﻿Hi guys, welcome to the lesson today. Today we're going to be looking at lesson one of unit: Understanding ecosystems. We're going to be looking at an introduction to ecosystems today. So we're going to be looking at some key terminology. We're going to be looking at some food chains and some food webs, and also some nutrient cycling. If you need to go and get a pen and paper now please do so and I'll see you in a few moments to start the lesson. Okay, so firstly, what is an ecosystem? an ecosystem is a natural system made up of living, biotic and nonliving, abiotic components, biotic are living features such as plants, animals and fish and abiotic or nonliving features, such as the sunlight and rocks. What I would like you to do first then is I would like you to draw a line down the middle of your page on one side put abiotic and on the other side put biotic having a look at the table that is in front of you, you need to decide which features go into the correct column. So if we do the first one together, sun, is that abiotic or biotic? I would say it was abiotic and therefore I would write it under the abiotic column. Have a go at doing the rest of them and seeing what features go into where and keep thinking to yourself, are they living or nonliving. Pause the video now to complete your task. Okay, so let's look at the answers then. As you can see that there are more biotic features than abiotic features in this table, a tricky one might have been bacteria. Bacteria is living and therefore biotic. Have a look at your answers and see if they're the same as mine. Moving on and having a look at the next part of this lesson, where we start to introduce food chains. So food chains are how energy is passed through an ecosystem. So if we can see at the first diagram looking at the leaves and the algae, they are the beginning of the food chain. As each animal eats the one before energy is passed on, leaves and algae, are considered what we call producers. They produce their own energy and they produce their own energy through photosynthesis. Next on that food chain is the caddis. Now, the caddis will eat the leaves and the algae and that's how they will get their energy. They are called a primary consumer. They are the first animal to eat the producer. So they are the primary consumer. The next is the fish. Now the fish will eat the caddis and energy will be transferred to the fish by eating the caddis. They are the secondary consumer. They are the second animal to eat along that food chain and therefore a secondary consumer. The Kingfisher is what we call the tertiary consumer. They are the third animal in that food chain to gain their energy from leaves and algae, caddis and fish. each time you might notice that every time the animal slightly gets larger in size. Looking at food webs, these are really complex food chains. So a food chain is a simple chain of energy. A food web could involve multiple producers, multiple primary consumers, multiple tertiary consumers, and they are all interlinked. This is important in an ecosystem, as we go on throughout this lesson, we will look at interdependence and how an ecosystem relies on everything within it in order to operate correctly and smoothly. In the following lesson, we'll be looking at how if something in that food web is changed, what can happen to the ecosystem So the key terminology here, producers, primary consumers, secondary consumers and tertiary consumers. If you want to pause the video here to make notes on that key terminology, that would be a really good idea. Okay, a quick learning check then: true or false. There are four statements on your screen. You need to decide which statements are true and which statements are false. If you want to pause the video here, and we'll go through the answer shortly. Okay, let's find out whether these statements are true or false. So statement number one, food chains are very complex with lots of producers. This is false. A food chain is a simple chain with one producer. Statement number two, food webs have many different food chains within it. This is true, and the food webs can have many complex food chains within it. Statement three, producers are carnivores and eat prey. Statement three is false, producers don't eat any prey. They gain their energy from photosynthesizing. Statement four, consumers can transfer energy to the next in the chain is completely true. That's how the primary consumer, the secondary consumer and the tertiary consumer all gain their energy. Well done if you've got those right. Next we are moving on and having a look at Slapton Ley. So this is a case study specific. So Slapton Ley is an example of a freshwater lagoon. Fresh Water means drinkable water. This means that it is cut off by the sea by a shingle barrier. And a shingle barrier is like a beach, a bar across from one headland to another. The lagoon riverbed provides habitats for a diverse range of animals and plants. And this makes the area a site of special scientific interest and is protected by the National Nature Reserve. If you look at the diagram, this is an example of a food chain at Slapton Ley okay, and this is case study specific. So we have these really common reef river reed beds that is the producer, so they gain their energy from photosynthesizing. The moth larva, eat the river reed beds and gain their energy and the eel then eats the moth lava, and the bittern eats the eel, a simple food chain specific to Slapton Ley. So what makes up an ecosystem? an ecosystem has producers and consumers that we've already looked at. But it also has other things that are really vital to the cycle of an ecosystem. So what makes up an ecosystem? So as we've already looked at, we've looked at producers and we've looked at consumers. Have a look at this