:04:19Summarize the result of your group, how the iodine reacted from A to D and how the Benedict's solution changed.
00:04:31Four of you will summarize the results of groups one, two, three, four, etc. After that, summarize the results.
00:04:39(1) What we can study from the iodine reaction; (2) what we can study from the Benedict's solution.
00:04:44Four of you, or maybe if you have five people, the five of you think together and summarize it. I will let you present it later.
00:04:50All right, I will let you form groups. Go ahead.
00:05:04Unless you move it in this way... this one is... oh, like this. That's good. Very good.
00:05:21What were the results in this group?
00:05:24I have them written here.
00:05:31I see.
00:05:51That's good, right? This group is almost all at a good position.
00:05:58What can we say from this?
00:06:02A and C are... what is this? Black? Iodine does not become black in a reaction.
00:06:09It was blackish, right?
00:06:11//Well, blackish-
00:06:12Bluish purple.
00:06:13Yes. This is a stage in which the bluish purple is very dark.
00:06:15Dark purple.
00:06:18Do we write down the things to consider?
00:06:19Yes. Think about the things to consider. Think about the things to consider.
00:06:22And this part... these are supposed to have starch but... they are pale purple or white. Not white, rather transparent, I think.
00:06:33Why did they become like that?
00:06:37That's what you should consider.
00:06:40Maybe because it cooled down.
00:06:42Tsk. If iodine reaction- it reacts to iodine, does it mean it has starch or not?
00:06:48It has.
00:06:49It means it has starch, right? That means, in A and C, there is only starch to begin with, so it is natural that they are bluish purple.
00:06:59It is B and D you have to think about.
00:07:02In B and D, what else is in there besides starch?
00:07:06Saliva is in there. Because saliva did something to the starch, they became like this, right?
00:07:12Became like this, right?
00:07:13That's what I want you to think about.
00:07:16And what are the conditional difference in the experiment between B and D?
00:07:22What was the conditional difference between B and D?
00:07:23Hot water and uh-
00:07:24Ice //water.
00:07:25//ice water.
00:07:26//ice water. This one is warm. This one is cold. From these differences summarize your results.
00:07:38The bluish purple is no longer bluish purple. That means the starch is?
00:07:43That means the starch is gone. How?
00:07:48By hot water.
00:07:49By hot water?
00:07:51How about this group?
00:07:55This group also had a good result.
00:07:59But teacher, this one became pale reddish brown.
00:08:05Well, pale reddish brown is sort of okay... they became a somewhat similar color, right?
00:08:15But this one is orange.
00:08:23Let me see... look, does the fact that they became bluish purple- they are bluish purple- mean they have starch or not?
00:08:34They have.
00:08:35They have, right?
00:08:36A and C only have starch. Since they have nothing but starch, it is natural that they become bluish purple.
00:08:45But in B and D, especially B, the bluish purple became pale. The fact that the bluish purple became pale means what happened to the starch?
00:08:54It dissolved.
00:08:55It dissolved or, in other words, the starch is disappearing, right?
00:09:00In B and D, especially in B, what did we add?
00:09:05What did we add?
00:09:07What did we add to B?
00:09:08Benedict's solution.
00:09:11We put spit in B. Spit, right? Slimy saliva.
00:09:14That's what we added, right?
00:09:16Then saliva is doing something to the starch.
00:09:22It's all right to say dissolved or some kind of expression like that. From that, saliva (does what) to the starch?
00:09:37Oh, one more thing. B and D are the same. They both contain saliva and starch. What is the conditional difference in the experiment?
00:09:46Hot water and cold water.
00:09:47That's right. Hot water and cold water. From that//-
00:09:48//Teacher, that part is (inaudible).
00:09:51Huh? Does this have a hole here?
00:09:54Work hard. If you include that, I think you will have a good summary of the study.
00:10:02Well, well.
00:10:06What is it?
00:10:09This group's results... This group's results are super.
00:10:15If you cannot write a summary of the study from this good result, you are-
00:10:20[mimetic expression]
00:10:22You mean (inaudible)?
00:10:24Did I say a thing like that?
00:10:26No, no.
00:10:27Well, so... should we look at it from here?
00:10:31Well, A and C became all bluish purple, right?
00:10:37Does that mean that there is starch or not?
00:10:41There is.
00:10:42There is, right? From the beginning to the end, there is always starch in these.
00:10:45But in B and D, a difference appeared. In B and D, although both have starch, we added something special. What was that?
00:10:55Saliva. Only those test tubes which have saliva have such a result.Especially B has a distinct change. It did not turn to bluish purple. That means what happened to the starch?
00:11:05There is none.
00:11:06Yes. The starch disappeared. The starch disappeared.
00:11:09Saliva blah blah blah.
00:11:15The one which we warmed up.
00:11:16Yes, that's it.
00:11:18A, B.
00:11:19This is the one which we cooled down.
00:11:20Well noticed. The conditional difference between B and D in this experiment is this one is warm, this one is cold.
00:11:27If you compare the speed in which the starch disappears, which is faster, B or D?
00:11:33B is faster. That means... (inaudible). You must be able to figure it out.
00:11:40One more push?
00:11:42If you can summarize this result, you are in perfect shape.
00:11:45Very good. Very good.
00:11:48Okay, this group.
00:11:55Looks good, looks good, looks good. Good. Good.
00:12:13When we looked at it... everyone look, all right?
00:12:17A and C got all bluish purple, right? Does that mean that there is starch or not?
00:12:26There is.
00:12:27There is, right? Because they turned to bluish purple. A and C have starch only, so it is natural to have an iodine reaction.
00:12:34But B and D... especially in B, a change has occurred.
00:12:40B has starch plus, like it is written here, saliva.
00:12:45B's test tube which contains saliva changed from bluish purple to not changed to bluish purple... that's an odd way to say
00:12:53It no longer turned to bluish purple, that means starch disappeared due to the saliva, right?
00:13:06It will be good if you can write things like that in the summary of the study.
00:13:09In addition to that, this group noticed that in comparing B and D, D did not turn pale around here, did it?
00:13:19It may have.
00:13:20It may have?
00:13:22Around here, only here became pale.
00:13:24It became pale? The conditional difference between B and D is the temperature, right? You noticed the difference in the temperature, right?
00:13:34That's a good point. That's good. In addition to that... which one had Benedict's solution... Oh, they became the same color?
00:13:44In that case, it will be difficult to write the summary of the study, huh?
00:13:48Well, well, well, well, well.
00:13:52Look. Look.
00:14:05These are (the results of) one group.
00:14:14Both of yours got this color?
00:14:20Well, if (your results) are like that, you cannot write the summary of the study. Since they turned to the same color, you cannot compare.
00:14:27This other group got these results. Why don't you think about it from these?
00:14:30Only B is reacting. We cannot say from this that A has reacted. From these (results), think about parenthesis two of the study. Only B has reacted.
00:14:52How about this group? Oh, nothing. What happened?
00:14:56We don't understand. We don't understand.
00:14:59You don't understand. Well then should we do it together?
00:15:02You have nice results, you know? Here we go.
00:15:06A and C all turned to bluish purple, right?
00:15:11Does that mean they have starch or not?
00:15:15They have.
00:15:16They have, right? From the beginning to the end, they all have starch.
00:15:18However, B and D, especially B here, lost its bluish purple color.
00:15:26B has starch in it just as A and C, but it has something plus starch. What does it have?
00:15:32Yes, saliva. In the one which contains saliva, the bluish purple is no longer bluish purple. That means, the starch... due to the saliva-
00:15:46Got eliminated.
00:15:47Yes, yes. Something like that.
00:15:48It got eliminated. Starch has disappeared. You can conclude like that.
