GRADE 12 BIOLOGY PAPER 2, 2016 SECTION B Q6 &7 . ECZ

everyone welcome to today's lesson in this video we'll be dealing with uh how to answer biology questions in paper 2 and particularly section b so biology paper 2 have got section b which has got about four questions out of the four questions you are supposed to answer at least three questions now biology paper two and section b is a very interesting section this is where they bring s-a-type questions so meaning you are also supposed to answer your questions in paragraph forms and not important forms so this is a point that you really need to bear in mind so it's essay type questions meaning you should be using paragraphs so in this video i'll be just answering two questions question six and question seven and then i'll first be explaining and also give a sample on how the questions should be properly answered please do not forget to subscribe to our to this channel like the video and share the video come with me as i take you through this portion of the exam okay so according to 2016 section b uh the instructions are answer any three questions so out of the four questions you're supposed to answer three questions each question carries for max and a question may have several parts it can have a b c whatever but this particular one it had two parts that question a and question b so the question reads what are the characteristics of the alveolus as a respiratory surface then b it says describe the mechanism involved in inspiration in human beings okay so basically when you read this question you figure out that it was about the respiratory system so the major thing here that was ingested is whether or not you understand the respiratory system okay so here we are dealing with the respiratory system now when we are dealing with the respiratory system here uh it basically involves the following parts so the respiratory system basically involves the nasal cavity the firings the larynx uh from the larynx there we have the trachea from the trachea you go to the uh to the land themselves then you have the uh the broncos here so the bronchus is one then the two of them they are known as the bronco that is the turtle then we have uh inside we have the bronchioles so from the bronchioles that's when now we have the the air sacs here at the far end here or the avioli okay so that is basically the respiratory system it involves what we call the thoracic cavity so in the thoracic cavity as you may know these lungs here they are protected by the ribs as you will see in the other illustrations so they are protected by the ribs so now just a quick one uh when you talk about the respiratory system it involves a process known as breathing okay now breathing is a component involving two parts there is a part called inhalation and exhalation so inhalation it is the taking in of air through the nose that is the normal some there are certain times where you can also use the mouth but the normal one is supposed to be through the nose because in the nose they are some uh hairs called syria which are able to trap the dust particles and the air is coming in okay so it is a safer way of taking in the air which is called inhalation or in this case we can also call it inspiration okay so when uh the air enters through the nose it passes through the pharynx from the pharynx there it goes all the way through the trachea and the trachea is made up over the rings of cartilage to prevent it from collapsing so these rings of cartilage they always ensure that the track yard is open at all times uh despite the positions of their names okay so from the tracker there the air can now be uh can go to the uh the bronx and the bronchi so from the bronchi it goes to the bronco from the bronco finally it goes now into the aviolas in the aviolas that is where now dasha's exchange takes place specifically so gasha's exchange will take place by what by diffusion so now i'll pay our question here it is trying to understand now what is it that the alveolus has okay so this is the structure of the alveolus in three dimension so structure of the alveolus in three dimensions now the question is trying to ask us what is it that the object that makes it possible for it to carry out the function of uh diffusion okay so now to start with uh this diffusion of gases this is where the gases will uh exchange so like i say breathing has got two parts inhalation and exhalation so the breathing in of air is called inhalation and the breathing out of air is called exhalation or the other way that can be used is inspiration and explorations of inspiration taking in then expiration taking out so the two processes they compose what is called breathing so during inspiration oxygen goes into the human being then during expiration carbon dioxide has to go out now these two gases they exchange in this specific part of the respiratory uh system known as the ideologues so the alveolus is is is suitably adapted to carry out this exchange of gases by the process of diffusion because it has the following facts okay so now to begin with it is well supplied by the blood vessels so it has got a good supply of uh blood vessels so you can see we have the pulmonary artery and the permanent vendor so this one makes it possible so this one it enables the blood so the blood to enter and the bloods to go out this is why it is able to carry out its function then the second feature is uh that the mucosal lining here as you can see the mucosal lining uh it is moist okay it is moist and then uh this causes diffusion to be swifter then like i said it is well supplied with the blood arteries and these batteries these blood arteries they are thin okay they are thin which makes diffusion to be swifter then another thing here that you can see is that the alveolus is folded many times thereby increasing its surface area for diffusion so these are the major features why the alveolus is able to swiftly carry out its function which is the exchange of gases by the process of diffusion because it has a few of these water features okay the second part also during breathing uh there are certain things that happen okay so for example uh this one is two diagrams here they are representing uh this one air air is entering so as the air is entering here this one is called the inhalation or inspiration now during these two processes there are certain things that happen because remember we say those are two lands okay remember these two lands here in the sides here they are protected actually by the water by the ribs okay they are protected by the ribs in the sides here and then we have the diaphragm now so these uh the the the ribs and the diaphragm