diagram. So the producers, they're the phytoplankton, they are gaining their energy from the sunlight. They are photosynthesizing. Consumers get their energy by eating other organisms. Depending on what part of the consumer chain you are in, or they are in will depend on where they're getting their energy from. So, if they are a primary consumer, they are eating the producers. If you are a secondary consumer or a tertiary consumer, you are getting your energy from eating other animals. There are two more important elements of an ecosystem. Scavengers and decomposers. Now scavengers they eat dead animals and plants. They are opportunists. Decomposers, which are normally bacteria or fungi, they break down dead matter, such as fallen leaves, dead animals, and they return the nutrients back to the soil. So looking at that diagram, the decomposes the bacteria, they are within the riverbed. And they are producing nutrients. So, once they have eaten dead matter, dead animals, their excretion has got nutrients within it and that nutrients is then in the soil and therefore allow grasses to grow which is another source of producer. Does nature recycle? Nutrients flow into the lake and they make the plants grow. So nutrients such as nitrogen and phosphorus they flow into the river, into the lake, into the lagoon and they lead to excessive plant and algae growth. Plants and algae die and they sink to the bottom. The decomposers then come along, break down the plants so that they disappear, and they release the nutrients back into the water. They can do this by excretion. So after they've had the animal, they then excrete, and the nutrients is then in the water. And then this allows new plants and algae to grow. This is a natural way of recycling, nothing goes to waste. Nature is very, very good at recycling. Looking at everything that we have learned so far then, what I would like you to do is I would like you to answer these four questions. Define a consumer. Arrange these into accurate food chain order. Explain the importance of a decomposer. And describe the nutrient cycle that occurs in a freshwater system. This is what we've just looked up. In your answers I need you to make sure that you are using connectives you are connecting one piece of information to another. Words such as this means that, which means, this leads to, so you are almost creating your own chain of reasoning. When you are answering these questions, please make sure that you look at the marks available. So, if it is one mark, I would be expecting a one full sentence written. If it is three marks as a rule of thumb, you should be writing three sentences in order to get the three marks. Pause the video now and have a go at those four questions. I look forward to seeing what you came up with. Okay, let's go through the answers to the questions that you have just complete. Question number one, define what a consumer is. I've written, consumers get their energy by eating other organisms. So whether that is the primary consumer, the secondary consumer or the tertiary consumer, they all get their energy by eating other living things. Question number two, arrange these into an accurate food chain order: consumer, producer, and secondary consumer. The correct order is: producer, then consumer, then secondary consumer. Question number three, explain the importance of a decomposer. Now, this is worth two marks. So, the first mark you would get if you said that decomposers break down dead matter. I've said that they are nature's bin collectors. And once they have done this, they then recycle the nutrients and pass back the nutrients, so to help the support and growth of the producers which will be worth another mark. you do not have to have written word for word what I have said. But have a look to say whether you have mentioned, decomposers break down dead matter, and that decomposers then recycle the nutrients and pass them back to the growth... to support the growth of the producers. Question number four, describe the nutrient cycle that occurs in a freshwater ecosystem. Now, this is worth three marks, so I would expect to three sentences here. My three sentences I have said, nutrients flow into the water and they create an excessive growth of the producers, worth one mark. The consumer eats the producers, worth another mark. Once the consumers die, the decomposers break down the consumers and return the nutrients back to the water, three marks, it's a cycle. You need to make sure that you have said, where the nutrients come from, the fact of the energy transfer from the consumer... from the producers to the consumer, and then once the consumers die the decomposers break down the nutrients of those consumers and pass back into the water. How did you do? If you want to, you can write these answers into your book. And you can refer back to them when completing other lessons. So that is the end of our first lesson an introduction to ecosystems of unit five; understanding ecosystems. From the lesson today, you should now know what an ecosystem is. What makes up an ecosystem. What is a food chain, as well as a food web and about nature's recycling. Next lesson, we will be looking at how a small change can affect a small scale ecosystem. And we're going to be looking again at Slapton Ley, and how changes that have occurred there have affected the ecosystem. I look forward to seeing you there. Bye

In this lesson we will be learning about key terminology for ecosystems, and what makes up an ecosystem. Also, we will be looking at food chains and food webs.

Geography

Y11 Geography

Key Stage 4

Year 11

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Lesson overview: An introduction to ecosystems

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3 lessons in Understanding ecosystems: