DOWNLOAD IT FOR FREE CLASS9 STUDENTS

1. PROJECT OF SCIENCE[BIO]
NATURAL RESOURCES
SUBMITTED BY – SURYANSH SHARMA
GRADE – 9A
ROLL NO. 40
TO – MS. GEETAKSHI MAM (BIO)

2. WHAT DOES BIOGEOCHEMICAL CYCLES
MEAN?
1.The biosphere , constitute the biotic and
abiotic , there is constant interaction between
these components.
2.The cyclic flow of nutrients between
non-living environment and living organisms is
termed as Biogeochemical cycle.

3. THERE ARE TOTAL 4 MAIN CYCLES TAKING PLACE IN OUR
ENVIRONMENT. THESE ARE NAMELY:-
1. WATER CYCLE
2. NITROGEN CYCLE
3. CARBON CYCLE
4. OXYGEN CYCLE
HOW MANY OF THEM ARE IN ENVIRONMENT?

4. WATER CYCLE
 There is a constant exchange of water in the environment.
 Due to the heat of sun , water evaporates from water bodies
and rises up in the atmosphere in form of vapour.
 Up in the atmosphere , small droplets are formed due to low
temperature by the process of condensation.

5.  Many droplets merge to form drops which fall on the Earth as
rain. This process is known as Precipitation.
 Some water is absorbed by the soil.
 The whole process by which water evaporates and falls on the
land as rain and later flows back into seas and oceans via rivers is
called the Water or Hydrological cycle.

6. HYDROLOGICAL OR WATER CYCLE

7. NITROGEN CYCLE
 Nitrogen is an essential part of proteins , amino acids and
nucleic acids. The atmosphere contains about 78% of nitrogen.
 It involves circulation of nitrogen in the biotic and abiotic
components of biosphere.

8. PROCESS INVOLVED IN THE CYCLE
1. Biological Nitrogen Fixation:
 It is the process of converting atmospheric nitrogen into water soluble
nitrates and nitrites.
 Nitrogen is present in diatomic form i.e. , N2. Therefore plants cannot
use it in this form.
 A number of free living nitrogen fixing bacteria take up free
atmospheric nitrogen and convert it into ammonia.
 This process is called Biological Nitrogen Fixation.

9. 2. Atmospheric Nitrogen Fixation :
 Atmospheric nitrogen is converted into nitrogen oxide [NO2]
by electrical energy of lightning and by natural ionizing
radiations.
 These processes are respectively called Electrochemical and
Photochemical fixation of nitrogen.

10. 3. Nitrogen Assimilation:
 It is carried out by plants. Plants absorb the nitrate and nitrites
ions through their roots and incorporate them to form amino
acids , that are later used to make plant proteins.
 This process is called Nitrate Assimilation.
 The plants can also use ammonium ions [NH4+] to form
proteins.

11. 4. Ammonification:
 Animals excrete nitrogenous waste materials.
 Nitrogenous waste are converted into ammonium compounds
and carbon dioxide by putrefying bacteria and some fungi.
 They also decompose the Nitrogenous compounds of the dead
animals and plants.
 The process of decomposition of nitrogenous wastes by
bacteria and fungi into ammonium compounds is called
ammonification.

12. 5. Nitrification:
 Most of the ammonium compounds formed by the bacteria
and fungi are oxidized by the nitrite bacteria
[Nitrosomonas and Nitro coccus] to soluble nitrites ,which
are further oxidized by nitrite bacteria [Nitrobacter] and
fungi [Penicillium] to soluble nitrates.
 The process of nitrate formation is known as Nitrification and
the bacteria responsible for it are called Nitrifying bacteria.

13. 6. Denitrification:
 Some ammonium compounds , nitrites and nitrates are
converted by certain bacteria and fungi into molecular
nitrogen[N2]which escapes into the atmosphere or is added to
water and is lost from the cycle. The process is called
Denitrification.
 The bacteria causing it are called Denitrifying bacteria.