Ocr Gateway A B4.1.8 - Decomposition


Welcome to our review on decomposers. So first thing we need to understand is what is a decomposer now decomposers are microorganisms and more specifically, they aren't bacteria and fungi. So a common question in the past always used to be named two examples of decomposers bacteria and fungi are the answers they're looking for. And what these decomposers actually do is they break down or decay that dead organic material as well as those waste products, things like urine and feces.

And as a result of. This it's going to return those useful minerals back to the soil. So they can go back through the cycles. Now, one other term we're going to use to actually describe these organisms that feed on dead material are sacrifice. And the way that they feed is very specific. So sacrifice will feed on the dead material by releasing enzymes onto the surface.

So basically they're producing extracellular enzymes. So enzymes that outside the cell. And once those enzymes are on the surface of that dead material or. The waste material, then it will be digested once it's been digested, the organism then reabsorbs, those useful nutrients. So what we find there is that as opposed to actually taking food into them, what they do is they release the enzymes onto the surface, and then only absorb the nutrients. The second type of organism that's, very important.

Here is a Detroiter oil. Now, go careful not to mix up decomposes and detritivores are small animals. And their purpose is to speed up decomposition by. Breaking organic material up into very small pieces. So when that happens, what we've done is, we've created a much larger surface area that the decomposes the bacteria in the fungi can then work on. And as a result of the combination these two, we have a faster rate of decay.

So three examples of our little detritivores are in the pictures there. We've got earthworms, we'll actually consume leaves and then release smaller bits of leaves that then are decomposes can break down the wood louse, which as. Its name suggests does the same thing with wood and maggots, which will do the same thing with animal material. We do need to know about the factors that would affect the rate of decomposition.

So if we're looking at a question that asks us how we could increase the rate of decay, then we need to specify that the temperatures need to be warm. Now, don't say, high temperatures, because remember these are living things. Therefore, enzymes are contained within them.

So if we've got high temperature, the. Enzymes will be denatured, and therefore it won't work. If the temperature is too low. Then what we find is the enzymes are much slower, therefore, they're less likely to collide with the substrates.

And therefore, the rate of decomposition will be low. So warm temperatures is the right phrasing. We need it to be moist, because we need a certain amount of water available. Because what we actually find is that if there's no water, then those reactions won't be taking place.

And finally, we require plenty of. Oxygen available, so these aerobic conditions because that's going to allow the microorganisms to respire, and therefore they will carry out decomposition. If we don't have the oxygen, and therefore it's anaerobic that's going to prevent most forms of decomposition. So in a question that asks you, how can we increase the rate of decomposition warm temperatures? Moist, conditions, aerobic conditions. The last thing we need to be able to do is to calculate the rate of decay.

Now when we're talking about the. Rate of decay, its units are in grams per day. And the way that we do, this is the change in mass divided by the time. So just go careful that if they give you some results and tell you how much mass there was on day zero and how much mass there was on different days, it's the change in mass. So work out the difference between those two days, and then obviously the time period that has elapsed. So hopefully at the end of this video, you can actually state what is meant by decomposition, you can state some.

Examples of decomposers, you can identify the difference between decomposers and detritivores. You can give an example of Detroit of all and also explain how environmental factors affect the rate of composite decomposition along with calculating the rate of decay.

Dated : 21-Mar-2022

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