00:15:57Can we write the starch is gone?
00:15:58Right, right. Expressing it like that is fine.
00:16:00Hm, that's fine.
00:16:06That's fine.
00:16:07That's fine.
00:16:09The guys have written nothing.
00:16:12I'm not a man!
00:16:14Oh, I'm sorry.
00:16:15Next, how about the Benedict's solution? It didn't turn reddish brown... Oh, I see.
00:16:21You put Benedict's solution in A and B, you put Benedict's solution in A and B, and when you heat it, only B has reacted.
00:16:28That means, what's in B?
00:16:30Sugar is in it. That means... as I said before... the starch in B has disappeared because of the saliva, and what is made?
00:16:41//Starch has disappeared.
00:16:41//Thank you. [play on words]
00:16:45You are welcome.
00:16:48How about this group?
00:16:50We have summarized most of it, even though we have not written yet.
00:16:55This sentence is wrong though.
00:16:57Whose answer is right?
00:16:58I don't know whether this is right or not, but we are summarizing by talking, and I did most of the summarizing.
00:17:04We were summarizing by talking.
00:17:06So, shall we check?
00:17:08Ah! These are wonderful results as well. If you cannot summarize these results, you are... Kenji-
00:17:17Well, when we look at this, A and C are all purple, that means that the starch has reacted. That means that there is starch in A and C till the end, right?
00:17:27But in B and D, (the circles) are colored red, which means that the starch has not reacted, iodine has not reacted, right?
00:17:33This means that in B and D, we put starch and saliva, but due to the function of saliva, starch has blah blah blahed, has blah blah blahed. What is it?
00:17:47Yeah, dissolved. In normal language, it has disappeared. We can understand that starch has disappeared due to the function of saliva.
00:17:57Then, what is the difference in the experimental conditions of B and D?
00:18:01Temperature. B is?
00:18:02Uh, 40 degrees.
00:18:03Body temperature.
00:18:04//Close to the body temperature.
00:18:04//Yes body temperature, and D is?
00:18:05Ice water.
00:18:05It's cold.
00:18:06Which has a faster rate of change in which starch becomes no longer starch, B or D?
00:18:13B is faster. That means that saliva's rate of effect on starch is... the temperature?
00:18:19Faster when it is closer to the body temperature.
00:18:20Ahh, wonderful. That's perfect.
00:18:24We said that before.
00:18:25In addition to that, which one becomes red brown?
00:18:31B. That means that while saliva changed the starch, what other than starch was made?
00:18:38Ah. Kenji.
00:18:40You have good friends.
00:18:42//Are we friends?
00:18:43//How about this group?
00:18:44I didn't know that we were friends.
00:18:50Are you writing now?
00:18:56Let me check it. Let me see. Let me take a look at Takashi's.
00:19:03This one, too.
00:19:04We did not do the first one.
00:19:05Oh, you didn't do the first one.
00:19:06This one, too.
00:19:10Ohh, it became reverse... Umm, what I want to check with you is that when they are bluish purple, when they are bluish purple. Does this mean they have starch or not?
00:19:25They have.
00:19:26They have, right? When they are not bluish purple, the starch is?
00:19:30Not there.
00:19:31Not there. Consider that. In the case of B, eventually, and in the case of D, from the beginning
00:19:38When we compare B and D, in both cases the starch disappears.
00:19:41Because of what? In B and D, there is starch plus what?
00:19:46There is saliva. You have to figure out what the saliva did. In addition to that, what was the conditional difference between B and D?
00:19:56Temperature. B is?
00:19:57Forty degrees.
00:19:58Forty degrees. D?
00:20:04That means that... saliva works differently depending on the temperature. What was that?
00:20:13You see that saliva works differently, right, depending on the temperature.
00:20:16And then, reddish brown... orange... oh, both changed...then it is hard to write the summary.
