In a food chain involving grass, grasshoppers, birds, and mammals, what is the original source of energy?

In a food chain, the original source of energy is sunlight. During the process of photosynthesis, plants, such as grass, capture sunlight and convert it into chemical energy. This energy stored in the form of glucose then becomes the foundation of the food chain. When herbivores, such as grasshoppers, consume the grass, they obtain this energy, which then transfers to higher trophic levels, like birds and mammals, when they eat those organisms.

Sunlight is crucial because it initiates the energy conversion process that sustains life on Earth. Energy flows through the food chain in a linear direction, starting with producers (like grass) that utilize sunlight. Other options, while related, do not serve as the primary source of energy: glucose is a product of photosynthesis, chlorophyll is the pigment that enables the capture of sunlight, and ATP is a form of stored energy in cells but does not originate energy itself.