Ecology Lecture Notes

hi everyone and you're very welcome to today's Saturday session which is on eventsert biology on the topic for today is going to be ecology so we're going to look at the main content around the topic of ecology entryways we're also going to look at some exam questions as well just so we can see how we can relate the content to the exam questions and making sure we're picking up as money marks as we possibly can in preparation for our exams so before we get into it we're going to talk about the definition of ecology so ecology is the study of the way living things and our environment both work together and interact with each other and any external factor is referred to as the environment so one key word which would be very common to you is the idea of a habitat so a habitat is a place where an organism lives and there's lots of different examples of this we can have deserts we can have Meadows we can have grasslands we can have Woodlands as part of your ecology study you would have done a habitat study and more often than not that's to a grassland or a woodland but differs from school to school so you would have got a real sense of what's actually involved in the habitat and the different features that make up that habitat so another word that's used quite often with the idea of a habitat is an ecosystem so an ecosystem is a place where all living organisms work together and with their surrounding environment so where the habitat is the place where the organism lives the ecosystem describes the interrelationships between the living organisms and the learning environment so remember the environment refers to all the external factors so that could be something like the weather okay so different ecosystems might have different weather patterns or different climates within them so a couple of different examples of ecosystems here so one example being the desert a feature that a desert would have would be that it has very low rainfall and a sample of that would be the Sahara Desert you could also have a desert like the Gobi Desert another ecosystem would be the grasslands so one feature of this is the mild temperatures and the low rainfall an example of that will be the steps of Asia and then the third ecosystem would be the freshwater ecosystems one feature that they would have would be have a non-salty water and rivers lakes and wetlands will be an example of a freshwater ecosystem now we mentioned a couple of times already about the environment being all of the external factors so these environmental factors there's four categories of factors that can affect the ecosystems so abiotic factors are the non-living factors the biotic factors are the living factors the climatic factors are the average weather conditions so anything associated with weather would fall underneath the branch of climatic factors and then adaptive factors refers to the soil So within that we could be talking about things like soil temperature soil pH or we could have soil moisture so water content within the soil so once we refer to adafik we're relating to honey thing to do with the soil so here's a table matter who of all the living and non-living parts of our ecosystem so the living things that affect the ecosystems are called the biotic factors and then the non-living things which affect the ecosystem are called the abiotic factors so a couple of biotic factors that we have there we could have competition and predation so we all know that animals compete for food and mates but plants will also compete for space and for light so there's competition happening all the time but in our ecosystems predation so this is where a predator which is an animal that kills and eats another organism hunts prey where the prey is the animal that's eaten by The Predator so this is going to control the number of organisms that we would have in ecosystems so the more predators that we have they're going to eat large amounts of prey so the number of prey could fall but if we didn't have large numbers of prey for the Predators to eat then the number of predators could fall and we'll have a look at that a little bit later on so some of the abiotic factors or non-living factors we have our weather and we have our soil so climatic factors for weather and traffic factors for soil so when weather the temperature and light can affect photosynthesis so the more sunlight the more photosynthesis will occur and climates can also influence the migration of organisms on Earth so there will be some species who would move to more warmer conditions at certain times of the year some might prefer some colder conditions so they will migrate across the Earth on the soil soil can impact the type of plants that can grow so some plants are going to prefer more acidic soils while their plants are going to prefer drier soils so again relating back to the term adafik it's anything to do with the soil so we're going to have a look at a couple of the climatic factors so again this is an abiotic factor because it's non-living and it's affecting the ecosystem so an abiotic factor and these are the elements of the climate or weather that influence the life and distribution of the organisms that live in a particular environment so some examples of climatic factors will be the temperature rainfall wind and also humidity so the moisture content in the air so if you have a look at temperature first of all temperature can affect the rate of reactions in living things so higher temperatures in summer increases plant growth but lower temperatures can lead to animals such as hedgehogs and frogs hibernating in winter storm metabolism slows down they're not going to be as active in winter rainfall but we know water is essential for life so plants such as cacti are adopted are adapted to store as much water as possible because again these can be found in desert ecosystems where low rainfall is very very common so being adapted to Source or to to store water is really important for them and then wind where wind can cause physical damage and also increases evaporation or it can increase transpiration with implants to evaporation of water off the ground for animals and we can see here the trees exposed to wind grow better on the sheltered side and bend away from the wind that's because they're not as exposed and wind can also help spread Parliament seeds so plants can grow in places they may not have before so really important for increasing the number of the plants as well through asexual reproduction so the adapting factors we've already mentioned that this refers to anything to do with the soil and these are the physical chemical and biological characteristics of the soil that influence the community so these can include the soil type the soil PH air and mineral content or the soil texture so if you have a look at the table down here we can see one factor that affects ecosystems is the soil PH okay so how acidic or how basic the soil is so plants and animals are adapted to specific PHS so acidic soils would generally be more suited to bog moss and Heather whereas neutral soils would suit most of the plants basic soils with soup plants such as bee orchids so some plants will be more suited to different PHS than others the water content is also really important so water is absorbed by The Roots again this is used for photosynthesis so plants need water for photosynthesis and also for other General metabolism as well and a lack of water can lead to wilting mineral content is also really important so this is needed by plants for growth and a lack of any mineral can result in stunted growth for the plant so the soil pH water content and mineral content are three of the adoptic factors or factors relating to the soil that can affect ecosystems so we're going to look a little bit now at energy flow throughout the ecosystem energy will filter out the ecosystem as all of the organisms feed so we mentioned a couple minutes ago about how we can help predators and prey so Predator being an organism that catches and kills another organism and as it feeds it's going to get some energy from what it's eaten okay so the energy is going to flow as organisms feed organisms that make their own food are called producers so we know plants make their own food through the process of photosynthesis so they are known as producers because they produce their own food whereas organisms that eat other organisms are called consumers okay so we will be an example of a consumer because we don't produce our own food we have to catch or we have to get food from other sources okay other organisms so we can see here we're going to be looking at this food chain in a couple of minutes but we can see the energy has been passed from organism to organism so where the arrow is pointing to is is to the organism that's doing the eating or the feeding so the caterpillar is eating the leaf the chameleon has eaten the caterpillar the snake is eating the chameleon and the Mongoose is eating the snake so we're going to have a look at the food chains now in a second before we do that though we're going to just have a look at the organisms that exist within the habitats so we mentioned a couple of minutes ago they're about the producer being the organism that makes their own food okay an example of that being green plants so we obviously can't make our own food following on from that we're going to have our first consumer okay a lot of the time we could be the first consumer so we're known as the primary consumer okay so this is the first consumer they eat the producer this can be anything in general we're going to look at an example here in terms of Roberts and green flies so they would eat the green plant now the secondary consumer is going to come next and the secondary consumer is the one that eats the primary consumer it eats the previous level so these are the second consumer some examples related to the examples we just seen there a second ago will be the foxes which could eat the rubbish which at the green plant or we could have our ladybird which eats the green fly which also at the green plant then we have our tertiary consumer so our tertiary consumer is generally our top consumer so we generally wouldn't go back or go any further than a tertiary consumer we'll explain why in a couple of minutes but they're going to eat the secondary consumer okay so again eaten the level before and an example of that being the spiral Hawk now we get to why we don't generally go above a tertiary consumer in a couple of minutes but it's to do with the energy levels so lots of energy is lost as these organisms feed so as the primary consumer eats the producer it gets some energy but most of it's going to be lost that energy then the primary consumer has the secondary consumer is going to get some of that by eating the primary consumer but again a lot of it is going to be lost but we come to that in a couple of minutes so just one note the consumers here can either be carnivores which means they eat meat or they can be herbivores which means we eat plants or they can be omnivores which means they eat both okay so the primary consumer here that eats producer if it only eats plants then it's going to be a herbivore the secondary consumer here it could be a carnivore meaning it only eats meat but it also could be an omnivore meat meaning it eats both meat and plants now we've already mentioned the idea of a food chain we've seen this example in a couple of slides ago but a food chain shows the feeding relationship that exists between organisms and a habitat so we've already mentioned the arrows would Point towards the organism that does the consuming so the leaf in this case is eaten by the caterpillar