The sun is considered the primary energy source since it is the source of nearly all the earth's energy. Plants produce food using sunlight, and the food we get from plants and animals also has its primary sunlight source.br What is the ultimate source of energy?br The Sun is the Ultimate Source of Energy. ... And that's what happens with energy from the sun—it changes into lots of different forms: Plants convert light energy from the sun into chemical energy (food) by the process of photosynthesis.br The three diets of animals include creatures that eat only plants, those that eat only meat, and animals that eat both plants and meat. Animals that eat plants exclusively are herbivores, and animals that eat only meat are carnivores. When animals eat both plants and meat, they are called omnivores.br The water cycle shows the continuous movement of water within the Earth and atmosphere. ... Liquid water evaporates into water vapor, condenses to form clouds, and precipitates back to earth in the form of rain and snow. Water in different phases moves through the atmosphere (transportation).