Paper 1 Scope | Grade 12 Life Sciences "Free State Only"

Ajouté : 2026-06-01

[00:00:05]Good. Good afternoon, grade 12, and welcome to life science revision paper one. I'm Tiara Tua. I'm from Fichardt Park High School.

[00:00:14]I've been giving life science for 16 years. It's a passion of mine. I love everything. I can't stand still like this. But I hope I will.

[00:00:23]And I've been a marker as well as a senior marker for 13 years for paper one. So, paper one is my ultimate ultimate passion. So, today you're already received notes because I don't want you to try and take notes. You already have everything you need.

[00:00:40]I just want to be there to say this is a pitfall. You must look out for this.

[00:00:45]Watch out for this. Maybe you should rather answer it like this. So, today you are more than welcome to write in, make a little star. I will tell my kids, "Make a rabbit there. You will always remember a rabbit's ear."

[00:00:58]So, remember the scope you have received at schools is already for trial exam.

[00:01:05]So, it have everything in. Plant hormones, all the endocrine systems, everything is inside there.

[00:01:12]But you're only going to write paper one about reproduction in vertebrates, human reproduction, which is going to be 50 marks. That's 30%.

[00:01:23]Responding to the environment, 66 of the marks.

[00:01:27]And then endocrine system, they were nice enough to highlight it, made it bold, and say "Homeostasis of glucose."

[00:01:35]That's what you're going to get. So, that's the one we are going to focus on.

[00:01:40]I want to also encourage you.

[00:01:43]There's a paper one virtual revision lesson on the 5th of June. Ask your teachers to please provide that link.

[00:01:53]They are usually the kind of people that will say "Make sure you are going to stress this." Or "Give attention to this." Then you can mark it. She's going to ans- ask it. That's what's going to happen.

[00:02:07]So, let's start with reproduction in vertebrates.

[00:02:12]Please always remember to start off with your headings.

[00:02:16]We tend to go to the pictures. We go to whatever is underneath.

[00:02:21]But, our headings is the most important because they want the headings out of us. They want to know what type of fertilization is this.

[00:02:31]And remember, grade 12, we can only ask you the ATP. We can never ever ask you anything else.

[00:02:39]We can give you a passage which you should read through, yes. And always read twice, write once. That's the rule for life science. Go and look at the amount of marks allocated.

[00:02:53]So, if you see that if First thing they want to know is it's external, meaning outside the female body, or is it internal? We are going to see right now that both of those have consequences.

[00:03:09]The second thing is now I am fertilized.

[00:03:13]Where am I going to carry them?

[00:03:15]Am I going to carry my embryo inside, outside, or keep them inside just before they hatch?

[00:03:25]The moment they are born or hatched, please, you hatch out of a egg.

[00:03:31]You get born out of a uterus.

[00:03:34]In biology, we are so concerned with our terminology. So, make sure what is happening here. Is it a egg or is it outside of a human or animal?

[00:03:46]If it is out of a amniotic egg, you have to know how are they able to still survive inside that egg? So, you have to know each and every part.

[00:03:57]If it is actually inside the uterus, we're going to do human reproduction for that.

[00:04:03]Then, after they are born or hatched, do I look after them or do I just let them go?

[00:04:08]Can they look after themselves or are they precocial?

[00:04:12]Or must I look after them? And if I have to look after them, what type of parental care do I have?

[00:04:19]So, always follow the story because I'm going to give you an elephant with a little baby.

[00:04:26]But the story is still the same. What happened there?

[00:04:30]Were there outside fertilization? If it was outside, there is not going to be much teamwork between male and female, not at all.

[00:04:41]So, you're going to get your eggs laid outside. She's going to swim away, don't care.

[00:04:47]The male gamete is going to be deposited. He doesn't care. Fish Best fish is winning. La-di-da-di-da.

[00:04:55]So, are they going to look after the eggs? No.

[00:04:59]But then you must remember there's less chance of survival.

[00:05:04]There's greater chance of predation.

[00:05:08]So, now they lay a lot of eggs. Why?

[00:05:13]To get the greater percentage to actually survive.

[00:05:17]We always need water if it's outside.

[00:05:21]Because if it's inside, it's protected by the female body. But outside, we want to protect against dehydration.

[00:05:31]If it's internal, that means you're going to have less gametes. You don't want to have as much kids as a fish.

[00:05:38]Imagine a 100 eggs, 100 children once. Done and dusted forever.

[00:05:45]So, we don't want that. Less gametes.

[00:05:47]More chance of survival, you will protect yourself, so you will actually protect your uterus always. And the embryo or the fetus inside. Because there's more protection against predation, against dehydration. There's a better chance of survival. So, make always sure you you go with the flow, you go with the story, you make sure what do they show you.

[00:06:14]The next thing is am I going to keep it in my body?

[00:06:19]First of all, you have to be big enough to keep something in your body. Imagine this little fish here.

[00:06:27]She has to keep a thousand little small fishes inside her moving around.

[00:06:36]That will make her chance of survival less.