which is then eaten by the chameleon which is standing by the snake which is then eaten by a mongoose so this example looks a little bit different it was just fitted in to the space that we had but generally it would just be continuous line so after the chameleon we continue on to snake and then continue on to one loose again it was just brought down to fit into the space so they usually will start with a plant which is the producer they produce their own food and then they are going to be consumed by the consumers so we have our primary consumer our secondary consumer our church free consumer and we also actually have a fourth consumer in this one but that won't always happen usually a tertiary consumer might be as far as we cash so there's a couple more examples of food chains we have here so we have leaves which is primary consumer or sorry primary producer again is going to be eaten by the caterpillar which is going to be eaten by the trush so if it's writing what each one of those are that's the producer or primary producer this is going to be our primary consumer and this is going to be our secondary consumer the next one is going to be very very similar we were a producer primary consumer secondary consumer this would be our tertiary consumer over here so that's the one that's different from the previous one we actually do have a tertiary consumer and this will be our fourth consumer over here but again won't always get as far as that now a food web on the other hand very similar to a food chain except a food web is made up of interconnected food chains so lots of food chains intermingles with each other so if we look at the entire food web down here we can actually pick out some individual food chains so we have our plant here primary producer eaten by the giraffe eaten by the lion so primary consumer secondary consumer same thing if we start off with the tree Weaver a rhino primary consumer eaten by the lion secondary consumer if we go over here we have our plants you can buy a grasshopper eaten by a bird eaten by a skunk eaten by our Hawk okay or a vulture so it doesn't matter where we start we can see that we can pick out individual food chains okay and what this shows us is that the food web shows us that all organisms are reliant on each other for survival so here's another example of a food web this time you don't actually have any pictures it's just words but it's the exact same idea here we have our Leaf which is our primary producer eaten by Green fly eaten by ladybird eaten by Blackbird eaten by spiral Hawk that same Leaf could be eaten by an earthworm eaten by a hedgehog which is then eaten by a fox or the same Leaf again could be eaten by a snail which is then eaten by a hedgehog which is then eaten by a fox so we can see competition really easily Within These food webs as well because if we have a look here the earthworm the snail the mouse the rubbish the caterpillar and the green fly are all eaten the leaves okay which should be in plentiful Supply but if we go up here to the top we can see that both the spiral Hawk and the Stout eat the mix so they're going to be in competition for the mouse because both of them are going to want to use it as their food source okay so the Stout obviously can eat the rabbits as well the sparrow Hall can also eat the Blackbird but if they were both reliant on the mouse they will be in big competition with each other to try and get that food source for themselves now we've already mentioned this briefly already but we're going to have a look at energy flow throughout the ecosystem as well so energy will flow throughout the ecosystem as the organisms feed okay so we can see over here on the right hand side we have our producer it's going to be eaten by the primary consumer which is going to be eaten by the secondary consumer now when the primary consumer eats producer it's going to gain some energy from eating the producer and when the secondary consumer eats the primary consumer it's again going to pick up some energy from that food source but the majority of the energy is going to be lost through heat energy and roughly 90 of all energy will be lost as we move from the bottom of the food chain right up to the top of the food chain so that's why we said a couple of minutes ago that normally the tertiary consumer will be the top consumer so we'd have one more level up here because after that there's very very little energy left over so the tertiary is usually the top consumer so we're gonna have a look at a quick exam question now based off of this and we can see the first one there a typical grazing food chain consisting of four trophic levels is shown below each letter represents a different species so a is eaten by B is eaten by C is eaten by D and we know that because the arrowhead is pointing towards B and then C and then d so the first question there says explain what is meant by the term trophic level and we know that this is the feeding position or position on a feeding chain so feeding chain position we'll have a look at the next one it says why are food chains generally short well we mentioned that a couple of minutes ago an awful lot of energy is lost as we move from level to level so by the time we get towards the top there's very little energy left so this is because of the low energy or little energy past to the next level and we could mention something there about 90 being lost okay so we give a figure just so we know our statistics 90 being lost part three it says which letter represents the secondary consumer so we know the first one is going to be the producer second one is the primary consumer third one is the secondary consumer so that's going to be C power four give a possible reason why the population of C May decline naturally well one way that this could happen is because of predation and more specifically we could say that there's an increase in D okay so we know that c is eaten by D so if the numbers of D increase there's going to be more of those to each C so the numbers of c are going to fall power 4. sorry part five suggest the possible consequence for the population of a if the population of C was significantly reduced so population of a would probably fall and the reason for that is because the number of C which are available to each B has reduced so in turn the number of B is going to increase which means more of a is going to to be eager to be consumed which means that the population of a is going to fall okay so we have to say suggest our members um sorry suggest the possible explanation we have to explain so we're going to say population will fall that's because a decrease in C that's an increase in b so more of a is eaten or more of a is consumed okay so that was part five part six I'll try and actually go up to the top here for part six just so we don't run out of space part six suggests how members of species D might respond if the population of C was significantly reduced well one way if they didn't have a food source they're probably just going to migrate and go and find a food source somewhere else so migration or if they could they're going to switch their prey so maybe they have something else that they can eat so they'll just eat that to get their energy instead of focusing on the one that's after been significantly reduced and part seven food web is a series of interactive food chains suggests how it may be possible for the secondary consumer so the secondary consumer up here is C explain how it's possible for the secondary consumer in the food chain above to be a primary consumer in another food chain so if it's a secondary consumer here it's eaten an organism which is most likely an animal for B but if it was if it was in the position of B it would have to be a plant so in that case it would have to be an omnivore okay so it eats plants and animals so it can be a primary consumer in the other food chain because it eat plants but here is the secondary consumer because it's going to eat the animals okay so we're gonna have a look at the trophic level now we mentioned that briefly in the last um exam question anyway but we'll go into it in more detail here so the trophic level refers to the position of an organism in a food chain now we've already mentioned these already with a primary and consumer with a secondary consumer we've producer at the start tertiary consumer we can go up towards the top of our fourth consumers and so on so the first trophic level is going to be the plants or is going to be the producers the second trophic level is going to be where the primary consumers are the third trophic level is going to be where the secondary consumers are and the four trophic level is going to be where the tertiary consumers are so we've mentioned this already so we can see there we have our producers primary consumers secondary consumers tertiary consumers so it's our first level our second our third and our fourth so it's just important to know that they're sometimes referred to as T1 T2 T3 and T4 now a parameter numbers then this is another concept which we look at in ecology and we can see here it's very similar to a diagram we looked at a couple of minutes ago when we were referring to the amount of energy that was being passed on from level to level so if we just relate it back to the energy diagram with a large amount of energy at the top at the bottom and a smaller amount of energy um exists right up until the top that's what a standard pyramid of numbers would normally look like as well so we would have a large number of producers at the bottom smaller number of primary consumers smaller number again a secondary consumers and then a smaller number again of tertiary consumers it's not always going to look like that and we'll see in examples in a couple of minutes but a standard pyramid of numbers would somewhat resemble that now what is a pyramid of numbers what does it actually do well the Pyramid of numbers represents the number of organisms at each trophic level so because the producer section here of the perimeter numbers is the largest the largest bar that means it has the largest number of organisms the primary consumers have slightly less but it's still larger than secondary consumers which is still larger than the tertiary consumers now generally the number of each organisms at each level is going to decrease as you move up not always the case and we'll see examples in a couple of minutes but the reason for this is because of the high level of energy loss from level to level so here's the standard pair of numbers you can see at the bottom we have our producers which are the plants we have a certain number of those quite abundant because they're plants even less primary consumers which are the snails even my secondary consumers which are the frogs and then even tertiary consumers which in this case is a fox so the number of organisms in this case is represented by the virus and the width of the virus and as we go from the bottom to the top it gets smaller and smaller now the pyramidal numbers does not always have a regular pyramid shape because it does not take into account of the biomass of the organisms so what do we mean by that well down here we have one oak tree so one organism that means we have a narrow bar but that one oak tree can feed thousands of insects so that's why this bar up here is much bigger so even though we only have one oak tree it can sustain thousands of organisms so an inverted pyramid of numbers can be found in an ecosystem where the community contains a few producers with very large biomass that support a larger number of smaller consumers so we can see this one here is inverted doesn't follow the standard pyramid shape which