Transcript Yr 11 Earth and Environmental Science

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