[00:06:41]So, the smaller you are, the bigger the chance that you are going to lay a egg outside your body.

[00:06:50]Make sure you have the right definitions.

[00:06:53]Ovipary means a egg are laid. It means literally outside the body.

[00:07:00]The development of the embryo is outside of the female body.

[00:07:07]And then you must remember this will increase the chances of predation. So, we want to have some kind of protection on the outside. Or we want them string together by mucus strings. Or we will attach them to something. So, go look where in the passage do they tell you that there's some kind of protection. I know one about the um frogs that will say that it makes a mucus ball around the eggs. It's always something on the outside is for protection.

[00:07:42]Then ovovivipary is one of the terms that we struggle with.

[00:07:49]It's an egg.

[00:07:51]Vivi means life.

[00:07:54]To give life.

[00:07:56]So, she keeps the eggs until they can give life. That's what it meant. So, internal fertilization, eggs are retained. It means inside the body until they are ready.

[00:08:11]Here we have something like a gecko.

[00:08:13]If she lays one egg at a time, it will get eaten each and every day by a bird.

[00:08:20]There won't be any geckos.

[00:08:22]She keeps all of them, lay them once.

[00:08:26]And then, the moment they are laid, I'm laid, it means they hatch together. So, there's a lot of little ones, and that just means they have a greater chance of actually survival.

[00:08:41]Then our own type, vivipary, means internal fertilization. You're not going to do it outside in a laboratory.

[00:08:50]It's going to be kept in the uterus.

[00:08:52]The nourishment is from the mother themselves, and this is a great way to always protect the embryo.

[00:09:00]Okay. Make sure you do go through different types of diagrams.

[00:09:06]This is biology. We do love to ask a diagram or give a diagram.

[00:09:11]If you see a uterus like that or umbilical cord, you know it's inside.

[00:09:17]The moment you see a egg, you know, okay, that can be inside kept or outside. So, look at the type of protection.

[00:09:27]The amniotic egg, I've been really marking for 13 years, nationals.

[00:09:33]These are the things they ask.

[00:09:35]Nothing else. I think everything because I copied and paste this thing to this. I don't want you to write. You can, of course, but I want you to have everything just as it is.

[00:09:47]So, what did I ask?

[00:09:49]I asked you how they get get gas exchange.

[00:09:53]You must be able to see the chorion. You must be able to identify it.

[00:09:59]The amnion, remember that is always with the embryo themselves as well. It has fluid.

[00:10:06]Fluid helps us to protect against temperature change, against dehydration, and mechanical damage.

[00:10:14]Then, of course, the allantois. That's like the little dust bin.

[00:10:18]All the um waste products go there. Remember, you have to grow.

[00:10:25]While growing, you make a lot of respiration, a lot of carbon dioxide, and of course, a lot of nitrogen-rich waste. So, that goes to the allantois.

[00:10:38]And then, the yolk. Remember, that's the nourishment of the embryo. And the shell on the outside is for protection. So, if you go and you see, okay, you have your egg, you make sure that you can identify on it.

[00:10:54]You will draw yourself a quick egg if you are studying at home.

[00:10:59]Make sure that you can actually put each and every name on it. And just a short version like this is almost enough. Just put it in a full sentence. That's all I ask.

[00:11:11]We want to know the biological term, and we want to know what it's doing.

[00:11:16]That's the only things that we want from you.

[00:11:22]So, this is just a little summary. It's everything I already told you.

[00:11:27]Um but it's just summarized. I think it's in the and the Gaps. Mind the Gaps is a very, very nice book, but it's just a bit too short to have everything you want to get to a good percentage in biology.

[00:11:42]Then precocial and um altricial, there's just one thing I want to tell you.

[00:11:47]Make sure if it's a bird, a fish, a mammal.

[00:11:53]That's the first thing.

[00:11:55]Because if it's a bird, we want to know that the learner is able to know it has feathers or down.

[00:12:05]If it's a mammal, we want you to know it is covered in fur.

[00:12:12]So now they're going to have a little bless book running around.

[00:12:17]And you say now it's covered.

[00:12:19]We do not give you the mark.

[00:12:22]We want to know in biology that this child knows this is a mammal, it's going to be covered in fur.

[00:12:29]Or this is a bird, it's going to be covered in down.

[00:12:34]Or this type of animal is going to be like a to a tortoise, it already has a shell to protect it.

[00:12:42]So please make sure what animal was mentioned in example. Because they always give a passage with these things.

[00:12:51]And I ask identify the type of parental care.

[00:12:56]And then they ask you why is the parental care? Yes, there's time and energy, that's what it means. Sorry.

[00:13:03]Time and energy spent.

[00:13:05]And then they ask you why.

[00:13:08]Precocial means you can already look after yourself. You can swim, you're covered, your eyes are open.

[00:13:14]Altricial, you will have a lot of parental care because you can't look after yourself. So the two of them are linked together.

[00:13:23]Yeah, so then we go to human reproduction.

