The Nitrogen Cycle

1
The Nitrogen Cycle

• An essential part of proteins, DNA and other
  compounds needed for life

2

• Plants use nitrogen (N), phosphorus (P) and
  potassium (K) for growth.
• Earths atmosphere is 80 nitrogen gas (N2).
• Nitrogen gas is a form that very few organisms
  can use (they cant absorb it directly).
• In order to be used by organisms, nitrogen gas
  must be fixed

3
Nitrogen Fixation

• When nitrogen gas is bound to other elements to
  make it usable by living organisms.
• add to oxygen to form NO3 nitrate
• add to hydrogen to form NH4 ammonium
• The job of fixing nitrogen is up to certain
  bacteria that are found in the soil and water.
  The most important of these is Rhizobium, a
  bacterium that lives in nodules on the roots of
  plants like legumes (peas, beans, alfalfa and
  clover).
• Plants can absorb the fixed nitrogen through
  their roots, animals must get nitrogen by eating
  plants or other animals.

4
(No Transcript)
5
Read pages 52- 60 Answer Questions 1-6 pg 65
6
Biodiversity
7
Biodiversity a measure of the variety of species
on Earth.

• Biodiversity is threatened by human pollution!
• Example toxins in the St. Lawrence River are
  threatening the Beluga whale population.

8
Bio-magnification

• Accumulation of toxins in a food chain so that
  the major effects are found in the food
  predators.
• Example DDT a pesticide used in the 50s and 60s
  to control populations of body lice, fleas and
  mosquitoes).
• Later used as a crop pesticide, after which sign
  of trouble appeared!!!!!

9
DDT- Belugas- St. Lawrence River
10
(No Transcript)
11
(No Transcript)