Transcript for:
Biology Exam Prep Crash Course

hello everyone and hope that you're doing great now today I'm going to run through biology as a crash course series I know the examination is on our tals and some of you are anxious at this time but there's no need to be anxious it's just that you need to prepare yourself as best as you possibly can and be comfortable all right so what I'm going to do is to give you some explanations and tips as I go along also I'm going to add some information in the description in terms of links so you can watch some extra lessons that will assist you in different aspects as I go along all right I think I've covered about 95% of the entire syllabus um which is good enough for you to at least aim for that grade one or a all right so the first thing first is look at the division of the syllabus or the course itself and the course is divided into three segments you have living organisms in the environment and then you have life processes and diseases and then you have continuity and variation now before I go into the specific topics what I'm going to look at is take a look at graphs all right because I know some of you at this point are still not so good in terms of drawing a proper graph what to do when you see a graph or to interpret graphs and so on so the first thing you have to know what a graph is and a graph shows the relationship between variables and the two variables that we have to wrestle with are independent variable and dependent variable so first one independent variable those must be placed on the x-axis again independent variable as word suggests it stands on its own nothing will affect it but it can affect other things so again this is a variable that can be manipulated that means when you are doing an experiment you actually can manually change this type of variable all right so in other words now you as the experimentor can adjust the independent variable according to producing a certain result or certain change or certain response all right that is you doing this so again what is important about independent variable is that independent variable causes another variable to change example of this is time what change will occur over a certain time what temperature is another independent variable temperature can cause something else to change like example evaporation and so on so the more heat you have you can have high evaporation rate and the other one is dependent variable as the word suggest it depend on other variable and so again the dependent variable must be placed on the Y AIS again this type of varable change or changes based on the changes in the independent variable an example of that is the rate of photo synthesis all right I'm I'm going to give you an example that will bring this out a little bit also growth growth or growth rate water loss for example in transpiration what are some external factors that affect the rate of water loss all right and notice that these things are the things that are being affected by the change in another variable which we call the independent variable all right so I'm going to bring this out in terms of an example and so what I have here is two VAR one is saying volume of carbon dioxide in cm Cube and one is saying mass of glucose produced in grams and I know as you see this you should know what topic this is related to and this is photosynthesis because the amount of carbon dioxide a plant receives will determing the amount of glucose that is produced all right these numbers I make up these numbers so these are arbitrary numbers all right and so what I want to notice a pattern right here as a know as a carbon dioxide increases you also have an increase in glucose however at a certain point the GL the amount of glucose produced will remain the same and there's a reason for that and of course we can discuss that later all right now the idea of plotting this information on a graph is that one you must remember when you're doing a graph you must have a title so a title is important for example this is saying the graph showing the mass of glucose produce for the volume of carbon dioxide absorbed all right so title is important you must label your access your y AIS and the xaxis you must label them must all right and you must use a suitable scale and notice I'm going through all of this for your benefit in terms of what you should look out for in terms of marks that's why graph will be like four or five marks up to six marks sometimes so your title is important your labeling is your labelings are important your scale is important and why scale is important because the graph should be at least half of a page going to 3/4s of a page the leas a small graph you're going to lose a mark for it so when you use large scales the graph will be bigger and full up the graph page all right so for example we have the variables again mass of glucose produced no this is on the y axis and volume of carbon dioxide is on the xaxis so if you look at the values and you realize the graph start the shape like this and then after a point you notice the amount of glucose produced Remains the Same and simp simp because no matter how much carbon dioxide put in some other Factor will be limited for example light or water and so therefore the plant can only produce glucose at a certain rate and no more based on the other limited factors all right and so also you need to learn how to interpret the graphs what is also important the line must be smooth and the points that the plot must be fine on on point all right so notice there are number of marks you can learn from just drawing a graph all right so that being said now let's go into our specific sections and we going go to section A first talking about classification and remember that in classification is the way of organizing or grouping organisms based on specific features and the largest group is Kingdom rang into species you must know them all right so you must know specific philm example mammals all right you must know Common versus scientific names you also need to know scientific names made up of genus and species as well all right so those are things you need to look out for and just to give you a little insight on this topic um you must know that we start from Kingdom philm class order family genus and species in that order coming from very large to very specific group a way to remember this is that King Philip came over for Grandma's soap back in the days when I used to go to to high school I used to remember that King philli came over from great Spain but of course as we go on we change it we change things and also adopt New Concept but once you remember it it will be good all right now again um a point to note is that you must know the specific Kingdom for example the Plante Kingdom the Animalia fungi including mushroom bacteria all right and bacteria is a procaryote just to make mention of that all right you also need need to know the protesta kingdom which include amiba all right speciic F that you need to know is vertebrae and vertebrates they're also called Cordata those are the one with backbones and you have the invertebrates those are the one without backbones so please need to know those you need to also know examples from different classes such as class fish reptile insects bird and mammals and what you need to know is also specific characteristics such for example um birds and mammals are the only one blooded all right the others will be cold blooded you to know things like that you to know to distinguish them in terms of those who have scales um for example birds have scales on their feet that's point you to not some people miss that all right uh insects with the different um segments of their bodies as well all right and also the amount of legs and segmented or jointed legs and so on so you need know the characteristics of these classes please you need to go through them all right very important all right um now let's talk about some specific things that you need to pay attention to all right again we talk about characteristics and um CC will test you on identifying visible characteristics such as heiness um color all right shape all right venation number of legs and also and also number of wings and also body segments which I mentioned earlier all right and so you need to know the differences and similarities between organisms such as insect and arachnids you need to know the difference between those all right the amount of um segments and I see this was an also a pass paper for multiple choice as well when they when they compare the different organisms and of course you the insect will have three body segments versus the AR will have only two the number of legs and so on all right antenna no antenna and all of those things so please number of wings wings or no wings yeah very important for you to know them all right and so again um just give you just brief information different sections all right the next topic I want to look at is ecology and ecological studies and um very importantly you need to know things like Niche and nich is specific role of organisms in an ecosystem or environment the specific role that organism is playing in that environment or ecosystem that's what they call a niche habitat is where the organism live and then a population very important for population it is the total number of a specific species so we don't mix species to get a population there only one type of species you add up together get a population within that habitat or in that ecosystem Community now is is the Interlink of different U populations or group of populations interacting and then ecosystem Now deals with the abiotic and biotic factors so it's a grouping of all the living and non- living aspect of the environment that's what that's one ecosystem is and how they interact with each other all right we also need to talk about adaptation of organisms to specific ecosystems such as those that live in water which are marine organisms those that are terrestrial those that live on land those that live on the rocks for example those that live in trees they talk about like camouflage they talk about adopting type of leaves for example Coti that will be in the desert they do not have true leaves or large leaves and so they have um they they they lose the leaves to adopt to conserve water and things like that all right some plants will have thick waxy cuticle to prevent water loss some of them will have small leaves or leaflets all right some of them will have also prickles for protection as as well all right so definitely you need to know adaptations of organisms um for them in a specific environment all right caging is also another one for for example fish um will camouflage and other organism that live different places whether be land or in water all right and also you need to know methods that are used to study organisms within the ecosystem and such one here is called poters and just give you an example of that because that one is not a common one that is normally used so what the poters is is really a device that will have two tubes one will allow the organism to enter and of course you can also suck on the other end if you want to do that um you don't have to but that's a typical way to do it so for example is a small organism instead of touching them you will suck on one end of the straw and the and the small organism will be stucked into the jar and notice there be like a mesh type of thing right here to prevent the organism from being sucked up into your mouth all right so that's a common way to collect small organism that you cannot really touch with the hands or if you touch them they may die or break up you see so you use this um poters or or poters you actually call it to really um collect small organism um you may use bottles you may use jars you may use Nets you may use um sivs you may use quadrants and quadrants you need to know what a quadrant is and those are pretty much square or rectangular shape divided into smaller segments or quadrants you call that those segments those are called um different quadrats or you may use line and belt transect as well Mark release and capture so Mark release and capture is actually one thing all right so so you capture something you mark it