together with uh the land there and its contents they form what we call the thoracic cavity so the thoracic cavity during breathing in and breathing out there are changes that have to happen to the thoracic cavity now what are some of these changes that happen during breathing in and breathing out these are the things that we want to understand in this video so now during breathing in uh the ribs they actually move outwards okay they move out up and outwards so this is what you're saying they move up and outwards so as they do this now this is brought about by the uh uh so we also have some intercostal muscles there okay so now these uh there's some action that happened in the in the custom muscles so that action will cause uh the ribcage or rather the ribs to move up and in outwards so when this happens it causes uh the the the the land capacity to expand meaning the volume will be increased so if the volume of the land is increased then uh then after after that increment it will force the air to go in okay to force the air to go in hence inspiration or inhalation then also you should note that the diaphragm also it moves downwards so some of the changes that happen during inspiration is that the ribcage moves up and outwards causes an increase in the volume or size of the lungs okay and if the volume of the lungs increase because of that large space in volume that large increase in volume the air will be forced to enter and also remember that the diaphragm it has to move uh downwards okay it moves downwards so they're moving downwards and they're moving upward and outward of the the ribs this one brings about an increase or expansion in the volume of the lungs okay now let's look at also during expiration or inhalation so here uh what happens is that the ribcage it actually moves down and inwards then you'll notice that the diaphragm also will now move up okay so the diaphragm will move up and these two changes here they are definitely going to cause the land uh the volume of the lungs to become smaller so the volume of the lungs here will become much smaller so once the volume of the lungs is smaller it will cause whatever air is inside to be expelled to go out so that is what we call expiration now we have our air here which is carbon dioxide living okay so those are some of the changes that will take place during inspiration and expiration okay having that explanation let's check now on how we can put these into answers that can be expected from you in the exam so there are various ways in which you can write these answers but one thing is for sure whatever language that you use ensure that the keywords are there ensure that they are in paragraph form this is essay type writing not point form essay type writing so ensure that they are in paragraphs okay so let's look at question a which uh asks us to describe the adaptations of the ideology so for this one example has been shown to you so you can write the are ideally afforded to increase their surface uh area to volume ratio so more volume of air can diffuse easily the lining of the agile wall are also moist so that the gases can easily dissolve there was a thing so the diffusion distance is short then they have a rich blood supply as the blood capillaries are closed and have inwards so there is a steep concentration gradient so everything that was being explained has been put together in a paragraph so just ensure that the keywords are there you use the correct conjunctions and so on and so forth okay so let's go to b now b uh it was asking us to describe the changes that take place during inspiration so these are the changes now that are being summarized for you so during inspiration the muscles of the diaphragm contracts okay causing the diaphragm to move downwards the intercostal muscles also contract causing the ribs to move outwards and upwards these changes results in the increase in the volume of the chest cavity and the air pressure inside the chest cavity decreases this causes the oxygenated air present outside the body being at a higher pressure uh to flow rapidly into the land by what diffusion so like i said the gaseous exchange it takes place by diffusion remember diffusion is the movement of molecules from a region of high concentration to a region of lower concentration okay so in the lungs oxygenated air reaches the alveolus the alveolars are inward and are surrounded by a network of blood capillaries then the oxygen passes through the walls of the agiola into the blood present in the blood comparisons the oxygen is then supplied to the tissues of the body so everything has been summarized that is example how you can answer such questions okay uh let's check question seven question 7 it reads explain the causes of coronary heart disease explain the causes of coronary heart disease discuss how coronary heart disease can be prevented so question seven part one and two it was about uh the coronary heart disease so i'm going to explain what coronary heart disease is to you then i'll show example on how the answers can be written okay then the second part is about uh the lymph nodes okay it's about the lymph nodes so i'm going to explain what these two are and then find and answer the questions okay so shall we look at the coronary heart disease so my diagram here is trying to illustrate uh what coronary heart disease is now the heart has got blood vessels so the blood vessels of the heart we've got the veins okay so what's the veins those are the blood vessels we've got the veins and we have what we call the arteries okay we also have the arteries now these things uh they can you can give an example of the veins you can talk about it from monarch veins the female cover then the arteries we can talk about the iota you can talk about the hormonal artery now you'll notice that uh you notice that uh these these these two guys they've got some general functions okay they've got some general functions so in the other videos we look into details about that but for now we are just interested in one particular artery so a coronary artery is simply the artery of the heart so this is the one that brings blood and oxygen to the heart as you can see here this one okay so that is the coronary artery there that brings blood and oxygen to the heart okay now the heart cost is constantly finding blood the heart is constantly pumping blood and uh this is one of the arteries that brings blood to the heart for pumping and registry for pumping under distribution so this is blood containing oxygen that is the coronary artery now you look at here the first part here i'll name it a so my diagram a here is showing you a healthy artery a healthy