I set a couple of minutes scope could happen now an inverted pyramid of numbers can also be found in an ecosystem where the community contains parasites so parasite is something that lives off another living organism and we can see that in the Pyramid of numbers over on the right hand side so the plants we've quite a large bar there because we've quite a number of plants in this ecosystem those plants even though there's quite a number of them would probably only sustain one red deer so they need lots of plants for their food source but then that wound deer can sustain money deer ticks okay so they're parasites many of those can survive on the one deer so there can be many more parasites than the hosts they feed on because each individual parasite has a very small biomass so because they're so small one deer is enough to host many many of those now the shape of the Pyramid of numbers does not change the shape of the pyramid of energy so for any food chain producers store the most energy and the energy stored decreases at each level given a regular pyramid of energy so even though down here we might have an inverted pyramid of numbers over here the pyramid of energy is the exact same shape so we're still losing up to 90 of the energy as we go from level to level so here's another exam question so it says draw pyramid of numbers to represent the information in the food chain below so we've won rose bush so that's going to be quite a small bar can sustain many caterpillars so that's going to be a larger bear we'll have even less black birds and we'll have even smaller Hawk okay so that's going to be an inverted pyramid of numbers for part one for part two what term is used to describe the organisms at the top of the food chain they're going to be the top or the tertiary consumers and then for part three explain why pyramid of numbers are usually restricted three or four levels we've seen this before it's because of the large energy loss from level to level so another exam question here where in the food chain are primary producers found that's normally the first level what term is used to describe organisms to feed and primary producers that's our primary consumers why are most food chains I am short so only consists of a few trophic levels so that's because of the large energy loss again so we can see there that's a very common exam question what deduction may be made if the organisms at the start of the chain are less numerous than those that feed upon them so what does this mean about a producer that means they most likely have a large biomass so that was in the inverted pyramid of numbers we've seen a couple of minutes ago about how one producer could feed many many organisms can a parasite be the first member of a food chain the answer for that is no and the reason for that is because parasites are not producers or you could say there that they need a living host okay so they're not producers they don't produce their own food they need to feed on something else so energy enters food chains in the form of light in which form do you think more most energy is lost from food chains so we mentioned that already in the Pyramid of numbers that's true heat energy we're now going to have a look at the habitat story which is something you might have done already as part of your leaving serbiology studies but if not you will okay so you will come across all of this information at some point anyway so we've already mentioned this already but ecology is the study of the way living things and an environment about work together and interact with each other and your habitat study is where you really would have started to investigate that we mentioned already about a habitat and where a habitat is a place where an organ organism lives so some of the examples include deserts Meadows woodlands and grasslands and most likely the habitat you would have studied was either a woodland or a grassland and you would have looked at the features of those within that now we're in the habitat study you would have used many pieces of equipment so that you could capture and identify different animals and plants so some of them are listed here we have a quadrash we have a sweetness we have a pitfall trap and we also have a pooter so the quadrash we can see there is a square shape this is randomly placed on the ground so normally if you're a randomly placed on the ground you would have stored with a pencil crew the pencil over your shoulder and then place the quadrat on top of where the pencil went we're obviously not going to troll the entire quadrash because it's just too heavy and could cause injury to somebody so what you will do then is you'll go to where the quadrat is examine the inside the square frame and the number and species of each plant and animal will be recorded using a key The Sweep mesh does exactly what it says you sweep long grass so you can collect small insects by brushing it through long grass or tree leaves and then a key again is going to be used to identify the organisms a pitfall trap is kind of hard to see there but there is a trap set into the ground there so a small hole is dug into the ground a cover is placed on top ensuring it is raised so that small animals and insects can crawl under and when they do they will fall into the cup or the Trap that you've set once it's covered with plants and Stones they won't be able to see it and fall in on small animals and insects will fall in and you can then once again identify them with a key on the pewter this is used to collect small animals so one tube was placed on or near the insect so that's the one that has um no gauze on it the other tube can then be used to suck the insect into the collection jar so just make sure you're putting the one that has no gauze at the end over the insect and the one that has the gauze is um is the one that you suck through now we've mentioned this already but when we collect our plants and animals how do we identify them so we do that with a key so a key can look like over here on the on the left arm or sorry on the right hand side so we can see here this was to identify some plants very very similar ones which you might have used to identify animals as well but a key is used to identify your plants and animals as part of your habitat study now when you were doing your habitat study he would have done two types he would have done a qualitative study and you'd also done a quantitative study so the qualitative study is any data that you would have collected using words so more often than not it was just a yes or no are they present or not and what's the name of the organism what's the plant what's the animal you're not actually counting them you're just saying they're present or they're not present and you're given the name by identifying them the quantitative study that on the other on the other hand uses numbers so you're counting the frequency how many of them were there what percentage of the entire habitat was covered by this particular plant so that's anything to do with numbers now one quantitative study you would have done was to calculate the percentage frequency of an organism and you most likely would have done this with the quadrat as well so the presented frequency gives an estimation of the chance that you would find specific species by randomly throwing a quadrat and a habitat and to calculate the percentage frequency we find number of trolls at the quadrat that the organism was present in divided by the total number of trolls and then times that by 100 to change to a percentage and we're going to see that in action now in a second so there's one example already done there for us so we can see this particular habitat study there was a Woodlands present and on the first row second third fourth fifth and the ninth Row the woodlex was present but there was four troubles where it wasn't so in total there were six trolls where it was present the frequency is six out of ten because it was 10 rows and times six out of 10 by 100 and we get 60 percent so let's say we had grass it was present on nine of the trolls so a total of nine which means the frequency is nine tenths times that by a hundred and we get ninety percent and it doesn't matter which organism you're doing this for it's the exact same steps find the frequency multiply it by 100 and you found the percentage frequency so we have a sixty percent chance of getting wood lights on the next row and a 90 chance of getting grass on the next trip percentage cover is slightly different then this is an estimation as to what percentage of a habitat an organism takes up and it's normally calculated for plants so what percentage of the entire habitat does grass take up what percentage of the entire habitat do daisies take up whatever the particular plant is so percentage cover is calculated as follows it's the total number of small squares an organisms present in So within our quadrash we know it's Square shaped but normally that's divided up into a series of smaller squares normally it's going to be 25 you're going to count the number of smaller squares it's present in divide that by the total number of small squares we have in total times that by 100 and we will have our percentage cover so an example here is already done for grass we could do the exact same thing there for a daisy so if it was present on 10 rows so we'll add up all those numbers now so 45 55 70 110 120 130 140. so it's present in 140 small squares the total number of small squares was 250 and then all you have to do is put 140 divided by 250 into your calculator times that by 100 and we will get 56 so in this case 56 of the entire habitat was covered with daisies and again it doesn't matter which organism you're looking at will be a plant for the most part and you can do it obviously for Animals as well but becomes a little bit more difficult but it's more accurate and more appropriate to do so for plants so there is some potential sources of errors or carrying out our habitat study as well so there is human error which we can make there can be change in conditions so if you're doing a habitat study today and then next week if there's been particularly bad weather some of the organisms might have retreated or gone underground so it would have made your results slightly different you might have an accidental Discovery so it might be an organism present that they either shouldn't actually be there just a complete accident and also your sample size as well so if you carry off a one-off habitat study today and don't repeat that ever again you can't take those results um as absolutely valid and absolutely representative of the entire habitat you would have to do the same habitat study at many different times at many different stages throughout the year to get a better picture of what's actually contained within the habitat so just a little bit more detail about the potential sources of error so where do we get human error well it's possible to make simple errors when you're recording the data you might be able to interpret the key 100 accurately and also when you're performing calculations you might make a little error as well changing conditions we've already mentioned The Accidental Discovery there it says it is possible that accented stories be made so a rare organism may be present on a particular day and then as we mentioned there about the sample size as well the larger the number of habitats that are studied with an ecosystem the more accurate the findings are going to be so another example question here answer the following questions in relation to a quantitative survey of a species of small herbaceous plant so name the method you would employ so we're going to calculate