The correct answer is - cyanobacteria.
The atmospheric oxygen came from the cyanobacteria. These were one of the earliest living organisms on Earth. The cyanobacteria was using photosynthesis in order to create its own food. The photosynthesis process requires sunlight, carbon dioxide, water, and oxygen. The oxygen is mostly released as a waste product from the process of photosynthesis, thus the cyanobacteria were literally releasing oxygen that was ending up into the atmosphere. As more and more cyanobacteria there were across the planet, more and more oxygen they were releasing into the atmosphere, slowly changing the composition of the atmosphere, and setting the basis of it as we know it now.
the most populous country in the world is CHINA
Answer:
Climate change threatens coastal areas, which are already stressed by human activity, pollution, invasive species, and storms. Sea level rise could erode and inundate coastal ecosystems and eliminate wetlands. Warmer and more acidic oceans are likely to disrupt coastal and marine ecosystems.
Answer:
Option: A. True
Explanation:
The Maya civilization covers regions that spread from northern Mexico southwards into Central America. The Maya stretched from modern-day southern Mexico through Guatemala, Honduras, and Belize. The culture is renowned for its massive pyramids, irrigation systems and agriculture, and symbols. Most of the ruins are still discover in the jungles of Mexico and Guatemala, which remain unknown since the colonial period in Mexico under the Spanish Empire. The civilization fizzled out between A.D. 800 and 1000 before the arrival of Spanish in Central America that led structures remain untouched in the jungle for centuries.
Answer:
Climatologically, the tropics are characterized by high year-round temperatures and weather is controlled by equatorial and tropical air masses. ... The temperate region also has many different climate regions with warmer and cooler temperatures and seasonal rainfall.