artery and now this particular artery is a coronary artery so now coronary artery is uh is coronary heart disease is simply the disease of the coronary heart coronary artery now how does this disease of the coronary artery come about so it comes about by a blockage so whenever there is a blockage in this artery here then we're going to have a problem so whenever we have a blockage let's say we have our blockage there it means we're going to have a problem the blood will not be propagated supply and if blood is not properly moving the heart will be stressing and if the heart is stressing it means generally the body functioning will not be okay so that is what a coronary heart disease is now let's look at b so now how does the coronary heart disease come about so the coronary heart disease is uh uh is caused by the buildup of fatty deposits on the walls of the other is so these are the walls of the arteries inside here as you can see inside here all these these are the ones inside there those are the walls of the atom so now if you are eating too much food that i've got a lot of if you're eating too much food that has got a lot of fats and then you don't even do regular exercises you tend to do a lot of things like smoking so you're usually going to be experiencing that there will be those fats they'll just be depositing in their team they'll be depositing in their words as you can see at to be here the deposits are just certain then when you go to see here this is a west coast scenario now where the the the atom is actually now completely been blocked now the implication is that when it is being completely blocked here you are not going to have a smooth blood flow and once the blood is not uh flowing smoothly then we are going to have a problem okay so like i said it is caused by the udac of the fat deposits along the walls of the atom so now these fat deposits here they are usually uh brought about when you are doing certain things like for example you eat a lot of uh meals that have a high content of fats and they are not even and then you don't even do regular exercises okay so uh lack of doing regular exercises is likely to cause to lead to coronary heart disease coronary heart disease chd okay then also we can talk about smoking now smoking uh tobacco smoking it contains uh so tobacco smoking it it actually contains the nicotine okay it contains nicotine and carbon monoxide so nicotine and carbon monoxide so these two substances here nicotine and carbon monoxide see all these they cause their heart to be pumping faster so as the heart is pumping faster it will be strange okay it will be strange and that is not good now as the heart is being strained it will lead to what we call the high blood pressure so it leads to what we call the high blood pressure which is not good okay then we can also talk about diabetes so that that is also it will be you know that that is now is a condition and and here we are talking about a condition called diabetes mellitus okay diabetes meditation is where you have too much sugar in your blood so if there is too much sugar it will also be causing some deposits okay it will be causing these guys to become thicker and once uh the walls of the arteries are becoming thicker then blood will not be planting very fast the blood will not be pumping smoothly sorry so if the blood is not planting smoothly then you are likely to have the chd which is a coronary heart disease okay so there you go to your causes and the remedy also stress okay one of the uh the factors that will also contribute to coronary heart disease is stress when you are emotionally stressed definitely it will lead to high blood pressure and high blood pressure will bring about heart conditions because the heart of this training they have to be stressing okay so your emotional stress will lead to the stress of the heart the stress of the heart is not good it will bring about the disease now what are some of the uh what are some of the words in which you can prevent or reduce the chds okay so very simple you need to have a healthy dieting a balanced healthy diet then you have to couple it with regular exercises which will just promote the smooth flow of blood then aside that you also have to reduce on your smoking avoid smoking okay and uh generally make sure you maintain a healthy dieting couple with some exercises and with on your um on on your habits of smoking okay so now uh let's look at on how best we can put all these together and just give an answer so we are saying uh coronary heart disease chd is usually caused by a buildup of fat deposits on the walls of the arteries around the heart okay so the buildup of the uh aroma makes the arteries narrower restricting the flow of blood to the heart muscle okay smoking is also a major risk factor for coronary heart disease tobacco smoke contains nicotine and carbon monoxide which puts a strain on the heart thereby making it work faster they also increase your risk of blood clots okay so that is what they do we continue furthermore lack of regular acts and a sluggish blood flow thereby causing fat deposits to build up in the utterance if the other is that supply bloods to your heart to become blocked it can lead to a heart attack emotional stress is yet another factor that causes chd this is because stress can often lead to high blood pressure or what we call hypertension thereby putting a strain on your heart then uh diabetes can lead to coronary heart disease because it may cause the lining of the blood vessels so the blood vessels in this question being the arteries to become thicker which can restrict the blood flow okay the second part was asking us to list the ways of uh prevention so there are several ways you can reduce your risk of developing coronary heart disease one such way is combining a healthy diet with regular exercise okay having a healthy weight reduces your chances of developing high blood pressure other ways of preventing heart disease uh is by giving up smoking and reducing alcohol consumption see paragraphs naughty point four okay essay type question so you do paragraphs b now the lymph nodes contain lymphocytes the lymphocytes are the types of white blood cells that determine this uh this specific uh the specificity of the immune response to infectious microorganisms and other foreign substances so how does the lymphoma how does the lymph nodes uh help in protecting the body against diseases it's very simple it's by just producing the white blood cells which are the lymphocytes now the white blood cells are the ones that do the job so that is how that question can be approached thank you for listening and see you next time