percentage cover and we're going to use a Quadra for that how would you ensure that your sampling was random so we're going to throw a pencil over our shoulder and we place the quadrash on top of that and then the last one there named monadaphic factor that could affect the distribution of this plant in the ecosystem so we mentioned earlier on about adaptive factors referring to the soil so a couple of those you could have soil pH you could have soil temperature you could have soil time sorry soil and moisture content or water content or even the soil type so type of soil there as well so lots of different answers which you could put in but we're looking for an Adaptive Factor so it had to be something relating to the soil now for the last couple of slides we're going to look at adaptations competition interdependence and so on so an adaptation is when an organism develops certain characteristics that make it more suited to the environment that it lives in it normally happens as a result of evolution and there are two main types of adaptations we can have we can have physical adaptations and behavioral adaptations now a couple of examples of adaptations which you might be familiar with polar bear has a physical adaptation a buffalo has a behavioral adaptation and squirrels also have behavioral adaptations as well so the polar bear the physical one they have they have white fur to protect or camouflage them from their prey and they also have thick layers of fat to keep them warm so they also live in them in very cold conditions so those thick layers of fascial make sure they stay warm Buffalo or behavioral so Buffalo will migrate to areas with better weather better breeding conditions and that has more food at certain times of the year so that's why you'll see these really famous images of the mass migration of the Buffalo from one area to another so they're moving because they want better weather better breeding conditions and more food squares also have a behavioral adaptation so squirrels will hibernate you've probably heard of that before so they enter a deep sleep to save their energy over winter where they would find it hard to get food okay so their metabolism is much much lower they don't need as much food because they're obviously going into hibernation and then when the weather conditions get better they can come out of hibernation there's more food available for them and their metabolism will then increase now interdependence so interdependence refers to when two organisms depend on each other for survival and it's a two-way process so what's really important about this is if an exam question ever come up on interdependence and given an example of interdependence you have to give both sides of the story so this example down here it's not just enough to say that bees rely on plants for pollen to make honey what do the plants actually getting out of the bees as well so plants need the bees to transfer the pollen to other plants so that they can reproduce so you can't stop there by just saying bees rely on plants for pollen to make honey give the second side of the story there as well the plants need the bees to transfer some pollen to other plants so that they can reproduce so just keep that in mind for interdependence really important that you give both sides of the story now competition is one of the last things we're going to be looking at today so competition is the struggle between organisms for things in short supply so what kind of things are going to be in short supply and they'll have to compete for both food water mates oxygen and light particularly important those last two there for plants so it can take place between different species but also between organisms from the same species so for example male deer are going to compete for mates and plants are going to compete for light and space so we can see that happening in the images over here so they're competing most likely for a mace the plants are competing for lice so you can see they're all going to grow towards the light and try and take up as much space as possible so they can absorb as much light as possible to get as much food produced in photosynthesis Now population control so population comprises of all the members of a species and there are a number of factors that can control the size of a population so we've mentioned this already but competition can control the size of a population predation parasitism and symbiosis all of those can control the number of species living in a particular area so the two types of computation we have are contest competition and scramble competition So within contest competition there is an active physical struggle between two or more organisms okay for a resource that's in short supply and we can see that in the diagram over here we can see there is an active physical struggle happening but down here when we look at the cows there is no Act of physical struggle because that's scramble competition everybody is scrambling for resources but all of the competing individuals are going to get some of the resources some are going to get more than others some are going to get less than others but everybody is going to get something so contest competition to competing is an active physical struggle scramble competition everybody is going to get something and this is exactly what's happening here so what do ecologists mean by the term scramble competition so this is where all individuals get some of the resource give one example of a factor other than light which may be a source of computation among plants so for this one we could say space you could say water minerals will be another example there there's a lot of different potential answers give one example of a factor other than food which may be a source of competition among animals so we're going to have mates again we could have water shelter even some territory okay all possible answers there for the animals and caterpillars have my parts that are suitable for chewing on leaves whereas the adult form the butterfly has long soaking mouth parts so just so having different types of mouth Parts reduces competition between the adults and the young of such species so what we can say there is they have different food so there's going to be less competition so obviously if they're eating different things there's going to be less competition so different food leads to less competition so they don't have to compete as much as they might have as if they're eating the same thing now predation predation is the catching killing and eating of another organism so the Predator is the one that catches kills and eats another organism which is the prey and the prey is the organism that is caught kills and eaten by the Predator so in this particular example over here the Predator is the bear and down here the prey is the fish so some examples would include ladybirds and aphids so ladybirds being the Predator black birds and earthworms again the Blackbird being the predator and Hawks and mice this time the mice is going to be the prey the hawk is going to be the predator parasitism we've already mentioned in terms of the Pyramid of numbers before but parasitism occurs when two organisms of different species live in close Association and one organism is going to obtain its food to the disadvantage of the other okay so the parasite is going to live on a living individual that has a living host and it's going to be the detriment or to the disadvantage of the actual host so the parasite is always going to be the one that benefits and the host which is the one the living one and that is supplying the food source to the parasite is the one that's going to face the disadvantage and finally for today symbiosis so symbiosis occurs when two organisms of different species live in close association with each other and at least one benefits but in contrast to parasitism nobody becomes disadvantaged so some examples bacteria and intestine and will produce vitamins for us and they also get shelter for themselves so in this case both of us are actually getting an advantage there and a nitrogen fixing bacterium plants will get food and Shelter From the plant but in turn will provide nitrates for the plant so again there's an advantage there for both of them there's benefits for both neither has become and disadvantaged which is the case for parasitism where at least one or one of them is going to become disadvantaged so just to finish up today I'm just going to quickly talk you through the exam revision website and tell you about all of the resources which are available to you not just for biology before they're leaving certain subjects as well so first of all if we look at the subjects which are available so we can see there we have I am leaving certain AG Science Biology business chemistry economics English French geography history Irish maths music and physics and within each one we're going to have the exact same features so video tutorials with quizzes presentations and exam Builder and a resource pack so if you wanted to watch some video tutorials and what we did today we go to unit one ecology and we can see there all of the different videos which are available for you to watch so if we wanted to watch a little bit more about the energy flow we click in the video will appear there for you to watch learning intentions will be given and if you wanted to watch it a little bit quickly you can change the speed up as far as two times speed as well now when we go back once you've watched all the videos in a particular topic you can test yourself in a quiz they're all McQ multiple choice you can do them as many times as you want until you get 100 just to make sure you're fully comfortable with the content that's involved and right down at the bottom as well we also have a resource pack so for Ecology we have 11 pages of H1 notes there all of the material which you need to know fully tailored to the exam will be available not just for Ecology but for every topic in the even cert biology we do have an exam Builder as well so all of the leave and search exam questions and more questions will be available here so we can see here there's a 2021 question we have another 2021 one there so we press the plus one to add it to our exam and once you go back up to the top you can download the questions and download the answers now if you want to find out a little bit more just go to the exam revision website exam revision.ie there is a free trial there as well and right down the bottom you'll be able to find out a little bit more about the plans and the pricing so if you did want to find out um what price was involved you'll be able to find that there there is now a monthly subscription as well so you don't have to pay for a full year in advance you can just pay as you go and pay as you need and the more subjects that you um subscribe for the cheaper it is so there's a discount for any additional subject which you might add so keep an eye on our YouTube channel and other social media Instagram Twitter Facebook we will be advertising lots more Saturday sessions over the next little while so make sure and set a reminder for every Saturday at 12 and I hope to see you again soon

