Plants too eat, drink and breathe like human beings. The process of making food of plants in the presence of sunlight, water and CO2 is called Photosynthesis.
According to a latest analysis by earth scientists at McGill University it has been estimated that the basis for photosynthesis in today's plants was set in place 1.25 billion years ago. The fossilized algae, Bangiomorpha pubescens were first discovered in rocks in 1990, in Arctic Canada. It is considered to be the oldest known direct ancestor of modern plants and animals. But it’s also true that there was no certainty about its exact age. It was estimated to be between 720 million and 1.2 billion years of age. Researchers focused their study on remote Baffin Island, where those fossils have been found. They collected the samples of black shale from rock layers for study that sandwiched the rock unit that contained alga fossils. For estimating the age they used Rhenium-Osmium (or Re-Os) dating technique, and found that the rocks are 1.047 billion years old. Scientists have determined earlier that the ancient alga, like green plants, used sunlight to synthesize nutrients from carbon dioxide and water. It was also concluded that the chloroplast, was created when a eukaryote long ago engulfed a simple bacterium that was photosynthetic. The eukaryote then passed that DNA along to its descendants, including the plants and trees that produced most of the world's biomass present day. After these all scientists concluded that the chloroplast must have been incorporated into eukaryotes approximately 1.25 billion years ago.
By: Anita Aishvarya