23 July 2020

welcome to eagles concept education room in this uh segment we continue with 2016 biology paper 2 theory we ended on question uh nine so proceed and finish up wrap up this paper with question ten so please uh pay attention and make sure you apply the skills on how to correctly answer the questions of paper tool nature in paragraph form because these are essay type questions all right question reads explain how flowers are flowering plants get rid of excess and unwanted substances from their bodies for max b discuss the importance of homeostasis in mammals so as usual i'm going to first explain these two concepts in detail such that you can even answer other types of questions that are in this um a similar manner so i'll begin by explaining excretion so by definition excretion is simply the removal of unwanted or toxic substances from the body of an organism now excretion is very much understood in terms of animals but it is also present in plants so in this case the leaf is the main excretory organ in a flowering plant okay that was supposed to be plants with plants so it's the main excretory organ plants okay so let's look at the leaf here okay so now we are saying what does the leaf excrete so the leaf is able so the plant is uh produces two excretory products so number one it produces carbon dioxide during respiration then it also produces oxygen during photosynthesis so these are the two excretory products that are produced from the plant so now during the day photosynthesis takes place remember photosynthesis is simply the process by which the green plants they use the sun's energy to convert carbon dioxide and water into glucose and oxygen so during the day photosynthesis takes place and the leaf is going to produce oxygen so oxygen is added to the atmosphere as a waste product okay then these things they're happening in the leaf the leaf uses the these tomato pods so in this tomato polls that is where these gases are able to diffuse into and out of the leaf okay now carbon dioxide uh carbon dioxide will be taken from the atmosphere plus the water that is coming from the the tree trunk all the way from the soil will combine and the oxygen is taken out but we also have excess water okay so excess water which also can be excreted during transpiration which is the evaporation of water from the surface of the leaf okay then we also have some carbon dioxide which is being produced during respiration remember residuation is the oxidation of sugar salt but this thing here the carbohydrates so the carbohydrates react with some of the oxygen that is being gotten from the atmosphere and it combines to produce the energy and some of the carbon dioxide which is given out so generally here you can see that these two gases are just exchanging at a different level okay so that is about how excretion uh takes place in a flowering flowering plant okay let's look at a more detailed view of the leaf so this is the surface of the leaf here as you can see uh this is uh the zoomed stomata here so the stomata here it has got the gut cells so the gut cells are the ones that that control the opening and closing of this tomato pulse so when there is uh uh there's too much water into the plant here now the water has to diffuse out of there out of the plant by the process of osmosis remember osmosis in the movement of water molecules from a region of high water potential to a region of lower water potential so if there is too much water in the plant excess water has to be released to the outside as an excretory product so it could be excreted by osmosis by osmosis with the help of evaporation there and to be called transpiration so the gut cells the control the opening and the closing okay then at the same time here uh the carbon dioxide when it is low into the plant then some of the carbon dioxide from the outside which the animals breathe out and other actions produce it will be taken into uh into the what into the uh the plant by diffusion the movement of molecules from a region of higher concentration to original concentration so the gut cells are very important the stomata here just the openings that are controlled by the gut cells so the gut cells they know when to open and drain to close depending on is the concentrations okay so the stomata opens to allow carbon dioxide to enter the leaf and water paper to leave the leaf okay so that is how excretion is done let's look at how an answer can be given so uh plants produced two gaseous wastes that is uh oxygen during photosynthesis and carbon dioxide during respiration so excretion of gaseous waste implants takes place through the stomatopods on the leaves by diffusion excess of water uh excess of water is also excreted from the plant uh body through the stomatopods and from the surface of the fruits and stems and this process of elimination of water is called transpiration so this is how you can uh uh uh phrase uh your answer okay the second part of the question was about homostasis so what is homeostasis so homeostasis is the maintenance and the regulation of a constant internal environment in an organism [Music] so cells and proteins like enzymes in the body of an animal functions at a specific physiological condition now we are talking about specific physiologicality conditions and these conditions are water so what happens here is that we need to have a specific potential of water now when there is uh water is a universal solvent and most of the chemical reactions in the body they depend on water so if there's neat water in the body those chemical reactions will be affected again if there is too much water in the body ah there'll be a problem actually this one can lead to a condition which is known as diabetes incidence having too much water in the body so the body has devised a mechanism in which these can be maintained and that mechanisms they are what forms the homeostatic system of the body so homeostasis is the maintenance of a constant internal environment so one of the biological conditions is actually water but from that we also have the concentration of glucose so now this concentration of glucose here uh we know there's a normal glucose level that a human body is supposed to have so if you have a little glucose you're going to have a problem with the issues of energy because remember the energy comes from the glucose so the glucose will be oxidized and then energy has to be produced so if you don't have enough glucose then you have issues of energy now if you have too much glucose you're going to have um you're going to have uh diabetes meditation so you're going to have what is known as diabetes mellitus so this is a disease commonly known as sugar disease so now the body has devised a mechanism using homeostasis where if there's too much glucose then the excess glucose is converted to glycogen the excess glucose will be converted to glycogen which is the storage form of water of glucose so in an event where the glucose has become low uh actually now this glucose will be converted to glycogen by and by insulin okay so there is a hormone insulin and when the glucose levels are low then the glycogen will be converted back to glucose using an enzyme using a hormone known as glucagon so there is an air the enzyme known as glucagon so this is how the concentration of glucose is maintained in the body the other physiological condition is temperature now most of the body cells and enzymes they are made up of protein so protein they work at a specific temperature and known as the optimum temperature so when the temperature is low the enzyme activity will also be slow and step but when the uh temperature is too high then the protein becomes nature otherwise it becomes destroyed so it cannot wait so now we need homeostasis to maintain this constant temperature so uh there is the hypothalamus or the heat center in the brain which uh plays along with other things such as the skin in just making sure that the temperature of the skin is maintained at a certain level so there are certain things that associate um for example when these when the temperature of your body is too high then the body automatically begins to do things like sweating uh just in order to get rid of some excess heat then when it's too cold when it's too cold there are certain things that are going to happen like shivering just to make sure that temperature goes up then uh there is also when it's too cold there's what uh is known as vasoconstriction that is going to happen so vasoconstriction is the narrowing of the blood vessels so that uh less blood can flow to the surface of the skin and once less blood is flowing to the surface of the skin and all the heat that is being produced from in the body due to metabolic reactions is being maintained from within the body okay so the opposite happens when the temperature is too high it's going to happen what is called vasodilation so this is the increase in the diameter of size of the blood vessels and this causes the blood to flow closer to the surface of the skin so that whatever heat is being produced from within the metabolic reactions of the body can easily escape through the surface of the skin and also uh these the erectile muscles are going to erect so that more heat can be lost so those are some of the things that uh take place okay another physiological condition uh physiological condition is the amount of oxygen and carbon dioxide these two they have to be maintained and they have to be maintained for the process of diffusion so if there's too much carbon dioxide in the body the body will become acidic if less oxygen a person cannot survive and also energy will not be properly produced so these things have to be maintained okay so now just to answer the question and explain the importance of homeostasis now homeostasis helps to maintain a constant level of water a constant level of glucose a constant level of temperature and the constant level of the gases oxygen and the carbon dioxide so it is very important okay so the control systems that keep such conditions constant constant are examples of homeostasis okay let's see now how probably we can phrase our answer homeostasis is very important because it helps so on your statistics is very important because it helps the body to maintain a constant internal environment by controlling the physiological factors so like i said it's very important because it helps the body to maintain a constant general environment by controlling the levels of water by controlling the levels of temperature by controlling the levels of glucose the levels of carbon dioxide and oxygen in the body as well as other conditions so how are these things done that is uh what is being explained here so concentration of glucose uh this one is the fuel for respiration so lack of it causes respiration to slow or stop depriving the cell uh depriving the cell uh depriving the cell of an energy source however too much of it may cause water to move out of the cell by osmosis again the metabolism of the cell so if the glucose level is high the pancreas produces insulin to convert excess glucose to language and the glucose levels so the insulin induces like a glucagon which conveys the glycogen back glucose [Music] temperature is another physiological condition that is kept constant by homeostasis so this is how you can phrase your answer as well okay you can see that on the screen it's just an example on how proper you can trace your answer okay so we also have water potential so if the water potential increases water may move out of the cell by osmosis causing metabolism reactions in the cell to stop on the other hand the water potential increases uh water may enter the cell causing it to swell and reverse therefore a certain constant level of water has to be maintained via osmoration regulation of carbon dioxide and oxygen the body cells needs a constant supply of oxygen for metabolic processes that are necessary to maintain life so the respiratory system works with the circulatory system to provide this oxygen and to remove the waste product of metabolism which is carbon dioxide carbon dioxide can also be uh can also damage the tissue and the organ fever in varying oxygenation of blood and as a result slow books in delivery to the tissues okay so we have come to the end of this presentation thank you so much uh keep watching the videos remember to subscribe and uh just share the link with your friends this will help you in your exams make sure you remember paper to theory section b it's answering in paragraph form because they are essay type questions thank you bye