hi everyone and you&#39;re very welcome to today&#39;s Saturday session which is on eventsert biology on the topic for today is going to be ecology so we&#39;re going to look at the main content around the topic of ecology entryways we&#39;re also going to look at some exam questions as well just so we can see how we can relate the content to the exam questions and making sure we&#39;re picking up as money marks as we possibly can in preparation for our exams so before we get into it we&#39;re going to talk about the definition of ecology so ecology is the study of the way living things and our environment both work together and interact with each other and any external factor is referred to as the environment so one key word which would be very common to you is the idea of a habitat so a habitat is a place where an organism lives and there&#39;s lots of different examples of this we can have deserts we can have Meadows we can have grasslands we can have Woodlands as part of your ecology study you would have done a habitat study and more often than not that&#39;s to a grassland or a woodland but differs from school to school so you would have got a real sense of what&#39;s actually involved in the habitat and the different features that make up that habitat so another word that&#39;s used quite often with the idea of a habitat is an ecosystem so an ecosystem is a place where all living organisms work together and with their surrounding environment so where the habitat is the place where the organism lives the ecosystem describes the interrelationships between the living organisms and the learning environment so remember the environment refers to all the external factors so that could be something like the weather okay so different ecosystems might have different weather patterns or different climates within them so a couple of different examples of ecosystems here so one example being the desert a feature that a desert would have would be that it has very low rainfall and a sample of that would be the Sahara Desert you could also have a desert like the Gobi Desert another ecosystem would be the grasslands so one feature of this is the mild temperatures and the low rainfall an example of that will be the steps of Asia and then the third ecosystem would be the freshwater ecosystems one feature that they would have would be have a non-salty water and rivers lakes and wetlands will be an example of a freshwater ecosystem now we mentioned a couple of times already about the environment being all of the external factors so these environmental factors there&#39;s four categories of factors that can affect the ecosystems so abiotic factors are the non-living factors the biotic factors are the living factors the climatic factors are the average weather conditions so anything associated with weather would fall underneath the branch of climatic factors and then adaptive factors refers to the soil So within that we could be talking about things like soil temperature soil pH or we could have soil moisture so water content within the soil so once we refer to adafik we&#39;re relating to honey thing to do with the soil so here&#39;s a table matter who of all the living and non-living parts of our ecosystem so the living things that affect the ecosystems are called the biotic factors and then the non-living things which affect the ecosystem are called the abiotic factors so a couple of biotic factors that we have there we could have competition and predation so we all know that animals compete for food and mates but plants will also compete for space and for light so there&#39;s competition happening all the time but in our ecosystems predation so this is where a predator which is an animal that kills and eats another organism hunts prey where the prey is the animal that&#39;s eaten by The Predator so this is going to control the number of organisms that we would have in ecosystems so the more predators that we have they&#39;re going to eat large amounts of prey so the number of prey could fall but if we didn&#39;t have large numbers of prey for the Predators to eat then the number of predators could fall and we&#39;ll have a look at that a little bit later on so some of the abiotic factors or non-living factors we have our weather and we have our soil so climatic factors for weather and traffic factors for soil so when weather the temperature and light can affect photosynthesis so the more sunlight the more photosynthesis will occur and climates can also influence the migration of organisms on Earth so there will be some species who would move to more warmer conditions at certain times of the year some might prefer some colder conditions so they will migrate across the Earth on the soil soil can impact the type of plants that can grow so some plants are going to prefer more acidic soils while their plants are going to prefer drier soils so again relating back to the term adafik it&#39;s anything to do with the soil so we&#39;re going to have a look at a couple of the climatic factors so again this is an abiotic factor because it&#39;s non-living and it&#39;s affecting the ecosystem so an abiotic factor and these are the elements of the climate or weather that influence the life and distribution of the organisms that live in a particular environment so some examples of climatic factors will be the temperature rainfall wind and also humidity so the moisture content in the air so if you have a look at temperature first of all temperature can affect the rate of reactions in living things so higher temperatures in summer increases plant growth but lower temperatures can lead to animals such as hedgehogs and frogs hibernating in winter storm metabolism slows down they&#39;re not going to be as active in winter rainfall but we know water is essential for life so plants such as cacti are adopted are adapted to store as much water as possible because again these can be found in desert ecosystems where low rainfall is very very common so being adapted to Source or to to store water is really important for them and then wind where wind can cause physical damage and also increases evaporation or it can increase transpiration with implants to evaporation of water off the ground for animals and we can see here the trees exposed to wind grow better on the sheltered side and bend away from the wind that&#39;s because they&#39;re not as exposed and wind can also help spread Parliament seeds so plants can grow in places they may not have before so really important for increasing the number of the plants as well through asexual reproduction so the adapting factors we&#39;ve already mentioned that this refers to anything to do with the soil and these are the physical chemical and biological characteristics of the soil that influence the community so these can include the soil type the soil PH air and mineral content or the soil texture so if you have a look at the table down here we can see one factor that affects ecosystems is the soil PH okay so how acidic or how basic the soil is so plants and animals are adapted to specific PHS so acidic soils would generally be more suited to bog moss and Heather whereas neutral soils would suit most of the plants basic soils with soup plants such as bee orchids so some plants will be more suited to different PHS than others the water content is also really important so water is absorbed by The Roots again this is used for photosynthesis so plants need water for photosynthesis and also for other General metabolism as well and a lack of water can lead to wilting mineral content is also really important so this is needed by plants for growth and a lack of any mineral can result in stunted growth for the plant so the soil pH water content and mineral content are three of the adoptic factors or factors relating to the soil that can affect ecosystems so we&#39;re going to look a little bit now at energy flow throughout the ecosystem energy will filter out the ecosystem as all of the organisms feed so we mentioned a couple minutes ago about how we can help predators and prey so Predator being an organism that catches and kills another organism and as it feeds it&#39;s going to get some energy from what it&#39;s eaten okay so the energy is going to flow as organisms feed organisms that make their own food are called producers so we know plants make their own food through the process of photosynthesis so they are known as producers because they produce their own food whereas organisms that eat other organisms are called consumers okay so we will be an example of a consumer because we don&#39;t produce our own food we have to catch or we have to get food from other sources okay other organisms so we can see here we&#39;re going to be looking at this food chain in a couple of minutes but we can see the energy has been passed from organism to organism so where the arrow is pointing to is is to the organism that&#39;s doing the eating or the feeding so the caterpillar is eating the leaf the chameleon has eaten the caterpillar the snake is eating the chameleon and the Mongoose is eating the snake so we&#39;re going to have a look at the food chains now in a second before we do that though we&#39;re going to just have a look at the organisms that exist within the habitats so we mentioned a couple of minutes ago they&#39;re about the producer being the organism that makes their own food okay an example of that being green plants so we obviously can&#39;t make our own food following on from that we&#39;re going to have our first consumer okay a lot of the time we could be the first consumer so we&#39;re known as the primary consumer okay so this is the first consumer they eat the producer this can be anything in general we&#39;re going to look at an example here in terms of Roberts and green flies so they would eat the green plant now the secondary consumer is going to come next and the secondary consumer is the one that eats the primary consumer it eats the previous level so these are the second consumer some examples related to the examples we just seen there a second ago will be the foxes which could eat the rubbish which at the green plant or we could have our ladybird which eats the green fly which also at the green plant then we have our tertiary consumer so our tertiary consumer is generally our top consumer so we generally wouldn&#39;t go back or go any further than a tertiary consumer we&#39;ll explain why in a couple of minutes but they&#39;re going to eat the secondary consumer okay so again eaten the level before and an example of that being the spiral Hawk now we get to why we don&#39;t generally go above a tertiary consumer in a couple of minutes but it&#39;s to do with the energy levels so lots of energy is lost as these organisms feed so as the primary consumer eats the producer it gets some energy but most of it&#39;s going to be lost that energy then the primary consumer has the secondary consumer is going to get some of that by eating the primary consumer but again a lot of it is going to be lost but we come to that in a couple of minutes so just one note the consumers here can either be carnivores which means they eat meat or they can be herbivores which means we eat plants or they can be omnivores which means they eat both okay so the primary consumer here that eats producer if it only eats plants then it&#39;s going to be a herbivore the secondary consumer here it could be a carnivore meaning it only eats meat but it also could be an omnivore meat meaning it eats both meat and plants now we&#39;ve already mentioned the idea of a food chain we&#39;ve seen this example in a couple of slides ago but a food chain shows the feeding relationship that exists between organisms and a habitat so we&#39;ve already mentioned the arrows would Point towards the organism that does the consuming so the leaf in this case is eaten by the caterpillar which is then eaten by the chameleon which is standing by the snake which is then eaten by a mongoose so this example looks a little bit different it was just fitted in to the space that we had but generally it would just be continuous line so after the chameleon we continue on to snake and then continue on to one