[00:13:27]I wish teachers in grade nine will actually do human reproduction much better because that's the time that you love to do it. Now you don't have time, you just stress about metric. In grade nine you have so much time for this.

[00:13:40]So I spend a lot more with mine and they really enjoyed it.

[00:13:45]With human reproduction there's just a few things that we're going to ask. We are going to give a diagram.

[00:13:52]We are going to ask you to identify Look out for the question in biology later and name.

[00:14:00]You only give us the letters at the end of the year or you just give us the names.

[00:14:06]Grade 12, the moment you read through the question just scan through the marks.

[00:14:13]If the marks are two, there's no Easter in biology. We are going to give you two marks for two facts.

[00:14:20]So make sure that you actually apply them.

[00:14:24]So first of all, we start from the beginning. You have to know the scrotum is outside of the body. This is very important. We ask it time and again.

[00:14:33]It is for temperature control.

[00:14:36]Make sure that you know it's two to three degrees lower than body temperature.

[00:14:42]People, two to three degrees, it will fall off.

[00:14:46]Two to three degrees lower than body temperature, it will be the ideal temperature for what?

[00:14:53]Inside it is the testes.

[00:14:56]Then obviously the testes will make or produce sperms.

[00:15:01]We want optimal sperm.

[00:15:03]You want the best sperm to actually fertilize the ovum.

[00:15:08]That's why. So make sure that you also, I think in the framework they say the cells of Sertoli gives nutrients.

[00:15:20]Sperm needs to travel a long way for a small microscopic board.

[00:15:26]So we want nutrients for them.

[00:15:29]Then the second one is we want testosterone.

[00:15:33]Because if a man has better testosterone, people will produce better sperm.

[00:15:39]So we want the cells of Leydig.

[00:15:42]We want the best sperm to fertilize the ovum.

[00:15:47]Then we have to travel. So now the sperms are made in the testis.

[00:15:52]But they have to mature in the epididymis.

[00:15:56]Your moms didn't just throw you out in grade one.

[00:16:00]Now you are going to get the vibe that out there, they ready to send you out in the world. They already have ideas for your room.

[00:16:08]So now you're in the epididymis. You're going out. You're going away.

[00:16:13]So now they uh you're here.

[00:16:15]Then we have to travel all the way through the vas deferens. Again, go to diagrams. Because you know your diagram, you will know that the vas deferens is going to be in between the epididymis.

[00:16:29]And then the next stop is going to be the urethra.

[00:16:34]So you will know that it's going to connect them.

[00:16:38]If you don't study with a diagram, you won't know what is the Where does it start? Where does it end?

[00:16:46]From here, we get the urethra that's going to take the base um or the sperm.

[00:16:53]And then of course, everything with the seminal vesicles. All the nutrients to create semen outside.

[00:17:01]Please make sure you will see that there's some of them in mine highlighted in red.

[00:17:07]That's what creates semen.

[00:17:09]So if I ask you in a question of what are semen or which um glands contribute to semen. Those are the four.

[00:17:20]First of all, you get a sperm from the testes.

[00:17:24]The seminal vesicle gives nutrients again because it's still a long way out.

[00:17:30]The prostate gland, the main function, it's alkaline because the vagina is acid.

[00:17:38]And if you put a alkaline and the acid together, it neutralizes.

[00:17:42]Remember, all proteins will denature if it's too acid.

[00:17:47]And then the last part is Cowper's gland, this little one there.

[00:17:51]Please make sure the little one is Cowper's gland because it will make it easier for you in exam.

[00:17:58]And that gives movement.

[00:18:00]So, it gives an oil-like, um, texture to the semen to make them move better.

[00:18:08]The penis itself is just for copulation and anti-ejaculation.

[00:18:12]It's actually just there for the final part, nothing else.

[00:18:17]You must be able to draw a sperm.

[00:18:20]Grade 12, if you put your hand out to get a pencil, always put it down and hear me say, "Take a pen."

[00:18:31]Because you have to write a heading.

[00:18:35]That's the first mark, it's a heading.

[00:18:38]And that's one of the things we tend to just forget. We are so excited and, "Oh, we know the sperm. We are going to write the duh duh draw it, give it every label it needs."

[00:18:50]But the heading is one of the four marks. It's 25% of the marks.

[00:18:56]Just because you wrote there, "Sperm cell."

[00:18:59]So, each and every one of you can get that 25. Make sure you do.

[00:19:05]If we, um, go to the acrosome itself, remember, you have to know it has enzymes to go through the ovum.

[00:19:14]The nucleus is the only one one of two that's haploid. The ovum is the other one.

[00:19:21]Then we don't the neck or the collar has the mitochondria. You must know that it gives energy through respiration.

[00:19:29]And the tail is going to s- cause the sperm to swim.

[00:19:34]Grade 12, they like to give you a weird sperm. Give you a weird sperm sound ask you is going to be better or is it going to be worse?

[00:19:43]Watch out from the top. Does it have the enzymes? Does it have an acrosome? If it doesn't have it, it can't penetrate the ovum.

[00:19:52]Is the nucleus normal? Is it haploid?