you release it and you recapture it all right and you will see those things mainly on documentaries where um those documentaries will be tagging different organisms and they may tag them with cameras or numbers or different Mark markers and then they catch them again and then release them some of them will also be tagged with with trackers to see where they're going and see different movement in terms of migration and all type of different things or how they feed how they hunt and how they reproduce all right so there different reasons why you want to study organisms in the environment all right all right so next thing going to jump into right now is just a look quick look in terms of abiotic versus biotic factors and so abiotic factors those are the non-living aspect of the environment and so those are the physical and also chemical um factors as well so not just the non living non living include physical and and chemical but chemical um sorry not chemical physical can all also refer to biological so you be careful to differentiate the two when say physical talk about just the structure of things being there all right and so example of that will be including water the air the soil the temperature the light those are the physical nature of the environment those are the non- living aspect of the environment as well and some of them have chemical nature or properties such as water can also refer to as a chemical air can refer to as chemical as well right and even the the component of soil can also be fall under the chemical aspect as well but generally speaking and for examination is a non living aspect of the environment and for biotic now refers to the living aspect of the environment so different organisms they are the biotic factor within that environment all right so technically now when you see that you should think about food chain and food webs all right or or or how organism relate to each other whether it be by feeding relationship or simply just a relationship in terms of um benefiting one or the other such as animals and plants in terms of relating to carbon dioxide versus oxygen or the exchange of those gases between those organisms so yes there are different ways that organism interact within the environment not always feeding relationship but other um relationship as well including nutrient cycling all right so that's a very important thing to look at all right so let's start food chain and food web now real quickly all right and just dive into some specific information about food chain and food web all right so things going discuss right now is energy decrease or energy decrease along the food chain or food web all right just to go back one second just to kind of point out something here what to notice difference here is that for food chain you only have one path for energy to flow and in a food web you have many parts for energy to flow and um point to note is that in a food chain you can well both food chain and food web You See Arrow and the ARs indicating the flow of energ I know that was on a past paper as well the arrows indicate the flow of energy or what is eating what all right a food web is normally more complex than a food chain as well also difference in a food chain you will not see omnivores you can only see herbivores and carnivores because omnivores eat both plants and animals right you're not going to see that within a food chain but a food able to show you omnivores all right that's very important to note also this important to not is also if you decrease one organism what will be the effect on the other organism for example if you take out the O what will happen to the mouse and of course um just let's show you this real quick what I'm talking about so let's say I take out the mouse for argument sake right stick out um the old for argument sake then there'll be an increase in the mouse and if there's an increase in the mouse there will be a decrease in Grasshopper And there if there's a decrease in grasshopper there should be an increase in the grass and of course once take out one organism going after that organism or before that organism you have an you have an alternate change in terms of what is happening all right and so again let must jump into the specific discussion here that I want to talk about now we're talk about decrease again along a food chain energy decreases and you must understand why because again the demand for energy increase and not only that the basic reason or the primary reason why iny decrease along the food chain is because each organism is using some of the energy for their own biological functions and also what you need to understand again energy is also lost due to heat as well in a food chain right so that is very important you have you have energy lost along the food chain as we go along the food chain again the number of organism tend to be less generally speaking the number of organism tend to be less and the reason for that of course because there at greater demand for energy and the organisms are normally larger so therefore they must be less to consume as much energy as possible all right again energy requirement is linked to the size of the organism and how far and how far the organism is in the food chain or food web the high go the high ener requirement due to larger size of organism generally speaking all right and of course the organism is larger then they tend to require more energy to sustain themselves and also carry out their life or biological processes all right bioaccumulation is very important to discuss as well and bi accumulation is when persistent chemicals will remain in a food chain or food web and increase in concentration as you go along the food chain a reason why chemicals will bu accumulate is simply because um organism are eating more to sustain themsel and also to maintain their energy requirement to satisfy that energy requirement so for example a bird may eat one fish for the day but but a man may eat three of the small birds for the whole day so therefore you know you eat more of that organism to sustain yourself because you're larger and end the concentration of your poison will increase we also need to talk about prator prayer relationship very important a prator that that will that will do the hunting and a prayer is being hunted all right and we also need to talk about feeding relationship which I'm going to give you some example examples shortly we also need to know about the importance of decomposers in terms of nutrient cycling also the decreased wastage in the environment and also the decrease diseases in the environment so decomposers are very important and of course decomposers will include fungi and also generally or mainly bacteria so even those these even though these microbes might sound a little bit disgusting by nature of the name or what we have used to our perception about them they're actually useful in recycling nutrients decreasing diseases decrease the builtup of waste in the environment which is very important all right so decomposers are absolutely important for us all right now some very important special notes right here we talk about the relationship between organisms and so some of the the relationship that you pay attention to here is parasitism commensalism and mutualism very very important um relationship that you must know all right as as a know parasites for example ticks and human beings or and other animals such as dogs and those are normally tested all right commensalism is when of course um none of them is being harm really but one only one being benefit um technically benefit in terms of feeding and mutualism is when both of them are benefiting all right so that very important right there so parasitism one being one one benefit and next one is being harm all right and then commensalism one benefit no harm and then mutualism both of them benefit all right and so typical example as we talk about I just jump over that too quick um lice and mammals for example talk about dogs and human beings as well all right talk about EP EP um epip fites on trees you know like shell fungi for example it may them on trees all right so the word Epi means surface so epip fites they feed on the surface of the the bark the Dead back uh nitrogen fixing bacteria in the roots nodules of legumes um those are very important to convert um nitrogen into nitrates for the plants as well all right um nutrient cycle is also important so let's talk about carbon cycle a little bit all right and carbon cycle as you know it I'm just going to show you a diagram and then of course you can add details as we go along and then of course you can also research and reread from your textbooks um about these Cycles all right um what is important about the carbon cycle is that photosynthesis is one of the very few processes that remove carbon dioxide from the atmosphere so trees are very important in maintaining the cycling of carbon dioxide and also to remove carbon dioxide from the atmosphere hence it plays a very important role in terms of reducing global warming so photo synthesis definitely is an important process but not only plants will take up carbon dioxide or out of the atmosphere CU algae also do that because once they photosynthesize they can take out carbon dioxide out of the atmosphere but photosynthesis is the process all right but not only Plants algae is another organism that will do that respiration both in plants and animals because plants do respire and plants respire every time just remember that all right but they respire morning night compared to day because in the day photosynthesis rate is greater than respiration but in the night respiration rate is higher than photosynthesis but plants respire all the time just like all other organisms all right so respiration put carbon dioxide back in the atmosphere all right as we know that when all organism die they will decompose and and by decomposers feeding on the dead organic materials they will release some carbon dioxide in atmosphere as well when Decay takes place and remain in terms of fosu and so on what will happen is that the burning of a fop fuel will also release carbon dioxide emission in the atmosphere and we know those processes again just go over it and spend some time right I'm I'm not going to spend too much time here the other important cycle is the nitrogen cycle okay the nitrogen cycle what is important in term of nitrogen cycle is that you have nitrogen fixing bacteria in the soil that is very important that will remove nitrogen gas from the atmosphere convert it into ammonia and that process called nitrogen fixation they are fixing the nitrogen gas into Amon amonia and then from ammonia we go into nitrites which is NO2 and also NO3 which is nitrate now that process called nitrification okay nitrification we convert ammonia or ammonium ions into nitrites all right and then we can convert that now into nitrates and plants use nitrogen in the form of nit nitrates okay and then to send it back in the atmosphere the nitrates are converted back into nitrogen gas by what we call D think about the word d nitrification all right all right and so that's how we end up with the different cycling or different aspect of a Cy of nitrogen within the atmosphere lightning also could fix n nitrogen gas as well into nitrate so there are two processes here that nitrogen in atmosphere can convert into nitrates one is by Nitro fix nitrogen fixing bacteria and lightning so those are the two processes that convert that and denitrification is the only process that returns nitrogen gas into the atmosphere all right now water cycle is very important and very simple as we know that we have water moving from the from the Earth by directly evaporation or by transpiration from Plants as well and also evaporation can takes place when animals were like us when we sweat and the water evaporates from our skin into the atmosphere all right so evaporation generally transpiration takes um water into the atmosphere and then when it reaches the cloud or a certain temperature then you have condensation taking place once condensation occurs enough then what will happen we have precipitation taking place that is rain hail sleep and snow all right will take place and we have