AP BIOLOGY

Detailed explanation-1: -The sun is called the ultimate source of energy because: It is the primary source of energy for the earth. With the help of solar energy, all green plants(producers) produce food by the process of photosynthesis. In turn, animals eat plants and use that same chemical energy for all their activities.

Detailed explanation-2: -The sun is called the ultimate source of energy because it is the source of almost all energies of the earth. Plants convert light energy from the sun into chemical energy (food) by the process of photosynthesis.

Detailed explanation-3: -The Sun is the only source of energy for all ecosystems on Earth except for deep sea hydro-thermal ecosystem. In deep sea hydro-thermal ecosystem, sunlight cannot penetrate and hence chemical deposits and hydrothermal fluids are the source of energy for the organisms habitat in this ecoystem.

Detailed explanation-4: -Sun is the source of almost all the energies in our earth. Plants make food using sunlight, the food that we get from plants and animals also has its prime source as sunlight. The fossil fuels that we use in our daily life comes from dead plants and animals which again have their source as solar energy.