loose again it was just brought down to fit into the space so they usually will start with a plant which is the producer they produce their own food and then they are going to be consumed by the consumers so we have our primary consumer our secondary consumer our church free consumer and we also actually have a fourth consumer in this one but that won&#39;t always happen usually a tertiary consumer might be as far as we cash so there&#39;s a couple more examples of food chains we have here so we have leaves which is primary consumer or sorry primary producer again is going to be eaten by the caterpillar which is going to be eaten by the trush so if it&#39;s writing what each one of those are that&#39;s the producer or primary producer this is going to be our primary consumer and this is going to be our secondary consumer the next one is going to be very very similar we were a producer primary consumer secondary consumer this would be our tertiary consumer over here so that&#39;s the one that&#39;s different from the previous one we actually do have a tertiary consumer and this will be our fourth consumer over here but again won&#39;t always get as far as that now a food web on the other hand very similar to a food chain except a food web is made up of interconnected food chains so lots of food chains intermingles with each other so if we look at the entire food web down here we can actually pick out some individual food chains so we have our plant here primary producer eaten by the giraffe eaten by the lion so primary consumer secondary consumer same thing if we start off with the tree Weaver a rhino primary consumer eaten by the lion secondary consumer if we go over here we have our plants you can buy a grasshopper eaten by a bird eaten by a skunk eaten by our Hawk okay or a vulture so it doesn&#39;t matter where we start we can see that we can pick out individual food chains okay and what this shows us is that the food web shows us that all organisms are reliant on each other for survival so here&#39;s another example of a food web this time you don&#39;t actually have any pictures it&#39;s just words but it&#39;s the exact same idea here we have our Leaf which is our primary producer eaten by Green fly eaten by ladybird eaten by Blackbird eaten by spiral Hawk that same Leaf could be eaten by an earthworm eaten by a hedgehog which is then eaten by a fox or the same Leaf again could be eaten by a snail which is then eaten by a hedgehog which is then eaten by a fox so we can see competition really easily Within These food webs as well because if we have a look here the earthworm the snail the mouse the rubbish the caterpillar and the green fly are all eaten the leaves okay which should be in plentiful Supply but if we go up here to the top we can see that both the spiral Hawk and the Stout eat the mix so they&#39;re going to be in competition for the mouse because both of them are going to want to use it as their food source okay so the Stout obviously can eat the rabbits as well the sparrow Hall can also eat the Blackbird but if they were both reliant on the mouse they will be in big competition with each other to try and get that food source for themselves now we&#39;ve already mentioned this briefly already but we&#39;re going to have a look at energy flow throughout the ecosystem as well so energy will flow throughout the ecosystem as the organisms feed okay so we can see over here on the right hand side we have our producer it&#39;s going to be eaten by the primary consumer which is going to be eaten by the secondary consumer now when the primary consumer eats producer it&#39;s going to gain some energy from eating the producer and when the secondary consumer eats the primary consumer it&#39;s again going to pick up some energy from that food source but the majority of the energy is going to be lost through heat energy and roughly 90 of all energy will be lost as we move from the bottom of the food chain right up to the top of the food chain so that&#39;s why we said a couple of minutes ago that normally the tertiary consumer will be the top consumer so we&#39;d have one more level up here because after that there&#39;s very very little energy left over so the tertiary is usually the top consumer so we&#39;re gonna have a look at a quick exam question now based off of this and we can see the first one there a typical grazing food chain consisting of four trophic levels is shown below each letter represents a different species so a is eaten by B is eaten by C is eaten by D and we know that because the arrowhead is pointing towards B and then C and then d so the first question there says explain what is meant by the term trophic level and we know that this is the feeding position or position on a feeding chain so feeding chain position we&#39;ll have a look at the next one it says why are food chains generally short well we mentioned that a couple of minutes ago an awful lot of energy is lost as we move from level to level so by the time we get towards the top there&#39;s very little energy left so this is because of the low energy or little energy past to the next level and we could mention something there about 90 being lost okay so we give a figure just so we know our statistics 90 being lost part three it says which letter represents the secondary consumer so we know the first one is going to be the producer second one is the primary consumer third one is the secondary consumer so that&#39;s going to be C power four give a possible reason why the population of C May decline naturally well one way that this could happen is because of predation and more specifically we could say that there&#39;s an increase in D okay so we know that c is eaten by D so if the numbers of D increase there&#39;s going to be more of those to each C so the numbers of c are going to fall power 4. sorry part five suggest the possible consequence for the population of a if the population of C was significantly reduced so population of a would probably fall and the reason for that is because the number of C which are available to each B has reduced so in turn the number of B is going to increase which means more of a is going to to be eager to be consumed which means that the population of a is going to fall okay so we have to say suggest our members um sorry suggest the possible explanation we have to explain so we&#39;re going to say population will fall that&#39;s because a decrease in C that&#39;s an increase in b so more of a is eaten or more of a is consumed okay so that was part five part six I&#39;ll try and actually go up to the top here for part six just so we don&#39;t run out of space part six suggests how members of species D might respond if the population of C was significantly reduced well one way if they didn&#39;t have a food source they&#39;re probably just going to migrate and go and find a food source somewhere else so migration or if they could they&#39;re going to switch their prey so maybe they have something else that they can eat so they&#39;ll just eat that to get their energy instead of focusing on the one that&#39;s after been significantly reduced and part seven food web is a series of interactive food chains suggests how it may be possible for the secondary consumer so the secondary consumer up here is C explain how it&#39;s possible for the secondary consumer in the food chain above to be a primary consumer in another food chain so if it&#39;s a secondary consumer here it&#39;s eaten an organism which is most likely an animal for B but if it was if it was in the position of B it would have to be a plant so in that case it would have to be an omnivore okay so it eats plants and animals so it can be a primary consumer in the other food chain because it eat plants but here is the secondary consumer because it&#39;s going to eat the animals okay so we&#39;re gonna have a look at the trophic level now we mentioned that briefly in the last um exam question anyway but we&#39;ll go into it in more detail here so the trophic level refers to the position of an organism in a food chain now we&#39;ve already mentioned these already with a primary and consumer with a secondary consumer we&#39;ve producer at the start tertiary consumer we can go up towards the top of our fourth consumers and so on so the first trophic level is going to be the plants or is going to be the producers the second trophic level is going to be where the primary consumers are the third trophic level is going to be where the secondary consumers are and the four trophic level is going to be where the tertiary consumers are so we&#39;ve mentioned this already so we can see there we have our producers primary consumers secondary consumers tertiary consumers so it&#39;s our first level our second our third and our fourth so it&#39;s just important to know that they&#39;re sometimes referred to as T1 T2 T3 and T4 now a parameter numbers then this is another concept which we look at in ecology and we can see here it&#39;s very similar to a diagram we looked at a couple of minutes ago when we were referring to the amount of energy that was being passed on from level to level so if we just relate it back to the energy diagram with a large amount of energy at the top at the bottom and a smaller amount of energy um exists right up until the top that&#39;s what a standard pyramid of numbers would normally look like as well so we would have a large number of producers at the bottom smaller number of primary consumers smaller number again a secondary consumers and then a smaller number again of tertiary consumers it&#39;s not always going to look like that and we&#39;ll see in examples in a couple of minutes but a standard pyramid of numbers would somewhat resemble that now what is a pyramid of numbers what does it actually do well the Pyramid of numbers represents the number of organisms at each trophic level so because the producer section here of the perimeter numbers is the largest the largest bar that means it has the largest number of organisms the primary consumers have slightly less but it&#39;s still larger than secondary consumers which is still larger than the tertiary consumers now generally the number of each organisms at each level is going to decrease as you move up not always the case and we&#39;ll see examples in a couple of minutes but the reason for this is because of the high level of energy loss from level to level so here&#39;s the standard pair of numbers you can see at the bottom we have our producers which are the plants we have a certain number of those quite abundant because they&#39;re plants even less primary consumers which are the snails even my secondary consumers which are the frogs and then even tertiary consumers which in this case is a fox so the number of organisms in this case is represented by the virus and the width of the virus and as we go from the bottom to the top it gets smaller and smaller now the pyramidal numbers does not always have a regular pyramid shape because it does not take into account of the biomass of the organisms so what do we mean by that well down here we have one oak tree so one organism that means we have a narrow bar but that one oak tree can feed thousands of insects so that&#39;s why this bar up here is much bigger so even though we only have one oak tree it can sustain thousands of organisms so an inverted pyramid of numbers can be found in an ecosystem where the community contains a few producers with very large biomass that support a larger number of smaller consumers so we can see this one here is inverted doesn&#39;t follow the standard pyramid shape which I set a couple of minutes scope could happen now an inverted pyramid of numbers can