Transcription
Okay, question. This is 2024, question 29. State two functions of the roots. The roots primarily have two functions. The first one is that it absorbs water and mineral salts. Please take note that mineral salts are actually needed, is non-negotiable. And if you are very good, you will say dissolved mineral salts because it's dissolved in the water, okay, from the soil or the ground, okay, it must come from somewhere. Then after that, your second function would be that it anchors or holds the plant firmly to the ground. Any questions? This is a function question, you need to memorize. Where do you find it? Last page of your notes. So it's either you get it or you don't get it.
Next, state the difference between the structure. So if you take a look at this, this is actually adaptation. All right. Yes. While it might be on plant parts, but it's actually subsumed under adaptations. So they ask you what is the difference in terms of structure, means physically. So some of you said that, okay, root E goes, uh, is deeper. No, deeper means that you can take a plant and bury it deeper, but it doesn't mean that the roots are longer. So say what you mean and mean what you say. One look at it and you know the difference between the length of the two. So you can, there are two answers. I'm going to write down one for you. The other alternative answer is to say that these roots for E are more spread out as compared for plant H, which is actually more clustered together or less spread out. Okay. So you have to compare apple with apple. So it's very simple. It will just be plant E has longer roots than plant H. That's it.
Next, plant E grows in a place with little rain. So that means the soil has got very little water. So explain why plant E has an advantage. So you take a look at these two. Flip the question around. So they are both roots. They both can absorb water. So the key thing here is about absorbing more water. So basically between E and H, because E has an additional amount of roots, it can grow deeper. Yes, this is the time that you say deeper. Not this question, but this question you will say with longer roots. Okay. It can go deeper and absorb more water. So you would say plant E has longer roots to grow deeper into the soil to absorb more water. Okay. So, because there's little rain, so the, the there may be not a lot of water at the surface. So the roots have to grow deeper to actually get more. Now, if let's just say you use the alternative answer earlier on on question one, talking about how the roots were more widespread, then for two, you have to say that plant E roots have more surface area in contact with the soil. Hence, it can absorb more water. Okay. But this is the best answer.
Next. So the diagram shows a bird feeding on the nectar. The bird helps in the process of reproduction in K. Name this process. There is only one process. While I've told you that usually when you see pollination, you will then talk about fertilization is together. However, in this case, they only ask for how many processes? How many? One. So therefore, you can only say one. So in this case, it is pollination. One mark. So some of you have said fertilization. That is not correct because fertilization happens all the way at the ovule, which is deep in the flower. Your bird cannot reach that.
Next. Now for this question, you know that dispersal is out. Why? Because they say process R comes right after dispersal, and then you get a young plant already. Fertilization will happen somewhere here. Okay, this part here. So, no, not fertilization. So you ask yourself, law, it's a bit like you form your own MCQ question. What are the processes that I learned that's got to do with plant reproduction? And you will know that it will be germination, dispersal, pollination, fertilization. Since pollination and fertilization happens in this area, the answer is wrong. Since they have already told you it's dispersal, the answer is also wrong. That leaves me with only germination.
Now, state how the dispersal. When you see dispersal. Okay. Now, the full answer, we have gone through so many practice papers. Okay. I'm going to tell you one more time the full complete answer. Okay, it could be extended to two marks. I say first, though this is a one mark question, you also should write this. Okay. So, seeds are dispersed further away from parent plants to reduce, sorry, not reduce, my bad, prevent overcrowding. Now, you cannot reduce overcrowding because it's a state. It's either you are overcrowded or you're not. Okay, prevent overcrowding and reduce competition between plants. The plants here can refer to the parent plants or the sibling plants, for they are all together. Four. You must at least state three. So what are the four? You have space, light, water, and mineral salts. Okay. Must take at least three. Now, some of you have written air and food. These two are wrong. You do not fight for air because air is plentiful. There is no need to compete for something that is in abundance. I'm very sure all of you that are sitting here, unless you have a medical condition, you're not gasping for air. So therefore, you're not competing. Same with the plant. Additionally, you cannot be competing for food because the plant makes its own food. As long as it has got light, the plant is good to go.
Next, this question is on living together. Is about how the different organisms interact with one another and its environment. So, uh, for these, you need to use details in the question to help you. Actually, this type of questions, the answer can be found in the context, especially for novel contexts. Here is the thing. The examiner will not expect you to learn anything or know anything that is out of the syllabus. Living together is a very generic, big topic that they can ask anything under the stars on earth, as long as it's authentic. So they don't expect you to know exactly what is this type of fungus or what is this organism. They never expect you to read about it. So all the answers usually can be found here, and your answers given must be grounded in what you have been taught for that topic. So, for example, in fungus, straight away I will think about, okay, fungus is not a plant, it feeds on dead matter, okay, and it grows well, okay, using wow again, which is warm, oxygen, and warm, oxygen, and water. Okay, write this down.
