[Music] have you ever wondered how energy and matter flow through the ecosystem from when it enters as sun energy to when things decompose and return to the soil [Music] [Applause] [Music] hi everyone welcome to a short lesson on energy in the biosphere this is outcome a 1.1 so the earth can be considered a closed system which means nothing leaves our atmosphere our biosphere our hydrological system or enters it i mean there are very few exceptions to this such as if an asteroid entered earth or a spaceship leaves earth but in general we consider the earth to be a closed system so whatever we have here is what we have and nothing new is coming um so the earth does not receive new and uh new matter like the energy system does with energy from the sun and so therefore we're bound by the first and second laws of thermodynamics so energy is not created or destroyed it is merely changed from one form to another this is the first law of thermodynamics so if you think back to your science 10 class and your physics lessons you talk about how we have kinetic energy and potential energy we can have chemical energy we can have um thermal energy so all these different forms of energy are here on earth and they just get transformed from one form of to another and the other one is no conversion is 100 efficient and again if we think back to our science 10 classes the loss of energy most often is heat and when you think about plants and animals and moving around we spend a lot of our time and a lot of the energy and all those calories that we consume just keeping ourselves warm and then also moving around so most of the energy that we consume is lost so we lose energy as it's passed along a food chain so as a general rule only ten percent of the energy that's present at one level is passed on so if we do just a quick if plants have 100 joules of energy in them and a deer eats them that deer would have 10 joules of energy left over in its muscle mass from the plants that it had eaten for a wolf to consume and then if something like a hawk was consuming that wolf there would only be one jewel of energy left in that system and that muscle mass to pass on to that next level so again our rule of thumb is that 10 of the energy is passed on to the next level so due to the fact that we have only 10 of the energy that's passed on to the next level this affects the number of trophic levels that we can have in an ecosystem and again each trophic level represents a level through which energy and matter are transferred so each step in a food chain so the first trophic level is our producers the second trophic level would be our primary consumers or herbivores the third trophic level would be our consumers or carnivores so the energy will go through each one of those levels a food chain is a model showing a linear pathway through which energy moves in an ecosystem so we would go sun grass grasshopper gopher hawk a food web shows connections between many different food chains so we would have sun grass and then from that grass we might go grasshopper gopher deer cow and then move on to different consumers that would consume those organisms so here we have one that goes grass mouse snake hawk so we'd have grass would be our first trophic level mouse would be our second trophic level snake would be third and hawk would be fourth trophic level so we have a producer a herbivore and then followed by two carnivores as opposed to the food web that you can see on the other side which has three different producers it has grass a cactus and leaves then it has the different primary consumers are our second trophic level the herbivores that consume those so we have a mouse a beetle a hummingbird a butterfly and another type of songbird which then could be consumed by lizards and scorpions possibly snakes roadrunners and then our final consumer is the hawk that would be our our tertiary consumer if we follow those food chain our food webs up so what we see in a food web is many more connections between the different organisms in an ecosystem as opposed to the linear one we can see that the effect that there would be if for example we took out the prairie grasses there are four different organisms that eat those prairie grasses and some of them don't eat the leaves or the cactus so that's their their only source of nutrition versus if we took out say just the cactus we might see less of an impact in that ecosystem based on this diagram only um also if we take out the hawk from the ecosystem what might we see then at our highest level of consumers what's going to happen to those mice and those snakes what type what effects are we going to see in the population so because of the rule of ten most food chains have very few trophic levels really it can max out at possibly five or six at the most and we'll see these usually in aquatic ecosystems that have very um a lot of levels a very small consumers so we'll see algae and therefore phytoplankton zooplankton minnows smaller fish bigger fish and then we can get up to our seals and whales and sharks and polar bears and we really only see those in aquatic ecosystems typically in um terrestrial ecosystems four maybe five is as many as we're going to get to um just because of the the type of animals that we have there so the amount of energy transferred from one level to the next ranges from five to twenty percent but again for the sake of um bio we're just gonna go with the rule of ten percent the remaining energy is not passed off because it's not stored in those tissues it's used up um for thermal energy so keeping our bodies warm movement producing waste um searching for food running away from predators all those different things use up our energy so i hope you guys had a great day today in your lesson and i'll catch up with you next time bye if you enjoyed this video check out our website online.plrd.ab.ca and visit us on facebook prairieland online academy you can find out all is going on with prairieland online academy [Music]