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The history of life on Earth is described in various publications and web sites ( e.g. , Speer, B.R. and A.G. Collins. 2000 ; Tudge, 2000 ; Lecointre and Guyader, 2001 ; Maddison, 2001 Eldredge, 2002 ); it is also discussed in the module on Macroevolution: essentials of systematics andtaxonomy. For the current purpose of understanding what is biodiversity, it is only necessary to note that that thediversity of species, ecosystems and landscapes that surround us today are the product of perhaps 3.7 billion( i.e. , 3.7 9 ) to 3.85 billion years of evolution of life on Earth ( Mojzsis et al. , 1996 ; Fedo and Whitehouse, 2002 ).

Thus, the evolutionary history of Earth has physically and biologically shaped our contemporary environment. As noted inthe section on Biogeography , plate tectonics and the evolution of continents and ocean basinshave been instrumental in directing the evolution and distribution of the Earth's biota. However, the physicalenvironment has also been extensively modified by these biota. Many existing landscapes are based on the remains ofearlier life forms. For example, some existing large rock formations are the remains of ancient reefs formed 360 to 440million years ago by communities of algae and invertebrates ( Veron, 2000 ). Very old communities of subterranean bacteria may have been responsible for shaping manygeological processes during the history of the Earth, such as the conversion of minerals from one form to another, and theerosion of rocks ( Fredrickson and Onstott, 1996 ). The evolution of photosynthetic bacteria, sometime between 3.5 and 2.75 million years ago Schopf, 1993 ; Brasier et al. , 2002 ; Hayes, 2002 ), played an important role in the evolution of the Earth's atmosphere. Thesebacteria released oxygen into the atmosphere, changing it's composition from the former composition of mainly carbondioxide, with other gases such as nitrogen, carbon monoxide, methane, hydrogen and sulphur gases present in smallerquantities. It probably took over 2 billion years for the oxygen concentration to reach the level it is today ( Hayes, 2002 ), but the process of oxygenation of the atmosphere led to important evolutionary changes inorganisms so that they could utilize oxygen for metabolism. The rise of animal and plant life on land was associated with thedevelopment of an oxygen rich atmosphere.

Questions & Answers

how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, What is biodiversity. OpenStax CNX. Feb 05, 2009 Download for free at http://cnx.org/content/col10639/1.1
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