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No Photosynthesis no life on the Earth

FROM two weeks ago we have covered topics about the long and complex evolution process, it was revealed that a prehistoric plant which used a primitive process of photosynthesis evolved into the ancient world about 3.4 billion years ago.

History of the world tells us that a primitive process of photosynthesis came into existence after the evolution of oxygen into the Earth about 3.5 billion years ago, scientists believe that this important chemical element appeared earlier about 3.7 billion years ago when the atmosphere was composed mainly by volcanic and greenhouse gases.

The evolution of plants which used photosynthesis became a catalyst for existence of life on the ancient plant because the process began to enrich the atmosphere with good amount of oxygen about 2.4 billion years ago when the world was still dominated with microscopic organisms.

Different researches indicate that about 1.5 billion years ago, the Earth passed through a long ice age which wiped out most of ancient plants that existed in the prehistoric world, but scientists say different kinds of earliest organisms continued to thrive.

To other creatures, the situation was a catastrophe because the Earth was dominated by four periods, with heavy ice sheets each lasting for 10 million years between 750 and 590 million years ago when the average temperatures were about −50 °C or −58 °F, which made life impossible on the third planet from the Sun.

It is estimated that about 580 million years ago, the availability of enough oxygen contributed again into the evolution of complex multicellular organisms, a group which was mainly made by bacteria, this shows that right from the beginning of time photosynthesis played a very important role in the existence of life in different ecosystem of the world.

Scientists say the history of evolution of plants on the Earth is very complicated, but it is estimated that the earliest plant appeared about 1.2 billion years ago, this was an algal scum which dominated the planet until about 450 million years ago when the first land plant evolved and thrived following advancement of the ancient photosynthesis process.

To survive in an ancient world which was experiencing low oxygen with big amount of carbon dioxide from volcanic activities, about 360 million years ago plants developed a well mechanism which used stomata and adapted xylem and phloem vascular tissues which enabled them to spread into different ecosystems, including arid and semi-arid lands where the savannah is available today.

It was during this period about 360 million years ago when ancestors of modern green plants got well defined leaves, that was an important stage of evolution for plants because the presence of vascular conducting system helped them to use their environment effectively by obtaining carbon dioxide from the atmosphere and roots which draw water from the ground.

Unlike other creatures such as lions, primates and wildebeests which live by eating food materials from others, from about 360 million years ago, plants survived by capturing light energy from the sky and drawing carbon dioxide from the atmosphere which was used with water during photosynthesis to produce their own food, which is sugar consisting of glucose and sucrose.

Ancient plants got further development when they adapted the ability to multiply through pollination, a process which started about 358.9 million years ago when average global temperatures rose to 20 °C or 68 °F, this kind of climate favoured the expansion of ancient forests.

Scientists say the presence of forests in different ecosystems around the world was an important step because they produced dry materials such as roots, foliage, barks, buds and woods which contributed into evolution of the first generation of termites that enjoyed an abundant supply of food.

With the world going through more changes, another generation of ancient plants evolved into one of the original ecosystem about 385 million years ago, scientists say these were plants which were very tall with wide leaves which enabled the primitive photosynthesis to work efficiently.

That stage was very important because it contributed to some trees in different ecosystem to have a unique capacity for living for several thousand years, but few had a unique capacity of extending their life span for more than 370 million years.

Some ancient plant clades such as Gymnosperms and Angiosperms, a group which consists of different species including cucumbers evolved about 319 million years ago and played a key role in the evolution of flowerlike plants about 150 million years.

Fossil records show that ancestors of flies and beetles were the first agents of the ancient pollination process, but about 145 million years ago prehistoric generation of bees contributed massively in this process as they collected nectars from one plant to another while playing a key role in distribution of pollens and enabled expansion of flowering plants into different ecosystems.

It was during this period when climate restricted ice sheets on high lands and mountains and opened the rest of the world for flowering plants to thrive in the world which supported evolution of wasp and termites into the growing forests and savannah of the ancient world.

Scientists say the Savannah is the latest ecosystem to emerge in Africa and other parts of the world as a result of a huge climate change accompanied by a rise of temperature and decrease of rainfalls.

Historians believe that these climatic and ecological changes took place on the Earth’s surface about 100 million years ago, fossil records dated this time indicate that the Earth came under Asteroids attacks from the Solar system which influenced geological and metrological changes on the ground and sky.

Scientists say at that time the world was very cold and dry, but due to these attacks, the climate in the planet became warm and humid. Worldwide different changes took place with subtropical vegetation growing in the northern hemisphere; the Earth’s poles became cool and temperate.

The Equatorial areas of the world adapted tropical climate while the southern and northern parts of Equator became hot and arid, these were rapid changes which became a havoc that forced many living creatures into mass extinction after killing all members of that particular species of plant and animals.

At the time of the havoc, because of different morphological weaknesses, different species of plants and animals were totally pushed into extinction, scientists say it was during this time when many species of plants, birds and animals changed their morphology and adapted new behaviours so that they could survive in a new environment.

To cope with these changes, the body of an ancestor of the modern aardvark had to go through morphological and behavioural changes, these included their digestive system which was specialised in feeding on termites and ants after volcanic and asteroids attacks on the Earth’s surface wiped out all vegetation.

Ancestors of the aardvark also specialized on ancient cucumber which was obtained creeping on rocks which helped the plant to avoid what was happening on the outside world, these plants were able to survive through the extinction because of the ability of the ancient photosynthesis.

Scientists say major group of plants which evolved between 100 and 40 million years ago had super metabolism mechanism which enabled them to survive in harsh conditions dominated with long dry seasons and low oxygen.

From that time, plants played a significant role to control erosion and moderate climate as they remove carbon dioxide from the atmosphere and contributed into the creation of good condition for existence of other creatures.

This shows photosynthesis is mainly responsible for producing and maintaining the oxygen content of the Earth’s atmosphere and supplies all of the organic compounds and most of the energy necessary for life on Earth, although it is performed differently by different species, the process always begins when energy from light is absorbed by proteins called reaction centres that contain green pigments.

Scientists describe photosynthesis as a process used by green plant to transform light energy from the sun into a chemical energy, during this procedure, light energy is captured and used to change water, carbon dioxide and minerals into oxygen and energy rich organic compounds, it is estimated that every year photosynthesis convert about 100 to 115 thousand million tonnes of carbon dioxide into biomass.

This shows that it is impossible to misjudge the importance of photosynthesis in the existence and maintenance of life on Earth, the stoppage of this chemical process will be a catastrophe to nearly all dwellers of this planet because oxygen will not be enough to support life, under that condition with exception of bacteria, all other species will be pushed into extinction.

This is due to the fact that the food web is made by plants which produce and eat their own food, herbivorous such as impalas, warthogs, zebras and wildebeests live by eating plant materials, carnivores like cheetah, leopard and lions eat meat from herbivorous, omnivore such as chimps eat variety of food, including plants and animals.

From the heat of the savannah in the Serengeti through villages such as Sangamwalugesha to high streets of big cities like Samora Avenue, the process of Photosynthesis may be less known, but scientists say if this mechanism stops, all plants on the Earth will not be able to use light to produce chemical energy.

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Mwandishi: REGINALD STANISLAUS MATILYA

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