Now, it says here, inside P, views its underground nest in a sunny area of a forest. Okay, it's specifically pegged sunny. Note, huh? Why? Because this would have corresponded with warmth. Forests are, uh, not typically sunny. I can tell you that's because the trees are usually very huge, and the canopy of the trees would have blocked off any light from touching the forest floor because all the leaves would have spread out to absorb maximum amount of sunlight for faster rate of photosynthesis. So it's rather shady on the forest floor. So the fact that they purposely talk about this, the answer is already here. Is flagging out at you, screaming out at you, "I am an answer." Small pieces of leaves back to its nest for storage. The diagram shows the area where the leaves are stored. I can also tell you that the, the diagram may would have answers. Look at it. Don't say I never stay already. Two years already. Adaptation questions are, you need to make use of what is given. So you see dry and moist. How come I don't plant it? I don't put, build my nest in the dry? I select the moist water. You should be able to form that connection already. So the young of P feeds on fungus L, which grows on the stock leaves. So that means now the stock leaves. Okay. If I were to draw a food chain, leaves are eaten by fungus L. Explain how the location of the nest helps fungus L grow. Hello. Straight away I will link here. Okay. So I think about it. I know that there are three things that I need. What is worthy to talk about? Two marks question. Do I talk about the oxygen? >> No. Because whether it's here, here, here, anywhere the nest is, oxygen is in abundance. Instead. Look, the answer is flagged out here, right? He specially selected a sunny area. Then you think, oh, if it's not sunny, what's the difference? Oh, the warmth. It cannot be the light because fungus cannot photosynthesize. So if you tell me, oh, it can photosynthesize, I will tell you, just because you see the word sun. No, this part hinted you that it's warm, right? And then the water part comes from the moist soil. Okay. So you would say that the area is warm and moist. Hence, it is suitable for the fungus to grow well, or it encourages the growth. Now, where are the marks distribution? One mark for telling me warm and moist. The second mark. But together, you have to say that it is suitable because you must tell me. You just say moist and wet. But you never link up together. Why? Because that's where it grows best.
Now, the eggs of insect P are laid among the stock leaves. Now I'm talking about the eggs. State two benefits. So sometimes you think about it. Flip the question. Flip the question. What happens if let's just say the eggs are not covered? Then it can be seen easily, right? So the first one would be, okay, it can hide by the leaves and not easily spotted or hunted or no, not sorry, spotted by predators. Okay. So cause and effect. See and E. This is one. You need two. So the second one, you can say that the fact that it is exactly on the leaves and L grows on the leaves. Okay, would be that the young, when they hatch, they have an immediate food source. Okay. So the young of P will get an immediate slash ready supply of food when they Okay, this is when use bracket are bracket L or fungus L. So if you remember last lesson, I told you that you shouldn't really put food. You need to be specific. But I know some of you are very uncomfortable or not, um, used to to putting the name of the organism. So you put food, wrong, but you bracket it to tell me what is the food. Fungus L. Okay. After he hatches. Okay. Any questions? Okay.
Next. So, this is a very common question which I've gone through many times in living together, which is actually, um, eutrophication. Okay. Whereby, you know, the growth of plants just overwhelms, blocks off the whole entire pond part. So because the whole entire pond part is now overgrown with plants, your light can no longer enter, okay? Is blocked. And so when light can no longer enter, your plant will then have no light. And when it has no light, it cannot photosynthesize and will die. Okay? And then, of course, you know, when it dies, your other organisms will also suffer. I'm taking the opportunity to teach your revise. So you imagine if there are fishes, okay, when G dies, there won't be any more oxygen, right? Because it's not photo, there's no more plant to photosynthesize. The fishes and other underwater organisms will have no more or insufficient dissolved oxygen. Ultimately, they will also suffocate and die. So now you've got two things dying, your fish and your plants. So they all undergo this process known as decomposition. And then when you decompose, your decomposers, the two that we know is actually bacteria and fungi. However, we are looking at bacteria. The bacteria will decompose all your dead things. And when they start to decompose dead things, they also need to take in oxygen and they will compete with whatever that is living, still alive there, for oxygen. Further decreasing the level of oxygen. Ultimately, your whole entire pond will just be a dead zone whereby there's no oxygen and it cannot support any more life form. I repeat myself many times at the end of this story.
So one look at this, all straight away I would say that, okay, they say increase already. What? The increase of F. There's only one plant. F has blocked sunlight from entering the. Now, you cannot just say that it's not good enough. It's not good enough. So you cause and effect. Correct? Cause and effect. C and E. This is my cause. What is my effect? Plant G. G cannot absorb light or has no light to absorb and cannot photosynthesize. Plant G eventually dies. Must say that the water cannot enter the water. The light cannot enter the water. Okay. So that is because of that. Yes. >> Yes. I need to know why. >> Yeah. Please be careful. The word absorb needs to be there. Once again, I'm marking you title because I do not want any reasons for deduction. I never know what type is going to be. So I'm marking you according to the highest possible standard.