[00:19:56]Otherwise, you're going to get something like trisomy. So, you're not going to have a normal embryo.

[00:20:03]Does it have enough mitochondria?

[00:20:06]Otherwise, it's going to be a lazy sperm. It's not going to have energy.

[00:20:10]Is the flagellum or the tail perfect? Is it nicely molded? Because otherwise, it's going to swim in circles or it's going to swim in one direction or it's too short. It can't swim optimal.

[00:20:23]So, start from the top and mark is it right or is it not?

[00:20:29]This you just take out of the exam guideline. You study it as it is.

[00:20:34]Our mark is always five.

[00:20:37]Remember what I said about headings.

[00:20:40]They will ask you what type of um production is happening in say A.

[00:20:51]And it will be the testes. So, your first mark will go for spermatogenesis.

[00:20:57]Make sure you give the headings.

[00:20:59]That is obligation mark. We can't give it anywhere else. If you have everything perfect, we can't hand it to you.

[00:21:07]Under the influence of this and in the seminiferous tubules in the testes, the diploid germinal epithelium cells undergo meiosis. That's why I do meiosis before this.

[00:21:19]And then it forms haploid sperm cells.

[00:21:22]Nothing else. If your teacher gives you smart words, nice words, ignore them.

[00:21:27]Bracket them. This is the answer we want. This is from the memos of the past 6 years. This is how they look.

[00:21:38]Then oogenesis, the same thing.

[00:21:41]You just study it as it is.

[00:21:43]Under influence of FSH, diploid cells, you see I already bracketed that one.

[00:21:48]It's not going to be necessary in the ovary, undergo mitosis. That's something you tend to forget, so please just make a little star there.

[00:21:58]To form numerous follicles.

[00:22:01]One of these follicles enlarge and undergoes meiosis.

[00:22:05]Only one of them survive, otherwise you will have twins, or you will have triplets, or you will have whatever. To form one haploid ovum.

[00:22:16]Please make sure that you also know the structure and you're able to draw it.

[00:22:21]Then we come to one of the most important parts for this exam.

[00:22:27]Because you just started with endocrine system, but you already finished all the female endocrine parts. They're going to put a lot of marks there.

[00:22:39]Because I can ask it in both sides. So please make sure that you do know it by heart. First of all, start again with the headings.

[00:22:50]It is hormonal control. That means FSH, LH, estrogen, and progesterone. That is why women are difficult. At men, we just have this restaurant. That was it.

[00:23:04]Every 7 days, we get a new hormone and we're on it for 7 days and then we start again. That's life.

[00:23:13]But, we do tend to drill it into you that every 7 days the hormones change.

[00:23:21]Please make sure you use the graphs that they provide.

[00:23:25]If this one is going to be on day 13, you write day 13.

[00:23:31]We want to see that you can actually interpret what we give you.

[00:23:35]So, what happens first?

[00:23:38]You have to use your pituitary gland. We have to think about it and give if it's FSH.

[00:23:45]So, that one follicle can actually grow.

[00:23:49]Remember, women are born with all your follicles.

[00:23:53]The if they're finished, they're finished.

[00:23:55]So, we just want one of them to start to grow.

[00:23:59]The moment it's mature enough, we want to actually have our endometrium in place. We tell it, "Okay, we are ready.

[00:24:07]Maybe we are going to have a baby this month."

[00:24:12]Or not this month, in the next 40 weeks.

[00:24:15]So, what is going to happen then? The endometrium has to develop. How?

[00:24:21]The development follicle will secrete.

[00:24:24]Please make sure that you know the developing follicle secretes estrogen.

[00:24:31]So, that makes the estrogen levels increase. These two are linked together.

[00:24:38]As the estrogen increase, it means the endometrium is going to thicken, get glandular, and more blood vessels. It's getting ready.

[00:24:49]The moment that it's thick enough, we say, "Okay, we are almost ready."

[00:24:54]Stop with FSH. We don't the second follicle.

[00:24:59]We want LH.

[00:25:02]We want this follicle that's already mature to ovulate and give us the ovum that's inside.

[00:25:10]You have to get it out to actually use it.

[00:25:14]So, this means the Graafian follicle will burst open, give us one haploid ovum.

[00:25:22]And now, we can't break down our endometrium.

[00:25:26]Where will it go?

[00:25:28]So, we take a second hormone.

[00:25:32]Make sure that you understand the Graafian follicle that opened up is the reason we get the second hormone.

[00:25:40]The Graafian follicle changing into a corpus luteum gives progesterone.

[00:25:47]Progesterone, remember, is the pregnant P pregnant hormone.

[00:25:52]The pregnant hormone is going to be there for 40 weeks. That's the reason why they get nauseous. That's a good sign. It's progesterone.

[00:26:01]Because it keeps your endometrium intact.

[00:26:05]It always also keeps it thick, glandular, blood vessels in intact. So, please, that's the reason why we can actually then get pregnant, get implantation.

[00:26:19]Is this person pregnant?

[00:26:26]Two reasons.