runoff water that is water running off on the surface of the Earth or soil and then we have underground water or groundw all right so next thing we want to look at here now is the impact of human activities on the environment just to give a brief information on on these things what you need to look out for is talk about things like biodegradable stuff versus non-biodegradable and impact of those things on the environment so biodegradable are things that can be broken down by biological means by use of bacteria for example so the process of decomposition decomposition takes place and for none by those things will not be degraded or break down in the atmosphere by living organisms such as bacteria all right so the only way they break down you have to break them down physically either by crushing grinding and so on all right that's the only way you will reduce them or you recycle them all right and of course also you need to talk about overpopulation as well and over fishing so these are human impacts on the environment over fishing over population because the higher the population is is the more impact it has on food is resources the use of land or also the release of carbon dioxide the use of Machinery so there are a number of things affected by over population even the spread of diseases as well because the closer we are together is the easier for us to spread diseases among each other over fishing of course and you understand over over harvesting of any organism a matter of fact CU once you over Harvest any organism you have a possibility of leading to what they call Extinction of that or or organism why you have a Extinction that organism because the rate of removal is greater than the rate of reproduction all right you also have chemical fertilizer and impact of chemical fertilizer of course it could damage soil um if you overuse chemical fertilizer not only that if fertilizer get into water ways then it can cause things like utation excess gr of back um algae as that refers to utri fication and so on all right and of course you need to know the effects of UT tropication U products of indro ization such as of course smoke um chemical waste sewage and all of those stuff all right chemical seep into the underground water um cause poisoning of water contamination of water and so on improper garbage disposal of course again can cause habitat for pest can also increase spread of diseases can also use up useful lands all right and also of course it can be unsightly all right and of course can give off bad orders as well so there are many different things we could have there and of course the in think about the ecotourism aspect of it of course nobody want to use Beach that is dirty and or nasty so if you dispose of a garbage in a in in in not a proper way then you realize then of course it may affect tourism or or the e or the economy of your country uh as well because of course it will reduce the income from tourism all right lot of habitat and species as well as I refered that earlier in terms of Extinction all right and if you destroy habitat because um you're dumping things environment then organism may have to migrate because they cannot survive they can't find food they're affected by the gases produced they affected by the poisons and so on all right and of course that can also lead to Extinction as well and also I as I mentioned as I was going along the impact on human health as well spread of diseases all right bi accumulation and so on all right and even mosquitoes um get into dumps and spreading diseases by means of vector so you think about malaria Deni and so on all right typhoid all right now in terms of section B now all right so that's pretty much section A completed so section B we're going to talk about um cell structures and function the first talk about again you to know the different structures identify structures and know their function such as cell wall cell membrane nucleus side plasm vacuum mitochondria ribosome chloroplast as you know cell wall is for General protection cell membrane controls what going in and out nucleus controls the interactivity of the cell cytoplasm is where chemical reactions take place vacul is for storage generally talk about storage of Water waste all right as well and food all right mitochondrian is the is what is producing energy that's why it's called the power of a cell where ribosomes that deals with protein synthesis or the formation of protein and we have chloroplast where photosynthesis takes place and also you need to know the difference between animal and plant which I'm going to talk about a little bit later all right you also need to know about microbial cells such as bacteria all right and structure of bacteria you need to know that and specifically notice the nucleid the cell wall the capsule and plaga which I'm most show these all right and of course protest an example of protest such as amiba all right you need to know those the uina and so on all right now um a quick quick quick difference between plant and animal cell right here as you know that cell wall is not in animal cell but in plants need to know that the vacle is large and c located for plants but you have many vaces within animal cells all right um the nucleus generally for animal cell is technically almost centrally located but the nucleus is more to one side or one end in a plant cell uh there's no chloroplast in in animal cell but chloroplast in plant cell you to know that as well all cells must have cell membrane all right so those are some of the basic differences you have to know between plant and animal cell all right in terms of bacterium or bacterium cell please identify the for example the plasmid with a circular plasmid in bacteria they might have flum or men or may or may not have fulum all right we have the three outer layers that you must know the first layer it is call a capsule then you have a cell wall in the middle and then a cell membrane you must know those three layers and then we have one circular chromosomal DNA so the DNA is pretty much circular one circular chromosome in a bacteria all right we have ribosomes that they use synthesize their protein all right and anba which is a protest pretty much the basic cell parts the cell membrane the plasm all right the nucleus and very important they have two types of vacu technically you have the contractile vacu that will send things in and out and then we have what they call the food vacu as well that they use to consume um food all right and also to synthesize certain products as well all right and amiba what is important about amiba amiba can change shape or indu shape to absorb um things by Endo cytosis all right all right so let's go to some very important notes that we need to function look at in terms of cells and so we need to talk about cell specialization where different cells will carry out specific functions based on where they are located their shape and their structures will allow them to do certain things and so a point to note in terms of tissues all right um very important you need to know that different tissues example epidermis you to know epidermis you to know the xylm tissue the Flem and and xyl and FL transporting tissues you to know those all right um epidermis as I mentioned you to know also that these are used to form organs as well all right and organs include things like leaf and stems and also Roots let me add that one in quickly all right and also organs now will form organ systems such as transpiration translocation the secretary system and so on right but these are to to plant systems that I have right here all right and of course again you must relate the same type of concept in terms of animals all right from cells into the organism all right all right so Next Movement is going a little bit away from cell is still on Cell but this is talking about the the the transporting in and out of cells and so there are two processes that we need to think about right here is the fusion and osmosis all right and you know must and a point to note right here is that the fusion and osmosis they are what they call passive transport all right which means there's no form of energy that is required passive transport no energy required what is also important is that they will move along a concentration gradient which means things are moving from a higher concentration to a lower concentration and so diffusion for example is the movement of particles from a region of higher concentration to a lower concentration until the particles are evenly distributed very important however now the difference with osmosis is the movement of water molecules and water molecules are moving from a higher concentration to a lower concentration across a semi-permeable membrane again what is important is that diffusion and osmosis requires well they require movement from a higher concentration to a lower concentration in other words make it very simple the movement of particles from where there lot of that particle or particles to where there's less of that particle okay all right so let's just demonstrate something real quick and so active transport now is opposite of passive transport and in active transport it requires energy and energy is required to move substances in active transport that's why it's called active requirement of energy so the movement is against a concentration gradient which means it's moving from a lower concentration to a higher concentration all right an example of this is minerals moving into plant roots so if you think about this if you have a if you have a a box and fill it with stones for example you have to put more stones in it you have to be stuffing and pushing the stone against other Stones so you're moving one or two stones into a box that already filled with stones so you're going against the norm going against where there's less to where there's more it's kind of hard to do that so the same thing active transport pushing a small amount of particles to a region where there are more particles that means you're going against a concentration gradient of course this an example that occurring plant rout nitrates moving into the plant rout by active transport because more nitrates is within the plant routs and put more in it is going against that concentration gradient moving from where they are low to where there is high amount of nitrate that is active transport all right so please note and know how to explain them all right let's dive down a little bit more now the next thing you need to know note here is now relating to us most is tonicity and tonicity refers to the comparative or the comparison between concentration in and out of a cell or it says comparative concentration in and out of cells now there are three types of tonicity we have hypertonic we have hypotonic and we have isotonic and so for hypertonic the cell normally shrinks or become flacid now what is happening with hypertonic look at the first diagram right here is that outside of the the cell will have more of the solute which is the solution this solution is more concentrated so in other words you have less water outside of the cell and you have more water within the cell again tonicity refers to osmosis which means the movement of water so therefore water going to move from inside so the the the blue the blue dots the small blue dots those represent water the green one represent the salute for example sugar or salt so water going to move from the inside to the outside and cause the cell to shrink in a similar way hypotonic water know we go the opposite way water moving from outside to the inside that mean the cell is in a dilute solution or a highly concentrated water solution that mean the water is high in that solution more water than than than the salute and so water enters the cell and cause the cell to swell and eventually burst or may burst espe if using a animal cell an animal cell or a red blood cell now for isotonic the concentration will be equal and if concentration is equal in and out of a cell technically water going in equals to water coming out and so therefore there's no net movement of water and the cell Remain the exact same all right if it was th before going to maintain it turgidity all right so that those are