[Music] Now, if you need to take a snack, I would appreciate if you totally do not make a single sound and be very respectful. I'm sure you can do that. Now, how would the population of bird A change when the population of F increases? So to do this, you must use arrows to indicate is it up or down. So they say F increase. So F will increase means that my bird should increase. Look at what I'm doing. This will help me solidify my answer. And this is very important because in exam, if you panic or you work under stress, you could have write the wrong, um, refer to the wrong organism, especially when there's so many. So this will help me, uh, cement who am I talking about and what happens to their population. So how would it change? So you must be very specific. You go down to eat because there's so many, um, organisms. You have to say bird A population will increase, and then cause and effect. Correct? Because they say explain, so cause and effect. So as there are more plant F, because now plant F increases, what? Correct or not? Bird A has more to feed off, or bird A can eat more F. Okay. But the most correct one is has more F to feed on, and so its population increases.
Next, the population of bird B remain the same. So, make sure you note that. Give two reasons. Many of you only gave one. Why the decrease of population B causes a decrease in the population of C. So when this decreases, this also decreases. But you don't know why. You don't know why. So basically, right, when you take a look at this, okay, who is it affecting directly? So when this decreases, you will realize that your bird B should probably decrease. But before the population starts decreasing, the next thing naturally any living thing would do is to look for alternatives. So, for example, you're a meat lover and usually every meal you have one meat and one veg, and then you will eat a lot of meat but a little veg. But one day your parents say, "I'm so sorry." Okay, there's a shortage of meat in the market for whatever reason, COVID or whatever. We only left with vegetables. So naturally your body, your body instinct would be to eat more vegetables, right, to survive. Okay. But you're starving and everything else, having any food is better than having no food. So if, so imagine bird, okay, you know, if I eat plant G, I like to eat plant G. Why? Because I'm lazy. As a bird, the bird cannot be running away. I've not seen a bird man run away from a bird before. So yeah, but now no more already. Okay, I have to hunt more of fish lock, like even though I don't like it, but I will actually hunt more of it in order to keep my population the same or to continue increasing. So therefore, it will turn to eating more fish. However, somewhere within your answer, you have to say that it eats more of, uh, fish C. Okay. Plant G population is decreasing, so it has less, or you must say that you can assume eventually it died out, and this is the only source of food. So, okay, what do you say? So as you would say that as the population of plant G decreases, as G's population decreases, there is less G for B to feed on. Hence, B will feed more on C. So in this case, I don't bother to put fish C, whatever, it's understood organism. So this is the first reason. Now, the second reason, right? A lot of you assume that C feeds on G. That's not the truth. A lot of you assume that C feeds on G. That's not the truth. It didn't show. If it's the truth, it will have shown. So you all cannot just write, oh, uh, G, uh, because there's less G, so H C will have less. No, you have to tell me that there is less shelter for the young of plant C, or with less G, less oxygen is produced. Okay, for C. So you would say with the second reason, why is this not changing? Okay. With less G, less oxygen is produced via photosynthesis. Hence, fish C will die from a lack of oxygen. Okay. So the third answer would be that, you know, um, with less G, the young of, uh, C will have less places to hide from predators.
[Music] This. Okay, next. Raj knows that the amount of light can affect the size of tiny openings found on leaves. >> Students, can I get your attention please? This is very important. >> So in PSLE, you see they drop hints. This is a hint. But your thing that is just putting it there as general knowledge is not, though it's something that you learned already that I've taught you, like any good teacher would already have taught you, is actually telling you somewhere within your answer, you are going to need this. It's not just there for fun. You are going to need this, and I will show you why. State the function of the tiny openings. Now, be very careful. You cannot, you cannot use "take in" and "give out." If you say "take in" and "give out," zero marks. You will, it has been marked out. Okay? Because it suggests that your stomata, which is just a hole, an empty hole, is able to carry out an active process of absorbing and expelling things. No, the, the so-called, um, gases going in and leaving via the stomata is a passive process, meaning it does not require energy. It just happens. Okay. So what you need to say is that, okay, it allows gaseous exchange to occur, where oxygen and carbon dioxide enter and leave the leaf. Okay. If you're not comfortable with this, exit is fine. Okay. So it is also okay for this part to be more specific. You can just straight away say where, uh, carbon dioxide enters and oxygen, uh, leaves the leaf. So that happens under bright light. Okay. Can you see light? So when there is light, you want photosynthesis to occur. So you will take in carbon dioxide and then, you know, you, the plant will give out, um, oxygen. However, the reverse is also true because at night, okay, oxygen will be taken in, okay, by the plant, by the plant, not the stomata.