[00:26:28]Progesterone is going to decrease. That's the first reason.

[00:26:34]But also, the second one is the corpus luteum is getting smaller.

[00:26:39]There's two visible reasons on this graph.

[00:26:45]The negative feedback, we only want one follicle at a time because we only want one child at a time.

[00:26:52]Kangaroos do that. They don't inhibit FSH. So, while they have still one kangaroo outside, one is inside, one is in the uterus. That's how they work.

[00:27:03]We don't want that. We want to actually get one child and get them at 2 or 3 years old and then have another, maybe.

[00:27:13]So, the moment FSH is is secreted by the pituitary gland, this whole thing starts. The varium starts of estrogen, but then the moment we get progesterone, we realize, okay, it's getting serious.

[00:27:31]So, it's going to inhibit the secretion of FSH.

[00:27:38]They will ask you why there's only supposed to be one follicle secreted per cycle.

[00:27:47]Otherwise, the other side will start with the next cycle.

[00:27:52]If the progesterone is going to go down, the levels is going to decrease.

[00:27:58]That stops this inhibition. And then the cycle will start again.

[00:28:04]Grade 12, please make sure you always have FSH.

[00:28:09]You always have progesterone, estrogen, LH.

[00:28:14]The level increase or decrease. It's never zero. It's never 100 %.

[00:28:21]Going down to nothing.

[00:28:23]It just increase or decrease. And make sure you say that in your answers, please.

[00:28:32]Okay, fertilization takes place in the fallopian tube.

[00:28:38]Because remember, our oven and the sperm is very, very small.

[00:28:42]So, if it doesn't take place in the fallopian tube, but somewhere here in the uterus, it's going to be like hide and seek. Where do I find you? Where do I find you?

[00:28:51]So, they just swim all the way up to the fallopian tube. Remember, there is thousands of sperms going up.

[00:28:57]One of them will actually swim into a ovum.

[00:29:02]But now we have normal mitosis. This cell has to grow, it has to become bigger, it has to become you eventually.

[00:29:09]So, the moment this zygote go through the mitosis, each cell becomes a ball of cells.

[00:29:18]And this ball of cells is called a morula.

[00:29:22]People they're going to ask you for the process. And you must be able to say what its name is and how will I identify it?

[00:29:31]If someone is pregnant, they will tell you, "No, it's the size of a pea or it's the size of a little um avo right now." They know. But how will you biologically tell them?

[00:29:45]You will tell them, "No, it's the size of a a ball of cells. It's about eight cells and we will call it a morula."

[00:29:52]It will have to grow further and it will have to form in the middle of it a hollow part that is going to be your digestive system later on in life. So, that's the first mouth you will have and obviously anus you will have is at that moment. And it will start to stretch and develop organs around it. So, it's actually so amazing for us to sit here like we are now.

[00:30:20]That hollow ball is called a blastula.

[00:30:25]Like if you burn yourself, the little blasty, the blastula is formed.

[00:30:31]Then it will embed, so it has to get chorionic villi.

[00:30:36]You have to implant somewhere, you have to grow roots to attach yourself.

[00:30:41]And the moment we that, we say that it can start to feed.

[00:30:46]So, we will talk about a trophoblast.

[00:30:48]Tropho means to feed. It is still a blastocyst, but it can feed now.

[00:30:54]And then it will form an embryo, later on in life, a fetus.

[00:31:00]So, if it's implanted like this, the umbilical cord will start to grow from both the embryo as well as the mother.

[00:31:09]The umbilical cord is very, very important because it's going to give the oxygen needed.

[00:31:16]It's going to take away the carbon dioxide. It's going to get the nutrients needed as well as take away most, let just make sure it's only most of the waste.

[00:31:28]But as this embryo develop, it has to have space where it can develop. And this is called the amniotic space.

[00:31:37]And with the amniotic fluid inside, and surrounding it, the chorion.

[00:31:43]Remember of the amniotic egg? We also had the chorion on the outside.

[00:31:47]So, it's enclosed like that. What does it do? It helps keep the temperature inside at the right temperature for the embryo to develop.

[00:31:56]It prevents dehydration.

[00:31:58]If you move and you're a mother, remember or not remember.

[00:32:05]Please don't remember.

[00:32:07]Imagine how it will feel if she's walking up and down and you are the embryo inside.

[00:32:14]So, it also prevents mechanical injury or shock.

[00:32:20]We already talked about the chorionic villi um creating the umbilical cord. And then, please just make sure make a little mark there.

[00:32:28]The umbilical vein is the one that carries nutrients and oxygen.

[00:32:36]The artery is the one that goes back with carbon dioxide and waste. It turns around because this is not a permanent organ.

[00:32:47]For 40 weeks, you only have the structure developing in you and it's going to go away.

[00:32:53]It's not like a lung or a kidney or anything else. So, the artery and vein does different things. Okay.

[00:33:02]Now, we got the central nervous system because you're born, you have to grow up, you got to further go to matric, and you have to have a good central nervous system.