the three um types of tacy that we must know and again we must also know to compare the difference between animal and plant cell within these type of solutions and I want to point out the first one is hypotonic difference between animal and plant in iponic I want you notice this big big difference here is that the plant cell will not burst but the animal cell will burst in hypotonic solution simply because the plant cell has a cell wall that prevent the cell membrane from collapsing or bursting that's the difference there now in the hypertonic situation both cells lose water however the boat become flacid but the difference between the plant and animal is that the animal cell become what they called plasmo lied which means the shape will be maintained but guess what would happen the cell membrane move away from the cell wall and cause the cell to shrink or become flacid all right so that's the difference there all right so the the cell M justes move away from the cell wall because the vacle decreases in size right so notice difference in the vacu in the plant cell larger vacle to very small vacle so when it gains water in the vacle becomes large increase what we call terg pressure so it pushes pressure against the cell wall okay and in the hyperonic it loses water from the vacu cell membrane moves away from the cell wall the turn sugar pressure decreases in hypertonic solution for the plant cell all right next thing we look at now is feeding relationship on the topic of nutrition now the thing that you must know is aops cell feeders we have atrops those are organism that feed on other organisms and on the etot tropes we must know things like sapry parasites all right you must know those at least so I'm going to show you the different types that we have all right that we need to um refer to so autot tropes you know they make their own food generally by photosynthesis or Cho synthesis so organism that use light as word suggest light is photo so photosynthesis photosynthesis making food in the presence of light we have chemo Cho um chemosynthesis those are making food based ons abbing different chemicals from the environment and make their own food that means there's a need need for light particularly now now sa um saat trophic organisms or nutrition refers to organism that feeds on dead plants and and and dead decaying substances all right so we call them saites okay saites and so saites example of those will be heast and mushroom notice they sit there and just absorb um parasites right or parastic nutrition those feed and other living organism such as ther and lice and lice is a common one to be tested on CC examination all right we also have our oazo nutrition we include us we ingestion of organic food material so we ingest U organic food materials amiba also is an example of that as well all right so these are different types of feeding this how we feed so generally in the in the C exam though they talk about saites even the last exam they talk about parasite know in the previous exam and then of course we are always there and we just refer to ourself as errs really all right but the correct term for us is allazo um feeders all right next on our list is leaf structures and functions all right and you have to know the external structures of a leaf you need to know the Apex which is the point of the leaf the margin which is outer um layer and then we have the mid RB which is Central vein and then we have our venules the one that are branching if it's a dcot and then we have again we have we have veins generally all through the leaves all right we have the petol also called a leaf stem we have a lamina otherwise called Leaf blade all right and we have base of the leaf which is not important because they don't reallya it to label that still all right now internal structures this is very important very very very very very important so I find this nice good diagram here online which indicates this internal stru of a leaf really good all right and so um we must start from the otic CL top um you must have the upper epidermis a point to note though generally you have more stoat and the lower surface than the upper surface just to point it out you will have stomat on both sides of the leaves or leaves but generally the bottom will have more I'm going tell well let me just tell you why because why you have more stom than bottom because gases when they get warmer they tend to move upwards so they can easily enter the stomata or enter the leaf through the stomata if gases are moving upwards so the cap the capture gas is better you have less on the upper surface because on the upper surface they exposed to sunlight and and once they exposed and they're open then you have a tendency to lose more water so you have less sto to prevent water loss or or to reduce water loss all right we have the polycade mesop layer this is the old layer right is called the poly mesop layer one of them is called a pade mesophile cell they have the most chloropus which means more more photos is taking place in the polycade mesophile cells or polycade mesophile layer then below that you have a Spong of mesop cells they are more spacious all right they are more spacious to allow easy diffusion of gases through the entire Leaf a point to note in terms of polycade cells is that they're elongated so they could capture more light and also contain more chlorophyll also more chloroplast as well all right so they actually close together as well that's very important so they F on the upper part of the leaf closer to the surface to absorb maximum sunlight and contain a lot of chlorophyll to do that all right again spongy mesophile they spread out a little bit to allow easy diffusion of gases and a point to note that both spongy and and SP mesophile as they calling the the mesophile cells or mesophile layers they are the main cells that responsible for photosynthesis all right we have a vascular bundle and our vascular bundle is made up of ayl and flm ZM is usually on top and the FL is usually in the middle or to the bottom all right we have our guard cells and guard cells they control the opening of a stor M to allow gases to go in or also the removal of warm water all right so gases exchange takes place at the sto just to mention that all right photo cences quick quick run through of this is that we know that photo word means light and so photosynthesis takes place in the presence of sunlight and a balanced chemical equation you must know and there's a big difference between the word equation and chemical balance equation and you must know I'm not even saying you should know must must know must know the balanced chemical equation for photosynthesis never go into a bio examination without knowing this so you have carbon dioxide water give you give you glucose and oxygen there's a six in front of everything except the glucose molecule the word equation you also need to know the word equation as well all right please make sure you know both all right now very important note here is that one is that the production of oxygen is done by splitting of water molecules by light so when light split water molecules you get oxygen and also get hydrogen and the hyrogen is used to combine with carbon dioxide to form glucose okay so again it said this the subsequent reduction of carbon dioxide to carbohydrate so in photosynthesis the carbon dioxide turns into carbohydrate which is glucose or sugar and that occurs when hydrogen ions react with carbon dioxide and that comes from water so in water split you get two things oxygen which is a byproduct waste and some ions hydrogen ions and they they combine with carbon dioxide now the chloroplast is the side of the the chemical reaction for photo sis you need to know that chlorophyll absorb light all right and just to make a note is that you need to know the different colors of light Ro G Biv and plants reflect green plants reflect green light because whatever color you see from something that's the light is been reflected all right and also you to know what happen to the products the fate of the products all right in terms of photosynthesis so one is that oxygen oxygen is a waste product that is given off as you know in the environment the the glucose that remains it is metabolized to produce energy by respiration all right or it is stored in the form of starch all right remember that and also some of the product can be also be used to make things such as cellulose so the carbohydrates or the sugars that are formed can use to produce energy can use as storage in the form of starch and also to make structures such as cell wall in the form of cellulose and those three things I call they all carbohydrates sugars that are produce carbohydrates monosaccharide sucrose that is been transported that is a disaccharide starch and cellulose those are polysaccharides all right so they all carbohydrates all right uh next thing on the list now again just continuation here we need to talk about adaptations for f SES um for example sto are used for gases exchange I know that was on the last exam or if not well a recent exam I should say and then you have intercellular spaces again we mentioned that in terms of the mesop cells and that for that um diffusion of gases we also have chloroplast in the polycade and they're closer to the epidermis as I me mentioned that earlier for maximum absorption of light all right and then we're going to take a look now the factors now affecting photosynthesis and these are the factors we have light intensity concentration of carbon dioxide water availability and temperature and these are the graphs that depict the relationship between the rate of phot senses and these variables so again notice that these variables are placed on x-axis because they what we call independent variable and the rate of photosynthesis um is placed on the y axis because the rate is the dependent variable all right as we know that in in in in low light so the first one talk about light in low light then of course photoes will decrease as we know why because it because lights make the opening of the stoat and if sto are not open carbon dioxide can enter moreover light is needed to split water molecules all right so less what so less light less water can be split and then now for temperature temperature is very important and and notice the graph of temperature that is different from the rest temperature goes up to a peak which is call optimal temperature then boom it drop right down what is important here now is that the reason why the rate of photosyn the rate of photosynthesis increases with temperature is simple this because as you increasing temperature enzymes that are needed for the chemical reaction of photosynthesis with will become activated and once these enzymes are activated then the chemical reaction can take place however after a certain point the enzymes will become denatured simply because enzymes are made of protein and can become destroyed by high heat not only that the stomata will also be closed to conserve the loss of water all right so of course temperature affect phos in a positive way then also increase a certain point in a very negative way carbon dioxide is just like light I don't you need to explain that all right all right and of course water is the same thing as carbon dioxide and light all right so three things will look similar carbon dioxide water and and light will look similar but temperature will look a little bit different because temperature could affect the entire chemical processes and also the enzymes needed now in terms of Plant Nutrition we need to know some very important nutrients that plants require such as nitrogen symbolized with n is it used to form proteins and proteins are needed for growth and development we also have magnesium and magnesium which is mg needed for chlorophyll production and also once you have enough chlorophyll then it also AIDS in the absorption of light we have phosphorus that gives strength to plants and then we have potassium and potassium symbolized by K is for fruit and flour development and of course you will see common fertilizer which is inorganic fertilizers called NPK which means nitrogen phosphorus and pottassium and those are very essential nutrients needed