Next, then, okay, for this question, all right, state the effect. So the effect over here is that you will note that as the percentage increases [Music] Okay, or sorry, as the percentage decreases. So what I will do here is that usually I will put here, read this way, directional reading. This is decrease, and this one is increase. Okay, this is measured variable, this is change variable. So I know that I will actually put my change variable first. So as the percentage of pollutant S increases, average size. Okay. Size of tiny openings. The, sorry, hold on, let me see. Okay, my apology. I want to change something to make things clearer for you. I will read in the same direction. So, decreases, size of tiny openings, increases. So I follow what is written here in my table. So can you see decrease, increase? Okay. So if you have written something along the lines that, oh, um, pollutant S causes the size of tiny openings to, uh, increase, or pollutant, sorry, pollutant S causes the size of, uh, tiny openings to decrease. But you never say increase or decrease. An increase of pollutant S causes. Okay, that one maybe can accept. But you know what? Tell me increase or decrease? Huh? You just tell me pollutant S causes this. So is it an increase of pollutant S or is it a decrease of pollutant S? Because I have to interpret myself. Is it increase or decrease? That's why those people who put pollutant S causes size of tiny openings to increase or decrease. I didn't award the mark because I don't know your pollutant S. Is it increase or decrease, right?
Next, to ensure a fair investigation, the size of tiny openings in all three time was measured at the same time. So my question here is, remember I told you, look back at here. Branch knows that the amount of light can affect the answer is staring at you. But I think 99% of the class got this question wrong. So all of you, right, you memorize the template that I gave you, those hardworking ones, but at the last part, you said, and not due to the different timings, but you didn't realize that at different timings, it will affect the brightness of the day, which is then over here, is staring at you. So at different times of the day, you have different light intensity, right? So because of that, your answer is wrong. So let's do it together. So we also say this is to ensure that what's the first one? Measure or change variable. >> Measure or change variable. >> Measure that the size of the tiny openings. Then after that, it is only due to change of measure variable, change the amount of pollutant S, okay, and not due to, and I told you already, yes, what does this equate to? The different light intensities at different times of the day. Okay. So, you look at my answer. Would you all agree that yes, that's exactly what you want? It is not the time that affects it. It is the fact that, you know, it was in the open space. So if the question, they tweak the question and they say it was conducted in a lab with light, then would time affect? If the, if you were, if you were using artificial light, would the timing affect? No, it wouldn't. I can conduct my experiment in the middle of the night at 2:00 a.m. perfectly fine because the environment is controlled. The only reason why it's not a fair test now is because it's open, and I have different amount of time. Okay? So be very careful about what you are saying.
Next, Joel investigated the effect of substance X on the eggshell animal. He placed three similar pieces of eggshell in 40 ml of water in each of the tubes A, B, and C. He then added different masses of substance X and then he recorded. Okay. Now, state the effect of X on the thickness. So one is three, one is six. So that means this one thinner, this one no change. This is your, this is known as what? Your control experiment. This is known as your control experiment or your control. Okay. So from here, the control actually ensures and confirms that the only change, okay, which is your eggshell becoming thinner, is due to this substance X and nothing else, not due to temperature, not due to light intensity, but due to the fact that you added X. Because without any X, there is no change. And from here, you can see that the one with a greater amount actually resulted in your eggshell being much thinner. So state the effect. Are the effect? So this is where you can say that, okay, X causes the eggshell to be thinner. X causes the eggshell to be thinner. So in this case, right, how come is not really a relationship question? Is because we have a control. We have a control whereby if you put nothing in it, no change. When you put something in it, which is X, this changed. Okay. So it can only be an increase. It cannot be a decrease in that sense. Okay.
So now, the female adult Y lays an egg in a nest made of dead plants. When the dead plants decompose, substance X is produced. So that means X must have caused the eggshell to be thinner. Right? So how it helps the developing animal in the egg. So why would you want the egg to be thinner? So think about it. So usually, right, if it's thinner, if it's thinner, okay, what will happen to the egg? It breaks easily, right? Compared to a thicker one. So the first thing that comes to your mind should be eggshell. Usually, you want it to be as thick as possible so it doesn't break so easily. But now I want it to break easily. What are the circumstances that will, uh, warrant, okay, that will justify that it should be broken easily? And that is where the young can hatch easily, right? Okay. So thinner eggshells allow the young to break out of the egg easier. Okay. When it's hatching. Okay. Uh, tighten it some more during hatching. Okay. Any questions? Right, straightforward.