00:20:37Because you cannot proceed to the conclusion when you have the same reaction- this is from a different group by the way- only B has reacted. Only B became reddish brown.
00:20:48A did not react. I hope that you can come to a conclusion from this result. Right?
00:20:59What is it, Nishi-kun?
00:21:00I don't understand it.
00:21:03This group is left.
00:21:08What should we write in number two?
00:21:10Is it because starch is made, that sugar is made? No, is it because the starch has disappeared, that sugar is made?
00:21:16In the beginning of the class- look at that- the result of breaking up the long chain of starch is sugar.
00:21:28Is it sugar because the long chain has been broken up?
00:21:31Sugar is the result of what was originally big becoming small. Sugar. It is part of starch.//
00:21:35//Part of starch is sugar? Because starch disappeared, sugar is made?
00:21:40Well, you may say it in that way.
00:21:42What is the best way to say it?
00:21:45Well, we will summarize that at the end.
00:21:50Then, this group last. How is it?
00:21:53Sorry, sorry. Which one?
00:22:02Okay, Okay, you got the results. In this group, A and C are all bluish purple. That means, do these have starch or not?
00:22:10They do.
00:22:11They all have starch, right? Because they have only starch in them.
00:22:15But B and D are no longer just bluish purple. So when we look at it, as time passes, does the bluish purple get lighter or darker?
00:22:27It gets lighter, right? What's in B and D besides the starch? What is it?
00:22:32Right. What? Sugar?
00:22:33Not sugar.
00:22:35Saliva. Hideki's saliva was real gooey.
00:22:40That means, do B and D have or not have starch at one point?
00:22:45They do not.
00:22:46They do not. Starch is... because of what effect?
00:22:51Saliva's effect.
00:22:52That's right. Due to Hideki's saliva, starch has... disappeared. That's what you should write. Let me see.
00:23:08In addition to that, what is the conditional difference between B and D?
00:23:12Right. //Ice and
00:23:13//Ice and hot water.
00:23:14Yes, hot water. Which one is hot water?
00:23:16B. What about D?
00:23:19Yes. Are these the same? Oh, these are exactly the same.... I see....
00:23:25Then it is hard to write about the different temperature. Okay, then you can write only this part.
00:23:30You can summarize the part that due to saliva, starch became no longer starch.
00:23:34Lastly, Benedict's solution. It's good.
00:23:37Only in B, only in B, has Benedict's solution reacted. This means that in B the starch has disappeared and what was made instead?
00:23:50It will be good if you can summarize that part. Okay?
00:23:56All right, since it has taken a long time, I would like to listen to each group's result now. So, be ready to listen to everyone.
00:24:07Now, everyone's- Ayamoto-san, okay? I will ask the results of each group. First, how the iodine reacted? For example, A was like this, B was like that.
00:24:24Or A and C were the same... It will be good if you can present the results in that way.
00:24:27Rock, paper, scissors... Rock, paper, scissors will do.
00:24:34And number two. Benedict's solution. We added Benedict's solution to A and B and heated them.
00:24:41Please describe what happened. Up to this point are the results.
00:24:43The conclusion is next. First, I will ask you about the results. I think I first want to ask you about the results.
00:24:50Where should I start? The results.
00:25:01Shall we start here? There? There? Over there?
00:25:06Group four, shall we? Okay. I see. Let's start with group four. It doesn't matter where we start. All right, please tell us your results.
00:25:16Please listen. Hey, Ayamoto, this is the second time.
00:25:22Please go ahead.
00:25:23A, B... oops. A, C, and D were bluish purple the whole way through. //B became paler little by little.
00:25:28//Yes. All the wa-
00:25:31From which point did it start getting pale?
00:25:32From about the third one, it started //getting paler.
00:25:36//Yes. Yes. A, C and D are all bluish purple, but... Oh, please don't sit down yet. B started getting paler from about the third one. That was the report.