by plants all right uh let's now jump into digestion so look at the digestive system again I'm just giving a brief notes and different aspect give a little bit more details so when you're revive um reviewing or or revising then at least some of these information pop up back in your head and so again to start out with with in the mouth we have and what takes place in the mouth which is physical digestion or mechanical digestion by chewing all right uh we call it m yeah chewing chewing all right chewing takes place in in the mouth by the teeth and tongue so you have chewing and chewing and the mixing of food also just me mentioned that all right all right and then we have um salivary glands in the mouth as well you know what happen in salivary gland salivary glands um they produce enzymes particularly salivary Ames you know that that star with the breakdown of starch so what I want to point out is that in the mouth you generally have all digestion begins in the mouth by chewing that's very important that physical digestion however now as you go down we have esophagus and esophagus you have peras is taking place when the muscles of this tube like structure relax and contract to send food down the stomach and the stomach is where the chemical digestion of protein Begins the pancreas produces different enzymes Trin amas all right and lipase all right and of course you need to know what those break down all right um we have G bladder all right and we have a liver that produces bile G bladder will Stow the bile we have large intestine the large intestine really is the production of vitamin D and reabsorption of water and also store undigested food in the rectum and they release that into form of feces they have small intestine small intestine is where all digestion ends we to know that and we to know what type of food is absorbed also the struct of V which I'm going to show you in a short little while all right so Villas and this a beautiful diagram here for Villas and uh point out some very important structures that you need to know is that we have the outer layer is called the epithelium and on the epithelium we have what it call the micro those are smaller vli structures that increase surface area or further increase surface area all right we have also the epithelial cell one cell is called epithelial cell and then inside of the epithelium we have some special cells that we call them the cobet um cells all right and those secrete mucus so sometimes they show this section as piece that is missing so the missing part of you're showing an exam is called the cobet cells all right and then we have we have here here the blood capillaries and the blood capillaries made up of what they call the venol and the arol all right and so the arol connect to the arterial end which leads to an archery and the and the venue leads to a vein that called hepatic portal vein that will carry food substances to the liver what is also important is that we have the lactal in the middle the lacle is what absorb fatty acids and glycerol the capillaries will absorb amino acids and glucose goes all right what is not absorbed here what absorbed in large large intestine all right just to make mention of that all right so nutrient test the test for different nutrients um you need to know these basic test for nutrients all right so you need to know about testing for protein or you test for fats so you test for um um sugar as well so and also the test for starch I have two different types of fat test right here so let's pay attention to them so let's go with the starch test first in the first row so starches is used you use the rent of iodine solution to test for starch iodine itself is yellowish Brown and iodine changes to blue black if star is present again it is not the food that is changing color but the solution changing color so please do not confuse that when you test for proteins you use BR solution and you change the color the color is blue bir is a blue solution and it changes to purple if protein is present there are two test for two common tests for fats and so one is using ethanol and water both both ethanol and water they are colorless but the but the mixture becomes cloudy if fat is present and then there's a next one is called the grease pot test or the paper test which you just rub the food substance on a piece of Grease Pap on a piece of Grease really a piece of paper really and you see a grease pot they know that yes um fat is present all right so do not use a part region just use a piece of paper the reducing sugar test use Bendix solution and Bend Bendix solution is also blue um just like the B solution and if sugar is present then you get a red brown or orange color of course more on the orange yellowish color as well that is also a positive test so anything that is reddish brownish orange in color Yes it show that reducing sugar is present all right and a matter of fact for the bending solution just to make mention to that you have to use Heat to to warm up the the mixture so the reaction can take place all right enzymes let's talk about enzymes a little bit now enzymes now they called biological catalyst why they call biological catalyst one is because they work in living organisms and they're also made up of proteins all right because protein is a is a biomolecule all right and we have Catalyst they are called Catalyst because they alter chemical reactions and so they called bical Catalyst because they alter chemical reactions in living organisms so that's why they called biological catalyst all right so some specific properties of enzyme that you must know is that they all made up of proteins all right they have they low activation energy so chemical reaction can take place they are substrate specific which mean they only act upon certain food or certain nutrients or certain substances all right so they are substrate specific so in other words whatever break down protein will not break down St all right they break they break down specific things they reuse they are reusable because they they not Ed up in the chemical reaction they remain unchanged so they are reusable they are sensitive to pH so they are pH sensitive they denat by high heat as well they in they they are inhibited by poison so poison will stop them from working or prevent them from working effectively all right so those are some of the things that you need to know about enzymes and properties of enzymes now the respiratory system and also gas exchange something that you need to pay attention to you to know different structures such as the nasal cavity FX which is your throat your larx which is your windpipe your traa and your traa is made of rings of cartilage to prevent it from collapsing when you're soling food you need to know that we have our broni one of them is called a Broncos and those are the subdivision from the trachea going into the what you call the bronchol so those lead directly into the lungs and then we have the bronchioles those are the subdivision of the broni and at the ends of brones we have the Alvi those are small sack like structures and below the lungs we have a muscle called the diaphragm and very important in breathing helps in breathing very very important all right next thing on the agenda is we want to talk about now is gases exchange real quick so this is a structure of the alveolus all right as you see right here um gas going in gas coming out um so you have inhalation the gas from inhalation coming in and the gas going out is what going to be exhaled and so around the alvus we have capillaries blood capillaries that carry blood cells and parly we have red blood cells that coming in that are that is deoxygenated blood coming in and what going out is oxygenated blood so the purpose of the Alvi is to carry out gases exchange remove carbon dioxide from the blood and and replace it with oxygen that's what it called gas exchange right there so what is important about the the structure of an alval loss to make it effective it has a lar of risk area for for gases exchange and effective gases exchange the walls must be thin so diffusion can take place easy must be moist I have moist twice must be moist and also great supply of blood capillaries all right so ignore one of one of the moist so it's moist thin lot oface area all right and supply of many blood capillaries all right and of course you know why because the blood capillaries will carry the carbon dioxide towards them and take in the oxygen that they are given all right so gases exchange takes place there all right what you also need to know is difference between AIC and hubic respiration need to know that and um to be honest with you have most of these lessons um posted on the bio biologic biology videos or biology um videos or topics so you can look look for that playlist on on on my um Channel you will see a lot of different videos on most of these topics all right I don't reach all yet but eventually all right um for Arabic respiration requires oxygen occurs in mitochondria produces more energy or ATP takes a longer time to occur because you have to have a complete breakdown of glucose so that's a big thing I should put that that one there so AIC is a complete breaking down of glucose what is produced for AIC respiration the waste are easier to removed for onic respiration no oxygen is required occurs in cytoplasm please make a note of that produces less energy or ATP this faster because it result in an incomplete breaking down of glucose no production of water generally the waste are harder to be removed as well such as lactic acid and and also alcohol all right now these are the three examples of the balanced chemical equations for the three different types of respiration need to know one is lactic acid fermentation fermentation and alcoholic fermentation those are the two un aerobic respiration and you notice you need to know the formula for lactic acid which is technically half of that of glucose half of glucose the exact half of glucose is a lactic acid all right and so you just put a two in front of that to balance it up all right and you get ATP out you get about 12 K of energy for alcoholic fermentation you get a little bit more energy than IC acid alcohol is produced is ethanol get carbon dioxide and if you Bing bread by using heast then definitely you get carbon dioxide to make the bread rise and the amount of energy get out of that is 210 K of energy now you have aerobic respiration that we need to know by heart and that produces 28 2,880 KJ of energy all right and you notice notice the value of ATP respectively in a in unic respiration you only get like 2 ATP a to have 36 ATP from aerobic respiration so you get much more energy all right uh now let's talk about transporting organisms and um just to give a general idea what it is is movement of substances within organisms and we we need to know about the transportation of oxygen minerals amino acids carbon dioxide nutrients sucrose for example um in Plants imp plants that's the make mention of that hormones GL glucose and also waste we need to know the movement of these substances or the transportation of these substances within different organisms all right let's talk about blood cells a little bit now there are four blood cells that you need to particularly pay attention to all right three different types generally but for specific ones you have the red blood cells which are called erthrocytes you have lymphocytes which are which is a form of a Lucy and we have fosy which is another form of a lucite all right um I make a mistake right here I'm going cross this out because this not a I put this here this is called a throy this is called platelets so I should have platelets right here okay so the last one is platelets is a thrumbo site so this is platelet all right so platelets I don't know how I made that mistake platelets all right so that's a platelet right there and a and platelet is definitely a trombos site okay it deals it blood clotting all right um lucos sites which are these two right here they are used in immunity to protect you against infections and red blood cells they are generally for transportation all right all right so let's jump into the next aspect right here now talk about blood vessels