Now, then the next question. So this question shows you the percentage of male and female Y that hatches at different temperatures. So obviously, okay, we need to understand that in order to successfully have a baby, okay, you need to have both a male and a female. If any one of it is not balanced, it is not optimal. In a typical situation, I know some of you are thinking, but there are some organisms that can assume the sex of another, uh, the opposite sex. They can sex change when the conditions, um, are right. Okay, for example, if there's no male, okay, one of the female will become the male. I know what you're thinking. But in a typical scenario, you want to have a ratio of 50/50. So therefore, if you look at it at 32 degrees, this is the temperature that you will get an equal number. Okay, equal number. So this must be in your answer. So even though you don't know what is happening, part of your answer should be talking about the graph. Okay. And then from there, you explain that, okay, in order to make one female and one male, is needed. So therefore, having an equal number of male and female will maximize, okay, the reproductivity of this species. So let's translate whatever we have said, okay, into, um, answer, okay. So 32 degrees Celsius. Make sure you put degrees Celsius or degrees. Okay. And then you should say at 32 degrees Celsius, equal number of male and female. [Music] Y is hatched or is produced. As both female, both male and female is required or are required for reproduction, slash, you can say breed. Made. Okay. Having an equal amount will maximize reproduction rates. Okay. The last part is just to tighten your answer. Actually, if you answer somewhere and here, you get full marks already, whereby you state that both male and females is required. Okay. So it justifies what? That's why you want 50/50, and at 32 degrees, that's where you get 50/50.
Question 35. Hawking no move no part L to compress a spring for launching a ball in the setup. There is no wind. So some of the key things we see the word spring, we see the word no wind. So no wind obviously they are trying to tell you that it is a factor that is not going to affect the experiment. Okay, they obviously put it in. And if you see spring, it's got to do with two things, either elastic spring force or elastic potential energy. This or that. Okay. Now, I want to also be very clear. I take this time to clarify and to stress again. Elastic spring force is only for spring. Okay. If they give you rubber band, the word spring is missing. It's just elastic force, minus the spring. So this came out before one of the years. He measured the distance moved by the ball as shown. His results are shown. Now, whenever you see a table, right? Okay. Or a graph. Now, uh, days, I'm not saying that I'm guaranteed. I'm just saying that it's a, it's, it's something that we observe. There are double trends in one data. So if you take a look at it, right, okay, you are supposed to see if there is any double trend. So sometimes you need to be careful. Okay. So this is actually increasing. But take a look at this. What is happening? So usually I tell you all to draw an arrow. The arrow tells you how you're reading it, but it doesn't tell you what is happening to the values. So in this case, this is actually increasing. Okay? And then you look at your first try and your second try, the other data, you will notice that from here to here, if you read direction of reading, this is increasing, correct. Okay. And then after that, from here to here, it actually decreased. So can you see this is trend number one, this is trend number two? There are usually, usually two trends. So you need to be careful. Once again, I'm not saying that it is for sure. Okay, I cannot predict what will happen or what will come out for sure for PSLE, but I'm telling you this is what it is. So be careful. Don't assume that what, oh, all the way from here, increase here, and then you just don't care. You ignore this thing as being decreased and you say the whole thing is increased. That's what some of you have done. So two marks, you must take two trends. So the first one would be as copy, cut, and paste. Okay. As launching angle increased from where to where? 15 to 45. Make sure you have the degrees there. Okay. What happened? Distance traveled. Copy. Cut and paste over here. Increased. So this is one mark. Then after that, trend number two. Okay. What happens? Above beyond. So as launching angle increased beyond 45, which is how I always teach you. Use the word beyond. Distance traveled by ball or moved by ball [Music] decreased. I should see two trends for two marks. Most of you lost because you just ignored the last one.
Name a force acting on ball at X. So X is over here. I'm talking about force. Some of you told me elastic spring force. No, it is wrong. The minute your ball departs from, no longer touches the spring, is there any more elastic spring force acting on it? No. Because elastic spring force is a what force? Contact force. So, and I also tell you already, on Earth, at least at any juncture, on all things, gravity is acting on it. So the answer is actually gravitational force. Okay. Gravitational force.
Now, suggest why is it difficult to measure? Let me give you a hint. Measure. The word measure here, right, tells you that you're dealing with the measured variable. And when you talk about measured variable, you're actually looking at accuracy. Remember, there are three things that I, uh, four things that I will tell you. They usually will test on control setup. Okay. Fair test, um, reliability, and accuracy. So reliability talks about repeating and getting consistent results. Accuracy talks about how you measure, okay? Or talks about the method that you measure, or talks about the instrument that you use to measure. The word M is there for accuracy. Okay? So it tells me it's got to do with accuracy. And the fact is that it cannot be accurate because when it splashes here, the ball can actually float away. It's not like the ball stays stagnant at this location. That's it. When it splashes, it will drift off. Don't know whichever direction. So because of that, you cannot accurately say where is it. Okay. So you would say that when the ball lands on the water, it will float away. So you are unable to exactly pinpoint where is the ball, where did it first land. Okay.
