What are we going to learn about today? Today we’re going to look at nutrient cycling in the environment particularly at the nitrogen cycle.
Jan 01, 2016
What are we going to learn about today?
Today we’re going to look at nutrient cycling in the environment particularly at the nitrogen cycle.
The Importance of Nitrogen
Proteins contain the elements carbon, hydrogen, oxygen and nitrogen
Proteins are made of units called amino acids.
etc
Amino Acids
Proteins are essential for growth and repair of body tissues in all living things.
The Importance of NitrogenWe and other animals need amino acids to
make the proteins to build our bodies our proteins from protein rich foods such as
EggsRed and white meatFishdairy productsbeanslentilspeas nuts
The Importance of NitrogenMost plants make their own proteins using
nitrogen. But not from the air as they can’t absorb gaseous nitrogen. instead they absorb it through their roots as nitrates from the soil that they grow in.
Animals then eat plants digest the protein and absorb the amino acids that they are made from into their blood to be carried to where they are needed to make protein for growth and repair.
Fertilisers contain nitrates to help with this.
Not all of the protein in plants or prey eaten by animals end up being absorbed. A lot of it comes out in faeces (dung).
In the bodies of animals excess amino acids not needed for making protein for growth and repair are broken down into urea- a nitrogenous waste (meaning it contains nitrogen).
The proteins in dead bodies and dung and nitrogenous wastes are broken down by bacteria and fungi (decomposers) into ammonia. This ammonia is then made into nitrates by bacteria.
Let’s summarise all of this.
ANIMAL PROTEIN
AMMONIA
DEAD ORGANISMS AND DUNG
NITRITES THEN INTO NITRATES
PLANT PROTEIN
Eating
Death and
excretion
Decay by fungi and bacteria
Conversion by
bacteria
Uptake by roots
Death
nitrogen fixing bacteriaOther bacteria take nitrogen from the air and convert it to a form that plants can use some live free in the soil and others such as Rhizobium live in a special relationship with legumes- plants such as peas, beans and clover.
Here is a clover plant showing the “root nodules” in which the Rhizobium lives.
ANIMAL PROTEIN
AMMONIA
DEAD ORGANISMS AND DUNG
NITRITESTHEN INTO NITRATES
PLANT PROTEIN
Eating
Death and
excretion
Decay by fungi and bacteria
Conversion by
bacteria
Uptake by roots
Death
NITROGEN GASIN THE AIR
Nitrogen fixing bacteriaDenitrifying
bacteria
In the roots of peas, beans and clover
(legumes) and free in soil.
Summary video- WARNING- This has some bad words in it
and so may not be suitable for your teacher!
Bacteria or fungi.
Decomposers break down organic matter by respiration. In the nitrogen cycle they convert protein and nitrogenous wastes into ammonium and nitrates that may be used by plants to build protein.
• Animal and plant proteins are made up of amino acids that contain the element nitrogen.
• Plants and animals cannot absorb nitrogen from the air.
• Plants gain their nitrogen in the form of nitrates through their roots in a process known as uptake.
• Nitrifying bacteria convert ammonia into nitrates.
• Denitrifying bacteria convert nitrates into nitrogen gas.
• Nitrogen fixing bacteria convert nitrogen from the air to a form that plants can use. Some are found free in the soil and others in the root nodules of legumes (peas beans and clover).
• Decomposers (bacteria and fungi) convert proteins and nitrogenous waste in urine and faeces (pee and poo) into ammonia.
Learning Outcomes