also be found in an ecosystem where the community contains parasites so parasite is something that lives off another living organism and we can see that in the Pyramid of numbers over on the right hand side so the plants we&#39;ve quite a large bar there because we&#39;ve quite a number of plants in this ecosystem those plants even though there&#39;s quite a number of them would probably only sustain one red deer so they need lots of plants for their food source but then that wound deer can sustain money deer ticks okay so they&#39;re parasites many of those can survive on the one deer so there can be many more parasites than the hosts they feed on because each individual parasite has a very small biomass so because they&#39;re so small one deer is enough to host many many of those now the shape of the Pyramid of numbers does not change the shape of the pyramid of energy so for any food chain producers store the most energy and the energy stored decreases at each level given a regular pyramid of energy so even though down here we might have an inverted pyramid of numbers over here the pyramid of energy is the exact same shape so we&#39;re still losing up to 90 of the energy as we go from level to level so here&#39;s another exam question so it says draw pyramid of numbers to represent the information in the food chain below so we&#39;ve won rose bush so that&#39;s going to be quite a small bar can sustain many caterpillars so that&#39;s going to be a larger bear we&#39;ll have even less black birds and we&#39;ll have even smaller Hawk okay so that&#39;s going to be an inverted pyramid of numbers for part one for part two what term is used to describe the organisms at the top of the food chain they&#39;re going to be the top or the tertiary consumers and then for part three explain why pyramid of numbers are usually restricted three or four levels we&#39;ve seen this before it&#39;s because of the large energy loss from level to level so another exam question here where in the food chain are primary producers found that&#39;s normally the first level what term is used to describe organisms to feed and primary producers that&#39;s our primary consumers why are most food chains I am short so only consists of a few trophic levels so that&#39;s because of the large energy loss again so we can see there that&#39;s a very common exam question what deduction may be made if the organisms at the start of the chain are less numerous than those that feed upon them so what does this mean about a producer that means they most likely have a large biomass so that was in the inverted pyramid of numbers we&#39;ve seen a couple of minutes ago about how one producer could feed many many organisms can a parasite be the first member of a food chain the answer for that is no and the reason for that is because parasites are not producers or you could say there that they need a living host okay so they&#39;re not producers they don&#39;t produce their own food they need to feed on something else so energy enters food chains in the form of light in which form do you think more most energy is lost from food chains so we mentioned that already in the Pyramid of numbers that&#39;s true heat energy we&#39;re now going to have a look at the habitat story which is something you might have done already as part of your leaving serbiology studies but if not you will okay so you will come across all of this information at some point anyway so we&#39;ve already mentioned this already but ecology is the study of the way living things and an environment about work together and interact with each other and your habitat study is where you really would have started to investigate that we mentioned already about a habitat and where a habitat is a place where an organ organism lives so some of the examples include deserts Meadows woodlands and grasslands and most likely the habitat you would have studied was either a woodland or a grassland and you would have looked at the features of those within that now we&#39;re in the habitat study you would have used many pieces of equipment so that you could capture and identify different animals and plants so some of them are listed here we have a quadrash we have a sweetness we have a pitfall trap and we also have a pooter so the quadrash we can see there is a square shape this is randomly placed on the ground so normally if you&#39;re a randomly placed on the ground you would have stored with a pencil crew the pencil over your shoulder and then place the quadrat on top of where the pencil went we&#39;re obviously not going to troll the entire quadrash because it&#39;s just too heavy and could cause injury to somebody so what you will do then is you&#39;ll go to where the quadrat is examine the inside the square frame and the number and species of each plant and animal will be recorded using a key The Sweep mesh does exactly what it says you sweep long grass so you can collect small insects by brushing it through long grass or tree leaves and then a key again is going to be used to identify the organisms a pitfall trap is kind of hard to see there but there is a trap set into the ground there so a small hole is dug into the ground a cover is placed on top ensuring it is raised so that small animals and insects can crawl under and when they do they will fall into the cup or the Trap that you&#39;ve set once it&#39;s covered with plants and Stones they won&#39;t be able to see it and fall in on small animals and insects will fall in and you can then once again identify them with a key on the pewter this is used to collect small animals so one tube was placed on or near the insect so that&#39;s the one that has um no gauze on it the other tube can then be used to suck the insect into the collection jar so just make sure you&#39;re putting the one that has no gauze at the end over the insect and the one that has the gauze is um is the one that you suck through now we&#39;ve mentioned this already but when we collect our plants and animals how do we identify them so we do that with a key so a key can look like over here on the on the left arm or sorry on the right hand side so we can see here this was to identify some plants very very similar ones which you might have used to identify animals as well but a key is used to identify your plants and animals as part of your habitat study now when you were doing your habitat study he would have done two types he would have done a qualitative study and you&#39;d also done a quantitative study so the qualitative study is any data that you would have collected using words so more often than not it was just a yes or no are they present or not and what&#39;s the name of the organism what&#39;s the plant what&#39;s the animal you&#39;re not actually counting them you&#39;re just saying they&#39;re present or they&#39;re not present and you&#39;re given the name by identifying them the quantitative study that on the other on the other hand uses numbers so you&#39;re counting the frequency how many of them were there what percentage of the entire habitat was covered by this particular plant so that&#39;s anything to do with numbers now one quantitative study you would have done was to calculate the percentage frequency of an organism and you most likely would have done this with the quadrat as well so the presented frequency gives an estimation of the chance that you would find specific species by randomly throwing a quadrat and a habitat and to calculate the percentage frequency we find number of trolls at the quadrat that the organism was present in divided by the total number of trolls and then times that by 100 to change to a percentage and we&#39;re going to see that in action now in a second so there&#39;s one example already done there for us so we can see this particular habitat study there was a Woodlands present and on the first row second third fourth fifth and the ninth Row the woodlex was present but there was four troubles where it wasn&#39;t so in total there were six trolls where it was present the frequency is six out of ten because it was 10 rows and times six out of 10 by 100 and we get 60 percent so let&#39;s say we had grass it was present on nine of the trolls so a total of nine which means the frequency is nine tenths times that by a hundred and we get ninety percent and it doesn&#39;t matter which organism you&#39;re doing this for it&#39;s the exact same steps find the frequency multiply it by 100 and you found the percentage frequency so we have a sixty percent chance of getting wood lights on the next row and a 90 chance of getting grass on the next trip percentage cover is slightly different then this is an estimation as to what percentage of a habitat an organism takes up and it&#39;s normally calculated for plants so what percentage of the entire habitat does grass take up what percentage of the entire habitat do daisies take up whatever the particular plant is so percentage cover is calculated as follows it&#39;s the total number of small squares an organisms present in So within our quadrash we know it&#39;s Square shaped but normally that&#39;s divided up into a series of smaller squares normally it&#39;s going to be 25 you&#39;re going to count the number of smaller squares it&#39;s present in divide that by the total number of small squares we have in total times that by 100 and we will have our percentage cover so an example here is already done for grass we could do the exact same thing there for a daisy so if it was present on 10 rows so we&#39;ll add up all those numbers now so 45 55 70 110 120 130 140. so it&#39;s present in 140 small squares the total number of small squares was 250 and then all you have to do is put 140 divided by 250 into your calculator times that by 100 and we will get 56 so in this case 56 of the entire habitat was covered with daisies and again it doesn&#39;t matter which organism you&#39;re looking at will be a plant for the most part and you can do it obviously for Animals as well but becomes a little bit more difficult but it&#39;s more accurate and more appropriate to do so for plants so there is some potential sources of errors or carrying out our habitat study as well so there is human error which we can make there can be change in conditions so if you&#39;re doing a habitat study today and then next week if there&#39;s been particularly bad weather some of the organisms might have retreated or gone underground so it would have made your results slightly different you might have an accidental Discovery so it might be an organism present that they either shouldn&#39;t actually be there just a complete accident and also your sample size as well so if you carry off a one-off habitat study today and don&#39;t repeat that ever again you can&#39;t take those results um as absolutely valid and absolutely representative of the entire habitat you would have to do the same habitat study at many different times at many different stages throughout the year to get a better picture of what&#39;s actually contained within the habitat so just a little bit more detail about the potential sources of error so where do we get human error well it&#39;s possible to make simple errors when you&#39;re recording the data you might be able to interpret the key 100 accurately and also when you&#39;re performing calculations you might make a little error as well changing conditions we&#39;ve already mentioned The Accidental Discovery there it says it is possible that accented stories be made so a rare organism may be present on a particular day and then as we mentioned there about the sample size as well the larger the number of habitats that are studied with an ecosystem the more accurate the