Next, Hawk Singh repeated the investigation using the same set of launching angles when there was no wind. He used the same setup but similar balls of higher mass. So this tells me that now this is the change variable. State a variable that you must keep constant for a fair test comparison. Okay. So in this case, all right, when we look at it, ask yourself, what are some of the things that you should be keeping the same? Okay, what are some of the things that you should be keeping the same? So one of it is that you can talk about the compression length of the spring, right? Because that will affect the angle in which that it is actually, um, going up. Okay? And then how far it lands. So don't tell me things like, uh, things like, you know, that won't directly affect it, right? So like, for example, light intensity. Yes, light intensity is a variable that you should keep the same because to be a fair test, everything else must be the same except the change variable. But then, you know, certain factors will affect it. One, and you know, one of it is actually the amount of compression of spring. Okay. So the compressed length of the spring because obviously the more you compress, the higher the elastic spring force is going to act on the ball. So when answering this kind of question, I always ask yourself, what will affect the distance moved by the ball?
Okay. Next. Okay. The graph shows how a length wire made of material S changes with temperature. So obviously, when you take a look at this, okay, it's got to do, uh, expansion and contraction. So they say when the length of wire is at 0 degrees. So temperature is here. 0 degrees is here. My length is 50. Make sure you actually write the units. No units, subtraction of half a mark. Sometimes even the whole entire mark, depending. So don't forget. State the increase in the length of wire when it changed from 0 to 80. So look at here, what is the increment? The increment over here is actually from 50 to 6, uh, 56. So the difference is 6 mm. I hope you all know how to calculate. Are don't know how to calculate? Never mind. Just in case, 56 mm minus away 50 mm, final length minus, uh, initial length. Okay. Any questions so far? Okay. Next.
Fio built a model of telephone lines in the day as shown. Okay. During the night, Fadil heard a crack and found that the wires snapped. There was no wind and the model was not disturbed by any person or animal. So usually, usually, usually, right, if there are different parts of it, it is related. One. So like I say, this, this has got to do with expansion and contraction. Okay. So you take a look at it, law. The lower the temperature, the shorter the wire. Okay. So at night, so firstly, ask yourself, what is the difference between night and day? So day. Okay. I know it's got to do with temperature because they talk about, you know, the temperature graph above. Okay. Mr. Chong said they are related. So, okay, must be temperature. Let me think. Daytime very hot, night time must be colder. Okay. You know, so because of that, it will be contraction instead of expansion. So when we talk about heat, remember, this is always heat gain, heat loss from where to where, cause and effect. Because this one says explain. So let's talk about it. What is the difference at night? Okay. So you need to say that, okay, the wires lost heat to the cooler surroundings at night. So this is the cause, right? What is the effect? The wires contracted and become shorter. Now, it becoming shorter is not a problem. Is not a problem. Sure, you can become shorter. If I give you 10 m extra length, you're shortened by 5 m. You still got 5 m of extra length. Were you shorter? Yes. But are you in trouble? No. Okay. So now you must talk about it being too tight. Okay. Too tight. So when it's too tight, it will snap. Okay. So, the wires became too short and tight, causing it to snap. Okay. The problem is that it's too short. Okay.
Using the same type of wires and equipment, suggest how Fadil can build the model at the same place so the wires will not snap. So for this case, you need to talk about how to make the wires more loose. Okay, they say same type, they never say same amount of wires. Okay. So the idea here is that you need to say that the wire needs to be hung loosely. Okay. Slack or dangle. Okay. You it so even if you move the posts closer together, it may not mean that it is loose enough. Okay. So basically, you need to hang it loosely or need to dangle. The idea must be there that there is extra slack. So by just saying put the pole closer to each other will not give you any marks. Okay. Another way you can do is hang it at night. Okay. Then of course, you know, because at night it is contracted by the wires. So you will need to account for that temperature change. Okay. The wires are already in the contracted mode. Okay. So if you really want to be safe, you can say hang the wire loosely at night. Okay. I'm going to go one step further. They didn't ask you to explain, but I want to explain so that you know if the question asks you why, you can explain. This gives allowance for the wire. Okay. When it contracts, okay, so it doesn't snap. They have a certain amount that it can, uh, contract and become shorter, but yet it's not too short until it pulls so tight until the wires snap. Any questions so far? All okay. All right.
The freezing points and boiling points of three substances P, Q, R are as shown. Okay. Now over here, seven, you see freezing point, you see melting, boiling points of three substances. This would hint you that this is a question on matter. And you know that under the topic of matter, you actually have the three different states. Okay. So, state what freezing means. So this is a definition question, you need to memorize. Where to find it? At the back of your consolidated notes. Okay. Definition questions are, you must get everything correct. So freezing is a heat loss process. So he's pre, uh, freezing means that, okay, occurs when a liquid loses heat to become a solid at a fixed temperature. Please note that it is fixed temperature. Don't use boiling, melting points. Okay. So, what am I looking out for? There must be lose heat. There must be, um, a change in state, and there must be fixed temperature. Any of these missing, zero marks.
Now, next question. May has a closed container, volume of 100 cm³. So, this is the capacity, maximum. She thought 150. Okay, so you know that this is more than 100 cm³. So meaning that the only way that you can squeeze this substance up is that this substance must occupy a smaller space of 100 cm³. So this, you need to reduce it somehow. And based on what you know about matter having three states, out of the three states, there's only one state that does not have a definite volume, and that is gas. Gaseous state. So, what in short, what they're trying to do is they're trying to ask you which of this is at gaseous state at 30 degrees? So what you could have done is you could have actually extended out the table at the same time. Don't need to draw and use me. This is for your own rough working, but I wanted to show you what you could do. So what you want to do is at 30 degrees, what are the various states? So you know that the boiling point of this is 15 degrees, meaning that by the time it reaches 30 degrees, substance P would have already boiled. Boiled means what? Change from liquid state to gaseous state. So this is a gas. Okay. At 30 degrees for Q, it's freezing point. H, I forgot to tell you, freezing point is also known as melting point. They are the same. So basically, at 6 degrees, this has already melted. It became a liquid, but it will only boil off at 80. So 30 degrees is lower than 80. That means at 30 degrees, this substance Q has not boiled. It is still a liquid. And then finally, the last one, it says that its melting point is at 50. So 30 is lower than 50. So what it means is that it has not even melted. So this is a solid. So based on this, you need a gaseous state. The only material or the only substance that is plausible is P. Okay. So answer P first. State. Okay. This is, and then this is a cause and effect question. Now, so for this question, right, you need to say that at what temperature? So you say that P is a gas at 30 degrees Celsius, as its boiling point is at 15 degrees Celsius, which is lower, lower than 30 degrees. Okay. Then after that, you have to say that it can be compressed. P being a gas has no definite shape. Sorry. Definite volume and can be compressed to fit the container. The 100 cm³ container. Okay. Any questions? Am I clear? So you cannot just say it is a gas. It is a gas at what temperature? How come alone is not good enough? If it's a gas at say, um, 80 degrees, they cannot what? Because if it's only a gas at 80 degrees, it will not fit. So you have to be specific and you have to tell me why, because its boiling point was lower than 30.
Next, state which you can store Q at 30 degrees. So at 30 degrees, Q is a liquid. So cannot. Why? Because if it's a liquid, it will flow through the gaps. So once again, you would say cannot. No. Okay. And then cause and effect again. So you would say that at 30 degrees Celsius, substance Q is a liquid. Hence, it is able or it can flow through the gaps. Use the keywords given in the diagram. So if they use gaps, use back gaps. Don't come and tell me openings or whatever it is. Okay? I want it to be exactly what it is. Any questions. Am I clear? Yes.
Next. This question. Okay. This question I'm going to take some time, um, to explain to you. Most of you have gotten it correct. Good job to you and to me. However, there are certain things I want to tweak and tighten. So, one look at it without even saying anything, I know this is electrical circuit. CEO comes into my mind. Correct. To answer this question. Okay. So, when I look at this, right, I must close the circuit. I must trace and figure out what is happening in order to tell the whole story. So when this is closed, I look at this iron cylinder. Okay. Got coil around it. My O will be it becomes an electromagnet. Okay. So when this becomes an electromagnet, okay, what happens to this now that is open? Open, open. When it's open, it's already being attracted. Okay? And then they tell you, okay, move up and down continuously. So that means if it's open when this is open, this is actually attracted. That means in order to go up, you must repel. So these two must repel, pushing this thing up. Then the minute it got pushed up, there is actually a gap causing it to be an open circuit. Okay? And then it will go back down again. And that's why it goes continuously up and down, up and down, up and down. So when I'm doing this question, before I even attempt, I must do this mental thinking or have this understanding. So that then after I understand how the whole mechanism works, then I start using CEO to craft my answer. Now, the main problem that many of you are having is your terminology. I have never taught you this before, but somehow very interestingly, many of you are telling me "demagnetize." I don't know why. I don't know how come. Let's be frank. Have I ever taught you "demagnetize" or "magnetize" iron rod? I got tissue or not. What did I always tell you? Yes. Becomes an electromagnet. Is no longer an electromagnet or becomes an electromagnet. Okay. I didn't teach you "demagnetize" and "magnetize." I'm stressing it. I'm putting on a recording for the 1 millionth time. No, you tell me "turn into an electromagnet." And yes, there is a difference between "turn into a magnet" and "turn into an electromagnet." So if you say "turn into a magnet," subtraction of marks. Magnetize. >> So if you put both, I will ignore the "magnetize." In fact, this time around, you put "magnetize" and "demagnetize," I gave you the marks because I see the effort. But then, you know, no, that's not the 100% correct one. I want "turn into a magnet." Okay. So let's talk about this. What are the, what are the things? Okay. So I want to know CEO. So when the switch was closed, the electric current could flow through the circuit. The iron cylinder becomes an electromagnet. Okay, I'm going to highlight this so that we are all clear about this, no discrepancy. Then after that, you go on to say the light poles of the electromagnet and the magnet, because there are two of them, are facing each other and repel. Okay. Pushing the captain up. So after the captain got pushed.