00:25:50And how about the Benedict's solution?
00:25:54The Benedict's solution in test tube A did not turn to reddish brown.
00:26:01B changed from blue to green, and when we kept heating it, it turned to reddish brown.
00:26:07That was a wonderful way to say that. It turned from blue to green, and when it kept being heating, it turned to reddish brown.
00:26:14So, in other words, B reacted. I see.
00:26:17Well then, group five. Please report your results.
00:26:28Go ahead.
00:26:34You only have to say it.
00:26:37A... The first one was bluish purple... and the second one did not change-
00:26:52Did not change, does that mean that it was bluish purple?
00:26:57And the fifth one was (inaudible).
00:27:00The fifth one? Did you just jump to the fifth? Huh?
00:27:07It became weaker and weaker.
00:27:09A got weaker and weaker? Huh? Is it reversed?
00:27:17Wait a minute. In which ones did you put saliva and starch?
00:27:22B and D.
00:27:23B and D. You put saliva in B and D, but A's color changed from purple to a weak purple, is that right? I see. And then?
00:27:31And B started losing its color after three minutes.
00:27:37This one, too, started losing its color?
00:27:42I see. Then?
00:27:46C... didn't change at all.
00:27:53All bluish purple. And?
00:27:56D... the color got weaker after 5 minutes. //The rest did not change.
00:28:01//After 5 minutes-
00:28:03The rest of the part were bluish purple. I see. Then what about the Benedict's solution?
00:28:12A became dark green, //and B was reddish brown.
00:28:18Ah, so only B reacted. I see. Group five has reported that A seemed to become pale, too. I see. Then, group six, please.
00:28:31A and C were bluish purple all the way, B changed from dark bluish purple to pale bluish purple-
00:28:43I see. Okay.
00:28:45D was bluish purple for about three minutes, and after that it slowly turned pale.
00:28:54I see. Then, what about the Benedict's solution?
00:28:58A and B both became reddish brown.
00:29:02I see, I see. Both of them became reddish brown. I see. Okay, group seven, please.
00:29:12A and C and D were all bluish purple, and B started off bluish purple and became lighter.
00:29:22From what point did it start getting lighter?
00:29:23From the beginning.
00:29:25Oh, I see, it got lighter from the beginning. I see. Then what about the Benedict's solution?
00:29:31Test tube A was pale reddish brown.
00:29:36Yes. Pale-//
00:29:37//And B, dark reddish brown.
00:29:40I see. Well... which one is the closest? This one I believe. Please take a look at this.
00:30:00This one is the same test results of students like you- I wonder which class it was? Class four, class five, or class three?
00:30:06The results of students like you in those classes.
00:30:11Although we heard slightly different test results in this class, basically A and C are all bluish purple. The reason is that we put only starch in A and C, right?
00:30:32So there is only starch and although the temperature is different, the starch remains starch from beginning to end.
00:30:41So, many of you have reported that the bluish purple continued all the way, although some have reported that it got pale around here.
00:30:51The question is B and D. The question is B and D.
00:30:55There is saliva in the starch in B and D. We see a reaction in both B and D; that is, their color eventually gets lighter.
00:31:07Does that mean there is starch or not?
00:31:11It's disappearing.
00:31:12It's disappearing, right? It doesn't, right? It is disappearing. The reason why is probably because we put saliva in them... that leads to our conclusion.
00:31:22In addition to that, when we look at B and D more carefully, the rate that saliva disappears, no, sorry, the rate that starch disappears, when we compare B and D, which is faster?
00:31:33B is faster, right? B is faster. What was the conditional difference between B and D?
00:31:40Temperature. B is... warm. As warm as body temperature. D is cold.
00:31:47When we compare these, this one works the best, and I think that it will be good if you can include things like that in the conclusion.
00:31:57And then there was such group... not this one, this one.
00:32:07This one also has similar results, right? A and C have only starch, so they are bluish purple all the way through.
