Nitrogen and Carbon Cycle

AQA A always love to put long winded Qs in about nitrogen and carbon cycles, and my notes r pretty rubbish on them.

I know the key points like in carbon cycle - Saprotrophs secrete enzymes onto material, and absorb the products, they respire and produce CO2 which can be used by plants.

and Nitrogen - Decomposers digest material, excete ammonia, nitrifying bacteria converts it to nitrites and nitrates, and then its available for plants. And there's nitrification my lightenin etc

But does anyone have any other decent points? Cuz i dont have enough to answer a 6 or 7marker

Reply 1

petrolhead

Hi,
I've just done my AS Biology so I should be able to help with this.
I think it would be well worth learning specific names for bacteria in the nitrogen cycle - there are always plenty of marks to be had here. Here a few basic points:

Rhizobium are found in root nodules of legumes or free in the soil - these are nitrifying bacteria which convert nitrogen in the air into nitrates for use in plants. Rhizobium need anaerobic conditions - a substance called leghaemoglobin in root nodules has a high affinity for oxygen and 'mops' up the oxygen, leaving anaerobic conditions. The plants also supply ATP for the bacteria.

Nitrosomonas convert ammonium compounds in the soil into nitrites and Nitrobacter convert nitrite to nitrate.

Denitrifying bacteria include Pseudomonas.

I hope there was some new stuff for you there and I hope it has helped,

Regards,
petrolhead

Reply 2

~*Sar*~

OP

1

mm ur doin a v diff spec to me! lol

I just wanted the steps of both cycles in a bit more detail, i'm not bothered about learning names, cus i won't get credited for it.

Reply 3

qexy-loz

10

The materials cycles section in this should help;
http://www.biologymad.com/master.html?http://www.biologymad.com/Ecology/ecology.htm

If I remember, I'll send more notes when I get home as I'm at 6th form right now.

Reply 4

aSian_cUtY

I'm doing AQA A.

Carbon cycle: Only way of getting CO2 out of the atmoshpere is through plants by photosyntheses. These respire releasing CO2 into the atmosphere. Plants are eaten by animals injesting carbon containing compounds. When these die, decomposers such as sapribiotic bacteria release enzymes which digest the dead matter. These then respire to produce CO2 which is released into the atmosphere. If the animals/plants not injested by dead matter then over thousands of years fossil fuels form which when burnt release CO2 into the atmosphere.

Nitrogen Cycle: You got the basic points except that nitrates are sometimes turned back into atmospheric nitrogen by denitrifying bactera. It can then be fixated into nitrates and taken up by plants!

Hope that helps, you doin module 6 and module 5 on Tuesday? Anybody got a cloo as to which module you do first??!?!

Reply 5

~*Sar*~

OP

1

aSian_cUtY

I'm doing AQA A.

Carbon cycle: Only way of getting CO2 out of the atmoshpere is through plants by photosyntheses. These respire releasing CO2 into the atmosphere. Plants are eaten by animals injesting carbon containing compounds. When these die, decomposers such as sapribiotic bacteria release enzymes which digest the dead matter. These then respire to produce CO2 which is released into the atmosphere. If the animals/plants not injested by dead matter then over thousands of years fossil fuels form which when burnt release CO2 into the atmosphere.

Nitrogen Cycle: You got the basic points except that nitrates are sometimes turned back into atmospheric nitrogen by denitrifying bactera. It can then be fixated into nitrates and taken up by plants!
Hope that helps, you doin module 6 and module 5 on Tuesday? Anybody got a cloo as to which module you do first??!?!

yeah i am... 3hrs of exams.. brill.

Erm on my exam timetable it has unit 6 before unit 5, but then i'd have thought 5 comes before 6... i dunno! lol

Reply 6

asianangel86

13

actually petrolhead is pretty helpful so thanks dude!
my teacher told me to try to mention names where i can. i have nitrosomona and nitrobacta drilled into my head; i just could never remember the rhizobium.