Up, the next thing that happened is that there will be a gap when, okay, the circuit is then open and the iron cylinder is no longer an electromagnet. The captain then drops back down. The process then repeats because they say continuously one and a half mark.
So a lot of you right, you will see me cross E do M A, that means that you didn't tell me that your electromagnet is no longer electromagnetic. So one and a half. Okay. Am I clear? And then you are really expected to write that much. Do you see how many lines they give? Okay. So this will tell you how much you need to write. See for a two marks question. So that's why I tell you MCQ must try to get full marks. Can we done one? Use elimination me. Uh method check and check and check. You see you write so much, my goodness. Talk too much and yes, you see the number of lines, not Mr. Okay.
Next, state another change. Excuse me. Some of you just ignore the question and go, captain move slower, and then explain why. Huh?
Yeah.
No. What is another change? Another change is not just that it moves slower. So a lot of you, you need to do reverse engineering. So they say right, after a few hours. So you will realize that after a few hours, something must have changed. And granted that the only thing that I would have changed in this case, y'all are very, think too much, tell me friction, everything, no, no, no, what worn out, wear and tear, no, it's just simply after a few hours, your battery, where's your battery? Yes, would have already been used quite used up quite significantly or would have, you know, um, been drained. Okay. So that's what we are looking at. Then you reverse engineer, law. Soon when there is less chemical potential energy being converted to less electrical energy, meaning that, you know, eventually your electromagnet will be less strong. So because it's less strong, the repulsion between this magnet and this electromagnet will also be reduced. So instead of going to this height, now it probably go to this height only. So the height of the captain is now lower. And can you all please don't say things that it didn't reach the original length? What is the original length? It didn't, uh, go as high. It didn't, you know, your, your answer needs to be more specific and more scientific. Okay.
Actually, this one they tell you a lot of things, right? But guess what? The answer is actually very short. It's just that the, the captain will rise up lower than before. That's the first thing. And then the second thing, right? Explain why. Okay. The electromagnet is weaker as the battery will be weaker, right, after a few hours. That's it. Make sense? Tell me. Worn out, wear and tear. Wow. I wonder what kind of quality is this? Play a few hours only, then wear and tear already. Okay.
Look at the next question. A boy has his height measured. Hello, people. This one. Okay. Look. So this is actually 112. This is 113. So this must be, okay. From here to here, there are intervals, right? So it's point. So this is 112.5. So over here it is 112.6. And your units must be there. Sorry. 112.6 CM. It don't have your CM, zero marks.
Or half a mark. I don't know. It depends on the examiner and the demands. Now, without using, uh, other apparatus and materials, describe one way to obtain an accurate. So there are two ways to go about is either you ask the boy to step up here. Okay. Or you bring this whole thing down to where he is standing. So the problem with some of you is you tell me that, bring the measuring tape to the same height as the boy. Huh? That means the measuring start here, same height, not here, you know, but here. So you need to be careful about what you're saying. So what you want to say is, bring, position the measuring tape, okay, with the zero marking at the foot, starting at the foot of the boy. But actually, the just asking to step up one step, that's it. Okay. That's it. So, get the boy to step up one step. That's it. Right. And then problem solved.
Next, this question. Okay. Carol glued two types of the blocks of the same size, A and B, and then placed them in the water. Based on the diagram, state the difference. Right? So one floats and one B doesn't float, law. Is as simple as that, isn't it? So, a material, a, okay, block A floats, but block B doesn't. Oh, sorry, sinks. We need to be more significant. Okay. That's it. Maybe to tighten it even more. Close on. Okay.
Next, Carol placed another two blocks and then they both float. She concluded the two blocks are made of the same material. Do you agree? This question is a matter of how you answer. I understand you went, oh no. Uh, because many materials can float on water. But you never tell me that C and D are made out of different materials that can float on water. So let me tell you what you are missing.
Will go. No, there are many different materials that can float on water. And you stop here. Zero marks. Why? Because you didn't relate it to the question. You should have. Full stop. Block C and D could have been made of different materials that float on water. That both floats on water. So the first part tells me that you understand. The second part, you apply this general knowledge or this knowledge whereby yes, you know they are different materials, but they both float. For example, plastic and styrofoam, wood and styrofoam, they both can float. But then you have to tell me, oh, so because there are different types of materials that can float, C and D could be made out of different materials that both can float. That was where you lost the knots.