00:32:15They put saliva in B and D, but in B, after about two minutes there was already no reaction for starch.
00:32:24There was no starch at this point.
00:32:26In D, the reaction to starch got weaker and weaker, and there was no starch at this point, then it revived. I don't get this. I wish this one weren't here.
00:32:38But we see the color got weaker and weaker.
00:32:43Then there is this one. This one is amazing. We discovered a new type of human.
00:32:50Do you see? A and C are okay. In B, it suddenly disappeared here. More over in D, the starch suddenly disappeared here.
00:33:03I won't say whose it was. It was Hiroshi Wakai's.
00:33:08All right. Anyway, all you need to understand is in B and D, the starch has changed to something else.
00:33:17In addition to that, we added Benedict's solution. We put Benedict's solution in A and B.
00:33:23Look at this. I think it should react and become something like this.
00:33:28A has only starch in it.
00:33:32From this color, we cannot say it has reacted, when we put this against a florescent light and look at it through the light.
00:33:40This one did. It got thicker and became reddish brown. It is the color of carrot juice.
00:33:47When it reacts like this, we can judge that there is sugar in it. Actually, there seems to be sugar in B.
00:33:56I wish to include this content in our conclusion.
00:34:02First, the conclusions from the results of the iodine reaction. Second, the conclusions from the results of the Benedict's solution. These two. Can you present them?
00:34:21We had eye contact. Group eight? Please.
00:34:30The iodine reaction: When saliva is mixed with starch, it becomes no longer starch.
00:34:37And the rate in which starch disappears is faster when we heat it.
00:34:40Mm, mm, mm.
00:34:42Concerning the reaction to Benedict's solution, when starch is mixed with saliva, sugar is formed.
00:34:49That's it.
00:34:50Mm, that's it? I see. That's good. That's good. That's good.
00:34:58Next, group one. Can you do it?
00:35:07Ryuutaro? or //Takashi?
00:35:08//Is only the first point, okay?
00:35:10The first point.
00:35:11Only the first point. That's fine. Since the conclusion is difficult. Okay, go ahead.
00:35:14When we compare test tubes A and B, A does not change, but the starch in B, in which saliva is added-
00:35:29The starch in B was dissolved by the saliva little by little. Yes. Yes. That's fine. When we compare A and B, we can see that in B, in which saliva was added, the starch has dissolved little by little. Okay. That's fine.
00:35:41Okay, group two.
00:35:47What do you mean by, "uh"?
00:35:49Human's saliva has a function of dissolving starch. And the closer its temperature is to body temperature, the faster the rate.
00:36:02B- oops- the second point is that the human saliva has the function of changing starch into sugar.
00:36:14Haa. I am amazed. Wonderful.
00:36:18Actually, I am the one who summarized it.
00:36:23I see. That was a nice presentation. It was very logical, good conclusion. Then, how about the group three?
00:36:33In terms of the reaction with iodine, the one with saliva became less and less starchy.
00:36:41Then, in terms of the reaction with Benedict's solution, by adding saliva, starch became sugar.
00:36:52Yes. I think it's very good. This was also a nice presentation, don't you think? I think it's good.
00:36:57Well then, I will summarize each group's presentation into sentences, so please write them down in your notebook. I think we can summarize like this.
00:39:18Oh, maybe it is hard to see. Should I lower this?
00:39:26Teacher, I think the OHP is not very useful.
00:39:28What are you talking about? I pointed to them like this.
00:39:31Isn't it faster to use that one? Rather than using the heavy OHP?
00:39:32No, you don't understand it. Because of this everyone understood well. Well, don't say that.
00:39:45Ok, did everyone finish writing?
00:39:48Um, from this experiment, we can see these two things, as you all noticed.
00:39:55The first one is that saliva seems to have the function of changing starch into something else.
00:40:03Saliva may have a function which changes starch into something else.