now so there are three blood vessels you need to know arteries veins and capillaries now arteries compar to veins They are thicker walls the Lumen which is the crosssection right here is narrow compared to veins veins have larger Lumen all right also veins have valves arches do not have valves capillaries they are one cell thick for easy diffusion of substances to cells and from cells into them all right that's very important capillaries also connect arteries to veins all right very important and blood flow blood is always flowing from arteries to veins towards veins all right so just please note the difference between arteries veins and capillaries in terms of the heart you need to know the structure of the heart the chambers of the heart need to know the different blood vessels that some of you already know know the direction of blood flow in and out of the heart you need to know that as well all right you need to know and go through that I have also circulation on my channel you can view that if you if you desire to do so if you forget certain basic stuff and I will explain in terms of the different chambers what is going where and not easy way to remember um how blood is FL matter of fact just write it down so I will put in that as well um as a link all right so I'm going to put some some link um in the description that you can watch specific lessons not all the lessons that I have some of them you have to search on your own if you do want them but I have most most of the lessons um in video forms or different lessons all right now what I'm talk about right here now is difference between two important type of pressure that you may experience in your body and that is called systolic and diastolic and just to make a note that normal blood pressure is 120 1 over 80 120 over 80 120 refers to the systolic pressure which means blood is moving from the heart into the body so that's what call systolic moving to the systems of a body and so that is when the heart is being emptied with blood pushing out so the heart is Contracting in other words all right and for dioic now is when the heart is being filled with blood so blood going towards the heart and Into the Heart your heart being fill with blood ready to go through systolic so it fill it blood first then push out fill push out that's a heart keep beating contract Contracting and relaxing to make these two processes work so they must work together all right now in terms of immunity um I'm not going to go through everything but there are some specific you need to know about natural immunity versus artificial immunity all right natural immunity of course that is you acquiring that in terms of exposure directly to the pathogen you think about when your babies and growing and growing up you know what I mean um you have also passive I think I miss passive you get it from from your parents and then artificial you get it through vaccines so when you develop on your own which is natural immunity you know you Expos to to the things in in a natural environment and you develop that naturally on your own artificial is the one that you make you take vaccines for and then you have passive is the one that you get from your mommy all right um you think about phocytes and their role in immunity lymphocytes as well phocytes will engulf as you know engulf and digest lymphocytic bodies and antibodies they those are chemicals that will destroy what they call antigens antigens are produced by microbes so bacteria viruses will produce antigens and those are spefic proteins that would be produced by these microorganisms that can destroy your body cells and so you antibodies will attack antigen and Destroy them pathogens now pathogens those are disease causing organism such as bacteria protes and so on vaccines are what are developed to produce or to trigger immunity and vaccines back in the days are normally a dead form or inactive form of the of the of the disease itself so your body could quickly develop um antibodies against it and just in case the real thing comes then it is ready and prepared to tackle that then we have transmission of diseases between persons or between other organisms such as mosquito which are vectors and human beings we have STDs or STI all right you need to look notice those and also pay attention to different specific ones so please go through the list and know them all right root yourself uh root cing to know about root ear cell root cell is very important in terms of increasing surface area of roots to absorb water and mineral salt R cell have large vacu all just like a regular cell there there will be there will be mitochondria there will be cytoplasm there'll be nucleus they'll be cell wall there be cell membrane just like a regular cell all right now adapt adaptations of rouer cell is that rouer cells again as I mentioned they have thin walls for easy diffusion just like any um absorb structures in living organisms they're normally thin they are lots of risk area for for Effective absorption they have large vacu to store large quantities of water um rouer cells have many mitochondria to provide energy for active transport and remember what moves into the roots by active transport is mineral Sals water will enter biosis all right but mineral salts nutrients nitrates will enter by active transport they contain they contain transporting proteins to taking specific minerals or mineral ions again mentioned like nitrates all right potassium and so on all right transportation in Plants particularly um we need to focus on evaporation of water from the uppermost part of the plant that's transpiration as a transportation so transpiration is removal of water from the upper part part of of the plants particular the leaves very important to note and water will escape through what they call the sto just to mentioned that so water will grow from the root all the way up all right so water is important to know about water properties that water is cohesive and adhesive and so because water is cohesive which mean it can stick to itself and what is adhesive mean it stick to other things and because of this property water can easily pass it through the xylem again we need to talk about capillary action and capillar action is the movement of substances through narrow tubes so water can move through the narrow tubes of a xym easily climb up the tubes um that's what they call capillary action when talk about transpiration and transmission pull um occurs when water evaporates from the leaf or from the plant and because water is cohesive and they interlock lock to each other that mean as some some is some particles are evaporating it will pull other particles be it right so that's what transp pull occurs is a pull or a suction caused as water evaporate from the plant and cause other water molecules to pull along with it what is important about transpiration pull is simply the warmer water in the leaf will be replac will be replaced by cooler water from the soil so it's very important to cool the plant as well and make cooler water available for photosynthesis all right now factors affecting transpiration we have temperature we have wind speed our air movement we have light intensity we have humidity so for temperature no higher temperature is the more kinetic energy the particles will get and so the more movement and evaporation and trans and also the faster diffusion I need to know these this very important notes right here wind speed now the faster the wind is the more water that will move away from the plant and this crate creates and maintain a steep concentration gradient for diffusion also we have light stimulate the opening of the stor that's for light intensity so I have more light mean stor will be open when stor are open there's a higher potential for diffusion of water for humidity which is opposite in terms of the rate so for high humidity you have more water which is more water in the atmosphere and if you have more water in the atmosphere then you have more you have more water being retained in the plant because guess what you have lower humidity create a steeper concentration gradient for more diffusion so high humidity less transpiration all right more hum so more humidity less transpiration decreasing humidity more more transparent so they're opposite so they are actually inverse of each other so the higher the humidity is the lesser the transpiration will be or the less the water loss will be cuz it's harder for you to put water into the atmosphere that already filled with water all right so that one the graph will be different for that one for sure all right now let's talk about excretion and what is important in terms of excretion is removal of waste from the body but importantly not just any waste but metabolic waste that's very important to note so removal of metabolic waste from the body all right so let's let talk about a little bit further now let's talk about the structure of the kidneys real quick you know the structure of of the kidneys I'm point out things you must know you must know about the the cortex you have to know that you have to know about the medula and the and the pyramids as well so the region right here where the pyramids are that's what they call the medula like in the middle section of the kidney okay and then we also have our renal arter renal vein but quite frankly you not see colors on the exam so what you're going to look out for is arrows archeries will go to so if you see the AR going to that will be the archery and the vein will come in from so you need to know that okay so arteries go in veins come from all right and what coming from the kidney Tu come from the kidney is what they call the urer that is carrying urine to the urinary bladder all right all right the nephron now the nephron is the filtering unit of the kidney you need to know that and the nefron is in two parts part is in the cortex and part is in the medula if you know that as well so the uppermost part of the kidney right there is in the cortex the lower part is in the medulla so the loop of Henley is in the medula the Bosman capsule is in the cortex all right so you definitely need need need need to know that as well and so the nephron now is a substance from the blood are filtered into the what they call the glamorus right here so the glamar is where filtration takes place matter of fact it's called ultra filtration all right because filtration occurs under high pressure so it's called ultra filtration we have our tubules of a kidney so we have Loop of at the bottom right here we have our convolution we have a proximal and we have a distal convolution we have a collecting duck and so on and specific pay attention to these notation right here all right uh that we have a lot of absorption taking place at the convoluted areas or the part that actually curve or bend and then we have some substance absorbing loop ofle as well into the capillaries notice the capillaries all covered around it and then by time reach to the collecting duct that's where urine is actually formed and urine is a mixture of salt water and UA all right so skeleton system at this point all right let's talk about that so what you need to know about the skeleton system you need to know about bicep and triceps you talk about antagonistic muscles you talk about types of muscles skeleton muscles smooth muscles and cardiac muscles notice know the difference between them and they to identify them you talk about bones um minerals needed for bone formation such as calcium you talk about ligaments that connect bone to bone and tendons that connect muscle to Bone you to know know to identify those you talk about diseases that affect the bone such as rickets which is like a vitamin D and also calcium and of course phosphorus to to to a lesser degree all right so I'm going look at some specific parts of the skeleton system right now so generally you to know different bones I would say notice things like the skull or or what is called Cranium you know the caval the sternum so the major one humorus you do know that radius andna all right tibia fibula all right the pathologies of kneecap you need to know those the femur need to know those the pelvic bone need to know those type of stuff all right the vertebral column so those are the very basic bones that you need to know you know I mean but very specifically this is what normally tested or generally you see most times and most BYO exam is the bicep and tricep muscles working together again bicep is in front Tri tricep is at the back and notice the tendon connecting the muscle to the Bone so those are things you need to identify there and uh let me go back one second um one quick second here all right so in terms of the the bone just to make mention of these muscles and Bone at the same time is that if arm is being you're going to flex the arm or pull the arm up notice what happened to the bicep the bicep is Contracting and the tricep is relaxing opposite happen here if if if you if you extend the arm then the bicep will relax and the tricep will contract get shorter all right and they work oppositely what they call antagonistically to get to each other to bring about movement so they antagonistic muscles all right now in terms of now irritability um just to make reference to this that you need to focus on in terms of irritability you think think about tropism and taism I have videos on those as well um you think about nervous system brain and reflex I'm going to look at that um going to talk about stimulus which is any change in environment that triggers a response in the body um again you need to look at the description for links for tropism and taism for sure I'm going to give you that all right the nervous system going to run real quick even though have videos on that you can also pay run over to do that as well if you want all right we want talk about types of neurons we want to label look at label diagrams of the brain and reflex arc so I have those coming up just now all right so the brain the three mjor the three major regions of the brain that you must know is the cereum we need to know the cerebellum we need to know the medula blata which is also called the brain stem and then connected to the brain we have the Spinal card so the Spinal card is not a part of the brain but the brain and the spin card make up what they call the central nervous system the peripheral nervous system is all of nerves which include the cranial nerves the spinal nerves so the cranial nerves connect to the to to the cranium or the brain well not as a cranium to the brain in the cranium and the spinal nerves connect to the spine Al cord all right so the cereum controls voluntary actions and memory example emotions and intelligence you're walking and talking and so on your cereum controls balance and coord ination the med obl um do Spinal card first the Spinal card controls reflex action and the medul blano controls involuntary actions such as a heartbeat and breathing and so on all right the neuron now you need to know a neuron and you need to know different parts of a neuron such as the dentrites D is like the Leaf branchy branchy part of it the most branchy part you have a cell body and in the cell body you have a nucleus like any other new um cell you have our Swan cell that make up part of the axon and what cover the swan cell or the axon is what it call Ming sheet that's for um insulation and the speed up the the mode of transmission of impulses you also have between two Shan cell Shan cells you have the node of ranir all right we also have Oxon terminal or what you call nerve endings all right and what to note also is that impulse will travel from the dentrites always the dentrites what pick up impulse and transmit it towards the nerve endings so so impulse always enter through the dentrites always always always never forget that okay so matter how the the nerves turn and shape the dent is what picking up the impulse first and foremost all right all right next we going look at now is the type of neurons and so we have three basic types of neurons right here where sensory neuron easy way to know the sensory neuron the cell body is at the side side s sensory neuron cell body at the side the cell the the the sensory neuron it transmit impulse from the sense organ to the brain or the spinal cord so pretty much is once it's run from the sense organ that's the sensory neuron the relay neuron now it's in between both sensory and motor neuron a matter of fact if you look at a reflex arc you see the relay neuron within the spinal cord all right right in the middle of the gr matter matter of fact all right so located within the gr matter and then now the motor neuron transmit impulse from the spinal cord to the effectors in the muscles all right all right so we're going to jump now to the reflex arc kind of bring this point out and so you need to know the direction of transmission of impulses I must put some ared to kind of give you what I'm saying right here so from our sense organ we have some small cells in that called receptor cells so the receptor cells pick up the impulse all right or the change in a stimulus and then now what will happen here send it along the sensory neuron how know the sensory neuron there's a cell body at the side again see right here and the cell body is usually situated in the root of gangon all right so in the root of ganglion that's where you find typically the cell body on the sensory neuron and then we have a Rel neuron within the gray matter that connects both um the sensory neuron and the motor neuron and then the motor neuron leads to the muscles all right and of course you have a gray matter and the Central Point within the gray matter right here we call the central canal and then we have the gray matter and the white matter make up the Spinal card all right all right so again need to know just how it works now let's look at sense organ real quick I'm not going to spend too much time on them all right so let's go to the to the air and please you need to know the different structures you need to know especially let just point out the aoes malus incos stapes or otherwise called Hammer Anvil sterup um those will vibrate and amplify the sound as it go going along the semicircle Canal is for balance all right and then we have the cocka the cocka will convert the vibration into impulse and then that will travel to the aary nerve to the brain all right and of course we have our round window an oval window and our round window they will help in terms of maintaining pressure along with the u station tube with in the air as well all right um in terms of skin must kind of for that again just please go through the diagrams and make sure you know the different parts the different layers epidermis dermis and we have the hypodermis and then um different structures that I talk about the cous gland which is the oil gland we have our erector Pei muscle I think that was on the last exam and again please need to note the skin function in terms of temperature control which is a part of homeostasis and we may sweat to to to to reduce heat we also have Vasa dilation versus Vasa constriction Vasa dilation is when it is when you're hot or the environment temperature is high and then V constriction now is when it is cold you retain heat by constricting the blood vessels and moving away from the surface of the skin to retain heat in the body you also need to know the skin help us to protect us from UV or ultraviolet radiation also protect us from pathogen as well and physical damages what is also important is the human eye to pay attention to that different parts as well you need to know the different structures of human ey the cide the retina the scare the functions of those parts the the the fobia which is also called yellow spot as well we get the the most Vision all right you did talk about um rods and cones all right that are the sensory cells that are within the retina that will detect light all right cones they are for color vision rods are normally for black and white all right you have the lens you to know how the lens are adjusted as well by the suspensor ligament and so on you to know about the iris iris control the size of the pupil you to know that the carag as well Rous humor and acous humor to know those as well all right so please make sure you know the different functions of the structur of the high what is is important is just a quick um look at what happened to the eye in terms of in dark and and and dim light so in the bright light now well bright light and dim light I should say so in bright light what happened to the eye is that the pupil itself would constrict why the people constrict is to prevent light less light from going into the eye and how this occur is because the radial muscle they relax while the circular muscle they contract the opposite is through in dim light in dim light the pupil dilates or get larger and how that occurs is because the radial muscle they contract while the circular muscle they relax I still need to know the difference in dim light versus bright light and the reason why all right now other important topics you need to pay attention pay attention to is reproduction in in flower sex sexual reproduction sexual reproduction and menstrual cycle I have all these um videos posted on and on on um the the bio playlist um you can check those out I also have pollination and fertilization as well um diseases you need to pay attention to diseases deficiency diseases STDs and so on so deficiency diseases such as anemia you need to know that as well rickets which I mentioned earlier I need to pay attention to to those lack of vitamin C talk about scurvy and so on need talk about infectious diseases non infectous diseases contagious diseases and non-contagious diseases you need to know those as well they're very important they normal test and those things you need to know things like malaria Deni and all those all right very important all right so we're not finished yet because we have a number of things we want to look at we want to jump into section c now which I covered not everything because I don't do Evolution and a natural selection but I I'm going to talk about that a little bit um but what is important now in terms of genes and and genetics you need to know this is that genes are segments of DNA that carry coded information or instructions for our individual characteris are traits and from pance to offspring genes are responsible to transmit those characteristics very important now some very important terms we need to know right here talk about alyss alyss are varant form of genes we need to know that alyss can be dominant or recessive for example if you uppercase R is for red and lowercase R is for white notice we use RS even though we looking at two different colors because looking at the same trait with this color all right so upper cases for dominant and lower cases for or recessive just to make a note of that all right genotype just to mention genotype so genotype now is the gentic makeup of an organism that determines the possibility or possibilities of its phenotype It's a combination of alyss that determing your phenotype in other words the gentic makeup of the organism now the different types of genotype that we may have we may have homozygous dominant which mean two uppercase letters don't have to be hard we can have ergos and Etro mean means different om means same so two same but if it's dominant it must be uppercase and if it's rygus mean uppercase and lowercase so ET means different and then we have omus recessive and again mean mean same recessive mean lowercase so that's why we have this and that's the combination notice difference between alls and genotype alls one letter genotype two letters all right so let's jump to an example so again we're going to use this now we get into the example shortly after this one all right let let's go through this first so phenotype is a physical is a physical or or the observable traits or features of an organism so they can notice or say about an organism that we called phenotype physical nature of all right and then now as an example now let's say we have alls red uppercase R is a red lowercase r a white so the possible genotype that we may have here is if we have toase r that mean this be R because the damant will always show the characteristic okay so uppercase and lower case which is heterozygous it will still be R because again it is it has an uppercase R and two small