The Nitrogen Cycle

okay so in this video we're gonna go over some of the stages and facts of the nitrogen cycle now one problem that we're gonna encounter when you talk about the nitrogen cycle is that the majority of our atmosphere about 78% of our atmosphere is filled with nitrogen that's not the problem the problem is that the nitrogen is unusable to life when you look at this picture right here n2 is the chemical formula for the atmospheric nitrogen and notice how there are triple bonds there's a triple bond holding this nitrogen atmospheric nitrogen and two together triple bonds aren't very very stable hard to break so that's the reason why nitrogen is just not usable to most forms of life most forms of life can't break the triple bonds but there are some forms that can and you'll get into that in just a moment so nitrogen is really important and one reason is because it helps to build DNA molecules here is a double helix in the picture and if we look at this picture right here remember it reminds us what a nucleotide is DNA is made from a Hulk a whole large collection of nucleotides and one of the parts of a nucleotide is called a nitrogenous base a nitrogen base therefore implying it's made from nitrogen so nitrogen is at the very heart of DNA molecules one of the reasons why we need to understand how the nitrogen cycle works so let's go ahead and look at the cycle now step one we're gonna break this down into six different areas in the picture so area one step one bacteria are gonna do a process called nitrogen fixation in the animation the bacteria in the animation are taking in atmospheric nitrogen and two and two molecule from the atmosphere and they're gonna do the process called nitrogen fixation and they're gonna convert the atmospheric nitrogen into ammonium and from the animation you can see ammonium x' formula is NH 4 so that right there is the first step the process called nitrogen fixation but then next comes step number 2 which is a process called nitrification similar in name however there's a bit of a difference nitrification still uses soil bacteria notice an area - of the animation NH 4 which is the ammonium is going to be converted into no.3 which are nitrates this is a more usable form so the purpose of nitrogen fixation and nitrification is to convert atmospheric nitrogen which is not usable really into more usable forms so that's the the job of area number 2 of the bacteria in area number 2 called nitrification well there's still bacteria in area number 3 and these bacteria in area number 3 do a process called denitrification so like it says in the notes soil bacteria are going to use those nitrates the no.3 is the nitrates and in the word denied to phi you can see that they're gonna remove the nitrogen so they're gonna denitrification it's a waste gas to them but they're using the oxygen for their cellular needs so I notice when you look at the animation we already have a nitrogen cycle we already have a complete cycle involving just bacteria and we haven't even gotten to plants and animals yet you so when we look at the area for of our diagram we're now going to involve plants there's a plant in the middle of the picture that's symbolic of our producer and in the arrows the arrows you can see that no.3 the nitrates are being absorbed through the roots of the plant well now that there's nitrogen in the plant I hope it's pretty straightforward what happens next nitrogen simply moves up the food chain we have a little rodent in area number five of our picture and nitrogen is going from the plant into the rodent that's because the rodent eats the plant and so nitrogen simply moves up the food chain a snake my teeth rodent a hawk might eat the snake and so on up the food chain and then we have some decomposers in the middle of the picture and it says decomposers are gonna obtain nitrogen by feeding on the dead so in the animation there's nitrogen going from the plant and from the rodent because when plants and rodents die they're dead remains are fed on by decomposers such as bacteria and fungus while every organism creates waste and decomposes are no different there decomposers are responsible for a process called ammonification and in the word ammonification i hope you can see the prefix for ammonium what ammonification is it completes this cycle is decomposers will give off NH 4 we saw NH 4 earlier NH 4 is ammonium which is created by the nitrogen fixing bacteria so notice how we have almost like an outer cycle in the animation and almost like an inner cycle in the animation but notice how there is a complete nitrogen cycle when you examine this animation here the main trick of course is to understand the various if occations the ammonification is the nitrogen fixation x' that's going to be the challenge for you this chapter so before we're finished I want to mention the role that lightning has in the nitrogen cycle lightning can help break apart some of that end to remember n2 atmospheric nitrogen is really stable and so one way that that the end to the atmospheric nitrogen can be broken apart is through the energy within lightning in our animation we have some lightning bolts flashing and watch what happens the end twos and the O twos that are in the atmosphere are broken apart because the energy from lightning breaks apart the chemical bonds and so what happens is ones once those ends and O's are broken apart they're gonna bond to form nitrogen oxides like you see right now well one thing you should know is that with lightning often accompanies rain and so the nitrogen oxides watch what happens when it starts raining the nitrogen oxides are going to react with water to form nitrates no.3 and you've seen nitrates before nitrates were created by nitrogen fixing bacteria so once it rains the nitrates are simply carried down and added into the soil and those nitrates simply become a part of the nitrogen cycle so that's a neat little way that that lightning can add usable nitrogen into the soil so wrapping up here is a little practice quiz go ahead and pause the video and if you're in my biology class by all means write your answers on a separate sheet of paper I need to be happy to check you check your answers before or after class one day so go ahead and pause the video good luck

Channel: Beverly Biology

Views: 26,203

Rating: 4.6992483 out of 5

Keywords: Nitrogen (Chemical Element), Nitrogen Cycle, Biogeochemical cycle, Biology (Media Genre), nitrogen fixation, Nitrification, Denitrification, Ammonification

Id: Fy3HSTkvvc8

Length: 7min 30sec (450 seconds)

Published: Wed Jun 18 2014