[00:33:11]So, first of all, grade 12, how do you know what is going on around you? You actually use your brain. You use your cerebrum. That's the one that tells you this is what I see, this is what I hear, there is this is what's happening.

[00:33:27]So, all your cognitive abilities is from your cerebrum.

[00:33:32]You have two sides, two hemispheres.

[00:33:35]They have to work together. Otherwise, the one will be running around outside and the other one will be sitting here.

[00:33:42]So, they have to work together, the corpus callosum. People, they look like big C's. The corpus callosum will connect the two hemispheres, making you work together.

[00:33:54]Then, this little one here at the back, the cerebellum, its main function is balance, but also it helps with coordination.

[00:34:04]But, usually I'll ask you which side helps you with balancing something and that's why because we're going to do the ear later on.

[00:34:13]The spinal cord going down, also part of the central nervous system, make sure that you understand what's the central nervous system and the peripheral one, the one that's going out to all the peripheries, to all the ends of odds.

[00:34:27]And then, one of the most important parts is the medulla oblongata.

[00:34:33]Not necessarily now because she didn't do carbon dioxide in the endocrine system.

[00:34:39]But the medulla oblongata is the part that house of breathing.

[00:34:45]It helps with our heart rate.

[00:34:48]So all the things we do not actually think about only goes up to here to the medulla oblongata. It's the upper part of the spinal cord. Because if we have to think about breathing, some people will never ever make it past 2 years old.

[00:35:07]So we don't think about it. It's a reflex reaction.

[00:35:11]But I like to ask you what if this part is injured?

[00:35:15]Can you actually go on living or not?

[00:35:17]No, you can't. You can't go on living without breathing, without oxygen, taking out carbon dioxide. You can't live without your heart rate, taking your blood to your cells. Your cells will stop respirating.

[00:35:32]So make sure that you also in biology know about the impact of an injury.

[00:35:38]Then the peripheral side, that's the neurons. You did a nice practical a few weeks ago about the neurons. So I think most of you that work already know.

[00:35:51]Please make sure that you know this is a motor neuron and that you're able to draw it.

[00:36:00]With all the parts again, the moment you start to draw, remember my voice.

[00:36:05]Remember me telling you to put down your pencil, take your pen and actually write the heading.

[00:36:10]This is important for us. We have We want to know that you know all the parts. It's also from grade 10.

[00:36:17]The motor neuron, that's why.

[00:36:20]Then every gland or every organ is controlled is going to be controlled by two sets of nerves. You can actually always be excited, sympathetic, or you can be parasympathetic. You can be relaxed, and you can be sleeping. That's also fine, because it's been a long week and a long term and a long 6 months already.

[00:36:40]So, it can be stimulated.

[00:36:43]The stress hormone. That's next week when you're going to that exam or when you know, oh oh, maybe maybe I'm should have just go through that again.

[00:36:53]That's the stress one. The moment you are there and you wanted to be participating in sport.

[00:36:59]Now you stress.

[00:37:02]Afterwards, when you're at home, you relax. So, always remember sympathetic nervous system is the stress one. It stimulates you.

[00:37:10]That increase heart rate. That feeling of I want to go to the bathroom right now. Right now, I can't keep. I have to go before the exam.

[00:37:19]After exam, you actually forget about it. You go home and you even go to the bathroom after you get home.

[00:37:26]If you're laying on the couch, you're relaxing. You're parasympathetic, just relaxing there.

[00:37:33]You don't get up to go to the bathroom.

[00:37:34]You tell yourself, ah, in 5 minutes.

[00:37:37]10 minutes.

[00:37:39]But you eat.

[00:37:41]So, go and see what type of systems it inhibits or it stimulates.

[00:37:48]Then I I can never ever stress enough the reflex arc, because that's the way we can ask all the neurons. It's the easiest way out.

[00:37:58]So, we give a diagram like this. We ask you, give us a heading.

[00:38:03]This is the reflex arc.

[00:38:05]Or we say, you have to give the reason for this, and it's always for protection. It's a fast reflex reaction to protect ourselves.

[00:38:19]So, first of all, you have to get a stimulus.

[00:38:23]If someone is not talking to you, you're not going to come from a site and just tell them something.

[00:38:29]You have to get a stimulus. You have to see something, hear something, smell something, taste something, or feel something. This is our five sensory organs.

[00:38:40]So, they have to be stimulated. That is why you did the eye after this and then the ear because I some of our sensory organs you still have to do the skin.

[00:38:52]We are going to or some of you already finished it, but remember you're not writing about it this exam.

[00:38:59]So, the first neuron, the sensory neuron, always goes from the receptor.

[00:39:05]And now it's so important that you know it goes through the dorsal ganglion of the spinal nerve.

[00:39:17]I just want to make sure because if I didn't put it in like that, you must please write that in. Oh, now I did. I just didn't do it on mine. I did the last memo we got um November 2025.

[00:39:32]The spinal nerve must be in your description. If it's not, you're not going to get So, you'll see it's actually bold and it's bigger.