RS will be white again because there's no uppercase R to show you red okay so so recessive trait can only SE in the homozygous form all right so once you have a uppercase letter the recessive characteristic will not show all right so Aon screen is a box to show the result of a combination or a cross between two two genotypes or two different parents all right and so the first thing want to do in terms of working out entic question is first you have determine the alls then look at the genotype look at the gametes that form they look at the cross and they look at the possibilities so this is the order which you do punet squares all right so let's say for example in flower red petals are dominant over white petals right hetus flower was crossed with a white flower this is only information given the fact that say red is dominant over white it tells you something so we know that red this is Al right here so red we know that red is dominant over so we give red uppercase R white must be lowercase R simply because red is dominant over white that's the information given now the second thing is said that we we we have now well let's put this back quickly and then we go to the second thing so red again uppercase R is red lower case r is white So based on information given we say one of the appearance is rygus and if you're rgos which mean you have upper and a lower but the thing is that this one will be red so this is a genotype so this has to be what red and it cross a white flower and if you're going to be white you can't have a uppercase R you must only have low case RS all right so these are the two parental genotypes now the gamit is how we separate the genotypes so when you separate the Gen types for example Theos is uppercase R lowercase R those are the possible gametes that we have and and for the white flower we can only have small R yamit now once put them in we going to put these now in the punet Square put them in the punet Square we have something like this from the Eros flower from The White Flower on the side so the white flow is on the side and Theus flower is on the top so the top part for Theus and on the side is a white flower there's no rule to say You must put one on the top one on the side there's no rule you can put anyone there the results will be the same now by Crossing in this box is row by column so you have uppercase R lowercase R this one row by column two lowercase RS row and column this box right here matching up um column and row again uppercase lowercase R so even if the lowercase R come before the uppercase r a rule of decency we just try to put upper case before the lower case right and then the last one now is two lowercase RS all right now the genotype possibilities here if you notice we only have 50% two of this and two of this so 50% chance of getting these genotypes so 50% of getting azygous dominant and 50% chance of getting homo recessive and then now for phenotype possibilities we know that these will be red these will be white so 50% 50% chance of getting red and 50% chance of getting white all right now let a Sex Link inheritance real quick and then we can of wrap up real fast this is pretty much on the last so this is a quick quick run through I don't want to Cluster it too much with too much information this Al kind of bring back some little points that you may miss in regular classes now for Sex Link inheritance very important information they must know generally speaking though CXC mainly focuses on xlink traits mainly Focus most of the question that we have seen in past they are xlink all right but point to note though is that fathers can pass on xlink alls to their daughters but not to their sons and you know why because guess what Sons will get their ex chromosomes only from their mother okay and then the third point to note here is that mother can pass sexlink alls to both sons and daughters because the son can get a ex well well the son has to get the ex chromosome from the mother the daughter now can get the ex chromosome from either mother or father all right and that is why and that is why in in in any case of a recessive SE exlink a recessive exlink trait is mainly affected males are normally affected by it because it is more likely to be transferred to the male from the mother now the fourth point you need to note here that only males are affected by traits linked to the Y chromosomes okay so if it's a y link only males are affected all right the next thing we didn't look at right here very important two points are important right here for recessive excelling traits a female will Express the phenotype only if she's homozygous recessive only if she's homozygous recessive however now if a male is recessive the recessive Al from the from his mother if a male receives a recessive Al from his mother he will Express that phenotype no matter what because a matter of fact you will only have one ex anyway so if you get that one recessive chromosome from his mother he going to show it up and for this same reason males are more likely affected by these excellent chromosome um traits for example color blindness for example all right so to understand this a little bit further this is a mother right here this is a father mother with X chromosome father with X and Y chromosomes all right so first thing let me just go by piece by piece look at the colors of these lines so let's say the the first daughter get the daughter get X chromosome from a mother this stripe X chromosome and this full dark X chromosome from from his father then she going to be this okay that's so you notice that now it's a exling it can be affected by mother or father okay so if a mother if a mother is carrying the recessive Al and the father is carrying recessive Al then definitely this this daugh will be affected okay okay next now look at this now a mother giv this chromosome and a father giv this ex chromosome that's the next possibility of a daughter so no this there are two ways a daughter can become one with a c with one type of EX chromosome for a mother the next ex chromosome from mother but the daughter will always notice the two daughters the two daughters will always have the father X chromosome but the ex the other ex chromosome in the daughter could be either or ex chromosome from the mother so notice it so if if your father is caring that X chromosome then there's a light chance of the of the daughter being affected especially mother is also affected now for a son a son can get this ex chromosome from a mother this Y chromosome from the father also next possibility here you could get this ex chromosome and also this Y chromosome so the the the sun is always getting the white chromosome from the father all right now let's look at this example now this is this is inheritance for hemophilia and this was given on one of the previous exams I think yeah since recently so this is a father right here X and Y chromosome and this is without ailia so it's normal so notice the color pink is for Amilia all right and hemophilia of course is the inability to clot the blood if a mother now is a carrier that means she's a carrier she she don't show the traits but she have it hidden because it's recessive okay now this is a son being born with the with the with the father Y chromosome and the mother unaffected hemophilic X so is unaffected is normal however if the daughter get this X chromosome which is normal from the father and affected X chromosome from the mother she becomes a carrier if the son gets this which is a pink chromosome which is a pink X1 is affected chromosome from his mother he has to be hemophilic because the white chromosome has no effect on the X you see next daughter could get a two dark chromosome from the mother and father and so therefore she' be unaffected and she's not a carrier she's just normal see so you have a a daughter could become a carrier a son be affected or a son be normal all right so that's a possibility right there all right so genetic variation now is the next thing we to look at I'm go through this real quick gen gentic varation is the difference between IND idual of populations all right and so we're looking at two different types of variation continuous and discontinuous all right and so in continuous and discontinuous what's the big difference here is that continuous influence by genes genes influence the continuous and also the environment influence the continuous but discontinuous is influenced by genes only only genes are affected by the discontinuous envir has nothing to do with nothing on this continuous variation all right and so by the examples you will see now a continuous variation it's on a Continuum is a gradual change over range of time the major the majority of individuals are usually in the middle all right so you have average weight for example average height yes so most people fall into that all right again just to make a note that continuous is transmitted by genes or Ed by genes and also influenced by the environment now for continuous variation as just to make a note or an example of this for example you have different traits for example height and of course the majority will be in the average so definitely it's an example of height in a population all right so you look at something like like that a graph looks something just like that all right in terms of examples now of continuous we have here all right just hold on example coming height we have height that's that's a continuous variation notice is not either or either so it's at various ranges of height all right our next example of continuous variation here with weight we have different weight as well among a population people may have different weight so there's no one weight for any given person all right there's no different category sh size example of continuous so some person have larger feet than others for sure all right we also have this continuous variation now thison variation now is either either so there's are distinct categories definitely no intermediate no in between no no no average nothing or it is either either it is not influenced by the environment it's the basically only solely based upon genes or chromosomes right so only genes affect the discontinuous and so examples of this we're going to look at them real quick all right and again if you look at the graph situation you will only have two categories is either a group one or group two or group a group b whichever the case may be and now for example of of this continuous as you all know the first I'm going to talk about is your gender either your boy or your girl you fall either of those categories there's no in between or know maybe so all right boy or girl all right your fingerprint is specific to you there's no categories of fingerprint that are discontinuous you born with you die with it tongue tongue rolling you can roll the tongue or not all right that's another discontinuous variation right there uh so we have different examples of of both of them just can make Leaf size for example in Plants length of leaf chunks chunk sizing in in elephant for example um speed defin definitely L the length of a hair uh the blood pressure yep those are continuous thing um discontinuous maybe the color of petals color petals don't really change texture of seed coat definitely High color and so on those really don't change blood group don't change your ear lobe whether be attach or detach or disattach those things don't really change all right so this is example of a ear right there attach or detach if you notice that factors that affect variation include the diet mutation migration genetic drift random meeting physical activi so these things can change how how you appear how you look over time all right so these are things that can definitely affect variation all right so please make sure Ure read on Evolution natural selection gentic engineering I really don't have the time to go through all of those to be honest with you hopefully in the future I'll will get to put in those in the next one all right so this is pretty much we're going to conclude this review and I thank you for being here thank you for just going through these points with me real quick and I wish you good luck on the examination I talk to you soon all right