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heehawultraMechanics

Feb 22, 2014 (3 years and 5 months ago)

49 views

Y
R

11 E
ARTH

AND

E
NVIRONMENTAL

S
CIENCE

DP1
-
I
DENTIFY

PHOTOSYNTHETIC

BACTERIA

AS

THE

FIRST

ORGANISMS

TO

RELEASE

OXYGEN

INTO

THE

ENVIRONMENT


Cyanobacteria
, the first organisms capable of
photosynthesis, appeared earlier than 3000 million years
ago.


They actively produced their own fuel for respiration
(sugars) making them more efficient


These organisms produce oxygen as a waste product.


At the time of their occurrence there was also a rise in
the volume of oxygen gas in the atmosphere


DP1
-

I
DENTIFY

PHOTOSYNTHETIC

BACTERIA

AS

THE

FIRST

ORGANISMS

TO

RELEASE

OXYGEN

INTO

THE

ENVIRONMENT


Oxygen is an extremely reactive element that readily
bonds with many other elements, particularly active
metals like iron.


As the first photosynthetic organisms released oxygen
into their marine environment, it quickly reacted with the
abundant dissolved iron in the mineral


rich seas. The
newly formed iron oxides (rust) were insoluble and so
settled to the bottom of the oceans.

DP2
-

D
ISCUSS

THE

ROLES

OF

PRECIPITATION

AND

PHOTOSYNTHESIS

IN

THE

REMOVAL

OF

CARBON

DIOXIDE

FROM

THE

EARLY

ATMOSPHERE


At first, the sedimentation was slowly deposited,
however as the number of photosynthetic
organisms exploded , so did the amount of oxygen
produced. This resulted in layers many of
kilometres thick being deposited over hundreds of
millions of years.


Most of the world’s iron ore deposits are the
remnants of these layers.

DP2
-
D
ISCUSS

THE

ROLES

OF

PRECIPITATION

AND

PHOTOSYNTHESIS

IN

THE

REMOVAL

OF

CARBON

DIOXIDE

FROM

THE

EARLY

ATMOSPHERE


Not until the production of oxygen exceeded its
loss by chemical combination in the oceans could
it start to accumulate in the atmosphere. This
became possible when the levels of dissolved iron
in the sea began to be depleted.


The effects of photosynthesis dramatically and
permanently altered the composition of the oceans
and the atmosphere.

R
EVIEW

Q
UESTIONS


Identify photosynthetic bacteria as the first organisms to release oxygen into the environment


1) What were the first organisms responsible for releasing oxygen into the environment?


2) Identify the biological process used by these organisms to release oxygen into the atmosphere


3) Identify the role played by the first photosynthetic organisms to appear on the Earth


Discuss the role of precipitation and photosynthesis in the removal of carbon dioxide from the early
atmosphere


4) Describe one way in which carbon dioxide was removed from the earth’s early atmosphere


5) Discuss the role of precipitation and photosynthesis in the removal of carbon dioxide from the early
atmosphere


Predict and explain the differences in composition of the oceans before and after the evolution of
photosynthesis


6) Predict
two

changes in the composition of the oceans after the evolution of photosynthesis


7) Explain why these changes occurred


DP3
-
P
REDICT

AND

EXPLAIN

THE

DIFFERENCES

IN

COMPOSITION

OF

THE

OCEANS

BEFORE

AND

AFTER

THE

EVOLUTION

OF

PHOTOSYNTHESIS


After the evolution of photosynthesis the
oceans were changed dramatically. This
included a reduction in the amount of carbon
dioxide in the water levels and the resulting
production of oxygen. There was also a
decrease in iron as it reacted with the oxygen
to form iron oxides which deposited on the
ocean floor