00:40:09Moreover, from the iodine reaction and Benedict's solution's reaction, starch into something else- so, what is it? Sugar. We wonder if there is a function of changing starch into sugar.
00:40:23As I said in the beginning of the class, starch is a long chain. A long molecule. At a glance, it is a huge molecule.
00:40:32But sugar is a small molecule. A short chain. From this, we understand that saliva has the function of breaking a big chain of starch into a small chain of sugar.
00:40:50Next, the second point. Um, from the conditional differences between B and D, the difference in the temperature,
00:40:59I think we understand that saliva works best when the temperature is close to body temperature.
00:41:10All right, please open your textbooks to page 94. There will be a part you should underline. So be prepared and listen.
00:41:22All right, we will start. Page 94.
00:41:29After "from experiment two," please underline.
00:41:33"Starch is dissolved by saliva and changes into sugar." Please underline up to this point. "Starch is dissolved by saliva and changes into sugar."
00:41:48Next you don't have to underline. "Also, because this sugar's molecule is smaller than starch, it can go through cellophane membrane." Okay, underline after this.
00:41:58"Other than saliva, such fluids as gastric juice and pancreatic juice, which have the function of digesting food, are called digestive fluid." Underline up to here.
00:42:09Next. This will be a long one too.
00:42:12"In digestive fluid..." Underline here, "In digestive fluid, there are different kinds of digestive enzymes.
00:42:18"Under appropriate temperature it dissolves components in food and changes them into nourishment which is easily absorbed."
00:42:28Mm. Our textbooks are all marked with red now.
00:42:32The next (section) too. This is all important. This page will be all marked with red. Sorry. Underline the next (section).
00:42:36"Each digestive enzyme dissolves particular food components such as: digestive enzymes in saliva (amylase) work on starch,
00:42:41"digestive enzymes in gastric juice work on protein, and so on." Underline up to here.
00:42:53It was a long explanation, but I will summarize for you to write in your notebooks. Since it is hard to understand otherwise.
00:46:18//Can you see it?
00:46:57I wonder whether people can see at the bottom. Chiho, can you see this?
00:47:01Can you see this?
00:47:03Can you see? Sorry.
00:47:07Can you see this part, gastric juice?
00:47:09You can. Sorry. This is very low.
00:47:28Are you all right? Oh, I should underline here.
00:47:47Today's topic, saliva. Which has the function of dissolving starch into sugar. Saliva.
00:47:54Saliva is called digestive fluid. Digestive fluid. Fluid to dissolve starch into sugar. Saliva is digestive fluid.
00:48:03Fluid which digests food is called digestive fluid. Digestive fluid is not only saliva. There is gastric juice which is in the stomach.
00:48:13When you throw up, you have a sour taste in your mouth. That's gastric juice. Go deeper down and we have pancreatic juice in the pancreas, or bile in the gallbladder, and so on.
00:48:26We call these fluids, which digest food, "digestive fluids." In addition, in the digestive fluids, there are digestive enzymes.
00:48:37We read this as "enzymes." You didn't write "oxygen" in your notebook, did you?
00:48:44Are you okay? It's not oxygen. It's enzymes. Okay? Chinese characters?
00:48:51In digestive fluid, there are digestive enzymes. These digestive enzymes are determined by the food components they dissolve.
00:49:02For example, saliva works only on starch, which we experimented with this time. You must have learned in home science.
00:49:07Five major nutrient categories. Protein, fat. There are many nutrient categories, but saliva only works on starch.
00:49:18And gastric juice in the stomach, which I mentioned before, works only on protein.
00:49:25Such digestive enzymes which have specific functions are included in digestive fluids.
00:49:33This is a little bit difficult, so we will look at this in detail in the next lesson.
00:49:41All right, we will finish today's lesson, but please turn in your report. All right, that's it.
00:49:49Stand up.
00:50:11Please turn in your reports.