The origin of life depends on a wide number of issues, all related to the existence of planetary and stellar bodies, chemical elements and the favorability of conditions for life created with such elements and under conditions not overly chaotic or disruptive and with energy sources that are balanced and moderate. As a result, the conditions for life can only result after the conditions of the universe are settled. It took the universe approximately 9.3 billion years to form galaxies and stars and planets that satisfy the demands of life on a fundamental level. It then took 4.5 billion years to condition the Earth through inorganic and organism progression to achieve the pinnacle of creation, which is humans.
When earth came into existence, it was very hot. The earth has no atmosphere. The environment of the earth was not suitable for the lives. There was no water, oxygen, which was needed for life. The earth was filled with ammonia, carbon dioxide, water vapor, and methane gas. Gradually the water vapor splits and forms oxygen and hydrogen. The oxygen atoms again combine with oxygen atoms from the ozone layer and the earth's atmosphere. The water vapors start cooling and start raining. Also, the splitting oxygen atoms combine with methane and ammonia and produce water. The raining in the earth had been going on till the earth got cool down. Thus the larger holes of the earth were filled with water and formed the ocean. After the formation of the ocean, life came to existence. The first organism was a unicellular organism lived in the ocean. By the process of evolution, many complex organisms were crowded on the earth. Thus the earth atmosphere became suitable for life.
Within an ecosystem, plants are often producers (meaning they produce their own food), and they serve as primary prey for herbivores. If many plants were removed, the extinction of many other species that are reliant on plants for their prey would be inevitable.
