Part 1 (Plants through time

Through this new series (Plants through time) I’am going to be putting together some gathered research on a specific topic that is of great interest to me and will prove and open your eyes to the dominance and efforts plants have made on our planet Earth.

Archean Eon– Understanding the origins of Earth and the Plantae kingdom takes us back to the desolated and lifeless period. Extreme heat ruled, about three times what they are today from Earths core being created and radioactive gases. In the deep water tiny single celled organisms drifted through the murky sediments of the sea, these were basic bacteria and had no more than a simple outer membrane and a few proteins (Hopper, 2012). This period occurred 3 billion years ago.

These interesting bacteria survived by absorbing the sun rays to create food for themselves, the light was used to convert the co2 and hydrogen from the water into sulphates or sulphur. This was the first forms of photosynthesis occurring. The first light absorbing bacteria had pigments called ‘Bacteriochlorophylls (Hopper, 2012). They were discovered by ‘Von Neil’ in 1932. These bacteria were purple in colour and produced no oxygen, just sulphur as a by-product in the group ‘Proteobacteria’.

Proteobacteria, Purple prokaryotic bacteria.

Then 2.7 billion years ago, in the late Archean eon, evolution of the purple bacteria developed. Producing the bluish-green organisms known as ‘Cyanobacteria’ they produce oxygen as a by-product instead of sulphur by photosynthesis. Stromatolite consist mainly of limestone, which have several layers produced by trapping sediments washed up in storms, they house the blue/green algae, known as cyanobacteria.

In fact the Earth was only about 70% as bright as it is today, three billion years ago, os theory suggests the Earth would have frozen, however due to the greenhouse gases in the atmosphere mainly methane and carbon dioxide, trapped enough heat to keep temperature above freezing (Forces of change, 2012)

According to Wilkins, (2012) microbes in the ocean 2.5 billion years ago pumped methane into the atmosphere, creating a giant cloud of smog that covered the entire planet. Earth would have looked like saturn’s moon ‘Titan’ which is covered in a methane fog.

This rise is likely to come towards the end of the Archean eon with the rise of the Cyanobacteria, which produced enough oxygen to overcome the methane microbes and the end the hydrocarbon hazes. The clearing of the haze happened at the start of the Proterozoic Eon 2 billion years ago. Resulting in the sky turning blue and was reflected in water below.

Cyanobacteria

These organism were a large group of prokaryotic photosynthetic bacteria from the Archean eon. According to Hopper, (2012) they developed a far more ranged set of pigments called phycobilins (the blue pigment) and carotenoids (yellowish pigment) as well as chlorophyll a, a green pigment. This combination produced the blue/green colour (Britannica, 2012). They range in size from 0.5-60 micrometers.

With the change in wavelengths allowed the new pigments to absorb new compounds and chemicals. Instead of the sulphur by-product the gas it got rid of was oxygen, vital for the successful and evolutionary development of Earth. The oxygen created by the cyanobacteria started to build up and move up in the atmosphere, at the same time hydrogen started to decrease, however it is still today not conclusively understood why, but it allowed oxygen to start to build up in Earth.

This process by which these organisms started to produce oxygen would dramatically change the future of the planet, during the Proterozoic era there was an explosion of evolution occurred known as the ‘Cambium Explosion’ and together produced some of the first known plants on Earth.