[00:39:43]Please make sure that you do write it like it because the old textbooks didn't show it. So, it will go into the dorsal root of the spinal nerve.

[00:39:52]It will form a synapse with the interneuron in the spinal nerve.

[00:39:58]The internal Do you hear the way I tell the story?

[00:40:04]The word I stopped with is the word I start with.

[00:40:09]The internal neuron will form a synapse with the motor neuron.

[00:40:15]The motor neuron will leave the ventral root of the spinal nerves and the impulse will travel to the effector.

[00:40:26]The effector will be stimulated.

[00:40:29]Grade 12, you must always remember we want to know what is doing what. What is doing what? If you can answer it like that, you'll be fine. The problem is sometimes children, you get lazy to write it or time runs out. You're not used to it and you say it will and we do not give a mark.

[00:40:49]And sometimes you think you're the child that doesn't write it until you say to your teacher, "No, this was a nice practical. I did well." And the marks come back and you see that you didn't. So, make sure of that what is doing what.

[00:41:07]Okay, and then we're going to the eye.

[00:41:09]The eye, we want to know which part.

[00:41:12]So, the cornea's at the beginning.

[00:41:15]The first one that's going to break our light for us.

[00:41:19]Remember we want our light to be on the yellow spot, so it's going to have to break all the way in.

[00:41:25]So, it also go through the aqueous humor all the way. The only entrance is the pupil, so it already has to break so it can enter the pupil. If you put your hand here, you won't be able to see it because it can't go in.

[00:41:39]Then, very important that the iris can regulate the size of the pupil to get more light or less light.

[00:41:48]It further refracts through the lens all the way through the vitreous humor and then always you will say it ends on the yellow spot of the retina to get a clear image.

[00:42:01]So, if we see why it's because it has the most photoreceptors.

[00:42:06]We also have the optic nerve here traveling into the cerebrum and at that place, we have also the blind spot because we don't want to see our blood vessels going in and out of our eyes. We don't want to see our impulses traveling in and out.

[00:42:24]Remember, please, that the image itself is in the cerebrum.

[00:42:29]So, who's going to tell you what you see? It's still your cerebrum. It might have to travel there.

[00:42:34]Then we have the protection layer, the ones that we can see, the white part of our eyes, the sclera. Everything on the outside is always for protection.

[00:42:44]They have this weird thing where where they will ask, "What is the difference between a lens and the sclera?"

[00:42:50]And all of you are like, "Hm?"

[00:42:53]The lens is what color?

[00:42:57]It's clear. The sclera?

[00:42:59]White.

[00:43:00]The lens is elastic. It can change shape. It can become become more or less convex.

[00:43:07]Can your sclera change shape? If your friend comes and don't have a round eye, square today.

[00:43:13]So, it can't change shape.

[00:43:16]The lens is there to refract light. The sclera is there to protect. So, there's three differences. It's seven marks.

[00:43:24]Just make sure you already have the knowledge, apply it.

[00:43:29]And then the choroid in the middle, of course, that's where our blood vessels is.

[00:43:37]Okay, this is the one I told you about the difference.

[00:43:41]When we do the pupil mechanism, please make sure of one thing. You know that we are going to react to light.

[00:43:51]Because in exams, they will ask you, "Okay, there's less or more light, or it's a dark room." That's no light. It's just the absence of light.

[00:44:00]The moment you see light there in your back of your head, you already begin and say, "Okay, maybe we are going to talk about a pupil mechanism. We are going to have to have more or less.

[00:44:10]Now, I teach my children to do it like this.

[00:44:13]If you open up your hand from the inside to the outside, it looks like a radio.

[00:44:20]Like a circle.

[00:44:22]So, if this is going to get tense, you will feel it and you will see your hand opening up.

[00:44:28]And if you do this with your hands, if you contract your hands like this, you will also see that this looks like a little circle.

[00:44:37]Little circle getting smaller. And your hand will get smaller.

[00:44:42]So, the moment the radial muscles is going to contract, the pupil is getting bigger.

[00:44:48]The moment the the circular is going to contract, it's getting smaller.

[00:44:55]Right, 12. By now, you know that two types of muscles can't contract at the same time. They're antagonistic.

[00:45:03]So, it means one has to relax.

[00:45:06]Please make sure that you are able to draw this.

[00:45:09]We do ask to draw a pupil at bright light, where it's small, or we do ask to draw a pupil at a dark room, where it's bigger.

[00:45:22]I think this is the one that most children suffer most with.

[00:45:28]First of all, here you are going to have to see that this is about distance.

[00:45:34]Light, distance.

[00:45:37]So, now they say it's far away, that means more than 6 m, or it's close, it's less than 6 m.

[00:45:46]You do start with a specific sequence. You can't change them around.

[00:45:54]In biology, they now say one thing leads to another.

[00:45:58]So, if you start with a clear image will fall on the retina because we are not going to mark it.

[00:46:05]I know it's difficult. I know I wish biology was easier. You just learn your work and you write it down. It's not like that.

[00:46:12]So, first of all, the ciliary muscle contract.

[00:46:16]People, the muscle if you are going to see it's here, it's part of the inside of the eye.

[00:46:27]So, we start in a sequence. The next thing is the ligament. Remember L ligament is linked to the lens. Then you will remember they go together.

[00:46:38]So, then you will tell me the ligament slackens. On this picture, you can see it goes in. It slackens.

[00:46:46]And if it does that, it means that this fiber will do this.

[00:46:55]It will come become rounder.

[00:46:58]But in biology, we can never ever ever in our lives say it will become um rounder. So, the tension decrease.

[00:47:07]Comes closer to the lens, but the tension decrease.

[00:47:11]And the lens becomes more convex. Now, if you have thicker lenses in your glasses, the um refractive power, of course, increase. It becomes more.

[00:47:25]And that means a clear image will fall on the retina.

[00:47:29]You only study one.

[00:47:33]Because all of you are able to say ciliary muscle will relax.

[00:47:39]You can say the suspensory ligament will tighten.

[00:47:43]You are able to do opposites. So, only study one. The moment you get your paper in the exam, you write it on the back.

[00:47:52]If your teacher tells you can't write, you go like, "It's fine.

[00:47:56]It's fine." And the moment they walk away you write it on the back. All right, that's it. That's what you do.

[00:48:01]That's what I teach my children.

[00:48:04]Okay, we have to also know the diseases.

[00:48:08]So, short-sightedness, it's too short.

[00:48:10]It doesn't fall under retina. That's what it says.

[00:48:14]How will we make that better? We will make biconcave lenses. The moment we just make it break more, we will get it on the retina. Long-sightedness, see the picture there, it's behind. It's too far. It's too long, the image.

[00:48:34]Astigmatism, it means that we have multiple visions in our head because we have We don't have a clear image. That's if you're wearing glasses at this age, it's probably about this reason. It means that the front of your cornea is not evenly curved. This is how it looks in your brain, in your cerebrum, a lot of images, and that's why you get headaches.

[00:49:01]People, this is corrected with a convex lens. This is how it look. This is a concave lens.

[00:49:07]So, just make sure about the image. They will give you the image, ask you what type of disease this is.

[00:49:14]Too short, too long.

[00:49:17]Multiple um images.

[00:49:22]And then the only one they can give you is cataract. But I don't usually give a diagram for that. They will tell you in biological terms the lens becomes cloudy and opaque.

[00:49:34]Your Some of you have cats or dogs that's very old, or maybe grandma at home, you can see that the light going over the eye.

[00:49:44]Then we have hearing.

[00:49:47]There's just a few things that I want to tell you about hearing that you must actually pay attention to.

[00:49:55]In the outside part from the pinna to the tympanum, please make sure that you know we have sound waves.

[00:50:03]That's the first thing.

[00:50:05]Inside the middle ear with the ossicles, you have to know it's so-called vibrations.

[00:50:12]But the moment we enter the inner ear, it's called pressure waves.

[00:50:18]If you're sure about those three, it's 100% fine and then the moment it is transmitted by a nerve, it's called an impulse. So, the stimulus is going to create an impulse.

[00:50:31]If you understand those different parts and you know what it's called inside as it travels, you're 100%.

[00:50:39]With balance, you please study it as it is in the exam guideline.

[00:50:44]But can I make sure that you do have a look and see that there is a difference?

[00:50:53]Sorry.

[00:50:55]The semicircular canals or the crista is stimulated by what? Direction and speed.

[00:51:02]This is direction and speed. So, you must remember that's the crista where a change in a position of your head, tilting it, will stimulate your macula.

[00:51:16]The rest of it stays the same. You will say the stimulus is converted into an impulse. The impulse is transmitted through the auditory nerve to the cere- bellum.

[00:51:28]Remember we do both parts, so it doesn't make it easy to the cere- bellum, which will interpret it.

[00:51:35]Here, the one part that I'd like to ask is where grommets are inserted. So, I just put a picture here. That's how a grommet looks. If your middle ear keeps getting if infected, the tube of his urine can't do his job, so we put a grommet in to help the um balance it out, the pressure.

[00:51:56]The lowest part, you only have to know the picture, the glands, the hormonal it stimuli or um was going to secrete, and the target organ that's going to be stimulated. What's happening there?

[00:52:13]And then, this is grade 11 work. So, I do hope you are a grade 11 teacher.

[00:52:20]Please make sure always if blood glucose is going up, it's rising, or it's dropping, who is going to see that?

[00:52:31]Always the pancreas is going to see, "Whoa, here's a problem."

[00:52:35]So, it's going to react. If your levels is rising, it's going to send a chemical, the hormone, that's a chemical messenger through the blood.

[00:52:46]Where is it sending it? It's sending insulin to the liver and the liver with the muscle cells. So, let's take all this glucose and turn it into glycogen.

[00:53:00]Blood glucose decrease, returns to normal.

[00:53:04]Grade 12, make sure that you know the difference between glucose, glycogen, and glucagon.

[00:53:13]And that's the final part. All the best of luck for June. I hope it goes well.