findings are going to be so another example question here answer the following questions in relation to a quantitative survey of a species of small herbaceous plant so name the method you would employ so we&#39;re going to calculate percentage cover and we&#39;re going to use a Quadra for that how would you ensure that your sampling was random so we&#39;re going to throw a pencil over our shoulder and we place the quadrash on top of that and then the last one there named monadaphic factor that could affect the distribution of this plant in the ecosystem so we mentioned earlier on about adaptive factors referring to the soil so a couple of those you could have soil pH you could have soil temperature you could have soil time sorry soil and moisture content or water content or even the soil type so type of soil there as well so lots of different answers which you could put in but we&#39;re looking for an Adaptive Factor so it had to be something relating to the soil now for the last couple of slides we&#39;re going to look at adaptations competition interdependence and so on so an adaptation is when an organism develops certain characteristics that make it more suited to the environment that it lives in it normally happens as a result of evolution and there are two main types of adaptations we can have we can have physical adaptations and behavioral adaptations now a couple of examples of adaptations which you might be familiar with polar bear has a physical adaptation a buffalo has a behavioral adaptation and squirrels also have behavioral adaptations as well so the polar bear the physical one they have they have white fur to protect or camouflage them from their prey and they also have thick layers of fat to keep them warm so they also live in them in very cold conditions so those thick layers of fascial make sure they stay warm Buffalo or behavioral so Buffalo will migrate to areas with better weather better breeding conditions and that has more food at certain times of the year so that&#39;s why you&#39;ll see these really famous images of the mass migration of the Buffalo from one area to another so they&#39;re moving because they want better weather better breeding conditions and more food squares also have a behavioral adaptation so squirrels will hibernate you&#39;ve probably heard of that before so they enter a deep sleep to save their energy over winter where they would find it hard to get food okay so their metabolism is much much lower they don&#39;t need as much food because they&#39;re obviously going into hibernation and then when the weather conditions get better they can come out of hibernation there&#39;s more food available for them and their metabolism will then increase now interdependence so interdependence refers to when two organisms depend on each other for survival and it&#39;s a two-way process so what&#39;s really important about this is if an exam question ever come up on interdependence and given an example of interdependence you have to give both sides of the story so this example down here it&#39;s not just enough to say that bees rely on plants for pollen to make honey what do the plants actually getting out of the bees as well so plants need the bees to transfer the pollen to other plants so that they can reproduce so you can&#39;t stop there by just saying bees rely on plants for pollen to make honey give the second side of the story there as well the plants need the bees to transfer some pollen to other plants so that they can reproduce so just keep that in mind for interdependence really important that you give both sides of the story now competition is one of the last things we&#39;re going to be looking at today so competition is the struggle between organisms for things in short supply so what kind of things are going to be in short supply and they&#39;ll have to compete for both food water mates oxygen and light particularly important those last two there for plants so it can take place between different species but also between organisms from the same species so for example male deer are going to compete for mates and plants are going to compete for light and space so we can see that happening in the images over here so they&#39;re competing most likely for a mace the plants are competing for lice so you can see they&#39;re all going to grow towards the light and try and take up as much space as possible so they can absorb as much light as possible to get as much food produced in photosynthesis Now population control so population comprises of all the members of a species and there are a number of factors that can control the size of a population so we&#39;ve mentioned this already but competition can control the size of a population predation parasitism and symbiosis all of those can control the number of species living in a particular area so the two types of computation we have are contest competition and scramble competition So within contest competition there is an active physical struggle between two or more organisms okay for a resource that&#39;s in short supply and we can see that in the diagram over here we can see there is an active physical struggle happening but down here when we look at the cows there is no Act of physical struggle because that&#39;s scramble competition everybody is scrambling for resources but all of the competing individuals are going to get some of the resources some are going to get more than others some are going to get less than others but everybody is going to get something so contest competition to competing is an active physical struggle scramble competition everybody is going to get something and this is exactly what&#39;s happening here so what do ecologists mean by the term scramble competition so this is where all individuals get some of the resource give one example of a factor other than light which may be a source of computation among plants so for this one we could say space you could say water minerals will be another example there there&#39;s a lot of different potential answers give one example of a factor other than food which may be a source of competition among animals so we&#39;re going to have mates again we could have water shelter even some territory okay all possible answers there for the animals and caterpillars have my parts that are suitable for chewing on leaves whereas the adult form the butterfly has long soaking mouth parts so just so having different types of mouth Parts reduces competition between the adults and the young of such species so what we can say there is they have different food so there&#39;s going to be less competition so obviously if they&#39;re eating different things there&#39;s going to be less competition so different food leads to less competition so they don&#39;t have to compete as much as they might have as if they&#39;re eating the same thing now predation predation is the catching killing and eating of another organism so the Predator is the one that catches kills and eats another organism which is the prey and the prey is the organism that is caught kills and eaten by the Predator so in this particular example over here the Predator is the bear and down here the prey is the fish so some examples would include ladybirds and aphids so ladybirds being the Predator black birds and earthworms again the Blackbird being the predator and Hawks and mice this time the mice is going to be the prey the hawk is going to be the predator parasitism we&#39;ve already mentioned in terms of the Pyramid of numbers before but parasitism occurs when two organisms of different species live in close Association and one organism is going to obtain its food to the disadvantage of the other okay so the parasite is going to live on a living individual that has a living host and it&#39;s going to be the detriment or to the disadvantage of the actual host so the parasite is always going to be the one that benefits and the host which is the one the living one and that is supplying the food source to the parasite is the one that&#39;s going to face the disadvantage and finally for today symbiosis so symbiosis occurs when two organisms of different species live in close association with each other and at least one benefits but in contrast to parasitism nobody becomes disadvantaged so some examples bacteria and intestine and will produce vitamins for us and they also get shelter for themselves so in this case both of us are actually getting an advantage there and a nitrogen fixing bacterium plants will get food and Shelter From the plant but in turn will provide nitrates for the plant so again there&#39;s an advantage there for both of them there&#39;s benefits for both neither has become and disadvantaged which is the case for parasitism where at least one or one of them is going to become disadvantaged so just to finish up today I&#39;m just going to quickly talk you through the exam revision website and tell you about all of the resources which are available to you not just for biology before they&#39;re leaving certain subjects as well so first of all if we look at the subjects which are available so we can see there we have I am leaving certain AG Science Biology business chemistry economics English French geography history Irish maths music and physics and within each one we&#39;re going to have the exact same features so video tutorials with quizzes presentations and exam Builder and a resource pack so if you wanted to watch some video tutorials and what we did today we go to unit one ecology and we can see there all of the different videos which are available for you to watch so if we wanted to watch a little bit more about the energy flow we click in the video will appear there for you to watch learning intentions will be given and if you wanted to watch it a little bit quickly you can change the speed up as far as two times speed as well now when we go back once you&#39;ve watched all the videos in a particular topic you can test yourself in a quiz they&#39;re all McQ multiple choice you can do them as many times as you want until you get 100 just to make sure you&#39;re fully comfortable with the content that&#39;s involved and right down at the bottom as well we also have a resource pack so for Ecology we have 11 pages of H1 notes there all of the material which you need to know fully tailored to the exam will be available not just for Ecology but for every topic in the even cert biology we do have an exam Builder as well so all of the leave and search exam questions and more questions will be available here so we can see here there&#39;s a 2021 question we have another 2021 one there so we press the plus one to add it to our exam and once you go back up to the top you can download the questions and download the answers now if you want to find out a little bit more just go to the exam revision website exam revision.ie there is a free trial there as well and right down the bottom you&#39;ll be able to find out a little bit more about the plans and the pricing so if you did want to find out um what price was involved you&#39;ll be able to find that there there is now a monthly subscription as well so you don&#39;t have to pay for a full year in advance you can just pay as you go and pay as you need and the more subjects that you um subscribe for the cheaper it is so there&#39;s a discount for any additional subject which you might add so keep an eye on our YouTube channel and other social media Instagram Twitter Facebook we will be advertising lots more Saturday sessions over the next little while so make sure and set a reminder for every Saturday at 12 and I hope to see you again soon

Transcript for:Ecology Lecture Notes

Transcript for:
Ecology Lecture Notes