Final answer:
Photosynthesis is the essential process that captures sunlight energy and converts it into carbohydrates, providing energy for all life on earth. It also produces oxygen necessary for living organisms. The energy extracted from fossil fuels represents sunlight energy stored by photosynthesis millions of years ago.
Step-by-step explanation:
Photosynthesis is essential to all life on earth; both plants and animals depend on it. It is the only biological process that can capture energy that originates from sunlight and converts it into chemical compounds (carbohydrates) that every organism uses to power its metabolism. It is also a source of oxygen necessary for many living organisms. In brief, the energy of sunlight is "captured” to energize electrons, whose energy is then stored in the covalent bonds of sugar molecules. The energy extracted today by the burning of coal and petroleum products represents sunlight energy captured and stored by photosynthesis 350 to 200 million years ago during the Carboniferous Period.